214 THE BEGINNINGS OF LIFE. 



be ranged under three principal heads, which are thus 

 spoken of by the authors above cited : c ist. The 

 cell membrane and nucleus of the formative vesicles 

 convert themselves immediately into the spermatozoon, 

 2nd. The nucleus of the formative vesicles alone meta- 

 morphoses itself into the spermatozoon. 3rd. A new 

 formation, which takes place in the interior of the 

 nucleus (or immediately in the cell cavity), performs 

 the functions of a spermatozoon/ But it appears that 

 of those produced by these different methods, c the sper- 

 matozoa resulting from endogenous formation are most 

 highly developed; they are the produce of a perfectly 

 new generative process ' and it should be remarked 

 also that this mode of origination is far more frequently 

 met with than either of the others. 



We will not bring forward any further details how- 

 ever; we will say nothing concerning the mode and 

 origin of antherozoids 1 in the lower members of the 

 Vegetable Kingdom, or of the pollen grains in flowering 

 plants, since these details would, in essence, be little 

 more than a repetition of modes of origin of indepen- 

 dent units, similar to what have been already described. 

 The instances already cited, although scarcely one 

 tithe of those which might have been quoted, are 

 abundantly sufficient for our present purpose. Of them- 

 selves they almost force us to come to a conclusion 

 similar to that at which we have already arrived. The 



1 See 'Botanische Zeitung' for March 25 and April I, 1853; also 

 'Ann. des Sc. Nat.' 1852, and Lindley's 'Vegetable Kingdom,' p. 19. 



