i. 
STRUCTURE. 
Wirnovut some knowledge of the structure of fungi, it is scarcely 
possible to comprehend the principles of classification, or to 
appreciate the curious phenomena of polymorphism. Yet there 
is so great a variety in the structure of the different groups, 
that this subject cannot be compressed within a few paragraphs, 
neither do we think that this would be desired if practicable, 
seeing that the anatomy and physiology of plants is, in itself, 
sufficiently important and interesting to warrant a rather ex- 
tended and explicit survey. In order to impart as much prac- 
tical utility as possible to this chapter, it seems advisable to 
treat some of the most important and typical orders and sub- 
orders separately, giving prominence to the features which are 
chiefly characteristic of those sections, following the order of 
systematists as much as possible, whilst endeavouring to render 
_each section independent to a considerable extent, and complete 
in itself. Some groups naturally present more noteworthy 
features than others, and will consequently seem to receive 
more than their proportional share of attention, but this seem- 
ing inequality could scarcely have been avoided, inasmuch as 
hitherto some groups have been more closely investigated than 
_ others, are more intimately associated with other questions, or 
are more readily and satisfactorily examined under different 
aspects of their life-history. 
AGanicini.—For the structure that prevails in the order to 
which the mushroom belongs, an examination of that species 
will be almost sufficient. Here we shall at once recognize 
