238 RESEARCHES ON FUNGI 



From the foregoing it appears that, contrary to the view held 

 by Brefeld, the basidium of Tilletia tritici is not primitive, but rather 

 it is more highly developed than the basidium of the Hymeno- 

 mycetes and the Uredineae. Its specialisation is doubtless corre- 

 lated with the peculiar parasitic mode of life of the fungus which 

 produces it. 



A recognition of the fact that Tilletia tritici produces true basidio- 

 spores which resemble in their special form and mode of discharge 

 the basidiospores of the Hymenomycetes and the Uredineae 

 strengthens the view generally held by botanists that the Tilletiaceae 

 belong to the great group of the Basidiomycetes. 



It has already been mentioned that violent basidiospore- 

 discharge with drop-excretion takes place not only in Tilletia 

 tritici and T. laevis but also in other species of Tilletia and in Enty- 

 loma menispermi, E. lobeliae and E. linariae. Judging by the form 

 of the sterigmata (primary conidia) and of the basidiospores 

 (secondary conidia), as illustrated by Brefeld and others, it is 

 probable that violent basidiospore-discharge takes place in Neovossia 

 and possibly in some other genera of the Tilletiaceae ; but the dis- 

 covery of violent spore-discharge in Ustilago is scarcely to be 

 expected, as the sporidia in this genus are not asymmetrical in 

 form and are not situated on slender conical sterigmata. According 

 to Buller, 1 when a basidiospore is shot away with drop-excretion, 

 the sterigma acts as an organ to bring about the discharge. The 

 absence of a typical sterigma and the absence of violent basidiospore- 

 discharge seem to be correlated. 



A malt-agar plate bearing rapidly multiplying sporidia of 

 Ustilago zeae was inverted over a freshly-poured second malt-agar 

 plate in the manner shown in Fig. 119 (p. 246), but no sporidia fell 

 from the upper plate, so that no new colonies of sporidia were formed 

 in the lower plate. This experiment clearly indicates that the 

 sporidia of Ustilago zeae are not violently discharged. 



Terminology, New and Old. — In subsequent Sections, a new 



nomenclature based on the discussion in the last Section will be 



adopted. The whole product of a chlamydospore, such as that 



shown in Fig. 108 (p. 222) and in Fig. 114, A (p. 232), is conceived 



1 A. H. R. Buller, these Researches, Vol. II, 1922, p. 31. 



