506 FRANK E. BEDDARD. 
trates a portion of the nephridium (n.) of two consecutive seg- 
ments; the anterior nephridium—that at the bottom of the 
figure—is the end of the “ mucous gland.” WN represents the 
duct of the nephridium following this; the duct is of greater 
calibre than the tubule from which it arises, and is always, as 
is shown in the figure, made up of denser—at any rate more 
darkly staining—protoplasm in the centre. Very constantly 
radial strands of this denser layer of protoplasm immediately 
surrounding the lumen were given off, reaching the periphery. 
The funnels of the nephridia of worms belonging to stage C 
have undergone a remarkable change, illustrated in figs. 16 
and 19. The funnel is still more or less funnel-shaped—that 
is to say, it contains a lumen; but the cells composing it have 
lost their cilia, and have begun to proliferate, forming (see 
fig. 19) several layers of cells. The section ofthe nephridium 
following the funnel has nolumen. The nuclei of the cells are 
arranged alternately, now on one side, now on the other. 
Embryos just before hatching (Stage D). 
I always found it possible to tell from an examination of 
the cocoon whether the contained embryo was nearly or quite 
ready to make its way out. After washing off the earth the 
chitinous layers, particularly when the outer one had been 
peeled off, were sufficiently transparent to show the principal 
blood-vessels, and even the outline of the worm in parts. 
At this stage the worm almost entirely fills the cocoon, there 
being but little room to spare; what room there is, is occupied 
by the remains of the albuminous fluid, which has undergone 
no changes visible to the eye. This fact rendered it somewhat 
difficult to extract the embryos without injury from the scissors 
or knife employed in cutting through the cocoon. 
The embryo, just before leaving the cocoon, measures about 
two inches in length. It is of a milky-white colour, and cer- 
tain of the principal blood-vessels show up very conspicuously. 
The dorsal blood-vessels are usually visible from end to end 
of the body, and they are separated by a very considerable in- 
terval. Between them a third trunk may be frequently made 
