Figure 40. War-nek* s drawings for his work on the development 

 of gastropodan molluscs (development of a slug) 



11 — in the place of the lost membrane of the nucleus, 

 the oval light spot is seen; 



12— the yolk has the form of a globule thickened from 

 one side; the light spot is elongated; 



13 — in the thickened side of the yolk the beginning of 

 the formation of a fissure is seen; the light spot becomes 

 more elongated; 



14— the fissure twists the yolk diagonally; the light 

 spot is extended; 



15 — the fissure envelops half of the periphery of the 

 yolk; at the ventral pole is the beginning of the formation 

 of a fissure in the form of a deepening; 



16 — deeper twisting of the yolk, viewed from the dorsal 

 pole; 



17 — the yolk globules are completely separated from each 

 other; the light spot is hardly noticeable; 



26 — the nuclei are deprived of membranes and begin to 

 extend in a direction perpendicular to the longitudinal pole; 



26a — still more distinct changes, the beginning of which 

 is illustrated in Drawing 26; 



29a— the stage of four yolk globules. 



550 



