92 



consideration to be discussecl; viz. \vhetlier the gland on each side 

 of the abdomen is mammary and lactifeious (as ^Ir. Onen thinks), 

 or vvhether it is not a gland of a dift'erent kind (as I, for my part, 

 believe). I call it a gland sui generis, and Iiave lately proposed to 

 denominate it Monotrematic, as it attains its maxmum of composi- 

 tion among the Monotremata. 



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

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

 invested with an erectiie tissue, and it is vvithout nipples Jn 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 Ne\v 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 «o nipples. 



" Thus the fact of a decidedly assimilated strudurels nanting: 

 the gland of Monotremata is not in its composition comparable \vith 

 a mammary gland. But I observe that 1 am an.swered here by a 

 fact of an assimilated fundion. Lieut. Maule and Mr. ^įArthur 

 speak of an abundant secretion, mUhy according to one, of a m'ūhy 

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

 reaiains at least this cliaracter (the fanction) 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 introducean unknoiun to characterizea new organ of a structure 

 hitherto equal!y ?f»A«0TWi. What! the organ is not in its compo- 

 sition ynammary, and yet its secretion hladeall What would become, 

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

 Jundion ? 



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

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

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

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

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

 its terminating branches into cavities with an external f xit. From this 

 more simple apparatus I expect a fluid in itself more elementary — 

 muctis, as I s\ippose. 



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

 thisdemonstration of the fact. On the Srd of June I laid before the 

 Academy of Sciences, of \vhich 1 am this year President, a paper 

 on the exjstence 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 Ec/iidna, — a Monotrematic gland consequentIy, 

 which I haveobserved in the JVater-Rat {3]iis amphibius, Linn.). I 

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

 of this dra\ving with that of Mr. 0«'en's plate. 



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

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

 monotrematic gland of the JVatcr.Rat ; his researches determine 



