202 RESEARCHES ON FUNGI 



Lohwag x has argued that, if secondary spores are discharged by 

 the drop-excretion mechanism, this proves that the drop-excretion 

 mechanism occurs not only in basidiospores but also in ordinary 

 conidia. This argument I am unable to accept. I regard a secondary 

 spore as a basidiospore and not as a special form of conidium. 2 

 Secondary spores, as Brefeld rightly says, are " exceptional struc- 

 tures or in reality only a Zwischenstation on the way to true germina- 

 tion." Sappin-Trouffy and Colley both refer to secondary spores 

 produced from sporidia in the Uredineae as secondary sporidia. In 

 future, I propose to call the secondary spores of both Hymenomycetes 

 and Uredineae secondary basidiospores. 



Summing up the above discussion of the fate of the various kinds 

 of spores produced by the Hymenomycetes and the Uredineae. it is 

 clear that the drop-excretion mode of spore-discharge is restricted 

 to the basidiospores and does not occur in connexion with any other 

 kind of spore. This conclusion tends to strengthen the view that 

 in Sporobolomyces the conidium is phylogenetically a basidiospore 

 and not an ordinary conidium. 



Miss Macrae and I observed that, when a conidium of Sporobo- 

 lomyces roseus falls on to exhausted malt-agar, it frequently pro- 

 duces an aerial sterigma and a secondary conidium which is just 

 like the parent conidium in its form and mode of discharge (Figs. 93 

 and 97, pp. 187 and 193). This process of secondary-conidium 

 formation resembles the process of secondary-basidiospore forma- 

 tion in the Hymenomycetes, the Uredineae, and Tilletia ; and this 

 fact may be taken as further evidence that the conidia of Sporo- 

 bolomyces phylogenetically are true basidiospores. 



1 H. Lohwag, " Sporobolomyces — kein Basidiomyzet," Annates Mycologici, 

 Vol. XXIV, 1926, p. 201. 



2 Lohwag (loc. cit.) says that, assuming that secondary spores are discharged by 

 the drop -excretion mechanism : " Denn, Basidiosporen, die an einem Sterigma 

 wieder Basidiosporen abschnuren, wurden in analoger Schlussweise dazu fiihren, 

 dass die jetzigen Basidiosporen die Basidien bzw. die Sterigmen der Sekundarkonidien 

 sind." If one assumes, as Lohwag evidently does, that only a basidium can pro- 

 duce a basidiospore, then, of course, it is impossible to regard a secondary spore as a 

 basidiospore without confusion in ideas and terminology ; but, if one does not make 

 that assumption, then one has no difficulty in regarding a secondary spore, which 

 exactly resembles in outer form, nuclear content, and mode of discharge the basidio- 

 spore from which it has been formed, as exactly what it looks like, namely, a 

 basidiospore. 



