DARWIN. 89 



closely studied. The comb, " so beautifully adapted to 

 its end," he enthusiastically admired. Yet he finds 

 gradation among bees, and can imagine a method by 

 which this beautiful construction has been gradually 

 developed. His ideas were tested by setting bees to 

 work on a solid piece of wax between two combs. The 

 detailed account of these experiments is most instructive. 

 It is quite charming to mentally follow the patient experi- 

 menter covering the edges of a single cell or the extreme 

 margin of a growing comb with a thin layer of vermilion 

 wax, and soon proving that many bees work in succession 

 at a single cell by the rapid diffusion of the vermilion 

 colouring as delicately as a painter could have done it, 

 atoms of the coloured wax being removed and worked 

 into the growing cells all round. 1 "It was really curious," 

 Darwin says, " to note in cases of difficulty, as when two 

 pieces of comb met at an angle, how often the bees would 

 entirely pull down and rebuild in different ways the same 

 cell, sometimes recurring to a shape which they had at 

 first rejected." Here surely he was watching evolution in 

 that slow, gradual process which appears to be the rule. 



The castes of neuter ants, constituting as they did 

 " by far the most serious special difficulty " Darwin had 

 encountered, were similarly studied ; but, as expected, 

 gradations were found connecting them, although the 

 extremes differ markedly in shape and size. The case is 



1 The full text of a large part of Darwin's original chapter on 

 Instinct, which was omitted from the " Origin of Species " for the 

 sake of condensation, is published in Mr. Romanes' "Mental Evolu- 

 tion in Animals," 1883, which also contains many other observations 

 by Darwin. 



