DEVELOPMENTAL HISTORY OF THE MOLLUSCA. 47 
Fig. 9. Transverse section of an egg not quite so far advanced. The nuclei of the cells 
ig. 18. 
Fig. 
Fig. 
Fig. 
ig. 10. 
sd. 
bas 
; he 
. 14. 
ig. 15. 
16. 
ee 
19. 
20. 
21. 
of the inner capsular membrane are given in the upper part of the figure. 
Letters as in fig. 8. Actual section. 
Longitudinal section of a full-sized ovarian egg of Sepia. The process of 
absorption of the inner capsular membrane and its ridges has advanced to 
some extent. The germinal vesicle has also disappeared. 
xv. Dwindled inner capsular membrane, forming the periphery of the inner 
capsule. Other letters as in fig. 8. Actual section. 
Portion of a transverse section of an egg in the same stage of growth. 
Letters as in fig. 10. Actual section. 
Transverse section of a completely formed egg of Sepia, magnified only four 
diameters, to show the existence in the yelk of three concentric zones of 
differing density. Actual section. 
Portion of a ripe ovary of Sepia, showing ova of various sizes and some empty 
capsules, ¢, ¢. 
One of the smallest egg-cells observed in the ovary of Sepia at breeding-time. 
Cells like connective-tissue corpuscles are seen to be grouped so as to form 
the capsule of the egg. Optical section. 
An egg somewhat further advanced—the capsule now definitely formed. 
Optical section. 
The capsule has become pedunculate; but as yet there is no blood-vessel 
traversing it. 
ic. Inner, and 
oc. Outer capsular membranes. Optical section. 
A more advanced egg, drawn in the fresh state. By its side is a very small 
egg-cell. Letters as before. Optical section. 
The separation between inner and outer capsules and the characters of their 
respective corpuscles have become definite. ‘The blood-vessels (dv) in the 
stalk of the egg-capsule have developed. Other letters as before. Optical 
section. 
Actual arrangement of blood-vessels between the inner and outer capsular 
membranes of a nearly fully-grown egg, as seen from the peduncular pole. 
The artery and vein are seen applying themselves at the point of attachment 
of the egg-stalk to the capsular surface, and spreading out in large longitu- 
dinal trunks connected by a network of smaller vessels transversely. 
The peduncle of the egg drawn in fig. 6, in optical section, so as to show the 
wall and contents of the blood-vessel (dv), the outer capsule (oc), and the 
cells of the inner capsule—. e. not in section, but focused so as to show them 
lying in one plane. 
Portion of an empty capsule in the fresh state from the ovary of Sepia, showing 
blood-vessel and yellow degeneration of capsular cells. 
