i6 WAR & STRUGGLE FOR EXISTENCE 



holds the field as the only hypothesis at present 

 before us which has a sound scientific foundation. — 

 But I do not know, I do not think anyone knows, 

 whether the particular view he held will be hereafter 

 fortified by the experience of the ages which come 

 after us. — Whether the particular form in which he 

 has now put before us the Darwinian doctrines may 

 be such as to be destined to survive or not, is more, 

 I venture to think, than anybody is capable at the 

 present moment of saying." 



I am sure that no one is yet in a position to be more 

 certain than Huxley. All who are acquainted with 

 the course of biological speculation know well that 

 from 1859 to 1893, and still more from 1893 to the 

 present time, the principle of natural selection has 

 been subjected to the acutest debate. We can see 

 for ourselves that the artificial selection of breeders 

 and horticulturists has produced changes in form and 

 structure at least as great as the differences that dis- 

 tinguish natural species of animals and plants. But 

 we do not know that these changes would be per- 

 manent if the watchful care of the breeder were 

 removed, or that the new forms could hold their own 

 and persist in a natural environment. The oppor- 

 tunity for natural selection comes about because of 

 the existence of variation, because of the observed 

 fact that individuals of the same parentage are not 

 identical but present innumerable differences from 

 one another and from their parents. These 

 differences may be minute, and perceptible only on 

 skilled measurement, or they may be of a magnitude 

 that attracts even the careless eye, ranging up to 

 what we call sports and abnormalities. When a 



