576 Mr. C. F. M. Swynuerton on 



difficult for me to make eggs a really strong item in the 

 animal's daily food, aud so avoid that over-eagerness for 

 them that I have referred to, and that was just possibly 

 responsible for the fact that the lemur's preferences were 

 not, as a rule, shown till somewhat near repletion-point. 

 In my experiments on the mongoose this difficulty was not 

 present, and, whether as a result of this or not, his prefer- 

 ences were very marked and decided. So, as a rule, were 

 those of the rat, an animal which from its smaller size 

 was far more easily supplied with an adequate diet than the 

 lemur. I ought to say that I found later that the lemur 

 preferred several species of Noctuid moths and of birds to 

 any of the insects and fruits used in the following experi- 

 ments, so that it is barely possible that he was sometimes 

 less replete in these experiments than he appeared. 



Experiments on a Rat [Mus ratius). 



Expt. 1. Feb. 2, 1913. — The rat has been a week in cap- 

 tivity and is accepting freely from the forceps. Of eggs he 

 has been offered and has accepted and eaten readily from 

 the very first those of Amblyospiza albifrons, Hyphantornis 

 Jamesoni, and Coliuspasser ardens : probably in sufficient 

 numbers to ensure the absence of any undue craving. 



Late this morning, having purposely kept him without 

 food since last night, I fed him a very little to avoid ac- 

 ceptances being the result of sheer starvation. He then 

 readily ate a fresh egg each of Amblyospiza albifrons and 

 Culiuspasser ardens, tasted well and rejected a rather hard- 

 set egg of Pycnonotus layardi, and continued to ignore it on 

 my leaving it in the cage, but readily ate a fresh A. albifrons 

 eg^^ repeatedly refused the Pycnonotus egg, and smelt and 

 rejected a second of the same species from another clutch, 

 and on my leaving them beside him continued persistently 

 to ignore them. I had to leave, but before doing so added 

 an egg each of Coliuspasser ardens and Amblyospiza albifrons 

 (each quite as hard-set as the first Bulbul's e^g)\ a Bulbul's 

 egg was left right under the rat's nose. 



On my return twenty minutes later the two Ploceid 



