338 



SENESCENCE AND REJUVENESCENCE 



(pp. 317-18) show the female gametes in some of the algae and 

 fungi. The development of the female cell in the liverwort Riccia 



162 



166 



167 



FIGS. 162-167. Some peculiar forms of spermatozoa from the lower inverte- 

 brates: Fig. 162, Plagiostomum, a turbellarian (from Bohmig, '90); Fig. 163, Castroda, 

 a turbellarian (from Luther, '04); Fig. 164, Mesostomum, a turbellarian (from Luther, 

 '04); Fig. 165, Ascaris megalocephala, nematode worm (from Scheben, '05); Figs. 166, 

 167, the two forms of spermatozoa in Paludina, a snail (from Meres, '03). 



is outlined in Figs. 133-39. Fig. 173 shows the archegonium of the 

 fern Nephrodium, containing the large egg; Fig. 174 is the fertilized 



