living leucocytes in vitro. 33 



Throughout this process the question of temperature is of some 

 importance ; it is advisable that the slide to which the leucocytes 

 are adherent should be kept at a temperature not much below that 

 of the blood, otherwise the cells become circular and are liable to 

 be washed off; on the other hand, if the preparation is heated much 

 over 40° C, the leucocytes become disintegrated and disappear. 



I have found that the leucocytes will continue their movements 

 for about three or four hours in the primary chamber, or for about 

 an hour in the secondary; this is probably to be explained by the 

 fact that the COg tension becomes so high as to terminate their 

 existence sooner when the red blood cells have been removed. 



VOL. XV. PT. I. 



