THE SEXUALITY OF THE FUNGI. 49 



and others. These conidia-bearing hyphse spring from a mycelium in 

 the leaves. In the mesophyll are abundauce of the usual brown usti- 

 laginous spores — very like those of Sorosporium, &c. — in dense clusters. 



In the autumn the Trientalis plants are found spotted with black 

 patches. These are due to the densely-clustered brown compacted 

 spores, as before, but no conidia occur now. The pyriform colourless 

 conidium germinates on the leaf surface ; the germinal tube bores its 

 way in, grows to a mycelium which ramifies between the cells, and 

 sends branched haustoria into their cavities. 



At certain points on the mycelium arise lateral branchlets, which 

 superficially resemble ascogonia, at least in some cases ; these — single 

 or several together — become enveloped by fine hyphse, and soon pre- 

 sent the appearance of a dense grape-like cluster of spores embedded 

 in the interwoven mass of fine hyphse. The investment becomes dis- 

 organised as the clusters of spores turn yellow, and then brown, and 

 acquire thick coats. The cluster of spores germinates as a whole, 

 putting out tubes (" promycelia ") at the end of Avhich the crown of 

 " sporidia " appear according to the type of Tilletia. These oval 

 sporidia may also " copulate " in pairs in the well-known manner ; but 

 this often does not occur, and it seems to be an unimportant point, 

 not affecting the future of the sporidia or their progeny at all. Secon- 

 dary and tertiary sporidia may arise from the primary sporidia by 

 budding. 



After sowing the brown spores on young plants of Trientalis, still 

 level with the ground or nearly so, the mycelium arises in the seed- 

 ling, and, as soon as the leaves unfold, produces the white conidia 

 externally and the brown compound spores internally. This is no 

 doubt the best established case of the existence of two generations 

 (producing conidia and spores respectively) that we as yet know of in 

 this group ; it is true, it is not the only case, for we have the same 

 thing in Entyloma. 1 Tubercinia also agrees with the others in being 

 antoecious, i.e. in passing its whole life on the same host plant. 

 Woronin is of opinion, however, that " a whole series of hetercecious 

 forms " will be discovered among Ustilaginece ; whether this remark is 

 inspired by facts not yet published does not appear. 



Of the remainder of Woronin's magnificent paper nothing need be 

 said here ; and space does not admit of our referring more in detail 



1 De Bary, ' Bot. Zeit., 1874 p 81 



