in order to test this concept the procedure described in example 2 was performed with the following modification no precast polymer matrix was inserted into the spacer means 20 an collagen hemostatic sponge collastat vitaphore corp chicago ill was suspended in phosphate buffered saline solution ph 7 2 and finely chopped in a blender for six 3 sec cycles a volume 0 5 ml of this suspension which consisted of particles of collagen matrix of various sizes mostly in the range of 0 2 to 1 0 mm diameter and representing about 0 5 v v of the suspension was mixed with 0 5 ml of a p388d 1 cell suspension approximately 10 7 cells ml the cell polymer suspension was centrifuged at 400 u00d7 g for 5 min into the outer sleeve 1 with a spacer means 20 an inner sleeve 10 was added and this assembly was inserted into the flow chamber casing 50 the metabolism of the cells as indicated by the rate at which they acidified their environment was monitored as described in example 1 after a period of acclimation to the microphysiometer environment stable rates of acidification were measured for the duration of the experiment fig8 these results demonstrate that the discontinuous matrix used in this experiment did immobilize the non adherent cells and that cellular metabolism was apparently not adversely affected by this procedure such a discontinuous matrix preparation may thus be appropriate for determining the effects.