1903 The Study of Microfungi 51 



the yellow spores. After these have dispersed there is nothing 

 more to be seen upon the Nettle. 



We now have to look for certain species of Carex, as hirta, 

 riparia, pscudo-cypcrus, &c. Upon the leaves of these Sedges 

 appear brown spots which contain the uredo-spores covered 

 over by a pseudo-peridium, which is merely the altered epi- 

 dermis of the leaf. Presently this ruptures, setting free the 

 spores, which are globose and finely echinulate or spiny. 

 When these have dispersed, other sori form on the now 

 withering leaves, which contain the double-celled teleuto- 

 spores. These last are so called because they form the last 

 phase of the cycle of generations. When the teleutospores 

 germinate after resting through the winter, they give rise to 

 promycelial spores, which in their turn give rise to spermo- 

 gonia upon the Nettle again. During the past three years 

 I was unable to find the Cluster-cups on the Nettle, but 

 during this last year it was common enough. 



It is upon the structure of the teleutospore that the generic 

 classification is based. In Uromyces it consists of a single 

 cell supported upon a pedicel or delicate stalk which con- 

 nects it with the mycelium in the tissues of the host-plant. 

 In Puccinia there are two cells placed one above the other. 

 In Triphragmium there are three cells, two placed laterally 

 and one beneath, to which is attached the pedicel. In 

 Phvagmidium there are from three to five cells placed in a 

 chain. They fall away from each other as they become 

 mature, and each is capable of germinating. In Xenodochus 

 there are many cells in a row. I have counted as many as 

 twenty-one cells on one pedicel. In Mclampsora the tel- 

 eutospores are cylindrical, with polygonal sides from mutual 

 pressure. In Coleosporium they are cylindrical or clavate, and 

 consist of three or four superimposed cells, the divisions of 

 which are not always easy to see. 



Not many years ago each of these spore-forms was thought 

 to indicate a distinct species, and they were then termed — 

 JEcidium, for the Cluster-cups ; Trichobasis, for the single- 

 celled uredospore ; Uvcdo, for the single-celled teleutospore 

 with a pedicel, now termed Uromyces ; and Puccinia, for the 

 two-celled teleutospore. 



Biological research, in the way of carefully conducted 



