276 



EMBRYOGENY IN MOSSES AND LIVERWOETS. 



bearing stalk is produced. Around the orifice of the canal leading to 

 the germ-cell and rudimentary spore-capsule are seen numerous sper- 

 matozoids, s s, which have been discharged from the antheridia. 



Fig. 490. 



Fig. 491. 



Fig. 492. 



In Mosses there is a free germ-cell (embryonal cell) at the base of 

 the archegonium. Spermatozoids, from the sperm-cells of the anthe- 

 ridium (fig. 494), reach it, and then it is developed into the sporangium 

 or spore-case (fig. 495), which is the second generation of the plant. 

 The spores produce the leafy plant, bearing antheridia and archegonia. 

 In fig. 496 is shown the conferyoid prothallium, p, of a Moss pro- 

 duced from the spore, and bearing buds, a b, which produce leafy 

 individuals with organs of reproduction. After the contact of these 

 organs, a single ceU of the archegonium is developed into the com- 

 plete fruit (theca or sporangium), which is often borne upon a stalk 

 (fig. 495). The complete fruit contains spores, which, when 

 discharged, again develop the foliaceous plant. 



In leafy Mosses and in Jungermanniae there is also an increase 

 by buds. The confervoid filament produced by the spore gives origin 

 to a number of buds (fig. 496), whence leafy stems proceed, and 



Fig. 490. Antheridiiun of Liverwort {Mcvrcliantia) discharging its sperm-cells, that is, 

 cells containing spermatozoids. Fig. 491. Thallus of Liverwort (Ma/rchantia polyvwrpha), 

 bearing a stallced fruit, a, which is the product of the impregnated cell of the archegonium. 

 The receptacle at the apex of the stalk bears on its under surface sporangia containing 

 spores and elaters. The spores, when germinating, produce a thallus, on which antheridia 

 and archegonia are formed. Fig. 492. Pistillidium or archegonium of Liverwort (Ma/r~ 

 clioMtia), containing in its interior a cell, which is impregnated by the spermatozoids of the 

 antheridium. 



