274 CREATION BY LAW. 
an average increase in the length of the probosces of 
the moths; and this would be a necessary result from 
the fact that nature ever fluctuates about a mean, or 
that in every generation there would be flowers with 
longer and shorter nectaries, and moths with longer 
and shorter probosces than the average. No doubt 
there are a hundred causes that might have checked 
this process before it had reached the point of develop- 
ment at which we find it. If, for instance, the 
variation in the quantity of nectar had been at any 
stage greater than the variation in the length of the 
nectary, then smaller moths could have reached it 
and have effected the fertilization. Or if the growth 
of the probosces of the moths had from other causes 
increased quicker than that of the nectary, or if the 
increased length of proboscis had been injurious to 
them in any way, or if the species of moth with the 
longest proboscis had become much diminished by 
some enemy or other unfavourable conditions, then, 
in any of these cases, the shorter nectaried flowers, 
which would have attracted and could have been ferti- 
lized by the smaller kinds of moths, would have had 
the advantage. And checks of a similar nature to 
these no doubt have acted in other parts of the world, 
and have prevented such an extraordinary develop- 
ment of nectary as has been produced by favourable 
conditions -in Madagascar only, and in one single species 
of Orchid. I may here mention that some of the 
large Sphinx moths of the tropics have probosces 
nearly as long as the nectary of Angraecum sesquipe- 
