THE GAMETES IN PLANTS AND ANIMALS 



335 



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

 spermatozoa from various invertebrate and vertebrate species, and 



151 



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

 restris, a liverwort (from Land, unpublished); Fig. 149, Equisetum (from Sharp, '12); 

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

 Webber, '01); Fig. 152, Helianthus, sunflower (from Nawaschin, 'oo); Fig. 153, 5*7- 

 (from Merrell, 'oo). 



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 



