EXPLANATION OF FOKM AND COLOURING. 217 



animal food after being deprived of it even for a day or two that their usual 

 discrimination in relation to it vanished and they became, till their meat- 

 hunger was satisfied, nearly useless for experiment in that particular direction. 



As the I'esult of my general experience, I would lay it down as, at any rate, 

 a safe rule: "To ensure thoroughly reliable results provide a mixed diet 

 and include as a fairlj important item the order of insects with which it is 

 proposed to experiment." Wherever, however^ experimentation is on a 

 sufficiently large scale and fairly continuous, the material used in it should 

 alone be sufficient to obviate over-eajgerness and too great lack of practice. 



Further jDoints. I made a point of always (four times a day) placing the 

 birds' food in their trays myself and also of chatting much to them, with the 

 result that they quickly became very friendly with the experimenter. At 

 the same time, after the initial taming, I avoided the continual offering of 

 dainties by hand, and would allow even their ordinary food to contain a 

 certain proportion of such highly unpleasant insects as the bird might most 

 frequently meet with in the wild state fas the grasshopper, Lentula, and the 

 Meloid beetle, Mylahris). The cages were wire-fronted packing-cases, with the 

 result that no bird could see what those in the other cages did; and^ further, 

 no complications arose with regard to the possible removal of insects by ants 

 or the birds' attendant, excepting, I believe, in one unimportant instance. 

 The cages were in proportion to the size and importance of the bird (the owl 

 even having a whole small shed to herself) ; they were kept, Avhen not in the 

 sun, in a dry, airy, sheltered verandah, and they were cleaned out daily. Each 

 bird, except where otherwise stated, had a cage to itself. 



It may still be objected that however successful the experimenter may be 

 in ameliorating its conditions, confinement must necessarily remain a highly 

 unnatural state for so active an animal as a bird. It is still, therefore, 

 exceedingly possible that my birds did not display the same preferences as 

 they might have done in the wild state. I fully admit the possible justice of 

 this criticism, and all I have left to reply to it is this : — 



1. Each sufficiently tested bird was found, on the whole, to be exceedingly 

 consistent. 



2. There has been quite a strong general agreement in the order of pre- 

 ference, not only between individuals of the same species, but between different 

 and quite unrelated species — so unrelated as a butcher-bird, a drongo, various 

 Picarians, an owl, a hawk, and a francolin ; also not only between the various 

 birds themselves, but between these and a monkey, a chameleoUj a beetle, an 

 Orthopteron, a dragon-fly, and an Asilid, in so far as these latter animals have 

 been tested. Thus Acrseinse (and certain beetles) have always been placed very 

 low, Mylothris (and certain motlis and grasshoppers) always just above them, 

 Belenois and some Lycsenids always next, and other Lycsenids and Pierines 

 and some Nymphaline and Satyrine genera and a skipper ( Cyclopides) 

 above these. Finally, came the yet higher grades, which included various 



