30 ON THE ANATOMY OF MEGASCOLIDES AUSTRALIS, 
The cells of the outer layer on the other hand are much more numerous, and 
form a layer more than twice as thick as the inner ones. Lach cell has the form of a 
unicellular gland, with a more or less swollen external end and a somewhat narrow 
neck internally, which may be seen sometimes passing in between the cells of the 
inner layer. These stain much less readily than those of the outer layer, and in them, 
as a general rule, nuclei are to be seen. Possibly, the deep staining of the inner cells 
may hide the nuclei, but these are not even to be detected in occasional cells which 
are more lightly stained. Between the two layers is a shght development of 
connective tissue and a layer of blood-vessels, which are sometimes seen, as in the 
figure, branching along the plane of division between the inner and outer cells. Other 
branches ramify in and out amongst the gland cells of the organ. Externally is an 
encasing layer of connective tissue (ct), beneath the surface of this are numerous little 
masses of yellow-brown pigment spots, which give a general brownish tinge to the 
prostate gland. It is difficult to say what is the function, if any, or origin of these 
little definite masses of colouring matter. The connective tissue over the various coils 
of the ducts is continuous, and thus the latter are massed together to form on each 
side of the body a structure of considerable size. | 
The Vesicule Seminales. These are seen as racemose glands attached to the 
anterior surface of certain of the anterior septa, directly the body is opened from the 
dorsal surface. (Fig. 2, vs.) They differ very much in appearance from those of 
Lumbricus, not being pouch-like, and are usually present in the eleventh to the 
fourteenth segments inclusive, but may not be so largely developed in younger 
specimens. They are quite diagramatically shown in Fig. 4. Their appearance at 
first sight is very much like that of both testis and ovary, and they have once been 
described as the former. The organ is generally best developed in the fourteenth 
and least in the eleventh segment. Sections at once show its real nature and prove 
that it is the place in which the spermatozoa undergo almost their entire development. 
How they get in is not easy to understand. _ 
The testis (Fig. 12) consists in part of a great mass of germ cells, which have 
undergone but very little of their definitive development, and in part of a mass of 
protoplasm in which numbers of nuclei are scattered about forming merely a 
syneytium. The stalk of the testis attaching it to the septum is eomposed mainly of 
muscle fibres (m.) and connective tissue, which serve as a support for the structure. 
These run out into the ray-like processes, one of which is supposed to be cut in section 
in Fig. 12. It consists almost entirely of a mass of protoplasm, in which cell outlines 
can scarcely and only in very few parts (though this might possibly vary at different 
periods of the year) be distinguished, but in which are an immense number of nuclei 
with very distinct specks of chromatin. The nuclei are of two or three different sizes, 
and here and there the outline of a cell enclosing one or two of them may be seen (a.) 
In the central part of the testis the nuclei are small and similar, or even more minute 
ones may be seen in the stalk. These nuclei always appear to have a single spot of 
