A MOSS 



89 



small independent plant. Between the antherids are short, 

 hair-like rows of cells (Fig. 44, C), the end cell of each row 

 being larger than the others. Similar structures are found 

 also in the clusters of archegones, but the end cells of these 

 sterile hairs are no larger than the other cells. 



117. Formation of Gametes. — An archegone (Fig. 44, A) is a 

 long, many-celled organ in whose basal part is a single female gamete, 

 here called an egg. Above the egg is a long narrow neck, surrounding 

 a canal filled with a thick, sticky liquid, which leads from the egg to 

 the open end of the neck. An antherid (Fig. 44, B) has the shape of 

 a rather slender sac. Its outer part is composed of a. layer of flat 



Fig. 45. — A, an antherozoid just escaped from the antherid. B, a swim- 

 ming antherozoid, freed from the surroimding sticky substance. 



cells; inside are produced many hundreds, perhaps thousands, of 

 antherozoids (Fig. 45), which are very small male gametes, each with 

 a slender body and two long vibrating hairs. If a drop of water is 

 placed upon a male head, the antherids that contain mature anthero- 

 zoids burst, and the mass of antherozoids oozes out into the water. 

 Each one can be seen moving about within a drop of a clear Hquid 

 which is enclosed in a denser, sticky substance. In time this sticky 

 substance is dissolved, and the antherozoids swim about freely in the 

 water. 



118. Union of the Gametes. — Since an antherid bursts only when 

 it is moistened, the antherozoids are most likely to escape at the time 

 of a rain, or possibly of a heavy dew. There must be water about 

 the archegone also if an antherozoid is to swim to the archegone and 

 enter its neck. When, as in Funaria, eggs and antherozoids are pro- 

 duced on distinct branches, some outside agency must carry the an- 

 therozoids to the female head. Probably they are carried often by 

 the splashing of raindrops from branch to branch or from plant to 



