126 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
although generally regarded as Basidiomycetes, are so far removed 
from the Hymenomycetes under discussion that they will not be 
extensively considered in this paper. Our acquaintance with other 
divisions of the Basidiomycetes is much more imperfect. It is true 
that we have a general conception of the course of development in 
the majority of genera, but in the case of very few species do we as 
yet possess a sufficiently minute knowledge, based on cultural study, 
to permit a clear understanding of all portions of the life history, 
particularly the occurrence and importance of secondary methods 
of reproduction. This is especially true of the Hymenomycetes. 
Although the existence of secondary spore forms has been reported 
in many species of this group, the descriptions of the alleged spores, 
in many instances, are very brief and inaccurate, and the necessary 
illustrations either indefinite or wanting. Moreover, few of the writers 
who report these conidia have attempted to germinate them and to 
obtain cultural knowledge of their nature and importance. 
Owing to the need of further investigation concerning the life 
histories of Basidiomycetes, the writer has undertaken, at the sugges¬ 
tion of Professor Roland Thaxter, a cultural study of certain Hymeno¬ 
mycetes, giving especial attention to woody and encrusting species. 
The primary object of this research has been to obtain further knowl¬ 
edge of polymorphism in this group. The investigation was begun 
in the Cryptogamic laboratories of Harvard university, and com¬ 
pleted in the botanical laboratory of Dartmouth college. 
The writer takes pleasure in acknowledging, at this point, his in¬ 
debtedness to those who have assisted him in the prosecution of this 
research: to Professor Thaxter, especially, under whose immediate 
supervision the first part of the work was accomplished, for his con¬ 
stant advice and encouragement, and for his assistance in obtaining 
a portion of the material; to Professor W. G. Farlow for many helpful 
suggestions at the time of completing the work and for the use of his 
herbarium and of a number of papers from his private library; to 
Professor E. C. Jeffrey for assistance in preparing the photomicro¬ 
graphs; to Professor E. A. Burt for naming a large number of the 
species studied; to Dr. G. P. Clinton and Mr. A. H. Chivers for the 
contribution of basidiomycetous bulbils. 
Before recording the results of these studies it will be well briefly 
to review our present knowledge of the nature and extent of poly¬ 
morphism among the Basidiomycetes. 
