Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 3: Ins-Pla
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit29464/319/
MARSUPIALIA. 
The tubuli testis are relatively smaller than 
in the Rodentia, but are similarly arranged, the 
corpus Highmorianum being near the surface 
and upper part, not at the centre, of the gland. 
The epididymis is large, and generally loosely 
attached to' the testis : in a small species of 
Kangaroo I found the connecting fold of serous 
membrane half an inch broad. The vasa de- 
ferentia pass from the globus minor along the 
infundibular muscular sheath formed by the 
cremaster as far as the abdominal ring, then 
bend downwards and backwards, and termi¬ 
nate below and external to the ureters, at the 
commencement of the urethra (a, fig. 135), 
on each side a longitudinal verumontanal ridge. 
There are no vesiculæ séminales in any Mar¬ 
supial quadruped. 
Fig. 135. 
A, Hypsiprymnus. B, Fhascolarctus. C, Phascolomys 
As the part of the urethral canal immediately 
succeeding the termination of the vasa defe- 
rentia is the analogue of the vagina, some mo¬ 
dification of this part might be anticipated in 
the male corresponding with the extraordinary 
form and developement which characterise the 
vagina in the female : accordingly we find that 
the combined prostatic and membranous or 
muscular tract of the urethra is proportionally 
longer and wider in the Marsupial than in any 
other Mammiferous quadrupeds (fig. 135, b). 
It swells out immediately beyond the neck of 
the bladder, and then gradually tapers to its 
junction with the spongy part of the urethra : 
it is not, however, divided like the vagina. 
Its walls are thick, formed of an external thin 
stratum of nearly transverse muscular fibres; 
and a thick glandular layer, the secretion of 
which exudes by innumerable pores upon the 
lining membrane of this part of the urethra. 
In a male Kangaroo I found that a glairy mucus 
followed compression of this musculo-prostatic 
tract of the urethra: the canal itself is here 
slightly dilated. 
Three pairs of Cowper's glands (c, c, c, fig. 
135) pour their secretion into the bulbous 
part of the urethra : the upper or proximal 
pair are not half the size of the two other pairs 
in the Kangaroo, but are relatively larger in 
the Koala and other Marsupials: the two 
lower pairs are situated, one on each side the 
lateral division of the bulb of the urethra; 
their ducts meet and join, above this part, with 
the duct of the smaller gland : each gland is 
inclosed by a muscular capsule. 
The penis consists of a cavernous and a 
spongy portion, each of which commences by two 
distinct bodies. The separate origin of each late¬ 
ral half of the spongy body constitutes a double 
bulb of the urethra (e, e, Jig. 135), and the ‘ ac¬ 
celerator urinæ/ as it is termed, undergoes a 
similar division into two separate muscles, each 
of which is appropriated to compress its par¬ 
ticular bulb. The two bulbous processes of 
the corpus spongiosum soon unite to surround 
the urethra, but again bifurcate to form a dou¬ 
ble glans penis in the multiparous Marsupials, 
in which most of the ova are impregnated in 
both ovaria, as the Phalangers, Perameles, 
Opossums, &c. (b, b, fig. 136). 
This modification of the opposite extre¬ 
mities of the corpus spongiosum, called ‘ bulb ’ 
and ‘glans/ was detected by Cowper in his 
dissection of a male Opossum ; and, in his 
account of the anatomy of that animal in 
the Philosophical Transactions for the year 
1704, he says, “ As the bulb of the urethra 
in man is framed for the use of the glans, to 
keep it sufficiently distended when required, 
so it seems it is necessary to have two of 
these bulbs, inclosed with their particular mus¬ 
cles in this animal, to maintain the turgescence 
of its double or forked glans when the penis is 
erected.”—Vol. xxiv. p. 1585. 
The force of this ingenious'reasoning on the 
correlation of the bulb to the glans might seem 
to be invalidated by the fact that in the uniparous 
Marsupials, as the Kangaroo, the glans penis 
(f>fië• 135) is single, and yet the bulb double