F. T. Brooks and A. Sharples 



69 



indicate an origin somewhat similar to that of a pycnidium, but we find 

 that the mycelium aggregates beneath the outermost layer of cells of 

 the branch, forming a kind of stroma which by growth ruptures the 



,Ob 



Fig. 7. Group of Necator spores, teased out, showing irregular size of spores, x 400. 



tissues of the host (Figs. 8, 9). The whole of this stromatic mass becomes 

 converted into spores by the separation of the cells one from the other. 

 The irregularity in the size and shape of the spores (Fig. 7) is due to 

 this peculiar method of spore formation. The dimensions of the 



Figs. 8. Section showing early stage in development of a Necator pustule: Stroma 

 forming under the outer layer of cells, x 160. 



spores are 14-20 fx x 8-10 fi. In other species of Corticium and 

 Hypochnus small sclerotia about the size of pustules of Necator are 

 produced and in Corticium salmonicolor such sclerotial aggregates may 

 have become modified into spore masses by separation of the constituent 

 cells instead of forming resting bodies. 



