Proceedings of the Royal Society of London
Royal Society (Great Britain)
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S28 5 5S i seat 24 a's Bq x o | Oe as o Sg ae sae = ‘a 4 q o 3 ear S| Se elle $ |88| & [B26] 2a |e 8] SVS Stead 2 Ale co Fa AB | OoF i@nman 38 | :001134 | 121 | 3,|1000+488 | 512 | 2000 | 2420 |13-461 |13 -461 qd | 20 | -0008141 | 123 | ,, 488 | 512 | 1000 | 1230 | 6-841 | 5-140 = | 18 | -0002544 | 104 | ,, 488 | 512 | 1000 | 1040 | 5-785 | 4-389 -= | 141 -0001539 | 142 | ,, 88 | 512 | 600 | 852 | 4:739 | 3-010 = | 11 | -0000950 | 100 | ,, ss | 512 | 600! 600 | 3:337 | 2-097 - 8 | :0000502 | 76 | ,, 88 | 512 | 600] 456 | 2-536 | 1-300 ———$$——— The results are plotted out in fig. 8. It will be seen that the observed and calculated results agree to a considerable degree of accuracy except in the case of platinum, which behaves as in the previous experiments, and is generally found to be irregular in its quality. These experiments were made upon wires exposed to the air, where radiation is free. I am anxious to repeat them upon wires covered in insulating material and buried in the ground, but I have not been able to do so up to the present moment. The law with reference to such wires has a very important bearing on the size of electric light leads, for it shows the necessity of making them large enough to prevent the possibility of their being heated above normal temperatures, otherwise points of danger are very easily reached by increments of current. III. “Spectroscopic Studies on Gaseous Explosions. No.I.” By G. D. Liverne, M.A., F.R.S., and JAMES Dewar, M.A., F.R.S., Professors in the University of Cambridge. Received March 28, 1884. Having occasion to observe the spectrum of the flash of a mixture of hydrogen and oxygen fired in a Cavendish eudiometer, we were struck by the brightness, not only of the ubiquitous yellow sodium line, but of the blue calcium line and the orange and green bands of lime, as well as of other lines which were not identified. The eudiometer being at first clean and dry, the calcium must be derived either from the glass or from some spray of the water over which the gases with which the eudiometer was filled had been confined. It seemed incredible that the momentary flash should detach and light up lime from the glass, but subsequent observations have pointed to that conclusion. Our next experiments were made on the flash of the combining gases enclosed in an iron tube, half an inch in diameter and about 3 feet long, closed at one end with a plate of quartz, held in its place by a screw-cap and made tight by leaden washers. Two narrow brass tubes were brazed into the iron tube at right angles to the axis, one near each end, and one of these was connected with an air-pump, the other with the reservoir of gas. Into one of these brass tubes was cemented a piece of glass tube with a platinum wire fused into it, whereby the electric spark was passed to fire the gas. The tube was placed so that its axis might be in line with the axis of the collimator of a spectroscope, and the flash observed as it traveled along the tube. It was seen at once that more lines made their appearance in the iron tube than in the glass vessel, and one conspicuous line in the green was identified in position with the E line of the solar spectrum. Several other lines were identified with lines of iron by comparison with an electric spark between iron electrodes. There could be no doubt that the flash in an iron tube gave several of the spectral lines of iron. We supposed that this must be due to particles of oxide shaken off the iron by the explosion, and proceeded to try the effect of introducing various substances in fine powder, and compounds, such as oxalates, which would give fine powders by their decomposition in the heat of the flame. Several interesting observations were made in this way. When some lithium carbonate was introduced, not only were the red, orange, and blue lines of lithium very brilliant, but the green line hardly less so. After the lithium had once been introduced into the tube, the lithium lines continued to make their appearance even after the tube had been repeatedly washed. When the lithium had been freshly put in, the red line was observed to be much expanded, very much broader than the line given by lithium in a Bunsen burner reflected into the slit for comparison. The light was dazzling unless the slit was very narrow; and it was noticed that if the spark by which the gas was fired was at the distant end of the tube, so that the flame traveled along the tube towards the slit, there was a reversal of the red line; a fine dark line was plainly visible in the middle of the band. When the spark was at the end of the tube next the slit, no reversal was, in general, seen. Later observations showed that some other metallic lines might be reversed in this way, and photographs taken of The reversals. These observations with the eye on the reversal of the red lithinum line were made with a diffraction grating, and were repeated many times. They show that there are gradations of temperature in the flame, and that the front of the advancing wave of explosion is somewhat cooler than the following part. The combination of the gases is not so instantaneous that the maximum temperature is reached at once. Subsequently, we had the interior of the tube bored out so as to present a smooth bright surface of iron, and noted the iron lines which were conspicuous in the flash. For the purpose of identification, the pointer in the eye-piece was first placed on one of the strong iron lines given by the electric discharge between iron electrodes, and then, the discharge being stopped but the field sufficiently illuminated, the eye was fixed steadily on the pointer while the gas in the tube was exploded. In this way, it was not difficult to see whether any given line was very bright in the flash. The lines thus identified were those having the wave-lengths about 5455, 5446, 5403, 5396, 5371, 5327 (4B), 5167 (0,). These lines were all many times observed in the way described, and as a rule were always present in the flash. Lines with wave-lengths about 5139 and 4352 were seen, and may possibly have been due to iron, and several more lines were seen occasionally, but were not so regularly seen that they could be well identified. The lines 4923 and 4919 were specially looked for, but neither of them could be seen. A group of blue lines were noticed, and were afterwards identified by photography, a method much less trying than observations by eye. To give intensity to the photographs, ten or twelve flashes were usually taken in succession without any shift of the instrument, so as to accumulate their effects in one photograph. For identification, the spark between iron electrodes was also photographed, but with a shutter over the lower part of the slit, so that the image of the spark should occupy only the upper part of the field. The following is the list of wave lengths of the iron lines thus photographed: AA CNISTIUSSY Fen aner teens 3920 FA QAR a0) i ok 3 eae AOE Is A sath Boog ante hs 3902 °5 BONO LNs) “is sks as AQG2 Oily ost earae 4 t 3898 *4: AOA if 1) isiinre 6 0 AAS ety yal degen 3885 OMY Ty} assesvays's AQOL SG ue” je heads 3877 °4: MEAs Bi be He sles acs SIO Maebiae, Litorcnsbot 3859 °2 AOE OS «0s oie tyeis SOOT Sesh iP asichseneks 3849 °7 MEO hot4) 1, sieed ort DO Mpa ik uieusttotaals 3840 °3 “02S re Oo ike ih osteitis 3833 °6 AT4 Profs. G. D. Living and J. Dewar. [Apr. 3, DOLL MOUNT EL Lae IAD BASE. N 3580 °5 BOZOLZS Miia aiets B1OOTO Geli a 3568 “9 SSL Saha cae B(B4°D ELE 3064 BELOTD Wl wan ael MEST AC TRING Ie dee 3520 °7 BLVD TR nee BALONC WNL 3496 °8 SQN T TRI ys SY AUS TELa ha ai un er 3489 °8  ie O 3440 SLOT We eshte SOLS 2 AE eae BIAS 2 Vi eke Glee SOO SMA Me sate T 3019 8 3747 °2 As a rule no iron lines above O make their appearance; in a few plates T is visible, and it is possible that other lines may be obscured by the water spectrum, which always comes out and extends from near s to below R. Above T no line at all is visible in any of the photographs, though the spark lines come out strongly enough, and several of the strongest groups of iron lines, both of spark and arc lines, are in the region beyond T. The spark by which the gas was fired passed in ochre between a platinum wire and the side of the small brass tube, and was out of view; but in order to make quite sure that the lines were not due at all to the spark, the brass tube was lined with a tube of platinum foil which projected beyond the brass tube a short distance into the larger tube, and the spark passed between the platinum wire and the platinum tube. It was found that the same iron lines made their appearance in the flash whichever way the spark was passed. Other experiments were made with explosions of carbonic oxide and oxygen, and with coal-gas and oxygen. The explosions of these gases were attended with much more continuous spectrum, and the metallic lines were not always as well developed as they were with hydrogen and oxygen, but on the whole there were as many metallic lines photographed from the flashes of carbonic oxide as from those of hydrogen. There is an uncertainty about the explosion of the carbonic oxide mixture which we cannot account for, even when we take into account the remarkable effects of relative dryness of the gas on the explosions discovered by Mr. Dixon. Sometimes the explosions were so violent as to break the plate closing the end of the tube, though this had resisted the explosions of the hydrogen mixture, while at other times the wave of explosion passed slowly along the tube. The gas was in all cases confined over water and passed directly from the gasholder into the tube. When the iron tube was lined with copper foil, only one copper line in the visible spectrum, was seen, and in the ultra-violet two lines, 3272 and 3245°5. All three lines were very strong, and the two ultra-violet lines were in some cases reversed. These lines were also frequently developed when no copper lining was in the tube, probably from the brass of the small side tubes. Copper also gave a line in the indigo, 4281 about, decidedly less refrangible than the copper line, 4275, coincident apparently with the strong edge of one of the bands developed when a copper salt is held in a Bunsen burner. A lining of copper which had been electroplated with nickel developed only one nickel line, 5476, in the visible part of the spectrum, but gave by photography the following lines in the ultra-violet: Reso pofyeiesei ties s DOAN, je pail lat sichlis 3445°d SMMC Ah) eC bicaeoees Dea ee cle odes 0432 S75) HAO hay Res aeereon 3422 RMR AC apes) S sea aja oS Pea aed 3413°2 2101100) SB) a eR OA Oh Oil Givens ap. 39391°5 210] E75 ee ae DAD Me liie tea ciated 3378 *4 2057) i SMO D ee ih probeiterss 6s 3369 6 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 PDN yo ua. « Bid os DAO a atric Sus, ks 3 When nickel oxalate was put into the tube, lines with wave-lengths 3670°5, 3470°3 and 3389°6 in addition to the preceding were developed. It is doubtful whether the line 13451 be a nickel line. That at X=3453 is ascribed to cobalt by Cornu, but it seems to be a nickel line as well. When copper wire electro-plated with cobalt was put into the tube, cobalt lines appeared with the approximate wave-lengths: AUSOE bleep sss BOOS M AM sree ee ee 3474 Or ia aes DOOM Meee thee 5462 30 We) able Re Ea as 355 | biradiitty oy 3453 260/21 rain GOL cise: 3431 30,07) tae ea Osman ees So che tart 3411 DiCAND) «Mae AE ae AO ERY Mare cle erat 3404 3601 The lines 13528 to 3522 form a continuous band in the photograph, so that these three lines may not represent the whole group at that spot. It is doubtful whether \ 3492 be a cobalt line as well as a Ni line. No other metal gave anything like the number of lines that were given by iron, nickel, and cobalt. 476 Profs. G. D. Living and J. Dewar. [Apr. 3, A lining of lead gave the lines \ 4058, 3683°3 and 3639°3 strongly, and these lines were frequently developed, though less strongly, when there was no lead lining; the metal being without doubt derived from the lead washers used to make the ends of the tube air-tight. A strip of silver gave the lines \ 3381°5 and 3278, and these lines were sometimes reversed. No trace of the channelled spectrum of silver was developed even when silver oxalate was put into the tube, and furnished plenty of silver dust after the first explosion. A magnesium wire about 2 millimeters thick and two-thirds the length of the tube gave the b lines very well; that is to say b, and by were well developed, and 6, was also seen, but as the iron and magnesium components of b, are very close together, and the iron line had been observed before the introduction of the magnesium, it was not possible to say with certainty whether or not the magnesium line were present too. No other magnesium line could be detected. The blue flame line was carefully looked for, but could not be seen. The photographs showed none of the magnesium triplets in the ultra-violet, nor any trace of the strong line 2852, which appears in the flame of burning magnesium, and is yet more conspicuous in the arc when that metal is present. Metallic manganese, introduced into the tube in coarse powder, gave the group at wave-length about 4029 with much intensity, but no other manganese line with certainty. In the visible part of the spectrum the channellings in the green due to the oxide were visible. A lining of zinc produced no zinc line, and zinc-dust gave only a very doubtful photographic impression of the line 13342. A strip of cadmium gave no line of that metal either in the visible, or in the ultra-violet part of the spectrum. Tin, aluminium, bismuth, and antimony, also failed to produce a line of any of those substances, and so did mercury which was spread over copper foil made to line the tube. Thallium spread as amalgam over the copper lining gave the lines 3775°3, 3528°3 and 3517°8. Chromium was introduced as ammonium bichromate, which of course left the oxide after the first explosion. This gave the chromium lines with wave lengths about 5208, 5205, 5204, 4289, 4274°5, very well and persistently, also the lines with wave lengths about 3605, 3592°5, 3578°5. Sodium salts (carbonate, chloride) developed the ultra-violet line 3301; and potassium salts give the pair of lines about wave lengths 3445; but no more refrangible line of either metal was depicted on the photographs. Lithium carbonate gave, besides the lines in the red, orange, green, and blue, the violet line, 4185°5; but no more refrangible line. Photographs of a flame of mixed coal-gas and oxygen, in which an iron wire was burnt, show, as might be expected, the same iron lines as are developed in the flash of the detonating gases, and of the same relative intensities. These intensities are not quite the same relatively as they are in the arc spectrum. Thus the lines 3859, 3745, 3737, 3735, and 3719 come out in great strength, much stronger than the lines 3647, 3631, 3618, which are remarkably strong in the arc. German-silver wire, burnt in the flame of coal-gas and oxygen, gave the same nickel lines as were given by nickel in the detonating gases, as well as those of copper and lead. Copper wire gave, besides the lines 3272, 3245°5 A set of bands in the blue, which correspond with those given by copper salts in flames, and are probably due to the oxide. The greater part of the lines which we have observed in the flames of the exploding gases have been observed by us to be reversed when the several metals were introduced into the arc in a crucible of lime or magnesia; which is quite in accord with the supposition that the metals experimented on are volatile, and emit as well as absorb these particular rays, at temperatures lower than that of the arc. That iron is volatile at a temperature below the fusing point of platinum, which is about 1700° C., has been pointed out by Watts (“Phil. Mag.,” vol. xlv, p. 86), who observed in the flame of a Bessemer converter almost all the green and blue lines of iron which we have seen in the exploding gases, besides one or two lines which we have not observed or identified. Having regard to this volatility of iron, it does not seem so surprising that iron lines should be observed accompanying those of hydrogen to great heights in the sun’s atmosphere as that they should not be always seen there. It is interesting to note that Copeland and Lohse (“Copernicus,” Dec. 1882) observed in the spectrum of the great Comet of 1882, amongst other lines, four lines, 5395, 53869, 526, which are nearly identical with iron lines observed in the flash of the detonating gas. It is remarkable that such volatile metals as mercury, zinc, and cadmium should give no lines in the flame of the exploding gases. The gases exploded in the tube were generally mixed in nearly the proportions in which they combine chemically; but experiments were made with oxygen in excess and also with hydrogen and carbonic oxide in excess. A small excess of any one of the gases did not seem sensibly to affect the result, but on the whole the metallic lines were more certainly developed when there was not much excess of oxygen, and more constantly developed when hydrogen was used than when carbonic oxide was used. The absence of any metallic lines in the flame of the exploding gases which are more refrangible than T may be in part due to a falling off in the sensibility of the photographic plates for light of shorter wave-length; but as the spark lines of iron seem to be quite as strongly depicted on the plates in regions of the spectrum far above T as they are in the regions below, we think that want of sensitivity in the plates cannot be the only reason for the absence of higher lines, but that the emissive power of the metals for these lines is feeble at the comparatively low temperature of the flame. This supposition accords with what we have observed of the lines seen in a carbon tube heated by the electric are "Proc. Camb. Phil. Soc., iv, 263). The iron lines photographed as reversed against the hot walls of such a tube were at certain stages of temperature the same, speaking generally, as those we have noticed in the flash of the detonating gases; but as the temperature of the carbon tube rose, more refrangible lines, including all the strong iron lines in the neighbourhood of T, the lines of aluminium near §, and the magnesium line 2852, were reversed in the photographs. Gouy (“Comp. R.,” 1877, p. 232), using a modification of Bunsen’s burner fed with gas mixed with spray of metallic salts, observed at the point of the inner green flame three or four iron lines which we have not observed in the flame of the detonating gas, the lines 6, and b, of magnesium, two cobalt lines in the blue which we have not seen, one line of zinc, and one of cadmium, and the two strong green rays of silver. Can the appearance of these rays under these circumstances imply that the temperature of the inner green cone of a Bunsen burner, when the proportion of air to coal-gas is near the exploding point, is higher than that of the explosion of hydrogen and oxygen? The interesting theoretical questions which are suggested by the facts recorded in this paper we must leave for future discussion. IV. “On the Action of a Secretion obtained from the Medical Leech on the Coagulation of the Blood.” By John B. Haycra, M.B., F.R.S. (Edin.), Professor of Physiology in the Mason and Queen’s Colleges, Birmingham. Communicated by Dr. LAUDER BRUNTON. F.R.S. Received March 28, 1884. The following is an offshoot from a more extended investigation upon the coagulation of the blood not yet ready for publication. The blood flowing from a leech-bite is not readily stopped, often flowing for upwards of an hour after the animal has been removed. The blood within the body of the creature remains fluid for an indefinite time; and when ejected it is found to have lost its coagulability. These are facts known to every surgeon, but they have received no explanation. While endeavoring to solve one very difficult problem, “why the blood does not coagulate within the living blood-vessels,” the above facts came to my mind and promised to throw some light on the general question. The explanation which at once suggested itself to me was, that probably the leech secretes some ferment-containing-juice which antagonizes the blood ferment, preventing coagulation within its body, enough remaining around the edges of the wound to prevent for some time the outflowing blood from clotting; the blood remaining fluid, in fact, until the leech ferment is all washed away. It will be seen that this explanation is in the main correct. In order to investigate its action on the blood, a salt solution extract of leech was obtained. In the first experiment, the gullets and buccal cavities of two leeches were removed, cut in small pieces, and placed in 5 cubic centimeters of 6 per cent. salt solution. The rest of the alimentary canals were also finely divided and placed in a similar volume of the salt solution. The extracts obtained were of a faint greenish-yellow tint, and alkaline in reaction. A leech was then applied to the nose of a young rabbit for a quarter of an hour, then removed, and held in a salted towel until it had disgorged. Meanwhile, the blood flowing from the nose of the rabbit was collected in a test-tube. The rabbit was then killed, and 3 cubic centimeters of its blood received into each of four vessels A, B, C, and D, which were placed under a glass shade, the air within being kept moist with blotting-paper soaked in water. Vessel A contained nothing but the blood, which coagulated in four minutes. Vessel B contained in addition 1 cubic centim. of 6 per cent. salt solution, and coagulated in four minutes. Vessel C contained in addition 1 cubic centim. of 6 per cent. salt solution, and coagulated in four minutes. Vessel D contained in addition 1 cubic centim. of 6 per cent. salt solution extract of gullet of leeches. This remained fluid for twenty-four hours, a thick clotted scum forming on the surface when the blood putrefied. . The blood collected from the nose of the rabbit and that from the interior of the leech remained fluid until putrefaction set in, when the same half scum half clot formed on the surface. It is evident from this experiment that something retarding or preventing coagulation may be extracted with 6 percent salt solution from the pharynx or mouth of the leech. The slight action of the rest of the alimentary canal in retarding coagulation, as this and many subsequent experiments indicate, is due to some of the secretion diffusing downwards. Its place of origin within the body of the leech is certainly the pharynx or buccal cavity, decoctions of which are more than ten times as strong as those of the rest of the body. The next experiment was undertaken to test my supposition that this substance belonged to the class of ferments, the most general character of which is that they are destroyed by boiling. At the same time solutions of the leech in distilled water were made in order further to test its solubility. Equal portions of the blood of a sheep were placed in four vessels containing equal volumes of leech extract. Vessel A contained salt solution extract of gullet of leech; the blood remained fluid for three hours and was not further observed. Vessel B contained distilled water extract of gullet; the blood remained fluid for a like period. Vessel C contained boiled distilled water extract; the blood remained fluid for a like period. Vessel D contained boiled distilled water extract; the blood remained fluid for a like period. The blood received in a test-tube from the body of the animal coagulated in five minutes. This experiment was repeated with similar results. We have then to do with a substance not a ferment, and soluble in distilled water, as well as in salt solution. It may be noted that when the leech extracts are added to blood the corpuscles subside to the bottom of the vessel, leaving, in the case of the salt solution extract, a clear plasma, and in the case of the watery extract a plasma coloured by the hemoglobin, which is partly dissolved. In order to obtain the active principle of the leech extract in a pure form an attempt was made to isolate it by means of the ordinary solvents. A watery extract of several leeches was evaporated to dryness, and divided into portions which were respectively extracted for twelve hours with chloroform, ether, benzole, and absolute alcohol. They were then filtered, and the filtrates evaporated to dryness and extracted again with water. They had no action whatever on blood, except in the case of the chloroform extract, and that was very slight indeed. The residues after extraction with these fluids were dissolved in water, and proved efficacious when added to blood. The substance is then insoluble in chloroform, ether, benzole, and alcohol. Its separation in a pure form being evidently a difficult matter owing to its insolubility in the most useful solvents, the attempts at its isolation were in the meanwhile abandoned. 1884. | Secretion obtained from the Medicinal Leech. 481 One useful result of this experiment was the preparation of a much purer solution to be used for experimental purposes. The gullets of the leeches were placed in absolute alcohol for a day or two, and then extracted with water. In this way a clear, somewhat coloured alkaline fluid was obtained, almost free from albumen, and giving but a very small residue, this, too, of unimpaired strength. A solution prepared in this way was henceforth always used. The next task was to find the exact action of this substance on the blood, and in the first case to see if it destroyed or hindered the action of the ferment. After trying in vain one or two methods the following suggested itself: The blood-coagulating ferment is not very soluble in distilled water, so that if a blood-clot containing it be soaked for some time in the watery leech extract, this can afterwards be removed by distilled water without dissolving out the ferment. On adding the latter to hydrocele fluid its activity can be tested (this fluid coagulates on the addition of active blood ferment). The washed finely divided cloth from bullocks' blood was dried and divided into two equal portions by weight. One portion was then placed in a watery solution of leech, and the other in a like volume of distilled water. After twelve hours the clots were removed, dried with blotting paper, and carefully washed in distilled water. The washing lasted for three hours, the wash water being four times renewed, each portion of cloth being treated with the same volume of water. They were then each placed in a few cubic centimeters of 8 per cent. salt solution in which the blood-coagulating ferment is soluble. Five drops of the salt solution extract of the clots were added to equal quantities (5 cubic centimeters.) of hydrocele fluid. The hydrocele fluid to which the extract of cloth, treated with leech extract, had been added did not coagulate at all, while the other portion coagulated in ten minutes. The action of the leech extract is then seen to destroy the blood-coagulating ferment. The next question is whether the blood corpuscles are in any way affected by the leech extract? A couple of drops of blood were obtained from the finger-tip, mixed rapidly with a drop of normal salt solution extract of leech, and a minute drop of the mixture placed on a glass slide. This was then covered, and a ring of oil was painted round the edge of the cover-glass to prevent evaporation. When this was examined on a warm stage, the red corpuscles rapidly formed rouleaux in the ordinary way; and the white corpuscles exhibited active ameoid movements which continued for a considerable time—the observations lasted for an hour. In the meanwhile, the blood had not coagulated. It is seen then that the vitality of the white corpuscles is not destroyed, and that the formation of rouleaux by the red disks is not necessarily a phenomenon of coagulation. The coagulation of the perivisceral fluid of the sea urchin is, according to the observations of my friend Mr. Patrick Geddes, not due to the intercellular formation of fibrin in the plasma, but to active ameboid movements of the white corpuscles. The pseudopodia of neighboring cells join, become welded together, and contract so that all the cells are massed together into a solid clot. Professor Schafer maintains that there is also a formation of fibrin in the ordinary way which has been overlooked by Mr. Geddes. I have not examined this fluid myself, and do not feel qualified to speak upon this subject; but certainly the blood of crabs, crayfish, and lobsters clots in the way described by the former of these authors, there being no intercellular formation of fibrin. In this case, then, the leech extract will probably not prevent coagulation. The blood of a crayfish was mixed with one-third of its volume of leech extract. A drop was examined microscopically at the ordinary temperature. The cells exhibited normal ameoid movements. and coagulation was apparently quite normal. Heretofore, we have spoken of the extract of leech gullet and buccal cavity, but it has not yet been shown which is the source of this excretion. All that can be said is that it comes from either the gullet or mouth and sucker of the animal. Careful microscopical preparations were made of the anterior half of the leech, to seek for glandular structures. The animals were hardened for ten hours in saturated picric acid solution, and longitudinal mesial sections were made with a freezing microtome. The sections were stained with picrocarmine. No signs of ordinary glandular structures were to be observed either opening into the sucker, or into the alimentary canal. Some of the epithelial cells forming the integument of the leech are much elongated, passing down even among the subjacent muscular fibers. These have been looked upon as unicellular glands (Ray-Lankester), and in the sucker one may see small collections of these. If the skin lining the sucker be removed, it is found to be active in preventing coagulation. Not in a less degree however is the anterior part of a leech from which the skin of the sucker has been removed. Probably then the secretion is derived from the epithelial cells lining the sucker and buccal cavity; it may be that the unicellular glands of the sucker share in its production. The products of the digestion of albumin by pepsin have an important action in retarding coagulation. Dr. Schmidt-Mulheim, working under the direction of Professor Ludwig, has shown that blood received from an open vein into a solution of peptone does not Archiv. Fir Phys.: Du Bois-Reymond, 1880, p. 33. 1884. | Secretion obtained from the Medicinal Leech. 483 coagulate with its normal rapidity, being retarded for nine or ten minutes. If the peptone solution be injected into the veins of a dog, and blood withdrawn from the animal at intervals after the injection, it will, if the injection be powerful enough (3 grm. peptone to every 1000 grms. body weight of animal), materially affect its coagulability. Dr. Fano finds that certain products of tryptic digestion also retard coagulation in dogs; but curiously enough neither digestion products have any action on rabbits. It may be mentioned that when injected into dogs in larger quantities the blood pressure falls, there being great determination of blood to the abdomen and visceral veins; convulsions are observed, and the animal dies in a state of coma, the blood found within the body being of course fluid. The coagulability of the blood produced by certain poisons is altogether a question of great interest; for instance, most snake bites (the cobra is an exception) produce permanent fluidity of the blood, and we know nothing either of the relation of that change to contemporary symptoms, or the specific action of the venom on the blood itself. Now inasmuch as the extract of leech is much more powerful than the peptone solution in preventing coagulation outside the body, its effects when injected into the system may naturally be expected to lead to striking results. The difficulties in obtaining a license to perform the experiments in England being very great, I availed myself of an invitation from my friend Professor Schmiedeberg, of Strasburg, who kindly placed his laboratory at my service. It is with the greatest pleasure that I remember his kindness and courtesy, I wanted nothing that his well-organized laboratory contained, and to him I owe much personal assistance in an attempt to isolate the active principle present in the leech’s pharynx. This attempt, although not as yet successful on account of the great difficulty of the task, will I hope at some future time be renewed with more fruitful result. In the following experiments the extract of leech was prepared by placing the anterior part of the animal in absolute alcohol for three days, then evaporating off the alcohol, grinding the leech with broken glass, extracting with water and filtering. Temperature 39°3 (rectum). 5.22 p.m. 20 cub. centim. solution of 8 leeches injected into left jugular vein. 5.25 P.M. 1 cub. centim. of blood withdrawn. It remained fluid until the next morning, never completely coagulating. "Archiv. für Phys.,” 1881, p. 276. Wek. RXXVI. 2. 484 Prof. J. B. Haycraft. On the Action of a [Apr. 3, 5.45 p.m. 1 cub. centim. of blood withdrawn, which remained fluid until morning. 6.5 P.M. 1 cub. centim. of blood withdrawn, which remained fluid until morning. 6.5 P.M. 1 cub. centim. of Blood withdrawn, which remained partly fluid till morning. 6:25 p.m. 1 cubic centim. of blood withdrawn, which coagulated in 25 minutes. 7:00 p.m. 1 cubic centim. of blood withdrawn, coagulated in 5 minutes. During this experiment, the respirations were somewhat increased in number, and the temperature rose gradually until it reached 40°-1 at 7 o'clock. In the case of peptone injection, a marked difference between its effects on dogs and rabbits is seen. A rabbit was therefore next chosen for the subject of an experiment. A, cannula was inserted into the carotid for the purpose of withdrawing blood at intervals. 1 cub. centim. of blood withdrawn. Coagulated in 0°8 minute. 440 p.m. 65 cub. centim. of solution from 5 leeches injected into left jugular vein. 4.45 p.m. 1 cub. centim. of blood withdrawn from the earotid. It remained fluid for 12 hours. 4.47 p.m. 1 cub. centim. of blood withdrawn from the earotid. A moiety coagulated in 2 hours. 5.20 p.m. 1 cub. centim. of blood withdrawn. In 25 minutes almost completely clotted. 5.40 p.m. 1 cub. centim. of blood withdrawn. In 10 minutes it clotted fast. 6.0 p.m. 1 cub. centim. of blood withdrawn. In 3 minutes it clotted fast. 6.0 p.m. 1 cub. centim. of blood withdrawn. In 3 minutes it clotted fast. In my first experiments when an animal was allowed to live after the operation, the wound in the neck was stitched up in the ordinary way. When examined next morning, a large swelling was always observed in the region of the wound. On observing these, they were found to consist of imperfectly clotted blood which had escaped from the divided capillaries, the fluid unable to clot had continued to collect often in very large amount, passing down under the skin in front of the chest, and often causing death. Subsequently, the wound was carefully painted with perchloride of iron before sewing it up, and no after-bleeding occurred. These facts are not without interest, as they throw light upon a similar symptom seen in many cases of hemophilia or hemorrhagic diathesis, where the slightest wound gives rise often to very troublesome bleeding. It was found by experiment that the injection of the leech extract has no immediate action on blood pressure. After the injection of the substance, the animals as a rule appeared somewhat dull, the respirations were somewhat increased and the temperature elevated, but they soon recovered even after the injection of large quantities; in one case a rabbit weighing only 1080 grains was hardly disturbed by an injection of an extract of twelve leeches. The action of the leech extract, like that of the digestion products of Dr. Schmidt-Mulheim, is not permanent. In a few hours the blood is again normal. This may be from various possible reasons, either that more and more blood ferment is excreted, overpowering as it were the action of the leech extract, or that the latter is oxidised and broken up in the tissues, or finally that it is excreted (probably with the urine). This latter surmise was from the first held by my accomplished friend, Dr. Kobert, and the following experiments show it to be true. The urine was withdrawn from the dog used in the last experi ment 14 hours after the injection of the leech extract. At the same time urine was obtained from a healthy animal. Two drops of each fluid were added to two equal portions (7 drops) of frog’s blood. Whereas the one mixed with healthy urine coagulated in-:10 minutes, the other remained fluid for more than 12 hours. The’ experiment was repeated with a like result. Before leaving the action of the leech extract on the blood, it may be well to contrast its action with the peptone injection of Schmidt- Mulheim and Fano. In the first place, I should be inclined to doubt whether the active substance in these investigations is peptone at all. It was found that after peptone had ceased to give any reaction in the blood, it was still uncoagulable; the conclusion of Dr. Fano being that it forms some compound with other blood constituents which prevents the coagulation. [sit not more natural to suppose that peptone has nothing to do with the question at all, especially as there are many other digestion products difficult to separate from the peptone. Suppose the same substance formed in the leech were present—which it is not—in the digestion products, it would not have been separated from the peptone prepared by these observers. At any rate, the action of the injection, whatever it is, shows a marked difference in its results from the leech extract. The latter produces far milder constitutional symptoms, is far more powerful in its action on the blood, and has the same action on rabbits as on dogs. Since my return to my own laboratory, I have investigated the action of the leech extract on the ferment, which, at any rate, is the conversion of the white cells into fibrin by the dead plasma (“Proc. Roy. Soc.,” vol. 31, p. 413). Without discussing the probability of such a view being correct or not, it certainly is not true in the clotting of the hydrocine fluid by an extract of clot (ferment). In this case, my experiments show a special action of the leech extract on the ferment, which, when active, converts large portions of the plasma into fibrin. Prof. J. B. Haycraft. On the Action of a leech extract on the coagulation of milk by rennet and on myosin. Rennet mixed with a watery solution of leech has no less power of clotting milk than another portion mixed with water alone. The leech extract does not hinder in any way the clotting of myosin. The latter was prepared from frog’s muscle in a somewhat shorter and, I think, a better way than that described by Kihne. Two mortars containing pounded glass were placed in a freezing mixture. One held a few drops of normal salt solution, and the other a like quantity of normal salt solution of leech extract. The legs of a frog were washed out with normal salt solution, the muscles cut out, dried on blotting paper, placed in the mortar, and ground with the glass into a frozen pulp. This was then tied up in a piece of calico, and the myosin expressed and filtered. Its preparation is most easy, and can be done without fail in the hottest weather. The myosin obtained from the muscle to which the leech extract had been added coagulated in 10—15 minutes, and the other in from 20—25 minutes. The experiment was repeated with like results. It may be remarked that if the clotting of myosin is due to a ferment, this has not yet been isolated. Inasmuch as during contraction chemical changes occur very similar to those seen in rigor mortis, and inasmuch as in the latter the coagulation of myosin is a prominent fact, some have held that a contraction of a muscle is due also to a partial clotting of the myosin. This view I have never held to be anything but fanciful, for reasons which cannot be stated here. Dr. Lauder Brunton, however, suggested to me, that by soaking rog’s muscle in the leech extract, and studying its contractility, some light might be thrown on the subject. I accordingly cut out from the limbs of a pithed frog some of the principal muscles, i.e., the sartorii, carefully removing them with as little injury as possible. Those of one side were placed in normal salt solution, and those of the Other in normal salt solution of leech. 