ON THE DISCRIMINATION OF SPECIES. 77 



treated might be considered as inferior species, incapable of being raised by 

 any treatment to our own elevation; and as thus falling legitimately under the 

 domination of the superior races, just as the lower animals have been placed 

 by the Creator in subservience to Man. This doctrine, which has had its 

 origin in the desire to justify as expedient what could not be defended as 

 morally right, finds no support from scientific inquiries conducted in an en- 

 larged spirit. In order to arrive at a just conclusion on the subject, it is ne- 

 cessary to take a very extensive survey of the evidence furnished by a number 

 of different lines of inquiry. Thus, in the first place, it is right to investigate 

 what are the discriminating structural marks, by which species are distin- 

 guished among the lower tribes of animals. Secondly, it should be ascer- 

 tained to what extent variation may proceed among races, which are histori- 

 cally known to have a common parentage ; and what are the circumstances 

 which most favour such variations. Thirdly, the extreme variations, which 

 present themselves among the different races of men, should be compared 

 with those which occur among tribes of animals known to be of the same 

 parentage; and it should be questioned, at the same time, whether the cir- 

 cumstances which favour the production of varieties in the latter case, are in 

 operation in the former. Fourthly, where it is impossible to trace back dis- 

 tinct races to their origin, it is to be inquired how far agreement in physiolo- 

 gical and psychological peculiarities may be regarded as indicating specific 

 identity, even where a considerable difference exists in bodily conformation ; 

 and this test, if it can be determined on, has to be applied to Man. Fifthly, 

 it must be attempted, by a detailed examination of the varieties of the human 

 race themselves, to ascertain whether their differences in conformation are 

 constant; or whether there are not occasional manifestations, in each race, of 

 a tendency to assume the characters of others ; so as to prevent a definite line 

 being drawn between the several tribes, which together make up the (sup- 

 posed) distinct species.* 



2. On the Discrimination of Species. 



64. Theirs/ of the foregoing questions is a fertile source of perplexity to 

 the Naturalist ; owing to the tendency that exists in certain races of Plants 

 and Animals, to exhibit variations of form much greater than those which 

 are relied upon in other instances as characterizing distinct species. In our 

 ignorance as to the history of the origin of the greater part of the dissimilar 

 forms or races of organized beings, with which the globe is peopled, we are 

 accustomed to regard two races of Plants or animals as of the same species, 

 that is, as having had the same or similar progenitors, when they are not 

 distinguished from one another by any peculiarities, but such as the one may 

 be supposed to have gained, or the other to have lost, by the influence of 

 external circumstances during a long period of time. On the other hand, two 

 races are regarded as constituting distinct species, that is,*are believed to 

 have descended from dissimilar parents, when a constant well-marked dif- 

 ference exists between them, such as exhibits no tendency to variation in the 

 individuals of either race (being equally characteristic of every one), and is 

 not affected by the lapse of time or by change in external conditions. 



65. Thus, if we compare together the different breeds of Dogs, we find 



This investigation has been most elaborately, and in the Author's opinion most suc- 

 cessfully, worked out by Dr. Prichard, in his profound and philosophical Treatise on the 

 Physical History of Man. The sketch of the argument given above does little more than 

 exhibit the conclusions at which he has arrived ; and for the grounds on which these are 

 based, reference .must be made to that work, or to the abridgment of it published by Dr. 

 Prichard, under the title of the Natural Histoiy of Man. 



