GEEMINAL SELECTION 143 



of the species nor a drawback thereto. In tlie next chapter we shall 

 discuss the influence of isolation upon the formation of species, and 

 it will be seen that in certain conditions even indifferent variations 

 may be preserved, and that saltatory variations, as for instance in the 

 evolution of species of land- snails or butterflies, may liave materially 

 contributed to bring this about. 



I should like to emphasize still more the part played by saltatory 

 variations arising from germinal selection in the origin of secondary 

 sexual characters. As soon as personal selection, whether sexual 

 or ordinary, prefers as useful in any sense a saltatory variation, it is 

 not only preserved and becomes a character of a variety, but it may 

 increase, and we have to ask whether such sudden variations are 

 frequently of a useful kind, especially when not individual characters 

 alone, but whole combinations of them are implicated. If we may 

 judge from the sports of the flowers and the leaves of plants, trans- 

 formations useful to the species as a whole rarely occur suddenly, that 

 is, they occur only in a few out of very numerous sports ; they are 

 much more frequently indifferent, although quite visible and often 

 conspicuous variations. 



For this reason I am disposed to attribute to saltatory vai-iations 

 a considerable share in the production of distinctive sexual characters. 

 From saltatory variations in flowers, fruits, and leaves we know that 

 these may be conspicuous enough even on their first appearance, and 

 so we are justified in finding in such variations the first beginnings 

 of many of the decorative distinguishing characters which occur in the 

 males of so many animals, especially butterflies and birds. As soon 

 as it is admitted that variations of considerable amount, which have 

 been slowly prepared in the germ-plasm by means of germinal selec- 

 tion, can suddenly attain to expression, one of the objections against 

 sexual selection is disposed of, for conspicuous variations are necessary 

 for the operation of this kind of selection, since the changes in question 

 must attract the attention of the females if they are to be preferred. 

 Without such preference, even though it be not quite strict and con- 

 sistent, a long-continued augmentation of the decorative characters 



is inconceivable. 



But as intra-germinal disturbances of the position of equilibrium 

 in the determinant system is at the root of the saltatory variations of 

 our cultivated plants, it must also have played a large share in the 

 evolution of breeds among our domesticated animals, wliich is tliere- 

 fore by no means wholly due to artificial selection operating upon the 

 variation of individual characters. In all breeds in the formation of 

 which the production of more than a single definite character was 



