16 Chapter I 



capable of inverting cane sugar, nor lipase, capable of digesting fatty 

 matters. 



The amoebo-diastase of Mouton must be classified with the 

 trypsins. It is very active in a distinctly alkaline medium and 

 continues the diastatic action even when the medium becomes 

 weakly acid (a feature that corresponds to the reaction observed 

 in Amoebae treated with appropriate staining agents). The amoebo- 

 diastase is affected at as low a temperature as 54^ C. and at 60^ C. 

 is rendered completely inactive. 



A question of especial importance is that concerning the action 

 of the amoebo-diastase upon Bacteria. The numerous experiments 

 of Mouton directed to the solution of this point, and made Avith 

 living Bacillus coli communis, gave negative results. If, however, 

 these bacilli were previously killed by heat or by chloroform, 

 they were at once attacked by the soluble amoebo-ferment. Opa- 

 lescent emulsions of these dead bacilli, incapable of undergoing self- 

 digestion of any kind, became transparent after remaining for some 

 time in contact with the extract of Amoebae. The amoebo-diastase, 

 then, undoubtedly digests dead bacilli in vitro, whereas in the body 

 of the Amoebae the ingested bacteria are attacked whilst still living. 

 As a result of these observations it must be concluded that only a 

 fractional part of the diastase is extracted in the solution prepared 

 by Mouton. 



This intracellular digestion in the Protozoa serves not merely for 

 the nutrition of these organisms, but also as a protection against 

 infective parasites. The protoplasm of the Infusoria, with its vacuolar 

 secretions, has a general digestive action on everything that comes 

 within its reach. If the internal structures, such as the nuclei and 

 the pulsatile vacuoles, resist this process, it is undoubtedly because 

 they possess a power of defending themselves against the attack of 

 the digestive secretions. Thus, as brought out in the beautiful 

 [19] researches of Maupas^, the macronucleus of the Paramaecia is, at 

 a certain stage in the life of the Infusorian, completely digested by 

 the protoplasm just as is any other nutrient substance introduced 

 from outside. It must be admitted that in this case the nucleus has 

 ceased to produce the protective substance which, under ordinary 

 conditions, interferes with its being digested. 



A struggle similar to that observed between the nucleus and the 

 digestive content of the Protozoa goes on between these latter 



» Arch, de zool. exptr., Paris, 1889, 2™« serie, t vii, p. 446. 



