EDUCATION 243 



birds, large enough to be able to hop on the branches or even on 

 the ground, will shriek for food with their bills gaping widely, 

 although attractive worms are wriggling and squirming within an 

 inch of their nose and eyes. When they are rather older and have 

 learned to go in quest of their food, they are still indiscriminate. 

 Opinions are divided as to how far old and experienced birds eat 

 the brightly coloured, nasty-tasting caterpillars and insects which 

 are supposed to warn prospective enemies of their unpalatableness 

 by their gaudy hues, but it is at least certain that young birds have 

 no instinctive knowledge of this kind of advertisement, and greedily 

 eat creatures with which their palates or their stomachs quarrel. 



There is much the same set of differences amongst young mam- 

 mals. The act of suckling seems to be purely instinctive and takes 

 place as soon as the little creature finds the warm nipple. An 

 artificial teat arouses the instinctive action nearly as well as the 

 natural organ, and young mammals take readily to the bottle. 

 But if the liquid supplied be cold, or very different in flavour from 

 milk, the reflexes do not work and the material is not swallowed. 

 When the milk diet begins to be varied with other substances, there 

 is an interplay of instinct with the results gained by experiment. 

 The vegetarians will not attempt to nibble flesh or fish or living 

 animals, but they take some time to learn the difference between 

 grass and dry paper, and so forth. The sense of smell and that of 

 taste are certainly present, but act at first only on acute differences 

 and lead them to reject certain substances rather than to show 

 preferences amongst those that they wiU take. When they 

 are a little older, they begin to select, but the choice they make is 

 difficult to understand. I have offered green vegetation of different 

 kinds to many young herbivorous mammals with most conflicting 

 results. They are attracted by green colour, and I have never 

 found any that would refuse such palatable and wholesome leaves 

 as willow, poplar, hawthorn and elm. Young camels, sheep, goats 

 and deer will take leaves like elder into their mouths, and some of 

 them will swallow it, whilst others reject it after having tasted it. 

 Antelopes and cattle are more wary or have a keener sense of smell, 

 for they generally refuse leaves of elder after smelling them 

 but before tasting them. Green French beans, of which most 

 young animals can have no experience, are approached with the 

 greatest caution and are generally refused until a good deal of 

 persuasion has been employed, although I cannot perceive that 

 these vegetables have any appreciable odour. When animals have 



