436 PROFESSOR J. STEPHENSON AND PROFESSOR HARU RAM ON THE 
We use the term “ prostate” in preference to “ spermidncal gland” in the present 
paper, since the glands, as has been said, are not, in this family, primarily connected 
with the sperm-ducts. There may be glands in other families which are so connected, 
and all the structures which have been grouped together as “ spermiducal glands” 
may not be homologous ; but for the present we confine ourselves to the Megascole- 
cidae, and express no opinion on these points. 
Some time ago, on dissecting a specimen of the common Pheretima haxvayana, 
one of us found two small supernumerary prostates, one on each side, a little way 
behind the normal glands. The larger was loosely attached to septum 21/22 on the 
right side ; the smaller was attached, also loosely, to the posterior part of segment 
xx. No ducts were to be seen. 
The portion of the specimen was immediately fixed in sublimate and acetic acid, 
and afterwards examined under the dissecting binocular. Before examination, how- 
ever, the mere changing of the 70 per cent, alcohol used for washing out the 
sublimate had caused the greater ' part of the larger gland to become detached, and 
it lay loose in two pieces in the tube ; and on pinning out the specimen the re- 
mainder also became detached. On close examination of the fixed specimen no 
trace whatever of a duct was found on either side, internally or externally. 
Since, therefore, there was no connection with the exterior, these supernumerary 
glands had, it would seem, been developed in situ , and hence would be mesodermal 
and not ectodermal in origin. And if these, then the prostates generally would be 
mesodermal, and would not — -as might be and has been supposed — have originated as 
invaginations or ingrowths from the surface of the body. We determined, therefore, 
to investigate the structure and development of both the tubular and lobular forms 
of the gland from this point of view. The common genus Pheretima, which is 
always to be obtained, was taken as a type of the forms with lobular prostate ; for 
the tubular form we have selected Eutyphoeus , a representative of a sub-family, the 
Octochsetinae, in which the histology of the prostate has not, so far as we know, 
been investigated. 
Historical. 
While we are not acquainted with any account of the development of the 
prostate of the Megascolecidse — either of the tubular or lobular form, — the 
histology has been described with more or less fullness by several authors. 
According to Spencer (4), the glandular section of the tubular prostate of 
Megascolides australis consists of an outer and an inner portion. The inner part 
is composed of a single, layer of columnar cells, loosely arranged, radially placed 
in regard to the lumen, staining deeply, and without visible nuclei ; occasionally 
these cells are very long, and .extend into the outer portion. The cells of the 
peripheral region are much more numerous, and form a layer twice as thick as 
the former; their necks, in some cases at least, pass between the cells of the 
