DARWIN AND THE ORIGIN OF SPECIES 221 



hair, with large or small hoofs, with peculiar colour, eyes, 

 teeth, perhaps. In short, whatever variation we perceive of 

 ordinary occurrence might by selection be carried to an extra- 

 vagant excess. If a large annual prize were offered for any of 

 these novel peculiarities, probably the variation in the first few 

 years would be remarkable, but in twenty years' time the judges 

 would be much puzzled to which breeder the prize should fall, 

 and the maximum excellence would be known and expressed in 

 figures, so that an eighth of an inch more or less would deter- 

 mine success or failure. 



A given animal or plant appears to be contained, as it were, 

 within a sphere of variation ; one individual lies near one por- 

 tion of the surface, another individual, of the same species, near 

 another part of the surface ; the average animal at the centre. 

 Any individual may produce descendants varying in any direc- 

 tion, but is more likely to produce descendants varying towards 

 the centre of the sphere, and the variations in that direction 

 will be greater in amount than the variations towards the sur- 

 face. Thus, a set of racers of equal merit indiscriminately 

 breeding will produce more colts and foals of inferior than of 

 superior speed, and the falling off of the degenerate will be 

 greater than the improvement of the select. A set of Clydes- 

 dale prize horses would produce more colts and foals of inferior 

 than superior strength. More seedlings of ' Senatsur Vaisse ' 

 will be inferior to him in size and colour than superior. The 

 tendency to revert, admitted by Darwin, is generalised in the 

 simile of the sphere here suggested. On the other hand, 

 Darwin insists very sufficiently on the rapidity with which new 

 peculiarities are produced ; and this rapidity is quite as essential 

 to the argument now urged as subsequent slowness. 



We hope this argument is now plain. However slow the 

 rate of variation might be, even though it were only one part 

 in a thousand per twenty or two thousand generations, yet if it 

 were constant or erratic we might believe that, in untold time, 

 it would lead to untold distance ; but if in every case we find 

 that deviation from an average individual can be rapidly effected 

 at first, and that the rate of deviation steadily diminishes till 

 it reaches an almost imperceptible amount, then we are as much 

 entitled to assume a limit to the possible deviation as we are to. 



