The Scottish Naturalist. 125 



the tissues of the leaf die at the spot. Frequently the dead tissues 

 fall out, leaving a hole. The species belongs to the group of 

 Entyloma that do not form conidia, i.e., in which the spores do 

 not begin to germinate while still on or in the spot; in the leaf. 

 On microscopic examination of a section of such a spot, the 

 tissues are found to be full of the small cells of the fungus. The 

 spores are rounded, .01-.012 mm. diam., smooth, with cell-wall 

 nearly colourless or pale brown. 



Entyloma Canescens, Schroter, (Beitr. z. Biol. d. Pflan- 

 zen, II., p. 372) occurred rather commonly on some plants of 

 Myosotis arvensis, near Aberdeen, in the month of October. The 

 presence of the fungus is indicated by spots on the leaves, 1-3 

 mm. diam., at first whitish, then turning brown or black as the 

 tissues of the leaves dry up, or again becoming whitish in the 

 centre, owing to the formation of conidia by the germination of 

 the spores while still in or on the spot. On microscopic examina- 

 tion of the leaf, it is found filled with the spores of the fungus. 

 These are nearly spherical, •008-.012 mm. diam., smooth, almost 

 colourless, and rather thin-walled. They germinate while still in 

 the leaf, forming a circle of sporidia at the end of a club-shaped 

 pro-embryo. The sporidia are spindle-shaped, and' are about 

 .020-. 040 mm. long. Dr. Keith sent me the same fungus from 

 Forres, before I had myself gathered it, as Protomyces Fergussoni 

 B. and Br., in which determination I believe he is right, so far as 

 the very brief diagnosis of that species will allow of identification. 

 It is, however, an F?ityloma. 



Protomyces Rhizobius, n. sp. While treating of internal 

 parasites of plants, I may describe one found by myself, in May, 

 1883, on the roots of Poa annua, growing on a dry and seldom 

 used road at Old Aberdeen. In the roots one finds from 

 one to eight cells in groups, but very seldom in absolute 

 contact. They lie in the cortex of the root ; but owing to 

 their size being much greater than that of the root-cells, it 

 is hardly possible to ascertain whether they lie in the cells of 

 the root or between them. Nor could I convince myself as to 

 the nature of the mycelium, though able to make out what seemed 

 to be a delicate mycelium. The fungus-cells are spherical, .o3-.o33 

 mm. diam., nearly smooth, and very thick-walled, the contents 

 forming a mass of only about .008 mm. diam., and the wall 

 occupying the rest of the diameter. It is pale^ brown or nearly 

 colourless. The characters seem to agree best with those of 

 Protomyces, but I can find no mention of a species living in roots 

 of grasses, hence I venture to name this species Protomyces 

 Rhizobius. Grasses attacked by it show very little sign of in- 

 jury externally, though they look weakly; but the starved appear- 

 ance might be passed over as due to the unfavourable place of 

 growth. 



