o 



128 Rev. S. Haughton on some points in the 



The cremaster muscle was found by me to have the followin 

 weights : — 



Giant Kangaroo (female) 0*38 oz. av. 



Wallaby (male) 009 „ 



Opossum (female) 001 „ 



„ (male) 0*02 „ 



In the male Wallaby the muscle was 6 inches in length, and 

 must be shortened to 2 inches during coition, which is, I believe, 

 a greater amount of contraction than is recorded of any other 

 muscle in the animal kingdom. The cremaster muscle, in all 

 the Marsupials I have examined, forms the lower border of the 

 transversalis muscle, taking its origin from the edge of the ilium 

 directly. The transversalis itself is only four and a half times 

 the mass of the cremaster, and takes its origin from the superior 

 anterior edge of the ilium, from the lumbar fascia, and from the 

 last two ribs, and is inserted into the fascia of the internal 

 oblique. 



It seems very strange that a muscle having so definite an ob- 

 ject as the cremaster should in the female Marsupials be diverted 

 to fulfil a purpose essentially distinct from its function in the 

 male. I think, however, that a little reflection and an applica- 

 tion of the doctrine of final causes will enable us to explain with 

 ease this apparent anomaly. 



The placental Mammals, which are higher in organization and 

 intelligence than the Marsupials, are not entrusted with the 

 responsibility of feeding their young, by voluntary efforts, 

 during foetal life ; and yet we find the young of the non-placental 

 Marsupials transferred from the uterus to the marsupium long 

 before they can exert the power of suction, and apparently 

 abandoned to the voluntary efforts of the mother, who supplies 

 them with milk by compressing the mammary gland from time 

 to time by means of the contraction of the cremaster muscle, 

 which spreads itself out over the back of the gland in a fan- 

 shaped form. 



As it was not possible for me to believe that so stupid a mother 

 as a kangaroo or opossum should be entrusted with a duty 

 withheld from a tigress, or even a woman, I examined carefully 

 the mechanism of suckling a young kangaroo, with the view of 

 discovering some self-acting cause of irritation to provoke the 

 cremaster muscle to contract, without the necessity of supposing 

 the volition of the mother to intervene ; and I believe that I 

 have discovered such a cause, quite adequate to produce the 

 effect required. 



The cremaster muscle, in the female Marsupials, winds round 

 the marsupial bone to the back of the mammary gland placed 



