OF THE ORNITHORHYNCHUS PARADOXUS. 
531 
fection, the glands did not exhibit a corresponding degree of development ; 
they had only begun to enlarge and to manifest their obedience to the law of 
the sexual impulse. But had their office been to secrete, as Professor Geoffroy 
supposes, an odorous substance attractive of the male, their maximum of 
development ought to have been exhibited in this specimen, in which the uteri 
evinced, by their size and vascularity, traces of high excitement, and the ova 
appeared ripe for impregnation. The greatest development of the abdominal 
glands, on the contrary, was observed where the ovary appeared to have 
recently executed its function. 
The variation in size of these glands, in individuals of the same bulk, evi- 
dently points out that they are not adapted for the performance of any constant 
office in the economy of the individual, but relate to a temporary function. 
Otherwise, the circumstance of their yielding oil on pressure, as in the instance 
above mentioned, might have led to the supposition that they furnished a lubri- 
cating fluid useful to an animal of the aquatic habits of the Ornithorhynchus *. 
That this temporary function, moreover, is peculiar to the economy of the 
female, cannot be doubted. For in the male, both Dr. Knox and Pro- 
fessor Meckel have been unable to detect these glands ; and after a careful 
scrutiny, with the same view, in a well preserved specimen of that sex, I have 
not succeeded in detecting more than a few minute lobules occupying a space 
of about four lines in situations corresponding to those in the female; but 
the nature of which, from the total absence of corresponding foramina on the 
external surface of the integument, may still be doubted. 
Lastly, from the evidence derived from the uterine system in the present 
inquiry, the period when these glands exhibit the greatest activity, appears 
to be after gestation. It therefore comes to be considered whether their 
structure is so widely different from the ordinary mammary gland as it has 
been represented to be. 
Now, whether the secretion of these glands be milk or not, it is highly pro- 
bable, from its being conveyed externally by long and narrow ducts, that it is 
of a liquid nature ; and this mode of being carried off is much more analo- 
gous to that exhibited in the ordinary lacteal apparatus than in the odoriferous 
* Since writing the above, I have ascertained that the mammary glands exist in a similar situation, 
and under a similar form, in the Echidna hystrix ; an animal which burrows in dry sandy situations. 
