N,N-dimethylamino, etc.), an aromatic group such as phe› nyl, pyridyl, etc., or -A-Z (wherein A represents an alkylene group having from 1 to 20 carbon atoms or CH$_{2}$ CH=CHCH$_{2 }$ and Z represents a hydrogen atom, a phenyl group which may be unsubstituted or substituted, a hydroxy group, an alkoxy group such as methoxy, ethoxy, etc., an acyl group such as benzyl, acetyl, etc., an alkoxy› carbonyl group such as methoxycarbonyl, ethoxycarbonyl, etc., a cyano group, an N-alkylamide group, an amide group, or a group shown by formula (a) described above. 

Also, in formula (N-I) and formula (a), R$_{2 }$ represents an alkyl group (methyl, ethyl, propyl, butyl, etc.), an alkyl group substituted with a hydroxy group, an alkoxy group, or an aromatic group such as phenyl, pyridyl, etc., [e.g., 2-hydroxyethyl, 3-hydroxypropyl, 2-methoxyethyl, 4-ethoxybutyl, benzyl, 2-phenylethyl, and 3-(4-pyridyl)pro› pyl], or an amide group (such as -CONH$_{2}$ , -CONHCH$_{3}$ , etc.); nl represents O or an integer of from 1 to 3; when plural R$_{2}$s exist, they may be the same or different; and X 31 represents an anion such as an iodine ion, a bromine ion, a chlorine ion, a p-toluenesulfonic acid ion, a perchloric acid ion, a methylsulfuric acid ion, etc., but when formula (N-I) is a betaine structure, X 31 does not exist. 

In formula (N-II), R$_{3 }$ represents an unsubstituted alkyl group or an alkyl group substituted preferably with a hydroxy group, an alkoxy group such as methoxy, ethoxy, etc., an aromatic group such as phenyl, etc., an acyl group such as acetyl, benzoyl, etc., an alkoxycarbonyl group such as methoxycarbonyl, ethoxycarbonyl, etc., an amide group, a cyano group, etc. Practical examples of R$_{3 }$ are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, pentyl, 2-hy› droxyethyl, 3-hydroxypropyl, 2-methoxyethyl, 3-ethox› ypropyl, 2-phenylethyl, 3-acetylpropyl, 2-benzoylethyl, 2-methoxycarbonylethyl, 2-cyanoethyl, and 2-carbamoyl› ethyl. R$_{4 }$ and R$_{5 }$ each independently represents a halogen atom, an alkyl group (e.g., methyl, ethyl, n-propyl, isopro› pyl, n-butyl, isobutyl, and pentyl), a substituted alkyl group, or an alkoxy group (e.g., methoxy and ethoxy). As the substituent for the substituted alkyl group described above, a hydroxy group, an alkoxy group, and a substituted or unsubstituted aromatic group (e.g., phenyl and alkyl-substi› tuted phenyl) are preferable. Also, practical examples of the substituted alkyl group are hydroxymethyl, 2-hydroxyethyl, 3-hydroxypropyl, 2-methoxyethyl, 2-ethoxyethyl, benzyl, 2-phenylethyl, and 2-tolylethyl. n2 and n3 each indepen› dently represents 0, 1, or 2. When plural R$_{4}$s and/or R$_{5}$s exist, they may be the same or different. x- represents an anion as an iodine ion, a bromine ion, a chlorine ion, a p-toluenesulfonic acid ion, a perchloric acid ion, a methyl› sulfuric acid, etc., but when formula (N-II) is a betaine structure, X $^{31 }$does not exist. 

In formula (N-III), R$_{6 }$ represents an alkyl group (such as methyl, ethyl, propyl, butyl, pentyl, etc.) or a substituted alkyl group; said R$_{6 }$ may form a 6-membered ring or a 5-membered ring together with R$_{8}$ ; R$_{7 }$ represents a hydrogen atom, an alkyl group (such as methyl, ethyl, propyl, butyl, pentyl, etc.), a substituted alkyl group, or an aryl group (such as phenyl, alkyl-substituted phenyl, etc.). As the substituent of the substituted alkyl group shown by R$_{6 }$ and R$_{7}$ , there are, for example, a hydroxy group, an alkoxy group (such as methoxy, ethoxy, etc.), and an aryl group (such as phenyl, alkyl-substituted phenyl, etc.). Specific examples of the substituted alkyl group are 2-hydroxyethyl, 3-hydroxypro› pyl, 2-methoxyethyl, 2-ethoxyethyl, 3-methoxypropyl, ben› zyl, and 2-phenylethyl. R$_{8 }$ and R$_{9 }$ each independently rep- resents a hydrogen atom, an alkyl group (such a methyl, ethyl, propyl, etc.), an alkyl group substituted with a 

hydroxy group, an alkoxy group, an aromatic group, etc., (such as 2-hydroxyethyl, 3-hydroxypropyl, 2-methoxyethyl, 3-ethoxypropyl, benzyl, 2-phenylethyl, etc.), an alkoxy group (such as methoxy, ethoxy, etc.), or an amide group. Furthermore, R$_{8 }$and R$_{9 }$ may form together an aromatic ring. R$_{10 }$ represents a halogen atom (chlorine, bromine, etc.), an alkyl group which may be unsubstituted or substituted (such as methyl, ethyl, propyl, 2-hydroxyethyl, 3-hydroxypropyl, 2-methoxyethyl, benzyl, etc.), an alkoxy group (such as methoxy, ethoxy, etc.), or an amino group which may be substituted with an alkyl group. Also, n4 represents 0, 1, or 2. When plural R$_{10}$s exist, they may be the same or different. X $^{31 }$represents an anion such as an iodine ion, a bromine ion, a chlorine ion, a p-toluenesulfonic acid ion, a perchloric acid ion, a methylsulfuric acid ion, etc., but when formula (N-III) is a betaine structure, X$^{31 }$does not exist. 

Then, specific examples of the pyridinium salt derivatives for use in the present invention are illustrated below but the invention is not limited to those compounds. t,0420 

These pyridinium salt derivatives can be synthesized by reacting corresponding pyridine derivatives, quinoline derivatives, or isoquinoline derivatives and alkyl halides as described in Munio Kotake, Dai Yuuki Kagaku (Principal Organic Chemistry), Vol. 16, (III), pages 7 and 125, pub- lished by Asakura Shoten, 1959. Practical synthetic methods of them are described in A. Grob and E. Renk, Helv. Chim. Acta., 37, 1672(1954); R. E. Lyle, E. F. Perlowski, H. J. Troscianiec, and G. G. Lyle, J. Org. Chem., 20, 1716(1955); M. R. Lamborg, R. M. Burton, and N. 0. Kaplan, J. Am. Chem. Soc., 79, 6173(1957); and W. Ciusa and A. Buccelli, Gazetta Chimia Italiana, 88, 393(1958). 

The foregoing dye or pyridinium salt derivative for use in this invention can contain in at least one negative-working silver halide emulsion constituting the silver halide photo- graphic material or other light-insensitive layer composed of a hydrophilic colloidal layer such as a protective layer, an interlayer, an antihalation layer, a filter layer, etc. 

The addition amount of the dye and the pyridinium salt derivative to the silver halide photographic material is suitable in the range of from lxl0- $^{6 }$mo! to JxJ0- $^{2 }$mo! per mo! of silver halide, and in the case of adding the dye alone, the amount is preferably from Jx10- 3 mo! to lxJ0- 1 mo!, and in the case of the pyridinium salt derivative alone, the amount is preferably from lx!0-4 mo! to lxJ0- 2 mo!, and when a polyalkylene oxide or the derivative thereof (here› inafter, they are referred to as simply polyalkylcne oxide derivatives) exists, the amount of the dye or the pyridinium salt derivative is particularly preferably from lx!0- $^{5 }$mo! to lx10- 3 mo!. 

Also, the dyes and the pyridinium salt derivatives for use in the present invention can be used singly or as a combi› nation of them. 

For adding the dye or the pyridinium salt derivative for use in this invention to the negative-working silver halide emulsion layer or the other light-insensitive hydrophilic colloidal layer, the dye or the pyridinium salt derivative may be added to the negative-working silver halide emulsion or an aqueous solution of a light-insensitive hydrophilic colloid for use in this invention as a solution thereof in water or an organic solvent miscible with water, such as alcohols, ketones, esters, amides, etc. 

The dye or the pyridinium salt derivative for use in this invention can be added thereto at any desired step during the production of the silver halide photographic material. For example, in the case of adding to the negative-working silver halide emulsion, the compound can be added thereto at an optional time from the initiation of the chemical ripening of 

