542 Mr. C. F. M. Swynnerton on 



of mere capricious likes and dislikes, — but one of intrinsic 

 difficulty of digestion, felt in greater or less degree by all 

 enemies alike. 



It matters little, in any case, whether my mongoose's 

 preferences were, or were not, those that would have been 

 shown by an English weasel or magpie. The important point 

 is that he showed preference in eggs at all. Every animal I 

 have experimented on — mammal, bird or reptile, vertebrate 

 or invertebrate — has shown tliese preferences, whether the 

 prey were plants, seeds, mammals, birds, worms, snails, 

 insects and their larvae, or insects' eggs. Is it likely that 

 birds' eggs are alone exempt from so general a rule? 



Arguments from analogy are frequently fallacious, and 

 I have used many such in the last few pages ; yet they 

 are apt to be highly suggestive, and what they suggest 

 in the present instance seems to me to be that preference in 

 the eggs of birds is, at any rate, worth approaching with an 

 open mind. 



I will onl}'^ add : — 



5. My own Criticism. — It is, that a wild minimal, having 

 more abundant exercise, will develop a moi*e ravenous 

 appetite than a captive animal. I had the opportunity of 

 testing this possibility on my wild insectivorous birds, and I 

 found that they probably did become hungry enough to eat 

 highly nauseous prey more frequently and easily than birds 

 in confinement. Yet it amounted to very little. Even 

 the wild birds soon discarded Acraeinse, &c., and eliminated 

 grade after grade from their merM as they gradually satisfied 

 their hunger. It would have been the same, I imagine, for 

 my egg-eating mammals had they been in the wild state : a 

 mere postponement of first rejection, accompanied, it might 

 be, by a compensating postponement of final repletion. But 

 it is on this rock, if on any, that my experiments may split. 



It is also true (another criticism) that I judged that 

 neither rat nor mongoose placed any e^^ at all so low as 

 the latter placed a Burnet moth, or as either might have 

 placed an Acrcea, a Myfabris, an adult Drongo, or a Wood- 

 Hoopoe. It may have been that, using so few species of 



