1314 



VARIETIES OF MANKIND. 



respective races. And thus a character which 

 is perfectly valid in one group, may be en- 

 tirely inapplicable in another. 



4. Two races can only be regarded ' as 

 specifically distinct, when the characters which 

 separate them are transmitted with complete 

 uniformity from parent to offspring ; when 

 there are no intermediate gradations tending 

 to connect them ; and when no such tendency 

 to variation has manifested itself in either 

 race, as shall make it probable, or, at any 

 rate, possible, that their differences may be 

 the direct result of external influences, or 

 may be attributed to an unusual divergence 

 in the characters of the offspring from those 

 of the parents. 



5. On the other hand, two races may un- 

 doubtedly be regarded as specifically identical, 

 when, however great the differences in stature, 

 conformation, psychical character, &c., pre- 

 sented by their respective types, these types 

 are connected with each other by inter- 

 mediate gradations, so close as to render it 

 impossible to establish a definite boundary- 

 line between the collections of individuals 

 which are assembled around them. 



6. Again, two races may be undoubtedly 

 regarded as specifically identical, when in either 

 race varieties present themselves, which ex- 

 hibit the distinctive characters of the other 

 race ; since we then have evidence, that, al- 

 though these peculiarities are so generally 

 transmitted from parent to offspring that each 

 race possesses a certain degree of permanence, 

 yet they are not thus uniformly inherited; 

 and, consequently, there is nothing to pre- 

 vent the transformation of the one race into 

 the other, if the circumstances which have 

 originated the variation, even in a single case, 

 should act with sufficient potency on the 

 whole mass. 



7. No character can be safely adopted as 

 justifying the assumption of the specific di- 

 versity of two races, which has been found by 

 experience to undergo considerable modifica- 

 tion in either race, even though such mo- 

 dification should not proceed to the extent of 

 conversion into the character of the other ; 

 for if a limited amount of change in external 

 conditions be found capable of effecting a 

 certain degree of alteration, the probability is 

 strong that the higher difference may have 

 had its origin in the more potent operation of 

 the same class of causes. 



8. The very fact of the extensive dispersion 

 of a race, and of its existence under a great 

 variety of external conditions, implies a 

 marked capacity for variation ; since without 

 such capacity, the race could not continue to 

 flourish. 



9. Among the conditions which most tend 

 thus to produce varieties, within the limits of 

 species, are those that are included under the 

 general term domestication ; and the widest 

 divergence among these varieties is to be 

 found in those species, which are brought into 

 the closest relation to Man. 



10. Among the domesticated races of quad- 

 rupeds, the characters most susceptible of 



variation are, 1. Stature ; 2. General con- 

 formation of the body, as dependent upon the 

 proportionate development of the limbs and 

 trunk, the proportion of the breadth and 

 thickness of bones to their length, the relative 

 development of the soft tissues in different 

 parts, &c. &c. ; 3. Conformation of the skull, as 

 shown especially in the relative development 

 of the cranial and facial portions, the capacity 

 of the cranial cavity, and the elongation of the 

 muzzle ; 4. Quantity, texture, and colour of 

 the hairy covering ; 5. Psychical character, 

 as shown in the increase of intelligence, in 

 the acquirement of new methods of action, 

 and in the disappearance of some of the na- 

 tural instinctive propensities. 



11. In every race of domesticated animals, 

 new varieties, departing more or less from the 

 parent stock, in one or more of these charac- 

 ters, are occasionally produced ; some of 

 these being directly traceable to the influence 

 of external conditions, whose action upon a 

 long succession of generations gradually mo- 

 difies the character of that part of the race 

 which is exposed to it; whilst others originate 

 in the production of offspring, which, from 

 some cause not understood, present a marked 

 departure from the parental type. In the 

 first case, the variety is permanent, that is, it 

 tends to hereditary transmission so long as 

 the same conditions exist ; and thus arise the 

 peculiar adaptations between the characters 

 and constitutions of races, which have been 

 dispersed through regions very dissimilar in 

 their physical conditions, and the climate, 

 food, &c., to which they have been respec- 

 tively habituated. In the second case, the 

 variety is transitory, the individual peculiarity 

 tending to disappear in the course of two or 

 three generations, by becoming merged in the 

 more general type ; but if it should happen 

 that the individuals thus distinguished should 

 breed together, the peculiarity shows a ten- 

 dency to perpetuation by hereditary trans- 

 mission ; and thus an entirely new race may 

 originate, which remains distinct so long as 

 it is not allowed to breed with others. 



12. The several races of any kind of do- 

 mesticated animals, which, according to the 

 foregoing criteria, are accounted as belonging 

 to the same species, breed freely and sponta- 

 neously with each other, when allowed to do 

 so ; and the offspring are fertile, not only with 

 either of the parent races, but with each 

 other. The mixed races thus originating, it 

 may be added, frequently surpass either of 

 their parent stocks, not only in the advanta- 

 geous combination of different attributes, but 

 also in general vigour, and in procreative 

 capacity ; so that the mixture of races which 

 are specifically identical, tends to the multi- 

 plication of the species as a whole. 



13. On the other hand, although propaga- 

 tion may take place between individuals of 

 undoubtedly distinct species, yet there is 

 little spontaneous tendency to such admix- 

 ture ; for each animal will select one of its own 

 species for sexual intercourse, in preference 

 to one of another species ; and it is, con- 



