]yO BOTANY. 



spores and the subsequent development of the vegetative 

 filaments. 



Praetical Studies. — (as) 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. 



(J) 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. In a 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 Ihey 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, 

 TI and VII. 



Class V. Chaeace^ {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 

 Coleochsete (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 Coleochsete, 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- 



