INTRODUCTION n 



frequent sneers of cytologists and others are the outcome 

 of ignorance, in expecting from practical systematic 

 botany information that systematists do not profess to 

 furnish. , \ 



Side by side with practical systematic botany, but in 

 a separate book, every one would welcome the ideal 

 systematic arrangement of plants based on cytology, mor- 

 phology, physiology, and everything else that collectively 

 constitutes plant-life; but recent pretentious works attempt- 

 ing a diluted mixture of everything known has resulted in 

 failure. The substance is too diffuse to enable any one 

 to determine a species with certainty, much less to become 

 acquainted with its life-history. A short time ago I 

 endeavoured to trace the origin of the Basidiomycetes 

 fr.om conidial conditions of the Ascomycetes. This idea 

 was founded on morphological agreement in the two 

 groups. In a criticism on this idea Harper says that the 

 occurrence of binucleate cells in the Basidiomycetes and 

 their absence in the Ascomycetes shows that the two groups 

 are widely separated phylogenetically ; in the face of such 

 differences, resemblance of outer form and method of 

 spore-formation between conidiophores and basidia must 

 be regarded as superficial and of uncertain value, and as 

 wholly inadequate evidence for the conclusions Massee 

 wishes to draw. Quite recently, while investigating a dis- 

 ease of the cultivated mushroom caused by Hypomyces 

 perniciosum, I observed that the cells of a conidial stage 

 of the Hypomyces, known as Mycogone, were constantly 

 binucleate. In the other conidial form of the Hypomyces, 

 called Verticillium, the cells are uninucleate. 



Woronin has shown that both hyphae and conidia are 

 multinucleate in the conidial form of Sderotinia fructigena, 



