ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 193 



eludes that the presence of acid is favourable to their production. 

 Comparative notes are given as to the size of the mycelium spores, etc. 



Notes on Puccinia malvacearum.*— W. Robinson has examined 

 the connexion between this fungus and the host-plant. He finds that 

 from the germ-tube is formed an infection vesicle which gives rise to 

 branches. These grow out into the intercellular spaces ; strands of 

 hyphre pass to the vesicular bundles of the host and haustoria penetrate 

 the phloem parenchyma. The hyphse in the cell lie within the proto- 

 plasm and grow towards the nucleus ; they were not observed to enter 

 the vacuole, and the cell is not killed for some time. 



Rusts on Hybrid Plants. f — Guinier has reported an instance of 

 the effects of hybridism. In the neighbourhood of Annecy he found 

 that while Sorbus torminalis was immune from the rust Gymnospor- 

 angium tremelloides, Sorbus Aria was covered with ascidia and spermo- 

 gonia. The hybrid form of these two trees presented a few indistinct 

 spots, partly sterile, partly covered with spermogonia, more rarely with 

 gecidia. The peridium of the latter are rudimentary, and while some of 

 the spores were normal, others were irregularly formed. 



Mycelial Formation in Ustilago Jensenii.J — E. Hils notes that the 

 smut spore of this fungus on germination produces usually a three-celled 

 promycelium which both at the septa and tips buds off conidia. These 

 conidia in water or culture solution give a vigorous yeast formation. In 

 the host-plant the mycelium does not produce conidia, and Hils has 

 sought to determine the factors that influence these different growths. 

 He found that the formation of mycelium was furthered by a high per- 

 centage of oxygen and an alkaline reaction of the culture medium, and 

 that an abundant and vigorous hyphal growth only occurs when the 

 atmosphere is rich in oxygen. In other fungi a super-abundance of 

 oxygen is favourable to spore-formation ; in Ustilago Jensenii the opposite 

 occurs. Hils further states that in the living host cells, especially towards 

 the apex of the stalks where the mycelium of the parasite is most active, the 

 presence of oxygen in large quantities has been verified ; and in these 

 cells there must be a very slight acid reaction. In older parts of the 

 plants the mycelium dies off owing to the reaction of its own products. 



Synopsis of the Genera Cladoderris and Stereum.§ — C. Gr. Lloyd 

 gives notes, descriptions and figures of Cladoderris, a genus of fungi 

 very frequent in tropical America, which differs from Stereum in having 

 a ribbed and generally papillate hymenium, and mostly a thick dense 

 tomentum layer on the pileus Most of the specimens are stalked and 

 fan-shaped. Lloyd recognizes five good species. 



* Mem. Proc. Manchester Lit. Phil. Soc, lvii. 3, No. 11 (1913) p. 22 (1 pi.). 

 See also Bot. Centralbl., exxv. (1914) p. 114. 



t C.R. Soc. Biol. Paris, lxxiv. (1913) pp. 648-9. See also Bot. Centralbl. exxv. 

 (1914) p. 11. 



t Diss. Tubin. (1912) 42 pp. See also Bot. Centralbl., exxv. (1914) pp. 84-5. 



§ Lloyd, Cincinnati, Ohio (1913) xii and 46 pp. (figs.). 



