218 SUMMARY OF CURRENT RESEARCHES RELATING TO 



also persists in the sheath leaves of the shoot and in the woody parts of 

 the twigs. In the latter case it penetrates deeply. This mycelium is 

 the product of a late autumn infection by the Pero/tospora. 



Membrane of Zygospore.*— P. Vuillemin has investigated the 

 formation of the outer layers of the mature zygospore, lie finds that 

 there are five principal layers, alternately thin and thick. The most 

 noticeable is the fourth layer, which is next to the outer coating. It is 

 distinguished by its elasticity and by the brown coloration. The 

 author terms it the carbon layer (assise charbonneuse). He discusses 

 the formation of these protective layers in various types of Mucorini, 

 Sporodinia Aspergillus, Spinellus rhombosporus, S. chdlybeus, Zygo- 

 rhynchus heterogamies, Z. Moelleri, and in Mucor fragilis. He states, in 

 conclusion, that the protoplasm of the zygospore manifests no special 

 dermato-genetic property. The wall formed is strong and thick, but 

 does not differ from the wall of the copulating gametes ; growth is 

 gradual and continuous both in time and dimensions. 



Hyphoids and Bacteroids.f— P. Vuillemin finds in the root tuber- 

 cles of Leguminosa3, filaments of a fungal nature resembling those of a 

 Pythium. They often show swellings, either terminal or intercalary, 

 which have no connection with the Pythium fructification. The author 

 describes them under the term hyphoid, as they have undergone some- 

 thing of the same transformation as the bacteroids of Rhizobium, and 

 they are not parasites, but, like the root bacteria, live in symbiosis with 

 the roots of the host. 



Tobacco Disease due to Sclerotinia.j — C. A. J. A. Oudemans and 

 <?. J. Koning have investigated a "rot" of tobacco plants due to this 

 fungus. It develops as fine white filaments on the surface of the leaf 

 )Y stalk. From these, conidiophores are developed, and, later, black 

 sclerotia are formed. The fungus was also cultivated successfully as a 

 saprophyte on malt-gelatin, etc. The Peziza from Sclerotinia NicoUarm 

 sp. n. was grown from the sclerotium. The disease only occurs in wet 

 years, and care should be taken to avoid moist conditions, such as too 

 great shade, and to secure the speedy drying of the leaves when 

 gathered, as the fungus spreads very rapidly among damp leaves. In 

 a further note,§ the authors record successful cultures of the Sclerotia, 

 and the growth of much larger Peziza forms than those at first obtained. 



Two Supposed Species of Ovularia.|| — E. S. Salmon gives reasons 

 for regarding Ovularia fallax and 0. Clematidis as synonyms of Oidium 

 Pohjgoni. The former has been found on Vicia, the latter on Clematis, 

 both of them hosts of Erysvphe Polygoni. These fungi are both forms 

 of Oidium, and identical with Oidium [leuconicum, the conidial form 

 of Ergsiphe Polygoni. 



Notes on the Occurrence of Black Rot.lf— A. Prunet gives various 

 details as to the time when the vines are most likely to be attacked by 



* Ami. Mycol., ii. (1904) pp. 483-506 (4 pis.). 



t Comptes Rendus, cxI. (1905) pp. 52-3. 



t R. Akad. Weten^cli. Amsterdam, vi. (1903) pp. 48-. r )8 (1 pi.). 



§ Tom. cit., pp. 85-6(1 pi.). || Journ. Bot. xliii (1905) pp. 41-4 (1 pi.). 



^f Re'v.Vitic, xxii. (1904) pp. 289-91. tSienlso Dot. Centralbl., xcviii.(1905) p. 37. 



