3 $4 EVOLUTION [Chav. V 



Letter 263 variations would ensue below the present size of bats' wings, 

 than above it. To this it may be added, that when the 

 influence of "speedy selection" is removed, it seems in itself 

 highly probable that the structure would, for this reason, 

 become more variable, for the only reason why it ever 

 ceased to be variable (i.e., after attaining its maximum size), 

 was because of the influence of selection constantly destroying 

 those individuals in which a tendency to vary occurred. 

 When, therefore, this force antagonistic to variability was 

 removed, it seems highly probable that the latter principle 

 would again begin to assert itself, and this in a cumulative 

 manner. Those individuals in which a tendency to vary 

 occurred being no longer cut off, they would have as good 

 a chance of leaving progeny to inherit their fluctuating 

 disposition as would their more inflexible companions. 



Letter 264 To G. J. Romanes. 



July 16th, 1S74. 



I am much obliged for your kind and long communication, 

 which I have read with great interest, as well as your articles 

 in Nature. The subject seems to me as important and 

 interesting as it is difficult. 1 am much out of health, and 

 working very hard on a very different subject, so thus I 

 cannot give your remarks the attention which they deserve. 

 1 will, however, keep your letter for some later time, when 

 I may again take up the subject. Your letter makes it 

 clearer to mc than it ever was before, how a part or organ 

 which has already begun from any cause to decrease, will go 

 on decreasing through so-called spontaneous variability, with 

 intercrossing ; for under such circumstances it is very unlikely 

 that there should be variation in the direction of increase 

 beyond the average size, and no reason why there should not 

 be variations of decrease. I think this expresses your view. 

 I had intended this summer subjecting plants to [illegible] 

 conditions, and observing the effects on variation ; but the 

 work would be very laborious, yet I am inclined to think 

 it will be hereafter worth the labour. 



Letter 265 To T. Mcehan. 



Down, Oct. 9th, 1874. 

 I am glad that you arc attending to the colours of 

 dioecious flowers ; but it is well to remember that their 



