MEMOIR ON THE REPRODUCTION OF THE OPOSSUM. 1G1 



The figure may lie depended on as correct for the form and proportion of this unique 

 orsnin, turned downwards to the breast. It was white, as a clot of milk. It was turned 

 up on the margins, so as to make of the tongue a complete groove, for the lodgement of 

 the nipple — the palatine vault being the superior half of a flask-shaped cavity in which the 

 mammilla being once lodged and engorged, by the act of sucking, is permanently detained 

 within — for it is difficult to draw the teat again through the porule, or stomal orifice. 



I was led to examine the tongue because I perceived that the animal was possessed of 

 a strong suction power; for I had several times touched the stomal dimple with the 

 smooth, rounded point of a drawing-pencil, and the creature sucked it so strongly that I 

 could draw it round the glass with the point, and even lift it partially oft* the surface by 

 the pencil. 



It is a very curious sample of the adaptation of the development forces of the animal 

 economy to the attainment of a special and transitory end. I find that as the embryos 

 proceed in their organic development, the tongue becomes rapidly smaller in proportion. 

 In the dissected specimen on the table, the tongue, though vast, is much less, relatively, 

 than in the first specimen. 



Does this fact, that the embryo of twenty-four hours' marsupial life could attach itself, 

 h\ <uction, to the end of my pencil, throw any light on the manner of its primary adap- 

 tation to the nipple, or of its power to find and seize it, while groping within the marsu- 

 pial cavity? 



I wish to be understood as saying, that I could not clearly make out the mouth without 

 a lens, though I could perceive the dimple which led to it. 



When I had split the under jaw and turned the tongue downwards, it was easy to see 

 tint the pnlato-glossal cavity was large, and that the nipple once freely drawn into the 

 t'auees must become, in a degree, strangulated. The constant suction would prevent it 

 from inflaminrr or sloufrhinfr. 



The yonnir animal adheres to the teat both sleeping and waking, and never lets go 

 until the marsupial gestation is at an end. 



The mechanism of its adherence is very intelligible. The delicate nipple bein<r drawn 

 within the stomal pore and acted on by the immense tongue, becomes engorged, and 

 cannot be withdrawn, except by such violence as I used. Its escape from the orifice 

 cannot take place suddenly, without lacerating the lips. When it is slowly withdrawn, it 

 becomes gradually disengorged in the process; and very certainly does not exhibit any 

 bulb at the end — or in the whole tractus of the teat; as represented by Mr. Owen in the 

 kangaroo teat. Its attachment is on the same principle as that of the female to the dog 

 in copulation. 



I very carefully sought, with a good doublet, for any vestige of an umbilicus, both in 

 this and in later specimens, without being able to discover any such mark of a former 

 placental union. I conceive that the absence of vestigia ought not in the least to awaken 

 any doubt as to the antecedent placental union of the embryonal animal. The I. 

 inasmuch as it is, at the end of the first day of its respiratory existence, found to he so 

 far developed as to deserve being regarded as a living, independent < -reature, and not as 

 an embryo, as I before remarked. \ow I cannot perreive. any reason to believe that a 



