NATURAL SELECTION 313 



obtained by accommodation within the life of the individual, 

 perhaps more often than is commonly supposed. The more 

 striking cases of resemblance to a specialised background are 

 one of the chief sources of indirect evidence for the Natural 

 Selection theory. The resemblance may be either to the general 

 background, particularly when this is unusually uniform 

 (e.g. deserts), or to particular objects in the habitat (e.g. eggs 

 of Cuckoos). The incidence of such specialised protection 

 is somewhat capricious and there are some puzzling exceptions. 

 If, however, we confine our attention to cases of clearly cryptic 

 coloration, the following points appear to be important : 



(1) There is often insufficient quantitative evidence as to 



the association of animals with the appropriate 

 background. 



(2) In some examples more evidence is required that the 



habits of the animals do not render the particular 

 coloration unnecessary (e.g. nocturnal animals). 



(3) There is still a lack of evidence that selection has actually 



produced the observed colour-correspondence. In 

 some cases an obscure method of accommodation 

 may be responsible. The examples of the eggs of 

 the Yellow Wattled Lapwing and of the eggs of 

 Cuckoos provide at least good presumptive evidence 

 for selection. 



In the special type of protective coloration commonly 

 known as ' warning colours ' we have to beware of attributing 

 conspicuousness to animals which are really concealed in their 

 natural habitats. The incidence of conspicuous colours is 

 somewhat capricious and is not universally associated with a 

 high degree of unpalatability. On the other hand, there is a 

 good deal of evidence suggesting that species with conspicuous 

 patterns, particularly those made up of bands or spots of black 

 and yellow or red, fall well below the average of palatability. 

 The recent work of Morton Jones (p. 247) provides some of 

 the most striking evidence amongst the Insecta. We still hold, 

 however, that there is a great need for large-scale investiga- 

 tions of the actual food of predators in nature and of the extent 

 to which different genera and species are attacked. The 

 evidence that predators distinguish between variants differing 

 only slightly in colour is still very meagre. Finally, we have 



