II. 



STRUCTURE. 



Without 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. 



Agaeicini. — For the structure that prevails in the order to 

 which the mushroom belongs, an examination of that species 

 will be almost sufficient. Here wc shall at once recognize 



