202 THE DESCENT OF MAN, 



improved breeds of the pig, which are descended from two 

 distinct species; and in a less marked manner with the 

 improved breeds of cattle. A great anatomist, Gratiolet, 

 maintains that the anthropomorphous apes do not form a 

 natural sub-group ; but that the orang is a highly devel- 

 oped gibbon or semnopithecus, the chimpanzee a highly 

 developed macacus, and the gorilla a highly developed man- 

 drill. If this conclusion, which rests almost exclusively on 

 brain-characters, be admitted, we should have a case of con- 

 vergence at least in external characters, for the anthropomor- 

 phous apes are certainly more like each other in many points 

 than they are to other apes. All analogical resemblances, as of 

 a whale to a fish, may indeed be said to be cases of con- 

 vergence; but this term has never been applied to super- 

 ficial and adaptive resemblances. It would, however, be 

 extremely rash to attribute to convergence close similarity 

 of character in many points of structure among the modi- 

 fied descendants of widely distinct beings. The form of a 

 crystal is determined solely by the molecular forces, and it 

 is not surprising that dissimilar substances should some- 

 times assume the same form; but with organic beings we 

 should bear in mind that the form of each depends on an 

 infinity of complex relations, namely, on variations due to 

 causes far too intricate to be followed on the nature of 

 the variations preserved, these depending on the physical 

 conditions, and still more on the surrounding organisms 

 which compete with each and lastly, on inheritance (in 

 itself a fluctuating element) from innumerable progenitors, 

 all of which have have had their forms determined through 

 equally complex relations. It appears incredible that the 

 modified descendants of two organisms, if these differed 

 from each other in a marked manner, should ever after- 

 ward converge so closely as to lead to a near approach to 

 identity throughout their whole organization. In the case 

 of the convergent races of pigs above referred to, evidence 

 of their descent from two primitive stocks is, according to 

 Von Nathusius, still plainly retained in certain bones of 

 their skulls. If the races of man had descended, as is sup- 

 posed by some naturalists, from two or more species which 

 differed from each other as much, or nearly as much, as 

 does the orang from the gorilla it can hardly be doubted 

 that marked diiferences in the structure of certain bones 

 would still be discoverable in man as he now exists. 



