REPRODUCTIVE CELLS. 



135 



[This process of maturation resembles that occurring in 

 the macrospore of the heterosporous Pteridophyta (Marsilea, 

 Salvinia), qua vide where oogonia (= archegonia) arise upon 

 a special female prothallium produced in that spore: see, 

 however, " Homology," at end of chapter.] 



\ I 



Fig. 103. — Three Archegonia at the Apex of the Emeryo-sac of 

 Pinus. — ar, Archegonium ; in the left-hand one an ooaphere with its 

 nucleus is present : the middle one shows at its lower end signs of 

 division ; end, endosperm (prothallium) ; c, canal of an archegonium • 

 pt, pollen-tube. ' 



c. Fertilisation and Subsequent Changes (Pinus). — The process 

 of fertilisation consists essentially in the fusion of a generative 



