12 TEXT-BOOK OF FUNGI 



better known as Afoniliafructigena. In Sclerotinia aucupariae, 

 an allied species, the same author shows that the cells of both 

 hyphae and conidia of its conidial form are uninucleate. 



This discrepancy in the number of nuclei in the cells 

 of closely allied species does not tend to confirm their 

 value in indicating either affinity or descent. On this 

 point, however, I am not inclined to be dogmatic. The 

 fact remains that binucleate cells are present in the 

 Ascomycetes. 



These remarks must not be interpreted as indicating that 

 cytological evidence is not of value; their object is to 

 show the abuse of such evidence. It is obvious in some 

 instances that the paramount importance attached to 

 cytology by its advocates is simply because cytology is 

 the only branch of mycology with which they are familiar. 



Specialists in the Uredineae have, during late years, 

 produced good work in the correlation of numerous hither- 

 to isolated forms, the results of which are of great value 

 both from a scientific and an economic standpoint. 

 Heteroecism, however, is not confined to the Uredineae ; 

 Woronin has indicated its existence in the Ascomycetes. 

 The ascospores of Sclerotinia heteroica are carried by wind 

 on to the young leaves of Vaccinium uliginosum, where they 

 form a mycelium which produces conidia a few weeks later. 

 These conidia are again conveyed by wind or insects to 

 the stigmas of Ledum palustre. The germ-tubes of several 

 conidia fuse to form a single stout hypha, which passes 

 down the style and forms mycelium in the ovary, that 

 results in the formation of a sclerotium. This sclerotium 

 produces the ascigerous form of fruit the following season. 

 The importance of this discovery turns on the probability 

 that many of the forms included under ' fungi imperfecti ' 



