292 CREATION BY LAW. 
amount of change has been effected it becomes slower 
and slower, till at length its limits are reached and no 
care in breeding and selection can produce any further 
advance. The race-horse is chosen as an example. 
It is admitted that, with any ordinary lot of horses 
to begin with, careful selection would in a few years 
make a great improvement, and in a comparatively 
short time the standard of our best racers might be 
reached. But that standard has not for many years 
been materially raised, although unlimited wealth and 
energy are expended in the attempt. This is held to 
prove that there are definite limits to variation in any 
special direction, and that we have no reason to sup- 
pose that mere time, and the selective process being 
carried on by natural law, could make any material 
difference. But the writer does not perceive that this 
argument fails to meet the real question, which is, not 
whether indefinite and unlimited change in any or all 
directions is possible, but whether such differences as 
do occur in nature could have been produced by the 
accumulation of variations by selection. In the matter 
of speed, a limit of a definite kind as regards land 
animals does exist in nature. All the swiftest animals 
—deer, antelopes, hares, foxes, lions, leopards, horses, 
zebras, and many others, have reached very nearly the 
same degree of speed. Although the swiftest of each 
must have been for ages preserved, and the slowest 
must have perished, we have no reason to believe 
there is any advance of speed. The possible limit 
under existing conditions, and perhaps under possible 
