XVII THE METHOD OF ORGANIC EVOLUTION 373 



this subject (in 1890), Mr. Gal ton said he had reason to 

 believe that the patterns are to some extent hereditary, 

 but that he had no evidence of it ; while in his paper in 

 Mind four years later, he could still only say that " they 

 are to be looked upon" as having "a slight tendency 

 towards transmission by inheritance." But the very 

 essence of specific and generic characters is, that they are 

 strictly transmitted by inheritance. Yet again, whatever 

 difference of opinion there may be as to the utility of all 

 the characters which distinguish species, every one will 

 admit that many are useful, and especially that the 

 general assemblage of characters that fit each species for 

 a somewhat different mode of life from its nearest allies, 

 must certainly be useful. But the very essence of Mr. 

 Galton's argument as to these finger-prints is, that they 

 are not and cannot be in any way directly useful. How, 

 then, can the manner in which these patterns may be 

 grouped, furnish us with any argument whatever as 

 regards such totally diverse things as generic or specific 

 characters — and still less as regards genera and species 

 themselves ? 



The fact is, no doubt, that these patterns are the 

 direct result of the laws of growth of the tissues of the 

 skin. The limited number and definite character of these 

 patterns are probably the mechanical incidental results 

 of these laws, under the ever- varying conditions of develop- 

 ment in each individual. A good analogy would be found 

 in snow-crystals, of which about a thousand varieties 

 have been recorded, which may, however, all be grouped 

 under five classes, while each snow-fall usually produces 

 crystals of one class. Here we have the fixed and definite 

 laws of the crystallisation of water, so modified by con- 

 ditions of moisture, temperature, motion, and perhaps 

 electric state of the atmosphere, as to lead to this wonder- 

 ful variety of the product, yet always subject to the law 

 of crystalline symmetry and to systematic grouping under 

 definite classes ; just as in these finger-prints we have a 

 more limited variety of forms, which also can be grouped 

 under a few classes. But neither the one nor the other 

 has any real bearing upon the problem of the nature and 



