ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 487 



criticisms. In Japan, species of Irldsea are used for sizins^ textiles and 

 other purposes. Iridxa pulchra is shown to be a valid species. Critical 

 and illuminating notes of the highest value are given in the following 

 species : — Sarcodia Montagnmna, two species of Hypnea, Glirysijmenia 

 Enteromorpha (which is also figured), Laurencia heterocladia, Pleono- 

 sporium venustissimum, Schizymenia Duhyi {=8. Binderi J. Ag.), 

 Nemastoma laciniata, and others. 



Fungi. 

 (By A. LoRRAiN Smith, F.L.S.) 



Peronospora on Hemp.* — Vittorio Peglion fonnd a fine growth of 

 this parasite on hemp plants in Ferrara. He therefore made a thorough 

 study of its life-history. He notes the method of attack and the 

 sequence of leaves to succumb to the parasite ; and he discusses the 

 stages at which infection takes place. 



Cultivation of the spores revealed the fact that these on germination 

 produce zoospores, about three zoospores in each conidium ; they swarm 

 for an hour or two, then loose their cilia and become more spherical, 

 after which germination by a tube takes place. Peglion has therefore 

 placed the fungus in the genus Peronoplasmopara. 



Study of Mucor.t— A. H. W. Povah is studying the genus Mucor 

 with a view to determining the species with more certainty, having 

 regard to their morphological characters and their cultural reactions. 

 He gives an account of work done by others and of the methods used 

 by them, and also gives a sketch of the taxonomic problems and of the 

 systems adopted by previous fungologists. 



An account is then given of his own methods of study, the collection 

 of material, the herbarium material consulted, and the cultures under- 

 taken. He found that, on the whole, complex substances such as bread 

 formed the most suitable media. 



In a second paper % the author takes up the question of classification. 

 He rejects the method of arrangement according to branching of the 

 sporophores, as the spores themselves give more satisfactory characters. 

 Eighteen species are described, several of them new to science. 



Studies of Rhizopus nigricans.§ — U. E. Stevens and L. A. Hawkins 

 have studied this mould in its relation to the " leak-rot " it causes on 

 strawberry fruits. In accounting for the loss of juice occurring in 

 strawberries attacked, the authors seem to think that " the fungus so 

 affects the protoplasm of the cell, perhaps by secreting some toxin, that 

 it is no longer capable of functioning as a serai-permeable membrane." 



* Atti Real. Accad Lincei, cccxiv. (1917) pp. 618-21. 



+ Bull. Tori-ey Bot. Club, xliv. (1917) pp. 241-59. 



I Bull. Torrey Bot. Club, xliv. (1917) pp. 287-313 (4 pis.). 



§ Phytopathology, vii. (1917) p. 178-84. 



