198 BIOLOGY OF THE PROTOZOA 



eating a cytolytic process possibly due to secretions of digestive 

 fluids. There is still some uncertainty, however, in regard to this 

 matter, and the possibility of participation by bacteria in the 

 reactions is not excluded. 



Notwithstanding the serious diseases in man and mammals 

 generally due to trypanosomes, there is very little positive evidence 

 that secretions are responsible for the effects produced. Experi- 

 ments with extractives from Trypanosoma brucei by Kanthak, 

 Durham and Blanford, and by Laveran and Mesnil, gave no indi- 

 cation of toxic effects. On the other hand, Novy and MacNeal, 

 injecting dead Trypanosoma brucei in guinea-pigs obtained definite 

 fever symptoms, loss of weight and local ulcerations which, however, 

 they did not trace to the effects of a specific toxin. 



Somewhat more positive evidence is accumulating in regard to 

 the possibility of endoenzymes locked up in the trypanosome proto- 

 plasm and liberated on disintegration. Thus a number of observers, 

 among whom may be enumerated MacNeal, Plimmer, Leber, 

 Martin and others, have interpreted the rise in temperature of 

 organisms with trypanosomiasis as due to the presence of endotoxins, 

 freed in the blood upon death and disintegration of trypanosomes 

 resulting from treatment with medicaments. Also Uhlenhuth, 

 Woithe, Hiibener and others have concluded that endotoxins fatal 

 to rats are liberated if blood containing Trypanosoma equiperdum 

 is first dried, then dissolved again and injected into rats. Schilling, 

 Braun, Teichmann, on the other hand, got no reaction upon injecting 

 dead pathogenic trypanosomes into the peritoneum or subcutane- 

 ously (see pp. 363 and 384). 



In all of these cases, with the exception of sarcocystin, the evi- 

 dence in favor of the secretion of exotoxins or the presence of 

 endotoxins is purely circumstantial and verification by chemical 

 and biological methods with exclusion of other possible contributing 

 factors has not yet appeared. 



Digestion of Carbohydrates and Fats. — Specific ferments for the 

 transformation of starch into soluble sugar have not been isolated; 

 nevertheless, the evidence that such action takes place is convinc- 

 ing. Curiously enough, this evidence does not apply to the Infusoria 

 where very little digestion, beyond a slight corroding of starch 

 grains, occurs. In rhizopods, however, especially in the ameboid 

 Pelomyxa and in species of Ameba, starch grains are entirely dis- 

 solved, according to the observations of Stole (1900) who found 

 that the characteristic refringent granules of Pelomyxa palustris 

 have a very definite relation to carbohydrate nutrition. These 

 granules (Glanzkorper) are filled with glycogen, the volume of 

 which increases up to fourfold when the animals are fed with starch, 

 and decreases to entire disappearance when they are starved. 



