118 THE DESCENT OF MAX. [Part I. 



reversion. Certain structures, regularly occurring in the 

 lower members of the group to which man belongs, occa- 

 sionally make their appearance in him, though not found 

 in the normal human embryo ; or, if present in the nor- 

 mal human embryo, they become developed in an abnor- 

 mal manner, though this manner of development is proper 

 to the lower members of the same group. These remarks 

 will be rendered clearer by the following illustrations. 



In various mammals the uterus graduates from a double 

 organ with two distinct orifices and two passages, as in the 

 marsuj^ials, into a single oi-gan, showing no signs of double- 

 ness except a slight internal fold, as in the higher apes and 

 man. The rodents exhibit a perfect series of gradations 

 between these two extreme states. In all mammals the 

 uterus is developed from two simple i")rimitive tubes, the 

 inferior portions of which form the cornua ; and it is in 

 the words of Dr. Farre " by the coalescence of the two 

 cornua at their lower extremities that the body of the 

 uterus is formed in man ; while in those animals in which 

 no middle portion or body exists, the cornua remain un- 

 united. As the development of the utei'us proceeds, the 

 two cornita become gradually shorter, until at length they 

 are lost, or, as it were, absorbed into the body of the 

 uterus." The angles of the uterus are still produced into 

 cornua, even so high in the scale as in the lower apes, and 

 their allies the lemurs. 



Xow in Avomen anomalous cases are not very infre- 

 quent, in which the mature uterus is furnished with cor- 

 nua, or is partially divided into two organs ; and such 

 cases, according to Owen, repeat "the grade of conccn- 

 trative development," attained by certain rodents. Here 

 perhaps we have an instance of a simple arrest of embry- 

 onic development, with subsequent growth and perfect 

 functional development, for either side of the partially 

 double uterus is capable of performing the proper office 



