SEXUAL REPRODUCTION. 



285 



387. The egg. — The egg is larger than the sperm, usually 

 non-motile and fixed. In aquatic algre the egg is sometimes 



Fig. 323. — Diagram of a lun^iti.iuni.il >cl tii.n of a pistil with one ovule, s, stigma, on 

 which are lodged two pollen grains ; ; . style ; a, 01 ulary ; /. >/, at, //, together form 



the Ovule ; /, stalk ; //, niega>poi,mgium ; ,; /', outer integument ; //. inner integument ; 

 r. megaspure. will) nucleus which is to develop later into vegetative part ol female 

 plant; i, antipodal cells ; k, egg, and near by another ; m, micropyle j /, polli 



entering it and reaching egg. -Alter I.ucrssen. 



free, escaping from the ovary in which it is produced, and 

 being fertilized by the sperms, which arc likewise tree in the 

 water, as in Fucus (fig. 324). Sometimes the egg itself is 

 ciliatedand hence motile. In these cases it meets the motile 

 sperms in the water. 



The form of the egg is much less variable than that of the 



