THE PBOBL/aM OF UTILITT. 489 



are indefinite in their character and very unequal in their amount. 

 Some species are much more variable than others, and Darwin 

 has shown reasons for believing that any change of conditions 

 induces variability, but not that it causes definite variations. 

 The two things are radically distinct. So far as I am aware, no 

 evidence has been adduced of any special conditions which have 

 produced a definite variation in the whole offspring of all the 

 individuals subjected to it. But it must do more than this. For 

 it must produce a variation so exceptionally stable that it con- 

 stantly recurs in all the offspring of successive generations, even 

 though those offspring are subjected to considerable change of 

 conditions, as are the individuals of all species except the rarest 

 or the most local. Only with such constancy and stability of 

 inheritance could a useless character become fixed in every indi- 

 vidual of a species, which it must be to be a " specific " character. 

 It must, therefore, from the very first have been invariable. 

 But this feature of invariability without selection has not been 

 found to characterize any variation, whether occurring among 

 wild or domesticated organisms. Such an occurrence would 

 necessarily have forced itself upon the attention of breeders and 

 horticulturists. For if the theory is true that the majority of 

 specific characters are of this useless kind, their occurrence as 

 permanent and unchangeable variations must be a common phe- 

 nomenon, and we ought to find that foreign plants when first 

 cultivated very often present new characters, not sporadically 

 but appearing in every individual, and which cannot be got rid 

 of, since they do not vary and selection would therefore be 

 powerless to eliminate them. Has any indication of a phenomenon 

 of this kind ever been noted? 



Let us come now to the actual causes said to produce useless 

 specific characters. According to Mr. Homanes they are five 

 in number : Climate, Food, Sexual Selection, Isolation, and Laws 

 of Grrowth. Let us consider how these are known to act or are 

 alleged to act. Climate and Food undoubtedly produce modifica- 

 tion in the individual, but it has not yet been proved that these 

 modifications are hereditary. If this could be proved the whole 

 discussion on the heredity of acquired characters would be settled 

 in the affirmative. The supposed proof that these causes produce 

 definite changes which are hereditary is derived from the fact 

 that there is often a simultaneous change in the colours of many 

 animals, or in the form or texture of the foliage of many plants, 

 in difi"erent parts of the area they occupy which are characterized 



