ZOOLOGY AND BOTANY, MICROSCOPY^ ETC. 503 



then lies in the stoma as an isolated round or irregular mass, re- 

 sembling some Synchytria. It is composed of two different kinds of 

 cells, an outer closely packed " palisade-like " layer of cells somewhat 

 elongated in the radial direction and strongly refringent, and a central 

 mass of closely packed polyhedral spores. 



The spores do not possess a distinct endospore. On germinating 

 they put out a germinating filament or promycelium, from the ex- 

 tremity of which are detached very narrow cylindrical sporidia ; and 

 from these are developed the secondary mycelia. In very rare cases 

 a conjugation of sporidia was observed by means of a transverse con- 

 necting-band. The most suitable nutrient fluids for the germination 

 of the sporidia were found to be solution of grape-sugar, and decoction 

 of plums or dung. 



The germinating filaments put out by the sporidia creep over the 

 epidermal cells of the host and become closely attached to them, and 

 reach the intercellular spaces by penetrating the lateral walls of these 

 cells. Here they develope into a dense mycelium, the cells of which 

 are filled with a strongly refractive substance, the glycogen of Errera. 

 In the spaces beneath the stomata the mycelium is especially luxuriant; 

 the filaments becoming interwoven into a dense felted mass. This 

 soon developes into a pseudoparenchyma, which then becomes the 

 fructification by the differentiation of the two kinds of cell already 

 mentioned. The cell-walls of the spores gradually become thicker 

 and browner, the cortical layer of palisade-like cells beiug formed 

 later. The surrounding mycelium then entirely disappears in 

 mucilage. The formation of the fructification is going on through 

 the whole year and can be observed in all stages at the same time. 



Fisch gives the following diagnosis of Doassa?isf a : — Fructification 

 multicellular, inclosed in a single cortical layer of sterile cells. 

 Germination of the spores as in Tilletia and Entyloma, but without 

 copulation of sporidia. Spores without endospore. On the leaves of 

 living plants. The three known species, D. Alismatis, Sagittarice, and 

 Farloivii, are also described, as well as Farlow's doubtful D. Epilobii 

 (on Epilohium alpinum), which is more probably a SyncJiytrium. 



Reproduction of the Hetercecious Uredinese,* — Mr. C. B. Plow- 

 right points out that when the Heteroecious Uredincfe are reproduced 

 without the intervention of fecidiospores, the resulting uredospores 

 are far more abundant than when they arise from implantation on the 

 host-plant of the secidiospore. This he states to be the case with 

 Puccinia graminis, P. ruhigo-vera, and P. ohscura. 



Glycogen in the Basidiomycetes.j — In pursuance of his previous 

 observations J on the occurrence of glycogen or animal starch in fungi, 

 Dr. L. Errera has now detected it in a large number of Basidio- 

 mycetes, a list of which he gives. Its presence he concludes from 

 observing a whitish substance in the interior of the cells, which is 

 amorphous and refringent, and which is coloured brown-red by iodine, 



* Jom-n. Linn. Soc. (Bot.), xxi. (1885) pp. 368-70. 

 t Mem. Acad. E> Sci. Belgique, xxxvii. (3 885) 50 pp. 

 X See this Journal, ii. (1882) p. 824, iii. (1883) p. 397. 



