264 Mary Dairies Swartz, 



CYTASES IN THE VEGETABLE KINGDOM. 



By the early investigators, Haubner (40), Henneberg and Stohman 

 (41), Klihn, Aronstein, and Schulze (54), it was accepted without much 

 question that, since cellulose disappeared from the alimentary tract of 

 herbivora, it is digested like starch, and equally valuable as a nu- 

 trient. But after Tappeiner (78), in 1884, showed that cellulose could 

 be decomposed by micro-organisms, and promulgated his theory that 

 this was the only way to account for the disappearance of cellulose 

 from the alimentary canal of ruminants, the matter fell into great dis- 

 pute,' and the question is not yet definitely settled as to how cellulose 

 is digested and what are the products of its digestion. A diligent 

 search has been made for enzymes capable of attacking it {cytases), 

 but so far, such cytases have been proved to exist only in plants and 

 lower animals. Many of these so-called cytases act upon hemicel- 

 lulose rather than true cellulose, and will be discussed in connection 

 with the hemicelluloses, though it is not always possible to make a 

 sharp distinction between the two. A careful review of the subject 

 of cytases in plant physiology up to 1898, has been made by Bieder- 

 mann and Moritz (34), from which it appears that the penetration of 

 wood by the mycelia of moulds is due to such cytases, and that a 

 powerful cellulose-dissolving enzyme has been derived from Peziza 

 sclerotium by de Bary (37) and from another botrytis (presumably a 

 Peziza) by Ward (84), while Brown and Morris (36) have described 

 cytases existent in germinating grasses which dissolve their cell walls. 

 That this is anything more than a diastatic enzyme is denied by Rei- 

 nitzer (67) ; but Newcombe (64) considers the assumption of the iden- 

 tity of all cell-wall dissolving enzymes with diastase as far from jus- 

 tifiable. Bergmann (32) reports such cytases in hay and straw. 

 Scheunert and Grimmer (71), on the contrary, find none in oats, corn, 

 horse-beans, lupine seeds, buckwheat or vetch. Thus we see that 

 even in the case of plants, these enzymes need to be isolated and 

 identified before we can arrive at any satisfactory conclusions. 



That cellulose can be dissolved by bacteria has been demonstrated 

 for such forms as Amylobacter butyricus, Vibrio regula and Clostridium 

 polymyxa (34). Omelianski (65) has described two organisms which 

 ferment cellulose, and Ankersmit (31) finding Omelianski's bacteria 

 on hay, has studied their behavior when introduced into the alimen- 

 tary canal of the cow on its food. He finds that they do not increase 



^For a review of this discussion cf. Lohrisch (56). 



