BioBLOw. — Development of Lepas. 



PLATE 2. 



Sections of eggs representing stages shown in Plate 1. 

 The vitelline membrane is represented in Figure 17 only. 



Fig. 17. Formation of second polar cell. Yolk uniformly distributed in tlie ecg, 



which is somewhat distorted into a form more than normally elongated, 



owing to pressure in the egg-lamella. 

 Fig. 18. Same stage as that represented in Plate 1, Figure 4. Male and female 



pronuclei in contact. Yolk collecting at the vegetative pole. The 



pronuclei in this stage, which is characterized by the presence of a 



yolk-lobe, are often separated as in Figure 19. 

 Same stage as that shown in Figure G. Pronuclei approaching; tliey 



are usually in contact in tliis stage, as in Figure 20. 

 From an egg fixed in mercuric chloride, showing the distribution and 



relative amount of the yolk. Early api)earance of the asters {?). 



Pronuclei in contact. Same stage as tliat shown in Figure 0. 

 Formation of first cleavage spindle. Yolk becomes eccentric, as shown 



in Figure 7. 

 Beginning of metaphase of first cleavage. 



