the Coloration of Eggs. 575 



have to be explained with a very full knowledge of the egg's 

 defences, aud of the habits of its parents and its enemies ; 

 but I have said enough, I think, to suggest that, if and 

 when the evidence for the existence of preferences in the 

 enemies of eggs becomes conclusive, so far from finding 

 variability a stumbling-block we shall begin to find it 

 reasonably explained. 



The Experiments. 



Method of Deduction. — If species A was eaten immediately 

 after B's refusal, A was regarded as probably preferred to B. 

 If, however, another acceptance, C, had intervened between 

 B's refusal and A's acceptance, A could not be regarded as 

 necessarily preferred to B. Its acceptance might have been 

 (and often certainly was) the result of a special stimulation 

 of the digestive secretions by C — a stimulation which might 

 even lead to B's acceptance now if reofi'ered. Depression of 

 the appetite by an unwelcome offering also occurred, and its 

 possibility has to be allowed for, but it was less frequent 

 and less marked than stimulation. Insufficiency of a par- 

 ticular class of prey in the animal's diet before and during 

 the period of experimentation had also to be noted, as it 

 sometimes led to special craving. 



Special complicating factors to be allowed for were these : 

 The lemur was found probably to possess a slight pre- 

 ference for freshly- opened eggs as against eggs of the same 

 species that had stood over, opened from the last experiment 

 — not that these were greatly used. The rat appeared to be 

 quite indifferent to this, but slightly preferred fresh eggs to 

 hard-set ones. To this the lemur seemed indifferent. The 

 mongoose, on the other hand, preferred incubated to fresh, 

 and ate readily (as I ascertained by special experiment) 

 even somewhat highly addled eggs of the species he 

 preferred. 



I was unfortunate in one of the conditions under which 

 my experiments on the lemur had to be carried out ; fowls' 

 eggs were scarce at the time, and it was, therefore, more 



