EXCITATION AND PHAGOCYTOSIS 155 



the number of bacteria ingested were compared with 

 those phagocytosed in control experiments where no 

 alkaloid was used, it was seen that the excited cells 

 did not ingest more germs ^than usual. Excitation, 

 therefore, does not increase phagocytosis; and we have 

 noticed that if a mixture of living leucocytes and 

 germs are mixed and spread on jelly which contains 

 atropine, the cells do not purposely extrude their 

 pseudopodia in the direction of any bacteria which 

 may be near them. On the contrary, if a pseudo- 

 podium happens to strike against a bacterium, the 

 latter is usually pushed out of the way. 



Whether leucocytes are excited or not, we have 

 never seen a cell actually ingest bacteria. We have 

 often seen cells with bacteria inside them, but we 

 have never seen the actual act of ingestion, nor have 

 we any explanation to offer as to how it occurs. 

 Moreover, we have often seen leucocytes with red 

 cells apparently inside them, although how they came 

 to be absorbed we do not know. It is possible that 

 the laws of diffusion may play some part in the 

 actual act of phagocytosis. 



Another point in connection with phagocytosis may 

 be mentioned. In the making up of fixed films, 

 germs and other substances may be crushed into 

 leucocytes. By the examination of living cells this 

 cannot happen. We have seen fixed specimens which 

 showed phagocytes apparently crammed with germs; 

 but on looking at another sample of the same cells 

 alive a very different impression was obtained. We 

 have mentioned this point in view of the possibility 



