GLANDS OF AUSTRALIAN EARTHWORMS. 133 
gland-duct are also to be found in this connective-tissue. The 
latter are lined by a well-marked cubical epithelium surrounded 
by a few muscle-fibres. Hach lobule has typically a radiate 
appearance, with sometimes a small lacuna or space (J.1.) in its 
centre, e.g. in Megascolex Dendyi, M. tasmanica, and M. dorsalis, 
which is however generally obliterated by the approximation 
of the inner ends of the cells. In very rare cases, a communi- 
cation can be traced between it and one of the terminal branches 
of the gland-duct (as in fig. 20). In no instance was an epithelium 
of any kind to be seen around the central lacuna. The cells 
forming the substance of the lobules are of three kinds :—(i) The 
chief are those having the appearance of ordinary long narrow 
gland-cells with swollen outer ends, which contain large darkly- 
staining granules with generally a nucleus. (ii) The second 
group of cells are a number which appear to be quite empty and 
rarely showing a nucleus: they are probably simply cells which 
have discharged their contents into the gland-duct. (iii) Here 
again in some forms, e.g. Megascolex Hrenchi and Digaster 
queenslandica, we find the cells seen in the tubular forms which 
stain readily with methylene-blue, and which serve here to 
accentuate the radiate appearance of the lobules, especially in 
D. queenslandica. The inner ends of the first and second sets, 
and of the third when present, come together in the centre 
of the lobule and evidently pour their contents into the gland- 
duct by means of the lacuna and duct before mentioned. 
As before stated, the three species Cryptodrilus illawarre, 
Megascolex dorsalis, and Digaster excavata, are intermediate 
forms between the tubular and lobate glands. In the two 
former there is a well-marked central duct running the whole 
length of the gland (fig. 24), and lined by columnar cells with a 
cuticular edge as usual in tubular forms. The main mass of the 
gland, however, is made up of lobules sometimes indistinctly 
separated from one another. In the centre of each lobule is a 
lacuna, which is connected with the central duct by a complex 
series of branches. Blood-sinuses run between the lobules. In 
Digaster excavata the branching is very much less complicated. 
There is but one series of branches from the central tube to form 
lobules, which are sometimes but seven or eight in number in the 
circumference of the gland. The central duct with its columnar 
lining is very conspicuous. It will be noted that this imter- 
mediate character agrees entirely in the first two cases with 
