A GENERAL SURVEY 21 



the emergence of the male bodies [spennatozoids) 

 from the antheridium, and their attraction to 

 the female organs (archegonia) of an adjoining 

 prothallus. Thus in the case of the SelagineUa 

 the process of fertilisation goes on in independent 

 organisms which are leading an existence apart 

 from the parent plant. This may seem to be a 

 very different method from that which is to 

 be noticed in the fir, where there is no obvious 

 formation of prothalli. Actually, however, it can 

 be shown that the prothallus and its male organ, 

 the antheridium, which arises from the micro- 

 spore, is not really very distinct from the group 

 of cells which are present in the grain of pollen 

 in the cone plant. The spennatozoids of the 

 SelagineUa may be considered to be equivalent 

 to the generative cells to be observed in the 

 pollen. 



In the same way we may compare the 

 prothallus of the SelagineUa which bears the 

 female organs, the archegonia. The endo- 

 sperm (the part which encloses the embryo) 

 of the cone plant may be said to equal the 

 prothallus of the Club Moss. The female organs, 

 with the speciaUsed ceUs which they produce, 

 are almost identical in both plants. So that, 



