100 



MICROBES AND TOXINS 



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\vvW 



\\\1 IX i Ml 



FlG. 37. Gromia oviformis in the act of 

 capturing in its pseudopodia a diatom, 

 which being too large for ingestion is 

 digested outside the body in this way. 

 (After Max Schultze.) 



dissolved by means of 

 the digestive juices. 

 A leucocyte which 

 seizes and digests a 

 bacterium in a higher 

 animal acts in precisely 

 the same way. The 

 amoeba is the proto- 

 type of that phagocytic 

 digestion which occu- 

 pies so large a place in 

 both natural and ac- 

 quired immunity. 



Of what nature is 

 this digestion from the 

 point of view of chem- 

 istry ? In the digestive 

 vacuoles the reaction 

 is acid and from certain 

 myxomycetes (Fuligo 

 varians) and rhizopods 

 (Pelomyxa palustris) 

 a ferment resembling 

 pepsine and acting in 

 an acid medium has 

 been isolated. On the 

 other hand, Mouton 

 and Mesnil have ex- 

 tracted from amoebae 

 and paramecia a fer- 

 ment which digests 

 gelatine and fibrin in 

 an alkaline medium 

 just like trypsin. 



According to other 

 investigators the diges- 

 tive medium is first 



