62 FREDERICK A. "WOLF 



Vinson 3 has shown that the same results may be obtained by num- 

 erous substances, and, moreover, has offered evidence that enzym- 

 otic activity is involved. Lloyd 4 has found that, whereas eight 

 or more days' treatment with carbonic acid gas is usually required 

 to render persimmons non-astringent, the same effect can be had 

 in less than forty-eight hours when they are subjected to the same 

 agent under increased pressure. In all of the examples cited, 

 just as in the production of gummosis, the complete chain of events 

 between cause and effect is not known. It does not then seem 

 unreasonable to suppose that enzymotic activity leading to gum- 

 mosis may be incited by any factor which would disturb the pro- 

 toplasmic activity of the wood cells. 



Beijerinck and Rant indeed hold that the formation of gum 

 is in fact due to the presence of an enzyme, cytase, within the cam- 

 bial cells. So long as these cells are alive it is unable to attack 

 the celLwall owing to the semi-permeability of the protoplasm 

 with respect to the enzyme involved. Just as soon, however, as 

 the embryonic wood cells become traumatic by the presence of 

 fungi, bacteria, wounds, toxic substances, etc., the cytase escapes 

 and attacks the walls of the surrounding cells. They offer as 

 proof for the existence of cytase that the hyphae of Coryneum 

 beijerincki, when present, are affected by gummous degeneration. 



Butler, however, considers that gummous degeneration must 

 be explained by some other hypothesis than the excretion of a 

 cytolytic enzyme. Because of the vast accumulation of evidence 

 of enzymotic activity in somewhat comparable cases in plants, it 

 would seem that the burden of proof of the non-existence of en- 

 zymes should rest on him. He does not arrive at this conclusion 

 as the result of micro-chemical tests for enzymes nor by attempts 

 to isolate them, if one may jlidge by the evidence presented in his 

 memoir. In fact no experimental evidence is presented in sup- 

 port of his view. He attempts to show that his observations can- 

 not be made to harmonize with the assumption of the presence of 



3 Vinson, A. E., The stimulation of premature ripening by chemical means. 

 Jour. Am. Chem. Soc, 32: 208-212., 1910. 



4 Lloyd, F. E., Carbon dioxid at high pressures, and the artificial ripening of 

 persimmons. Science, X. S., 34:924-928, Dec, 1911. 



