SSO Analyses of Books, [Mat, 



Dr. Prichard, without pledging himself to any opinion, inves- 

 tigates ill the first place the criteria by which species are to be dis- 

 tinguislicd, and after examining those already offered, particularly 

 that of John Hunter, who considered the sterility or fruitfulness of 

 a hybrid the proof of difference or identity of species of the parents, 

 he endeavours to lay down a general rule, derived from analog)', 

 which, although imperfect, yields more satisfaction to the inquirer, 

 than any solitary assumption can do. It has, too, the sanction of 

 two of the most eminent naturalists of the present day. The rule 

 whicii Dr. Fritcliard lays down is, that after having observed a 

 number of the changes produced in living bodies by adventitious 

 causes, when any particular deviation is found frequently to recur, 

 all parallel diversities may be ascribed to analogous causes, although 

 the relations between these latter causes and their eflects should not 

 be so distinctly traced as in other more ordinary events. According 

 to this rule, all the remarkable varieties of mankind, when com- 

 pared with those of the inferior animals, particularly when domes- 

 tication has displayed its effects, fall within the limits of one 

 species ; and Dr. P. makes the inference, that as the strictest ana- 

 logy exists between the changes which almost the whole of the 

 inferior tribes have a tendency to assume under known circum- 

 stances, and those diversities existing among men, it is consistent 

 with the strictest rules of philosophizing to infer, that these changes 

 originate in " the principle of natural deviation, and furnishing no 

 specific distinction." 



The next branch of the, inquiry is how far men are to be con- 

 sidered as having uU proceeded from one common stock. This 

 question has been treated of by several writers purely on historical 

 evidence ; Dr. Pritchard, however, without disregarding the power- 

 ful arguments afforded by the historical researches of Sir VV, Jones, 

 Bailey, and others, still proceeds on analogy, and endeavours to 

 solve the general problem as it regards all organized tribes, but 

 more particularly animals. With much acuteness he has examined 

 the distribution of animals, more especially in those vast regions of 

 the southern hemisphere, so little known until the important dis- 

 coveries of Cook, Bougainville, VVallis, Flinders, and others, had 

 removed the veil which was spread over Nature; and concludes by 

 inferring, " that every existing species may be traced witii proba- 

 bility to a certain point which appears to have been its original 

 abode ; and that few or no species have been found in countries 

 separated from their primary seats by barriers which their loco- 

 motive powers and peculiar structure do not enable them to sur- 

 mount." This inference, if true in general, includes the particular 

 case of the human species. 



liaving tiius established the criteria of species, and rendered it 

 probable that species were originally confined to one point, it is 

 Uetefsary to determine as far as possible, what are the causes that 

 produce the very extraordinary diversities which exist among man- 

 kind. The commonly maiatuined hypotheses of those who adopt 



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