PACIFIC COAST OLIGOCH ATA. 149 
body-wall passes straight through the ccelomic cavity to the anterior septa, which they 
pierce immediately at the base of the ovaries and testes (fig. 78). A double lumen 
is seen only after it passes posteriorly to the ovary. The rosettes are not large, 
but thick with a wide base; the latter is furnished, where it passes through the sep- 
tum, with several small sac-like glands, each with a distinct lumen, which I followed 
through the muscular layer of the spermduct and which I suppose empties into the 
neck of the rosette (fig. 79). The rosettes are not enclosed in the sperm-sacs. 
Sperm-sacs. The three pairs of sperm-sacs are racemose, but not exceedingly 
so. There are four or five large lobes of globular shape seen in every section sus- 
pended from the septum and on the under side of the intestine, though somewhat 
projecting above it. The two anterior sperm-sacs in x and xi are smaller than the 
posterior one in xii, the one in x being the smallest of the three pairs. Those in 
x and xi are suspended from the anterior septum separating x/xi and xi/xii. Of the 
position of the posterior sperm-sacs I am uncertain, but it appears suspended from 
the posterior septum, the one separating xii/xiii, as far as I can judge from a eross- 
section. 
Spermatogonia. In the two anterior sperm-sacs the spermatogonia offered 
nothing peculiar as regards the development of the spermatozoa. There is in each 
sperm-sac a large central zone of peculiar cells, staining differently. They re situ- 
ated very close together, and possessed in my preparation rather shrunken nuclei 
(figs. 63 and 75). This zone exists in all the various sperm-saes in the anterior as 
well as in the posterior ones. The development of the spermatozoa in the two an- 
terior pairs appeared entirely normal, the spermatogonia possessing the same form as 
in other species, the large nuclei standing out freely like beads above the wall. But 
in the posterior sperm-sacs the spermatogonia, one and all, looked quite differently. 
They were here of many varying sizes, some small, some enormously large, and the 
nuclei, instead of standing out from the wall of the spermatogonium, were always 
bunched in the center, or strung across it as a central band (75). In other spermat- 
ogonia the nuclei were arranged as ina ring along the cell walls, but without pushing 
out. When the nuclei were in the center there appeared always a row of large and 
small vacuoles along the cell-wall. I find two sizes of nuclei, the smaller being al- 
ways less in number, and about four times smaller than the large nuclei. When 
counter-stained with orange, the larger nuclei give quickly up part of their heema- 
toxylon, the smaller ones giving it up slowly and not at all. The eytoplasma of the 
spermatogonia presented a very strong polarity as regards its position, it being always 
massed towards the cell-wall nearest the central germinative area (fig. 63). A some- 
what similar-process of developing spermatogonia have been described by Vernon in 
the sperm cells of Bombyx. The central germinative cell in Bombyx appears to 
correspond with the central area or cell agglomeration in Aleodrilus, but I haye seen 
no such budding out of the germ cells as figured by Vernon, but this may depend 
on the insufficient material at my command. 
A large number of similar spermatogonia were found in very large numbers 
in nearly all the anterior somites, either loose in the ccelomic cavity, or in a 
