Pflanzenkrankheiten. — Bacteriologie. 289 



&' 



enzymes are secreted bj^ the lungus. These enzymes are diastase, 

 invertase, cytase and lipase. It was also shown that glucosides were 

 broken down and that the t'ungus was able to live on protein deri- 

 vatives. The Botrytis investigated secretes very little cytase and it 

 seems that too much importance has been atiributed to this enz3^me. 

 It may be that diastase assists the cytase in breaking down the 

 cellulose and in digesting the amylodextrin formed. In agreement 

 with the other authors, the experiments show a varying abilitj'' of 

 the conidia to cause direct infection of the host. This abilit}'- is 

 <alwa3'^s directly proportional to the conditions favoring the lungus. 



Jongmans. 



Pritchard, F. J., A preliminary report on the yearly ori- 

 gin and disseraination of Puccinia graminis. (Bot. Gazette. 

 LH. p. 169—192. PI. 4. 1911.) 



The annual reappearance of Puccinia graminis Pers., the black 

 rust of cereals, and its dissemination among the various species of 

 the Grami)ieae, have long remained obstinate problems. The author 

 made several investigations to find the Solution of this problem. 

 Before describing bis own experiments he reviews the literature, to 

 bring out certain points which have been too much overlooked by 

 those who are committed to the conception that the barberry is the 

 sole source of spring infection. 



The results of the investigations are summarized as follows: 

 Puccinia graminis passed readily from wheat, Agropyron tenenim, 

 A. repens, Hordeum jtthatum, and Elyimis triticoides to the barberry. 



Observed tacts seem to oppose the theory that aecidiospores and 

 xiredospores are carried considerable distances by the wind. 



Uredo pustules of P. graminis appeared upon the experimental 

 plot of winter wheat as early as upon grasses near the barberry 

 bushes, and with one exception were generally present upon the 

 spring wheat earlier than they appeared upon the grasses remote 

 from the barberr}''. 



P. graminis does not appear to spread to the wheat fields by 

 aid of the grasses. The few experiments made seem to show three 

 distinct biological forms of this fungus: one for wheat, one for barley, 

 and one for rye, oats, Hordeum jiihatiim, Agropyron tenentm, A. 

 repens, and Avena fatua. 



Uredospores of P. graminis failed to survive the winter of 

 1904—05 at Fargo, North Dakota. 



The wintering of P. graminis as a mycelium in plant tissues in 

 North Dakota is very doubtful, as shown by the late appearance 

 of the uredo pustules in the spring and the failure of rusted grasses 

 to produce the uredo again after being housed during the winter. 



The pericarp of rusted wheat grains is frequently filled with 

 rust mycelium and numerous pustules of teleutospores. 



Teleutospotes in some of the germinating grains appeared to be 

 germinating in a palmella-like stage. 



Pieces of mj'celium resembling rust were found in the cells of 

 •the scutellum close to the growing plant. Jongmans. 



Barthel, Chr., Das kaseinspaltende Vermögen von zur 



Botan. Centralblatt. Band 131. 1910. 19 



