€2 SUMMARY OF CURRENT RESEARCHES RELATING TO 



as to the duration of life of P. californica, as deduced from the struc- 

 ture, and comes to the conclusion that the rings in the stem are annual 

 growth-rings. The greatest number of rings recorded is 24, in a stalk 

 5 cm. in diam. Stems measuring 7 • 5 cm. in diam. have been recorded, 

 but their rings were not counted. Alaria tenuifoUa shows also annual 

 growth-rings. E. S. G-. 



Fungi. 



Study of Phytophthora infestans.— Jakob Eriksson (Rev. Gen. 

 J3ot., 1918, 30, 16-30 ; 50-61) has now completed his study of potato- 

 mildew. He has reviewed the results obtained by previous workers, 

 and adds an account of his own researches. As a result of his own 

 observations, he finds that the continuance of the disease is assured by 

 the presence of a mycoplasm, which lives in symbiosis with the normal 

 cytoplasm of the cell, and in the chlorophyll cells of the plant ; after 

 undergoing a series of changes, it passes into the intercellular spa,ces as 

 a fine mycelium. The subsequent development is mycelial. Eriksson 

 has found oogonia and antheridia as well as the " conidial " stage, which 

 is the mildew form of the disease. A. L. S. 



Life-History and Cytology of Olpidium. — A full account of a new 

 Olpidium {0. Viciae) has been given by S. Kusano {Journ. Coll. Agric, 

 Tokio, 1912, 4, 141-99, 3 pis.). He notes that some of the zoospores 

 become planogametes, and form by copulation the motile zygotes. He 

 concludes from this that " the Chytridiales are not a degenerated series, 

 but form the lowest class in the progressive phylogenetic series of the 

 fungi." He also deduces from other evidence that the Olpidiace^, or 

 at least Olpidium, may have derived from an ancestor below the level 

 of the alg£e, perhaps in common with the latter. A. L. S. 



Daldinia vernicosa. — Arthur S. Rhoads {Mycologia, 1918, 10, 

 277-84, 1 pL, 1 fig.) has described this fungus as one that lives on 

 "burnt wood. It is constantly associated with Nummidaria Bidliardi, but 

 the latter is not confined to burnt surfaces. D. vernicosa differs from 

 the more familiar D. concentrica in the form of the sporophore ; it is 

 somewhat pyriform, narrowing to a stalk at the base. A. L. S. 



Peziza proteana var. sparassoides in America. — E. J. Durand 

 {Mijcologia, 1919, 11, 1-3, 1 pi.) describes this species and the variety, 

 which have been collected recently in America. He is inclined to think 

 that the variety agrees exactly with Massee's Gyromitra Phillipsia, though 

 only a study of authentic specimens can settle the difficulty. A. L. S. 



British Species of Melanconium. — These have been listed and 

 diagnoses published by W. B. Grove {Kew Bull., 1918, 161-78, 1 pL). 

 He divides the genus into three sections :— (1) Melanconium, with 

 smoky-brown or blackish spores, exuding in tendril-like masses ; (2) 

 Lamproconium, with bright-coloured spores ; and (3) Ectoconium, with 

 olivaceous spores that do not exude as tendrils. The latter grow on 

 reed-like grasses, and have often been mistaken for other genera and 

 species of fungi. A. L. S. 



