44 EVOLUTION [CHAP. II 



On p. 91, in speaking of the idea that the species which make up a 

 genus may have descended from a common form, he says : 



" There must, indeed, be some principle on which the phenomena of 

 resemblance, as well as those of diversity, may be explained ; and the 

 reference of several forms to a common type seems calculated to suggest 

 the idea of some original affinity ; but, as this is merely a conjecture, it 

 must be kept out of sight when our inquiries respect matters of fact 

 only." 



This view is again given in Vol. II., p. 569, where he asks whether we 

 should believe that " at the first production of a genus, when it first grew 

 into existence, some slight modification in the productive causes stamped 

 it originally with all these specific diversities ? Or is it most probable 

 that the modification was subsequent to its origin, and that the genus at 

 its first creation was one and uniform, and afterwards became diversified 

 by the influence of external agents ?" He concludes that " the former of 

 these suppositions is the conclusion to which we are led by all that can 

 be ascertained respecting the limits of species, and the extent of variation 

 under the influence of causes at present existing and operating." 



In spite of the fact that Prichard did not carry his ideas to their 

 logical conclusion, it may perhaps excite surprise that Mr. Darwin should 

 have spoken of him as absolutely on the side of immutability. 



We believe it to be partly accounted for (as Poulton suggests) by the 

 fact that Mr. Darwin possessed only the third edition (1836 and 1837) 

 and the fourth edition (1841-5 1). 1 In neither of these is the evolutionary 

 point of view so strong as in the second edition. 



We have gone through all the passages marked by Mr. Darwin for 

 future reference in the third and fourth editions, and have been only able 

 to find the following, which occurs in the third edition (Vol. I., 1836, 

 p. 242) : 2 



" The variety in form, prevalent among all organised productions of 

 nature, is found to subsist between individual beings of whatever species, 

 even when they are the offspring of the same parents. Another circum- 

 stance equally remarkable is the tendency which exists in almost every 

 tribe, whether of animals or of plants, to transmit to their offspring and 

 to perpetuate in their race all individual peculiarities which may thus have 

 taken their rise. These two general facts in the economy of organised 



1 The edition of 1841-51 consists of reprints of the third edition and 

 three additional volumes of various dates. Vols. I. and II. are described 

 in the title-page as the fourth edition ; Vols. III. and IV. as the third 

 edition, and Vol. V. has no edition marked in the title. 



2 There is also (ed. 1837, Vol. II., p. 344) a vague reference to 

 Natural Selection, of which the last sentence is enclosed in pencil in 

 inverted commas, as though Mr. Darwin had intended to quote it : "In 

 other parts of Africa the xanthous variety [of man] often appears, but 

 does not multiply. Individuals thus characterised are like seeds which 

 perish in an uncongenial soil," 



