140 HISTORICAL -NOTES ON" THE PLATYPUS, 



But Geoft'roy was not daunted. He returned to the charge. The Monotremes 

 must be removed from the Mammalia, because their reproductive organs and 

 several other parts of the great systems placed them amongst the oviparous 

 classes. They could not be included in the birds, because they had neither wings 

 nor feathers. Nor could they be placed amongst the reptiles, for their blood 

 was warm, and their lungs were enclosed in pleura, and shut off by a diaphragm 

 from the abdomen. Still less were they fish, which breathe by means of gills. 



They were mammals without the mammalian character, without the special 

 organisation of viviparous animals, without all the consequences and functions 

 of an apparatus capable of producing a placental foetus. Therefore they must 

 have a special class to themselves. 



And Meckel dared to discover mammary glands! Geoff roy rushed off to 

 examine a specimen, found the glands, saw that they differed from those of the 

 higher mammals, and triumphantly asserted that they were not milk-glands at 

 all. But, notwithstanding his strenuous opposition, the Monotremes came to be 

 included in the Mammalia, as the lowest sub-class of the three comprising the 

 class, despite the fact that the actual method of reproduction did not become 

 known until 1884. 



Geoffroy's final despairing effort to disprove the mammary nature of the 

 glands is too good to be omitted. He compared them to the "so-called" mam- 

 mary glands of whales and porpoises, which secreted, not milk, but mucus. This 

 coagulates on being ejected into the water, and is then devoured by the young. 

 Unfortunately, just as he had elaborated this hypothesis, he had the ill fortune 

 to secure a nursing porpoise, and found that the glands secreted milk. 



The production of milk by Ornithorhynchus was definitely recorded by 

 Maule (1832) and Bennett (1833). 



The second great controversy was concerned with the method of reproduc- 

 tion. Home (1802), from an examination of the reproductive organs in the 

 female, suggested that the Platypus might be ovo-viviparous. By 1819 he has 

 become so convinced of this that he makes the following categorical statement, 

 for which no scintilla of evidence existed : — "In the ornithorhynchi the yelk-bag's 

 are formed in the ovaria; received into the oviducts, in which they acquire the 

 albumen, and are impregnated afterwards; the foetus is aerated by the vagina, 

 and hatched in the oviduct, after which the young provides for itself, the mother 

 not giving suck." 



Those zoologists who considered the Platypus to be definitely a mammal of 

 course believed that it brought forth its young alive. Among these we may in- 

 clude Blainville, Cuvier, and Oken. The last (1817) suggested that the mam- 

 illary glands might occupy some unusual situation, and so have escaped notice : 

 and later (1823) commenting on the ovarian ovum described by Hill (see below) 

 points out its resemblance to the mammalian Graafian follicle, and concludes by 

 saying that the tales of oviparity and ovo-viviparitv have all arisen from the 

 fact of mammary glands not having been observed. Oken's assurance of the 

 existence of mammary glands was justified, as we have seen, by the discovery 

 of these glands by Meckel, announced in 1824. 



It seemed likely, then, that despite the opposition of Geoffroy St. Hilaire, 

 and the extraordinary form of the animal itself, and of its reproductive ap- 

 paratus, Ornithorhynchus would turn out to be quite an ordinary mammal, which 

 produced its young alive. But persistent reports came from the colonists of 

 New South Wales that it laid eggs. Sir John Jamison (1818) wrote without 

 comment, as if citing an established fact : — "The female is oviparous, and lives 

 in burrows in the ground." This would seem to indicate that nesting burrows 

 and eggs had definitely been observed, yet no evidence was forthcoming to calm 

 the agitation of European zoologists. 



