196 



BOTANY 



after it is fertilized, is developed the embryo, which becomes a more 

 or less highly organized plant, the sporophyte. The latter, sooner 

 or later, gives rise to the spores, which are invariably produced 

 in tetrads, derived from the division of a common mother-cell. It 

 has lately been suggested that the spore-fruit of the Red Algae may 

 be considered as a sporophyte, but, aside from this, the nearest 

 approach to the condition prevailing among the Archegoniates is 

 that found in the genus Coleochaete, where a rudimentary sporo- 

 phyte is developed from the oospore. 



FIG. 157. Madotheca (Bellincinia) Bolanderi. Development of the archegonium 

 (X 600). C, cross-section of young archegonium. G, cross-section of the neck of 

 an older one. The others are longitudinal sections ; b, ventral canal-cell ; o, egg. 



Gametophyte. The gametophyte of the Archegoniates may be a 

 plant of large size, attaining a length of thirty to forty centimetres 

 or more in some of the larger Liverworts and Mosses ; or it may be 

 reduced to a microscopically small body composed of a few cells, as 

 in the male gametophyte of some Ferns. Whether large or small, 

 the structure of the reproductive organs is remarkably uniform. 



The Archegonium. The archegonium (Fig. 157) is usually a flask- 

 shaped body composed of many cells, instead of being a single cell 



