308 OF THE DIFFERENCES 



to the Preputium of the male. 6. Twins are usually of the same 

 sex, as if the same cause had influenced 'the generative organs of 

 each j when they are of different sexes, it is a common remark 

 that they seldom breed, nature probably having been disturbed 

 in her operations. 7. When among black cattle twins are pro- 

 duced of different sexes, that which appears the cow is really an 

 hermaphrodite, incapable of breeding, and vulgarly termed a free 

 martin ; a circumstance in every respect analogous to the pre- 

 ceding.* It may be added, that the round ligaments of the 

 female descend, like the two spermatic chords of the male, to 

 the abdominal ring ; that marsupial bones exist, without any 

 function whatever, in the males of some marsupial animals ; that 

 the hen has a Bursa Fabricii j and that the glans clitoridis of the 

 female opossum is bifid. Comparative anatomy furnishes many 

 similar facts. But the existence in both sexes of parts that 

 can be useful only in one, confessed by Paley to have been 

 a complete puzzle to him,f is now universally regarded as 

 merely an instance of Nature's observance of general rules in 

 the formation of beings : J even some species of animals have 

 parts that are useful only in others, and so general are the 

 laws of formation now found that naturalists are at this mo- 

 ment arranging all vegetables and animals in natural orders, 

 and the artificial classifications of Linnaeus are rapidly crum- 

 bling to dust. The resemblance of the Scrotum to the Labia, 

 and of the Nymphse to the Preputium, and the original iden- 

 tity of the situation of the testes and ovaria, may be similarly 



* J. Hunter, Observations on certain parts of the animal economy, p. 55. 



f Natural Theology, ch. 25. p. 472. 



J " It shews in the function of generation an union of the teleological and 

 mechanical principles, which were formerly thought to be incompatible with 

 each other." In one sex we have " a clear instance of the teleological princi- 

 ple, i. e. a peculiar part formed for a certain purpose." In the other sex, 

 " where the end and purpose of the part do not exist, we have the mechanical 

 principle ; as if the part bad been merely framed in compliance with some ge- 

 neral model for the structure of the species." Bluraenbach, Comparative 

 Anatomy. Ch. ii. 38, 49. 



