﻿80 BOTANICAL GAZETTE [january 



havior of Monilia (Sclerotinia) cinerea with reference to its parasitism, finds 

 that the spores are incapable of infecting young green plums whose skin is 

 uninjured, but that such fruits are easily attacked by grown mycelium applied 

 to their surfaces. The ripening fruits, however, are readily infected through 

 the unbroken skin by spores. The acidity of the fruit, the author finds, 

 increases as ripening progresses. The fungous hyphae penetrate the fruit in 

 all directions, but they do not follow the middle lamellae, nor is there a general 

 disintegration of the host tissue due to the action of the fungus on the middle 

 lamellae. From histological observations it appears that the host cells are 

 not injured in advance of the penetrating hyphae. The observation that the 

 juice of much decayed plums had no cytolytic action on the flesh of sound 

 plums seems to be in accord with the observation on the action of the hyphae 

 themselves, yet it can scarcely be doubted that if a sufficiently concentrated 

 extract of the young mycelium had been prepared, more positive results would 

 have been obtained, for, as the author himself states, it is probable that the 

 juice was too dilute to be effective. Other objections to the use of the juice 

 of decayed fruit are obvious. In agar tubes containing cellulose prepared from 

 the plums by different methods, very slight action on the cellulose was observed, 

 but filter paper cellulose was readily dissolved. In tubes containing pectin 

 a coagulation was produced by Monilia, but in tubes containing suspensions 

 of calcium pectinate without soluble carbohydrates the fungus made little 

 growth and the pectinate was not hydrolyzed. In expressed fruit juices in 

 which the fungus had grown, oxalic acid was found in small quantities, and 

 also in peaches inoculated with Manilla, but not in others inoculated with 

 Penicillium and Aspergillus. The fungus grows best in acid media. 



Brown 4 investigated the less strictly parasitic fungus Botrytis cinerea. 

 By using large quantities of germinating spores, he was able to prepare extracts 

 whose enzymatic activity was much greater than that of the extracts used by 

 DeBary, Ward, and others who investigated the cytolytic action of extracts 

 of this or closely related species of Botrytis. The extracts prepared by Brown 

 brought about a rapid disintegration in the tissues of roots, tubers, fruits, leaves, 

 and petals of various plants. Thin discs (1-1.25 cm.X0.5mm.) of potato, 

 turnip, beet, apple, etc., were disorganized in 15-90 minutes. The tissues of 

 bryophytes and filaments of algae appear not to be affected. The process 

 of disorganization begins with solution of the middle lamella, as a result of 

 which the tissue loses its coherence. Finally, the cell wall itself is disinte- 

 grated and the tissue is completely disorganized. The death of the cells does 

 not take place until some time after the cells have been separated by the solu- 

 tion of the middle lamella. The activity of the extract is destroyed by heat 

 and by shaking, the toxic action being destroyed simultaneously. When 

 the extract was dialyzed by means of collodion thimbles, the dialysate showed 



* Brown, W., Studies in the physiology of parasitism. I. The action of Botrytis 



