CHAP. VI.] MAN. 179 



may be refuted from his own notes on the very next page, 

 where we read that he was at first similarly disposed to 

 attribute the development of abnormal, erratic mammarv 

 glands (breasts placed in unusual parts of the body) to 

 reversion, but from observations of Professor Preyer as to 

 the appearance of such structures on the lack leads our 

 author to candidly admit that his &quot;argument is greatly 

 weakened or perhaps quite destroyed.&quot; 



The same power which could produce so complex a struc 

 ture as a mammary gland, in a situation which showed that 

 it was not due to reversion, could also produce the con 

 ditions of a completely divided and double uterus. 



In attempting to trace man s origin Mr. Darwin has even 

 been betrayed into slight inaccuracies. Thus, in other mis- 

 combating the position, advanced in the Quar- takes - 

 terly Review, * that the hands of apes had been preformed 

 (with a view to man) in a condition of perfection beyond 

 their needs, he says : 



&quot; On the contrary, I sec no reason to doubt that a more perfectly 

 constructed hand would have been an advantage to them, provided 

 and it is important to note this, that their hands had not thus been 

 rendered less well adapted for climbing trees. We may suspect that a 

 perfect hand would have been disadvantageous for climbing; as the 

 most arboreal monkeys in the world, namely, Ateles in America and 

 Hylobates in Asia, either have their thumbs much reduced in size and 

 even rudimentary, or their fingers partially coherent, so that their 

 hands are converted into grasping-hooks.&quot; Vol. i. p. 140. 



In a note, Mr. Darwin refers to the Sindactyle Gibbon as 

 having two of the digits coherent. But these digits are not, 

 as he supposes, digits of the hand but toes. Moreover, 

 though doubtless the Gibbon and spider-monkeys are ad 

 mirably organised for their needs, yet it is plain that a 

 well-developed thumb is no impediment to climbing, for 

 the strictly arboreal Lemurs are exceedingly well furnished 

 in this respect. 



We shall see later \ that Mr. Darwin tries to account for 



* See Quarterly Keview, April 1869, p. 392. 

 t See infra the chapter on sexual selection. 



N 2 



