88 THE EVOLUTION THEORY 



a piece of bark, a stone overgrown with lichen, an eye, and so on. 

 In such a case the individual colour-spots stand in a particular, 

 indirect relation to each other; although they are independent of 

 •each other in their variation, they are not indifferent and due to 

 chance, for together they produce a common picture; this is har- 

 monious adaptation of many parts, where the Lamarckian principle 

 is absolutely excluded. 



It may, perhaps, be objected that this mimetic picture does not 

 arise all at once, but ver}^ slowly in the course of long series of 

 generations, and, indeed, of species. This must of course be so ; 

 the simple beginnings are complicated and perfected through the 

 course of long ages. This is implied in the principle of selection 

 as we understand it. But does any one suppose that the gigantic 

 a,ntlers of the giant-stag were developed in a few generations'? In 

 this case, too, must not numerous races have succeeded each other 

 before the primitive antlers attained this enormous size? If this 

 must be assumed there was abundance of time for the adaptation, 

 through gevniinal variations, of the secondarily varying parts, the 

 muscles, tendons, nerves, and bones, for all these parts function 

 actively, and can without difficulty meet, in the individual life, the 

 increased claims made upon them by a slight increase in the size 

 of the antlers. For the certain and indubitable consequence of 

 exercise, of increased use, is the strengthening of the functioning 

 parts. 



Thus the appropriate germinal variation of the secondarily 

 varying parts may be delaj^ed for a little without the individual 

 being any the less effective, or being obliged to succumb in the 

 struggle for existence. I do not, however, assert for a moment 

 that the whole explanation of the phenomena of co-adaptation is 

 included in this; on the contrar}^, I hope soon to be able to show 

 that we may in such cases assum.e a preponderance of variational 

 tendencies in a favourable direction, and that there is thus an 

 indirect connexion between the utility of a variation and its actual 

 occurrence. In the first place, however, I must refer to the other 

 group of facts which I have indicated, which show, likewise, that 

 the simultaneous co-adaptation of different parts may arise in 

 certain circumstances, although the Lamarckian principle be excluded. 

 These are the facts presented to us by the sterile forms of those 

 insects, which, like bees, termites, and ants, live together in large 

 societies. 



Ants and bees are of special interest to us in this connexion, 

 because they have long been carefully watched by a number of 



