I04 



FERN-SEED 



and other minute growths upon the fern leaf were described 

 as being the stamens, the producers of the fertilising male 

 element ; but all in vain ! No attempted demonstration 

 of such organs was successful, and, as a matter of fact, they 

 do not exist ! It was not until the nineteenth century, 

 actually within living memory, that the real history of the 

 reproduction of ferns was discovered. It was not possible 

 to ascertain the fact until the microscope had been improved 

 and the methods of study of the structure of plants 

 and animals had made vast progress and yielded a mass 

 of new knowledge. 



It was discovered in 1 844 (Nageli and Suminski) that 

 upon the under surface of the flat green prothallus which 

 develops from the fern spore, two kinds of minute warts 

 take their origin (see Fig. 8, A). The one are little volcano- 

 like protuberances, each containing a single ovule or egg- 

 cell, and may be called egg-pits (Fig. 9, d' and D) ; the 

 other kind are tiny sacs which contain liquid full of 

 actively moving spiral filaments (beset with vibrating 

 hairs or cilia), resembling in essential character the sper- 

 matozoa or motile sperm filaments of animals ; they are 

 the sperm-sacs (Fig. 9, A and A^). The excessively 

 minute microscopic motile " sperms " escape by the burst- 

 ing of the sacs, and swim through the film of water on 

 the surface of the "prothallus" (Fig. 9, B and c). When 

 one of these microscopic sperm-screws (Sp.) thus arrives 

 at one of the volcano-like egg-pits, it plunges into its 

 opening and fuses with the contained egg cell, thus fer- 

 tilising it (Fig. 9, d). It is then, and not until then, 

 that the egg cell commences to grow and divide, and 

 gives rise to the young fern plant (Fig. 8, B, d). The fern 

 plant nourishes itself and develops rapidly, whilst the little 

 green prothallus, having borne its crop of eggs and sperms, 

 withers, and is seen no more. The fern plant, on attaining 

 full size and maturity, produces, as did its grandparent, 



