Rudiments. 49 



ing animals the appendix is more or less a continuation of the coecum, 

 giving to that intestine needed additional size, but in man and tin- 

 apes, whose food is more concentrated, the size is not required, so this 

 section of intestine is atrophied. In the carnivorous animals, it is also 

 smaller atrophied. The wombat, a marsupial, has the appendix^ and 

 it is found in the gibbon, orang, chimpanzee and gorilla. It is a source 

 of some danger, as occasionally a grape seed, or some such object, gets 

 into it, producing chronic inflammation with usually a fatal result. 



The intermaxillary bone is another rudiment which the human family 

 inherits from our relations below. It is a " bony portion wedged in 

 between the two superior maxillary bones, which supports the upper 

 incisors. This bone is found in the mammalia ; and also in the human 

 foetus. " * It is permanent in the adult ape, but is eliminated in human 

 life and does not appear in the adult man. 



Among the most remarkable rudiments in the human system, are 

 those resulting from the ancient forms of the urinary and reproductive 

 apparatus. 



The primitive kidneys, or wolffian ducts, which are early developed 

 in the mammal embryo, are equivalent to the corresponding organs as 

 they exist permanently in the non-amnion craniota, cyclostomi (lam- 

 preys, &c.), fishes, dipneusta (mud fishes), and amphibia. 



But to these primitive kidneys are soon added, in the mammal em- 

 bryo, the permanent kidney and the miillerian duct, after which the 

 primitive kidney duct is converted in the male, into the testis and 

 sperm duct, while the miillerian duct becomes the useless rudiment 

 called the male uterus. ( See fig. 30. ) 



In the female, on the other hand, the primitive kidney duct (or wolf- 

 fian duct) is sunk into the useless remnant called the parovarium( "near 

 the ovary"), while the miillerian duct becomes the fallopian tube and 

 uterus. The significance of this remarkable development, cannot be 

 mistaken. It shows that mammals have inherited, and all pass through 

 the ancient invertebrate condition of hermaphroditism, in which both 

 testis and ovary are formed in every individual. If all are blood rela- 

 tions and spring from a common hermaphrodite ancestry, this tempor- 

 ary possession of the rudiments of both kinds of sexual organs, is ex- 

 plained us hereditaiy. We have them because our ancestors had them, 

 back through all the generations of mammal, lower vertebrate and in- 

 vertebrate. 



The forms of the organs have been infinitely varied and modified by 

 the local and tribal necessities of the myriad races that have borne 

 them, but the principle has IKM-H infinitely stolid and persistent. 



The mii/e mammiUary glands are probably also an outgrowth oi' the 

 *Dunglison's Medical Dictionary. 



