THE SPERMATOZOON 



107 



to the spermatozoon. The spermatozoids are in f^^eneral less highly 

 differentiated than spermatozoa, and often show a distinct resemblance 

 to the asexual swarmers or zo5spores so common in the lower plants 

 (Figs. 52, 53). They differ in two respects from animal spermatozoa; 

 first in possessing not one but two or several flagella ; second, in the 

 fact that these are 

 attached as a rule not 

 to the end of the cell, 

 but on the side. In 

 the lower forms plas- 

 tids are present in 

 the form of chromato- 

 phores, one of which 

 may be differentiated 

 into a red " eye-spot,' 

 as in Volvox and 

 Fuais (Figs. 41, 53, 

 A\ and they may 

 even contain contrac- 

 tile vacuoles {Volvox) ; 

 but both these struct- 

 ures are wanting in 

 the higher forms. 

 These consist only of 

 a nucleus with a very 

 small amount of cyto- 

 plasm, and have typi- 

 cally a spiral form. 

 In C/iara, where their 

 structure and devel- 

 opment have recently 

 been carefully studied 

 by Belajeff, the sper- 

 matozoids have an 

 elongated spiral form 



Fig. 



53. —Spermatozoids of plants. [A, B, C, E, after 

 GUIGNARD; D, F, after StraSBURGER.] 



A. Of an alga {Fuciis) ; a red chromaiophore at the right 

 of the nucleus. B. Liverwort (Pellia). C. Moss (Spha^nnim). 

 D. MarsiUa. E. Yt^rn {Aiiglopteris). F. Ysm, Phegopferis {\.\\& 

 nucleus dark). 



with two long flagella 

 attached near the 

 pointed end which is 

 directed forwards in swimming (Fig. 52). The main body of the 

 spermatozoid is occupied by a dense, apparently homogeneous nu- 

 cleus surrounded by a very delicate layer of cytoplasm. Behind the 

 nucleus lies a granular mass of cytoplasm, forming one end of the 

 cell, while in front is a slender cytoplasmic tip to which the flagella 

 are attachtd. Nearly similar spermatozoids occur in the liverworts 



