SEXUAL KEPRODUCTIOX. 



279 



that for the ovaries (fig, 326). (See also fig. 42.) The 

 sperms are set free by the rupture of the wall of the sperinary, 

 382. A compound spermary consists of one or more cells 

 in ^\■hich the sperms are to be produced (each corresponding 

 to a simple spermary), surrounded liy a ^^■all formed of a 

 single layer of cells (rarely more). Compound spermaries 

 are found only in Characefe, mossworts, and higher plants. 

 The spermary is a spherical or elongated sac, raised upon a 

 stalk, or sessile ; free upon the surface of the plant, or sunk 

 in a pit (fig. 311). The cell in which each sperm is formed 



Fici. 311. — .4, a longitudinal section ot a male Itead of Marchantia. ^.portion of 

 th alius ; ha. enlarged head or receptacle: a. spermaries, sunk in pits opening at o. 

 Magnified about 15 diam. B. compound spermary'. 71', its wall, surrounding the 

 immense number of minute regularly arranged sperm mother cells; st , its stalk. 

 Magnified about So diam, — After Sachs. 



is called a "sperm mother tell," Each contains a single 

 nucleus which enlarges to form the sperm of that cell (fig. 

 312). The sperms are set free by the breaking down of the 

 walls of the mother cells at about the same time that the 

 outer wall of the s|iermary is ruptured by the destruction of 

 one or more of its cells. 



The form of the vegetative body of the gametophyte in all 



