^278 MOSSES AND FERNS chap. 



longitudinal wall, and each of the resulting cells is further 

 divided by a periclinal wall, so that the antheridium consists of 

 four peripheral cells and two central ones. The latter finally 

 divide again, by vertical walls, making four central cells, which 

 become at once the sperm cells. According to Belajeff^ the 

 walls of the peripheral cells become dissolved finally, so that the 

 sperm cells float free within the spore cavity. Each sperm cell 

 forms a single coiled spermatozoid, which is more slender than 

 those of Marattia, but like them is multiciliate. 



The macrospores are very many times larger than the 

 microspores, and are of the tetrahedral type instead of bilateral. 

 They are nearly globular in form and show plainly the three 

 converging ridges on the ventral surface. If the fresh spore is 

 crushed in water, its contents appear milky, and microscopic 

 examination reveals numerous oil -drops and some starch- 

 granules, mingled with roundish bodies of albuminous nature. 

 The latter absorb water and swell up so that they look like free 

 cells. 



The wall of the spore is very thick. The perinium is thick 

 and transparent in appearance, and in the species under 

 consideration provided with short recurved spinules. The 

 interior, in microtome sections, is filled with coarsely granular 

 cytoplasm, which often appears spongy, owing no doubt to the 

 dissolving out of the oil. Scattered through the cytoplasm are 

 round starch-granules with a central hilum. The large nucleus 

 lies in the basal part of the spore. ^ It is broadly oval in outline, 

 and the cytoplasm immediately about it is nearly free from 

 large granules. Before germination begins there are few 

 chromosomes, and the nucleolus does not stain readily. 



After the spores have lain a few days in water, the nucleus 

 increases in size, and then the nucleolus stains very intensely 

 and the chromosomes become more conspicuous. The nucleus 

 divides while still in its original position, and undergoes division 

 in the usual way. A very evident cell plate is formed in the 

 equator of the nuclear figure (Fig. 146, A), but no cell wall is 

 found, and the result of the division is two large free nuclei. 

 The next youngest stage observed (Fig. 146, B) had four free 

 nuclei, which now had moved to the ventral side of the spore. 



^ Belajeff (i), p. 797. 



^ Fanner {Annals of Botany, December 1 890) states that in /. lacustris the 

 nucleus lies near the apex of the spore. 



