349 



draws the conclusion that the life-cycle of the fungus embraces 

 the two conidial forms: Hormodendron and Cladosporium. 



G. MASSEE. Evolution of parasitism in Fungi. (Linnean So- 

 ciety, London, Feb. 17, 1910); Nature^vl. 83, March 3, 1910, p. 29. 



Parasitism is mainly the outcome of opportunity and the fact 

 that fungi present all stages of parasitism, and that a saprophytic 

 fungus can be educated to become a parasite, proves that para- 

 sitism is an acquired habit. Incipient or imperfectly evolved pa- 

 rasites promptly kill the host, and consequently curtail the period 

 of their own existence as Pythium De Baryanum. A higher stage 

 of parasitism is reached by many of the rusts and smuts, Ustilago 

 Avenae, etc., where the host is attacked as a seedling, and is sti- 

 mulated to an unusual condition of growth throughout its normal 

 period of growth/ More advanced parasites show a tendency to 

 arrest the production of spores and Conidia, and to perpetuate 

 themselves by perennial mycelium located in some perennial ve- 

 getative portion of the host (root, tubers, etc.), or in the seed. 

 On the most highly evolved parasites reproductive bodies are enti- 

 rely arrested, and the parasite is perpetuated by hibernating my- 

 celium only. 



M. C. POTTER. Bacteria in their relation to Plant Pathology. 



- (British My cological Society); Nature, vol. 84, July 7, 1910, p. 18). 



Presidential address by Prof. Potter to the British Mycological 

 Society. 



At least ten plant diseases are considered as caused by bacteria: 



The pear-blight (Bacillus amylovorus}; 



Yellow disease of Hyacinth (Pseudomonas Hyacinth?)', 



Canker of the olive (Bacillus Oleae)', 



Corn-blight (B. Zeae)', 



Potato wet-rot (B. solaniperdd) ; 



Soft rot of hyacinth (B. hyacinthi-septicus)', 



Bacteriosis of the vine (B. uvae)', 



Cucurbit Wilt (B. tracheiphilus]\ 



Brown rot of Crucitera (Pseudomonas campestris); 



Potato and tomato disease (Bacillus solanacearum). 



