180 BOTANY. 
spores and the subsequent development of the vegetative - 
filaments. 
Practical Studies.—(a) Collect a few toadstools in various stages 
of development, securing at the same time some of the subterranean 
vegetative filaments. Note the appearance of the young spore- 
fruits, and how they develop into the mature toadstool. = 
(0) Select a mature (but not old) spore-fruit with dark-colored 
spores, cut away the stem, and place the top (pileus) on a sheet of 
white paper, with the gills down. Ina few hours many spores will 
be found to have dropped from the gills upon the paper. 
(c) Examine the minute structure of various parts of the spore- 
fruit and the vegetative filaments, and observe that they are com- 
posed of rows of cylindrical colorless cells joined end to end. 
(d) Make very thin cross-sections of several of the gills and care- 
fully mount in water or alcohol. Note the layer of spore-bearing 
cells (hymenium), with spores borne upon little stalks, as in Fig. 98, 
VI and VII. ‘ 
Crass V. Cnaraces (the Stoneworts). 
376. The plants of this class are small green aquatics 
with jointed stems bearing whorls of leaves (Fig. 99). Both 
stems and leaves are very simple, being often no more than 
a row of cells, but sometimes a cylindrical mass of cells. 
The sexual organs occur upon the leaves. They consist of 
an ovoid carpogone and a globular antherid, which are 
‘barely visible to the naked eye. 
377. The carpogone (Fig. 100, s) is a single cell, as in 
Coleochete (p. 150), which soon becomes covered by the 
growth of a layer of cells from below. This covering, 
which here develops before fertilization, is homologous with 
the protective covering which in Coleochete, Red Sea- 
weeds, Blights, etc., forms after fertilization has taken 
place. 
378. The antherids (Fig. 100, a) are globular many-celled 
bodies, in the interior of which certain cells produce an- 
