THE CELLULAR BASIS 



B 



d 



FIG. 38. 



FIG. 



FIG. 38. OUTLINES OF THE UNFERTILIZED EGG OF A SQUID, 

 Loligo, showing the polarity and symmetry of the egg with 

 reference to the axes of the developed animal; d, dorsal; v, 

 ventral; /, left; r, right; a, anterior; p, posterior. (After 

 Watase.) 



FIG. 39. MEDIAN SECTION THROUGH EGG OF A FLY, Musca, 

 just after fertilization, showing the relations of the polarity 

 and symmetry of the egg to the axes of the developed animal; 

 the long axis of the egg corresponds to the antero-posterior 

 axis of the animal; d, dorsal; v, ventral; TO, micropyle through 

 which sperm enters the egg; g, glutinous cap over the micro- 

 pyle; r, polar bodies; p, egg and sperm nuclei; do, yolk; 

 k, peripheral layer of protoplasm; dh, vitelline membrane of 

 egg; ch, ehorion. (After Korschelt and Heider.) 



