BRYOPHYTA. 



89 



a number of irregular lobes that curl back and allow the mass of sperm 

 cells to escape. The spermatozoids, which are derived principally from 

 the nucleus of the sperm cells (53, D) are so small as to make a satis- 

 factory examination possible only with very powerful lenses. The ripe 

 spermatozoid is coiled in a flat spiral (53, E), and has two excessively 

 delicate cilia, visible only under the most favorable circumstances. 



The female organ in the bryophytes is called an "archegonium," and 

 differs considerably from anything we have yet studied, but recalls 

 somewhat the structure of the oogonium of Cham. They are found in 



C 



FIG. 54. A-D, development of the archegonium of Madotheca. B, surface 

 view, the others in optical section, o, egg cell, x 150. E, base of a fertilized 

 archegonium, containing a young embryo (em.), x 150. F, margin of 

 one of the leaves surrounding the archegonia. G, young sporogonium still 

 surrounded by the much enlarged base of the archegonium. h, neck of the 

 archegonium. ar. abortive archegonia, x 12. H, short branch containing 

 the young sporogonium, x 4. 



groups, contained in little bud- like branches (54, H). In order to study 

 them, a plant should be chosen that has numbers of such buds, and the 

 smallest that can be found should be used. Those containing the young 

 archegonia are very small ; but after one has been fertilized, the leaves 

 enclosing it grow much larger, and the bud becomes quite conspicuous, 

 being surrounded by two or three comparatively large leaves. By dissect- 

 ing the young buds, archegonia in all stages of growth may be found. 



When very young the archegonium is composed of an axial row of three 

 cells, surrounded by a single outer layer of cells, the upper ones forming 

 five or six regular rows, which are somewhat twisted (Fig. 54, A, B). As 

 it becomes older, the lower part enlarges slightly, the whole looking some- 

 thing like a long-necked flask (C, D). The centre of the neck is occupied 



