364 



BOTANT. 



below, where there are two layers. The neck of the arche- 

 gonium at first contains an axial row of cells, but these 

 become dissolved and transformed into a mucilaginous mass 



just before the time of 

 fertilization. The germ- 

 cell lies in the lower 

 swollen portion of the ar- 

 chegonium ; it consists of 

 a naked rounded mass of 

 protoplasm. At the time 

 of fertilization the upper- 

 most cells of the neck of 

 the archegonium diverge 

 from one another, and 

 thus form an open chan- 

 nel to the germ-cell. 



463.— Fertilization 

 takes place in the water, 

 or in the presence of a 

 considerable amount of 

 moisture. The spermato- 

 zoids, which are produced 

 in great numbers, move 

 through the water by 

 means of their vibratile 

 cilia, and some of them 

 find their way down the 

 channels of the archego- 

 nia, where they unite their 

 substance with the germ- 

 cells. As a result of this 

 union, the germ-cell sur- 

 rounds itself with a wall 

 of cellulose, and soon un- 

 dergoes division in various 

 directions, giving rise to a 

 many-colled mass, the young sporogonium (/, /', Fig. 343, 

 A). In most Mosses the young sporogonium elongates rap- 

 idly, and while its upper end carries up the remains of 



Fiff. 243. — Development of the Bporogonium 

 of PunaTia hygr&mett'iea. A, longitudinal sec- 

 tion of the archegonium, 5, 6, shortly after fer- 

 tilization ; A, neck ; /, apirnl portion of young 

 sporogonium ; f\ basal portion of yotmg sporo- 

 gonium. B, veVtical section of a female tlower ; 

 f, young sporogonium elongating, and carrying 

 up the remains of the old archegonium, o (now 

 called the calyptra) ; h, neck of old archego- 

 nium. G, a later stage of the same. In B and 

 C the sporogonia are seen to be growing down- 

 ward into the tissues of the lealy stem A X 

 600; B and (7 much less. — ^After Sachs. 



