86 THE PSYCHIC LIFE 



when the fusion is complete, — the female cellule loses 

 its fixatory filament and the little zygote, the result of 

 the fusion, is set free. 



When the male zoospore is obliged to go a long 

 distance to reach the female zoospore, it has been 

 thought that the latter secretes a substance which acts 

 upon the male cellule as a chemical excitant and 

 which marks out for him the direction to follow. The 

 supposition is quite probable; it was suggested by 

 Strasburger, who had shown that the sperm'atozoids 

 of the Marchantia polymorphd are attracted by the 

 substance that issues from the archegonium. It will 

 only be necessary to assist at an experiment of artifi- 

 cial fecundation with fish-spawn, in order to come to 

 the same opinion. The sperm introduced into the 

 liquid preparation does not spread about homogene- 

 ously in all directions; the spermatozoids are observed 

 to whirl about the ovules in great masses; it must be 

 supposed, further, that there is some excitation of an 

 unknown nature which attracts the spermatozoid to- 

 wards the micropyle,.for this minute opening, of which 

 the diameter is scarcely that of the head of a sperma- 

 tozoid, is the only orifice through which the male ele- 

 ment can enter into the ovule to fecundate it. 



These ingenious opinions have been latterly con- 

 firmed by the very interesting experiments of M. 

 Pfeffer, professor at the University of Tubingen, upon 

 the movements of spermatozoids.* His investigations 

 had to do principally with the spermatozoids of cryp- 

 tograms. M. Pfeffer discovered that certain chemical 

 substances have the property of attracting these sper- 

 matozoids. 



* Pfefifer, Unierstuhungen nits dent botanischen Instltut zu Tjihingeny 

 Vol. I. Leipzig, 1884, p. 363. 



