GUMMOSIS 63 



enzymes. It is my purpose to consider further the several objec- 

 tions which he raises against the role of enzymotic activity in 

 gummosis. 



Gum pockets are fusiform in shape with the greater extension 

 upwards from the initiatory center. Butler argues as follows. 

 If gummosis is due to the action of a cytolytic enzyme diffusing 

 outwardly from the moribund cells, it would seem that the disease 

 should extend equally in all directions from it original center, 

 analogous with the diffusion of solutes in a solvent. We should 

 therefore expect a spherical gum pocket. In this, however, he 

 overlooks the well known fact of the local action of enzymes in the 

 cell. For example, enzymotic activity is concerned during the 

 process of growth of fungi. At certain places, usually at or near 

 the end of the hypha, the ferment causes a metamorphosis of the 

 walls enabling the hypha to extend its length or originate a new 

 branch. Fertilization in many fungi and algae is made possible 

 only by the local dissolution of the contiguous walls of the anther- 

 idium and oogonium through the action of a solvent. The escape 

 of the zoosphores in forms like Saprolegnia and Achlya is effected 

 (either apically or laterally 5 ) by the gelatinization of the apex 

 of the sporangium. The penetration of many parasitic fungi 

 is dependent upon the local excretion of an enzyme. Elfving's 6 

 observations on the pollen of grasses point to the secretion of 

 cytase at the tip of the pollen tube enabling it to penetrate the 

 tissues of the style. Since protoplasm is not a homogeneous col- 

 loid, as evidenced by such structures as plastids, chromosomes, 

 sap vacuoles, etc., we must expect localization of function. 



But even if we assume the equal diffusion of the solvent, the 

 affected area would not necessarily be spherical, since autolysis 

 may overtake cells seriatim in one direction and not in another. 

 Lloyd 7 has observed a condition which illustrates the point in 

 question. He finds that in the fruit of the Japanese persimmon, 

 aside from the tannin-idioblast in the mesocarp, the cells of the 



5 Coker, W. C, Another new achlya. Bot. Ga*.., 50: 381-382, 1910. 



6 Vide Green, Reynolds, Fermentation, p. 98. 



7 Lloyd, F. E. The behavior of tannin in persimmons, with some notes on ripen- 

 ing. Plant World, 14: 1-14, 1911. 



