GLANDS OF AUSTRALIAN EARTHWORMS. 131 
M. victoria, M. tuberculatus, Digaster excavata, Fletcherodrilus: 
unicus, Diporocheta Copelandi, and D. Bakeri (occasionally in 
the latter they appear singly). 
In some forms there are a limited number of cells which are 
generally scattered and are similar to the gland-cells around 
them, except that they are more granular and stain very much 
more readily with methylene-blue than the others, and are there- 
fore very conspicuous, e. g. in Megascolides victorie and Fletchero- 
drilus unicus, in both of which cases they are very numerous; also 
in Digaster armifera and Diporocheta Bakert. At other times 
similarly staiming cells form a more or less distinct layer at about 
half the thickness of the wall of the gland. These cells have a 
more rounded club-shaped end than the ordinary eland-cells, 
and are very well-marked in Megascolides insularis (P1. 14. fig. 16) 
and M. hobartensis. The blood-vessels in these forms are some- 
times found in the connective-tissue immediately around the 
columnar-cell lining; but often the main blood-vessel runs down 
the side of the gland, branching there and sending in fine 
capillaries amongst the glandular cells (0.v., Pl. 15. fig. 17). The 
forms Cryptodrilus illawarre, Megascolex dorsalis, and Digaster 
excavata will be described with the lobate forms. 
In Acanthodrilus sydneyensis (Pl. 15. fig. 18) the structure of 
the three parts of each tube is as follows :—The proximal part is 
the gland-duct (fig. 18 a), which as usual is lined by columnar 
cells, the cell-outlines being rarely seen while the nucleus is large 
and distinct. The muscle-layer forming the thickness of the 
wall (¢.m.’) is composed, as in other forms, chiefly of circular fibres. 
The next part forms an intermediate region between the duct 
and the glandular part proper. The lining of non-glandular 
epithelial cells is continued back from the duct (fig. 186). The 
glandular cells (.c.) are quite distinct in appearance from those 
previously described. They are almost columnar in shape, with 
an inner slightly rounded end and a nucleus near their outer 
end, surrounded by the granular cell-contents. This is succeeded 
by the third and most distal part (fig. 18 c)—the most glandular. 
This is most striking in appearance, owing to the rapidity with 
which the cell-contents stain in methylene-blue, as may be 
seen on reference to the figure, where it is indicated by the 
depth of the shading. The facts show that the deeply- 
staining material (mucous or other secretion) is situated 
variously at the inner or outer end of the cell; and it may be 
