THE MUSHROOM DIVISION 503 
Hal) 
Ai 
RSS 
A, vertical section through part of cap (h) 
Fig. 331.—Field Mushroom. 
at right angles to gills (/), slightly enlarged. J, cross-section through 
a gill, showing the mass of hyphe (f) continuous with that of the cap, 
the spore-bearing layer or hymenium (hy), and the layer (sh) from 
which it developes. C, a part of B (282), showing the development 
of dust-spores (s’—s’’’’) upon the tip of projections from swollen hypha- 
tips or basidia, and other swollen tips (paraphyses, q) which form a 
large part of the hymenium but do not produce spores. (Sachs.) 
The possession of basidia characterizes the class, in which, more- 
over, sporangia are entirely lacking and scarcely a trace of any 
sexual organ has been found. | 
184. The mushroom division, fungi in general, are most 
fittingly named after a type which has departed as far as 
possible from the holophytic condition. 
In trying to conceive by what course the higher fungi have evolved, 
naturalists encounter a peculiar difficulty, for although alge of 
some sort are presumably the starting point of all, the hysterophytic 
mode of life soon obliterates almost every peculiarity characterizing 
