ig. 21. 
Fig. 
BigELow. — Development of Lepas. 
ae i 
, 18. 
. 20. 
22. 
PLATE 2. 
Sections of eggs representing stages shown in Plate 1. 
The vitelline membrane is represented in Figure 17 only. 
Formation of second polar cell. Yolk uniformly distributed in the egg, 
which is somewhat distorted into a form more than normally elongated, 
owing to pressure in the egg-lamella. 
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 6. Pronuclei approaching; they 
are usually in contact in this stage, as in Figure 20. 
From an egg fixed in mercuric chloride, showing the distribution and 
relative amount of the yolk. Early appearance of the asters (?). 
Pronuclei in contact. Same stage as that shown in Figure 6. 
Formation of first cleavage spindle. Yolk becomes eccentric, as shown 
in Figure 7. 
Beginning of metaphase of first cleavage. 
