266 Mary Davies Swartz, 



the effective agents. So, also, the fact that Lohrisch was unable to get 

 cellulose digestion in sterilized fluid again inoculated with unsteril- 

 ized fluid is attributed to the medium's being an unfavorable one for 

 the development of these organisms, inasmuch as the addition of pep- 

 tones to similar preparations caused in several cases an increased de- 

 composition. It seems fairly well established, therefore, that the 

 action of the coecal fluid of the horse is due to enzymes of bacterial 

 origin. 



CYTASES IN LOWER ANIMALS. 



There is no doubt that cytases occur in some of the lower forms of 

 animal life. Biedermann and Moritz (34) found a powerful cellulase 

 in the secretion of the liver of the common snail {Helix poniatia), and 

 their observation was verified by E. MuUer (61), also by Lohrisch (57) 

 who reports two series of experiments in which snails fed tender let- 

 tuce leaves digested from 40.1 per cent to 81.6 per cent of the cellulose 

 present. On the other hand, Miiller (61) could not verify Knauthe's 

 report of a cellulase in the hepato-pancreas of the carp (50) ; Pacault 

 found none in the saliva of Helix pomatia (66) ; and Biedermann none 

 in the digestive juice of the meal worm {Tenebrio molitor) or of the 

 cabbage worm {Pieris brassica) (34). Biedermann also examined the 

 faeces of the cabbage worm microscopically and found unaltered par- 

 ticles of leaves, from which he concluded that much of the plant food 

 eaten is excreted unchanged. Lohrisch (56) has obtained similar re- 

 sults with caterpillars of sphinx moths {Sphinx euphorbiae) , not only 

 in experiments with intestinal juice in vitro, but also in feeding expe- 

 riments in which the cellulose was quantitively excreted. 



Selliere (75-76) has recently added some interesting contributions 

 to this subject, showing that cotton treated in various ways; namely, 

 that recovered after solution in Schweitzer's reagent, that treated 

 with concentrated zinc chloride, or with 25 per cent caustic alkali hot 

 or cold until the fibers are swollen, and subsequently washed with 

 1 per cent acetic acid and water, is attacked by Helix pomatia much 

 more readily than the untreated substance. Subsequent drying of 

 the treated cotton diminished its digestibility somewhat, suggesting 

 that the physical condition of the cellulose is a definite factor in its 

 utilization. SeUiere believes that only the more tender portions of 

 plant cellulose are attacked by the digestive juice of this snail. It 

 would seem that the pre\dous treatment of th? cellulose is a factor to be 

 kept in mind in the interpretation of the results of feeding experiments. ^ 



iCf. the experiments on cellulose utilization in the dog, p. 263. 



