Chap. IV.] MANNER OF DEVELOPMENT. 119 



of gestation. In other and rarer cases, two distinct uter- 

 ine cavities are formed, each having its proper orifice and 

 passage. 86 No such stage is passed through during the 

 ordinary development of the embryo, and it is difficult to 

 believe, though perhaps not impossible, that the two sim- 

 ple, minute, primitive tubes could know how (if such an 

 expression may be used) to grow into two distinct uteri, 

 each with a well-constructed orifice and passage, and each 

 furnished with numerous muscles, nerves, glands and ves- 

 sels, if they had not formerly passed through a similar 

 course of development, as in the case of existing marsu- 

 pials. No one will pretend that so perfect a structure as 

 tho abnornal double uterus in woman could be the result 

 of mere chance. But the principle of reversion, by which 

 loifr-lost dormant structures are called back into exist- 

 enoe, might serve as the guide for the full development 

 of the organ, even after the lapse of an enormous interval 

 of time. 



Prof. Canestrini, 36 after discussing the foregoing and 

 various analogous cases, arrives at the same conclusion as 

 that just given. He adduces, as another instance, the 

 malar bone, which, in some of the Quadrumana and other 

 mammals, normally consists of two portions. This is its 

 condition in the two-months-old human foetus ; and thus it 

 sometimes remains, through arrested development, in man 

 when adult, more especially in the lower prognathous 

 races. Hence Canestrini concludes that some ancient 



35 See Dr. A.Farre's well-known article in the ' Cyclop, of Anat. and 

 Phys.' vol. v. 1859, p. 642. Owen, ' Anatomy of Vertebrates.' vol. iii. 

 1868,' p. 687. Prof. Turner in 'Edinburgh Medical Journal,' Feb. 1865. 



36 ' Annuario della Soc. dei Naturalisti in Modena,* 1867, p. 83. Prof. 

 Canestrini gives extracts on this subject from various authorities. Lau- 

 rillard remarks that, as he has found a complete similarity in the form, 

 proportions, and connection of the two malar bones in several human 

 subjects and in certain apes, he cannot consider this disposition of the 

 parts as simply accidental. 



