FIG. 503. Fertilization of the OL r ir of a round-worm (Ascarifs mefjaloceplttila} : A, the ends 

 u-i-ntrosomes) of the spindle formed. B, the spindle completed; ./>, sperm-nucleus, with its 

 chromosomes; ei, egg-nucleus ; p, polar bodies. After Boveri, from Field's liertwig. 



a 



m 



FIG. 493. Eggs of Corixa : .4, early stage before formation of the embryo, from oue side. B, the 

 same viewed in the plane of symmetry. C. the embryo in its final position ; a, anterior, j>, posterior, 

 end; I, left, r, right, r. ventral, <7, dorsal, aspect. (The letters refer to the Jinal portion of the 

 embryo, which is nearly diametrically opposite to that in which it first develops) ; in, micropyle ; 

 p, pedicle. After Metschnikoff, from Wilson. 



