ZOOLOGY AND BOTANY, MICROSCOPYj ETC. 97 



or the more or less branched spores, composed of a varying number 

 of cells. Excluding the pedicel-cell, the number of cells of which the 

 spores are composed is usually five or six, though there may be a 

 larger or smaller number. The separate spore-cells are often very 

 beautiful in form, bearing a distant resemblance to the teleutospores 

 of Puccinia coronata. The walls of the cells are usually more or 

 less thickened, and often with considerable projections ; though the 

 thickening is often entirely wanting. They are cylindrical or ovoid 

 in form, but with considerable variations, the length varying from 

 17 to 47 /x and the breadth from 15 to 21 /m ; the terminal cell frequently 

 differing very considerably from all the rest. A nucleus is present, 

 but disappears before the commencement of germination. The spores 

 germinate with great readiness, frequently even under the cover- 

 glass. 



In larger patches the teleutospores are often accompanied also by 

 the uredo-form. The uredospores also vary greatly in form, having 

 perhaps an average diameter of about 26 /x. They differ from those 

 of species of Phragmidium which are often also found on the bramble, 

 in the entire absence of paraphyses. They are probably identical with 

 the bodies described by Fuckel as the secidial fruit of Phragmidium 

 asperum. The uredo-form occurs abundantly on other parts of the 

 plant besides the leaves. 



Physoderma.* — J. Schroter describes this genus of parasitic fungi 

 as characterized by being altogether destitute of a mycelium ; the 

 spores forming directly abundant masses of spores within the paren- 

 chymatous cells of the host. Small colourless lumps of protoplasm 

 gradually swell up into a spherical form, and become invested first 

 with a simple, afterwards with a thick coat. This process resembles the 

 formation of the resting-spores of Synchytrium ; but Physoderma differs 

 from Synchytrium by the spores being formed in the parenchymatous 

 and not in the epidermal cells of the host, and by the resting-spores 

 of Synchytrium having a firmer inner layer of the cell-wall, so that 

 the outer layer bursts easily. 



The author has observed for some years in the neighbourhood of 

 Breslau a very remarkable species of Physoderma on Chenopodium 

 glaucum, and apparently confined to this species, completely deform- 

 ing it, and causing the stem and leaves to assume a reddish or yellow 

 colour. In the coloured pustules which appear in the summer are 

 found very large zoosporangia with orange-coloured contents. From 

 the base of the zoosporangiura a dense tuft of very fine branched 

 hyph^e penetrates into a parenchymatous cell of the host. Within 

 this cell are formed very large zoospores endowed with very active 

 motion, which pierce the tissue of the host and form new sporangia. 



In the autumn are formed black pustules which contain the resting- 

 spores, which are formed by a process of conjugation. The zoospores 

 attach themselves to a cell-wall ; from this spot proceed very long 

 and delicate threads of protoplasm bearing at their apices small 

 spherical vesicles. On the summit of these vesicles is a tuft of delicate, 



* JB. Schles. Gesell. Vaterl. Cult., 1883, pp. 198-200. 

 Ser. 2.— Vol. IV. H 



