534 Mr. C. F. M. Swynnerton on 



careful, and were based on the experience afforded by nearly 

 seventeen hundred such experiments that I had already 

 carried out in other directions. Both animals showed un- 

 mistakable preferences as between the eggs of different 

 species. The lemur, it is true, showed them (like some few 

 insectivorous birds) only when nearing repletion-point — an 

 inadequate support for the hypothesis I was testing. The 

 rat commenced to refuse certain eggs even when fairly 

 hungry. And their preferences coincided. 



Nothing could have been more marked than some of the 

 contrasts between obvious repugnance and eager acceptance 

 that occurred throughout the experiments on the rat. I 

 wished, nevertheless, to suspend judgment until I should 

 have tested the point on some other animal. A Butcher- 

 bird (Lanius collaris humeralis) was secured later in the year, 

 but it would eat no eggs at all except under pressure of 

 great hunger. I had all along been particularly anxious to 

 obtain some bird of the Crow family for these tests, an adult 

 bird with wild experience, but I failed, both in Africa and, 

 later, in England. They have been scarce latterly at Chirinda. 

 A young Jay, which Mr. Seth-Smith was so good as to let me 

 have from the Zoological Gardens (with the kind permisson of 

 Mr. Meade-Waldo, the original donor), gave me some very 

 interesting preferences as between different species of earth- 

 worms and of snails ; but, to judge from its early mistakes 

 even here (and from my experience of hand-reared nestlings 

 generally), its education in egg-tasting would have entailed a 

 wholesale robbery of nests that 1 should have been sorry to 

 undertake. With a carnivorous mammal the experimenter 

 is not confronted with this difficulty. Its choice (by smell 

 and taste) is at all times so wonderfully unhesitating and 

 accurate, that, to all appearances, it is partly instinctive. 

 So, failing in an attempt to get a weasel, I used an Indian 

 mongoose. 



Genuineness of the Preferences. — The mongoose eagei'ly 

 smelt or tasted every kind of egg offered it ; but, from the 

 outset, it resembled the rat in showing the strongest 

 preferences — though probably none of the eggs tested were 



I 



