331 



Carolina thirty-eight edible species of Agaricus, eleven of Boletus, nine 

 of Polyporus, seven of Hydnum, and thirteen of Clavaria. 



(/) Pvlyporites Bowmani of the Carboniferous is the oldest known 

 member of this order. In the Tertiary the modern genera Lemites, 

 Polyporus, and Ilyilnum are represented. 



V. CLASS CHARACE^;. 



430. In this small group of chlorophyll-bearing aquatic 

 plants the sexual organs, while still preserving essentially 

 the structure common to other Carposporeae, present con- 

 siderable modifications. The female organ consists of a 

 " central cell " or carpogonium (Fig. 227, c), which is the 

 terminal one of a row of cells (a, 

 b, c, Fig. 227). From the basal 

 cells there grow out five elongat- 

 ed cells (d, d, Fig. 227), which 

 take an upward direction and 

 surround the carpogonium ; they 

 cohere laterally, so as to form a 

 complete covering. The top of 

 this enveloping sheath becomes 

 modified into a projecting crown 

 of five (or by division ten) more 

 or less divergent cells (i, i, Fig. 

 227 B; and c, Fig. 228, A). 

 Finally, the whole envelope be- 

 comes twisted, so that each en- 

 veloping cell passes spirally around the carpogonium (A, 

 JFig. 228). 



431. The male organ, or antheridium, consists of a 

 globular body composed externally of eight spherically tri- 

 angular cells, culled the shields, which are united by their 

 zigzag margins (a, Fig. 228, A). From the centre of each 

 shield there projects into the cavity of the antheridium a 

 cylindrical cell (mannbrium), and upon each of these there 

 are borne large numbers (twenty to twenty-five) of long 

 coiled and bent many-celled filaments (b and c, Fig. 229). 

 Each filament contains from one to two hundred cells, 



Fig. 227. Development of tUe 

 carpogonium of NittUa .flaellis, 

 shown in vertical section, partly dia- 

 grammatic. A, very early *tage ; 



c, the central cell supported upon 

 the small nodal cell, b. and the 

 larger cell, a; d, d, rudimentary 

 enveloping cells. B, the same some- 

 what later the enveloping cells, 



d, d, have almost completely en- 

 closed the centra cell, c; i. i. cells 

 which form a crown upon the en- 

 veloping cells, x 300. After Sachs. 



