THE GAMETES IN PLANTS AND ANIMALS 



335 



i6i, and 166 show more or less "typical," fully developed 

 spermatozoa from various invertebrate and vertebrate species, and 



Figs. 148-153. — Male gametes of various plants: Fig. 148, Sphaerocarpus ter- 

 restris, a livenvort (from Land, unpublished); Fig. 149, Equisetum (from Sharp, '12); 

 Fig. 150, Nephrodkim, a fern (from Yamanouchi, '08); Fig. 151, Zamia, a cycad (from 

 Webber, '01); Fig. 152, Helianthus, sunflower (from Nawaschin, '00); Fig. 153, Sil- 

 phium (from Merrell, '00). 



in Figs. 158-61 four developmental stages of the guinea-pig sperma- 

 tozoon are given. A few of the aberrant spermatozoan forms 

 among animals are shown in Figs. 162-72. Figs. 162-64 are from 



