Zoological Society. 55 



" Is it a mammary gland ? Mr. Owen's concessions militate 

 strongly against this conclusion; for it is not conglomerate, it is not 

 invested with an erectile tissue, and it is without nipples. In Meck- 

 el's time the appearance of the latter was hoped for, the nipples 

 being frequently developed under the action of sucking; but at 

 present this can no longer be anticipated. Females have been seen 

 in full nutritive action, in New South Wales, by Lieut. Lauderdale 

 Maule and Mr. James M' Arthur, and at London by Mr. Owen 

 himself; and each observer has insisted on the circumstance that 

 there were no nipples. 



" Thus the fact of a decidedly assimilated structure is wanting: 

 the gland of Monotremata is not in its composition comparable with 

 a mammary gland. But I observe that I am answered here by a 

 fact of an assimilated function. Lieut. Maule and Mr. M'Arthur 

 speak of an abundant secretion, milky according to one, of a milky 

 appearance according to the other. It is therefore inferred that there 

 remains at least this character (the function) in common, to prove 

 mammary a gland of a different structure. But, I may reply, begin 

 by being certain that the product of the secretion is a true milk; do 

 not introduce an unknown to characterize a new organ of a structure 

 hitherto equally unknown. What! the organ is not in its compo- 

 sition mammary, and yet its secretion islacteall What would become, 

 then, of the principle, Such as the organ is, such necessarily is its 

 Junction ? 



" The vascular system does not go the length, as in conglobate 

 glands, of folding itself round, of mutually anastomosing, and of pe- 

 netrating itself, in obedience to the law of affinity of self for self 

 {de soi pour soi); whence, at the proper period, a compound fluid, — 

 milk. But this vascular system, as in mucous membranes, extends 

 its terminating branches into cavities with an external exit. From this 



more simple apparatus I expect a fluid in itself more elementary 



mucus, as I suppose. 



" But I do more than believe this by way of conjecture : I offer 

 this demonstration of the fact. On the Sid of June I laid before the 

 Academy ot Sciences, of which 1 am this year President, a paper 

 on the existence of a gland in all respects similar to that which is 

 described and figured (Phil. Trans. 1832, pi. 17, fig. 2 and 3,) by 

 Mr. Owen in the Echidna, — a Monotrematic gland consequently, 

 which I have observed in the Water-Rat (Mus amphioius, Linn.). I 

 subjoin the figure of this gland magnified, and invite a comparison 

 of this drawing with that of Mr. Owen's plate. 



" I begged of our learned chemist, M. Dumas, Member of the 

 Academy of Sciences, to analyse the product of the secretion of the 

 monotrematic gland of the Water. Rat ; his researches determine 

 that it is not milk. M. Dumas has obtained this result still more 

 positively by microscopic observations. Each of these products 

 is invariable in its form : milk has the appearance of perfectly sphe- 

 rical globules ; while the matter from the gland of the Water- Rat 

 exist* under the form of thin (lakes strongly angular at the edges: 

 Tiie mucus of the saliva presents the same aspect, except that the 



