Feb. i, i92 1 Onion Smudge 691 



three germ tubes, which are pushed out at any point on the surface. 

 Septation of the spore commonly occurs during germination. 



Perithecia^— Stevens and True (30) report the development of an 

 ascigerous form on onion sets heavily infected with Colletotrichum cir- 

 cinans and have referred the same to the new genus Cleistothecopsis. 

 The writer has never been able to prove C. circinans to be connected 

 with any ascigerous form found on onion. Stevens and True claim the 

 connection between the perithecia of Cleistothecopsis and C. (Volutella) 

 circinans on the following evidence: 



(1) they occurred on sets badly infected with the Volutella; (2) no other fungi or 

 other types of mycelium were seen to be connected with them; (3) when studied in 

 various stages of development, the typical Volutella mycelium, which offers definite 

 characters for recognition, was seen in organic connection with them, as illustrated 

 in figure 18 (1), (4) the outgrowths from the perithecia are like those of the Volutella. 



This evidence is hardly sufficient to prove that the two forms are stages 

 of the same fungus, especially since a large number of saprophytic or semi- 

 saprophytic forms very commonly occur on the dead outer scales of 

 onion bulbs and the differentiation of these from C. circinans on the basis 

 of the characters of the mycelium is sometimes very difficult. The writer 

 has, therefore, considered it advisable to use the binomial of the imper- 

 fect form until cultures from a single ascus or ascospore of the ascigerous 

 form are shown to be identical with C. circinans both as to morphological 

 characters and pathogenicity upon onion bulbs. 



TAXONOMY 



The taxonomic questions involved in this study concern first, the 

 proper position of the fungus in the present system of classification, and 

 second, the possible identity of the organism with other described species. 



Berkeley (4) in the original description of the fungus refers to the 

 fruiting body as a perithecium and places it in the genus Vermicularia, 

 giving it the name Vermicularia circinans. Thaxter's (33) description 

 implies that the fungus has an open fruiting body, but he states that 

 in the early stages of its development a "sort of membrane" extends 

 over the basidia. Miss Stoneman (32) describes a thick basal stroma 

 bearing an open fruiting body. She also suggests that the characters 

 of the fungus resemble more closely those of the genera Colletotrichum 

 and Volutella than of Vermicularia. Voglino (33), believing the 

 fruiting body to be an acervulus, which would thus place the organism 

 in the order Melanconiales, transferred the species to the genus Colletotri- 

 chum. However, he gives no report of any study of the formation of 

 the fruiting body. 



Stevens and True {30) in discussing the fungus describe a sporodochium 

 consisting — 



of a pseudoparenchymatous inner tissue covered by a continuous surface layer. . . The 

 young sporodochium eventually ruptures its covering membrane.. .In all cases the 

 conidiophores are borne upon a raised superficial base which constitutes the sporodo- 



