S07ne new Species of Drawida. 511 



occupying the anterior end of sacs, and I have been com- 

 j)letely unable to discover the oviducts. lu the fully mature 

 forms, tlie ventral portion of the septal mesentery forming 

 the anterior end of the egg-sac has mostly atrophied, per- 

 mitting the escape of ripe ova into the ccelomic chamber 11. 

 I cannot state with certainty how the eggs escape outside. 

 Each sac is full of granular matter, which escapes from it 

 on the rupture of the wall and comprises masses of yolk- 

 spherules. Under the microscope numerous ova in all 

 stages of maturity cau be detected in the mass of spherules, 

 Avhich obviously are reserve food of the egg as well as the 

 developing embryo. 1 have not obtained the cocoons of this 

 species, which must have a quantity of this reserve-food 

 laid up for it. 



If an egg-sac, removed from a fresh specimen dissected 

 out of water, is passed through alcohols for fixing, it is seen 

 that the wall of the sac gradually becomes transparent and 

 the volume of yolk-material really occupies about | of the 

 sac, and the rest of the space is tilled by a kind of albuminous 

 matter, which is soon dissolved. That it is an albumin can be 

 readily ascertained by the simple salt-solution test, and this 

 second class of proteinaceous substance does not belong 

 to the globulin series. I have not proceeded further in 

 the chemical analysis of the contents of the egg-sac of 

 this species of earthworm, and in microscopic structure 

 (PI. XVII. fig. 10) the wall of the vesicles comprises 

 small glandular oval cells, which form the internal lining 

 covered over by the septal mesentery. In the mass of the 

 yolk-spherules is a rich network of blood-capillaries derived 

 from the ventral and lateral longitudinal vessels. The 

 albumin must be derived from the unicellular glands, which 

 are modified cells of the ccelomic epithelium. It is an inter- 

 esting fact in the physiology of the egg-sac that a part of it 

 functions as vitellarium, and the female oiifice must become 

 considerably large for the extrusion of the eggs and the 

 contents of the vesicles. The yolk i^, however, the product 

 of the vitellin or lecithin degeneration of the cytoplasm of 

 the oogonia themselves. In the immature forms of this 

 species the teased preparations of the egg sac show only ova 

 as the principal contents of the vesicle, and the process of 

 the formation of yolk in the sac can be followed in the 

 slightly maturer worms. The nucleolus of some of the 

 oocytes disappears in the nuclear sap, and perhaps escapes 

 into the general mass of the cytoplasm, while that of 

 others destined to become mature female cells remains un- 

 affected. These modified cells increase in size, owing to a 



