THE PLAY OF ANIMALS. 83 
in some languages—will spend hours in imitating what they 
have seen man do. With hesitation and timidity and many 
a failure, but with every manifestation of joy when success 
is reached, a monkey will learn to open a match-box and 
strike the matches. 
It has been shown for a few-—perhaps a dozen—young 
birds that they will utter the characteristic cry although the 
eggs were artificially incubated and the young not allowed to 
hear their kin. A plover’s ery has been heard from within 
the ege. 
In these cases we are justified in saying that the cry is 
instinctive and forms part of the general inheritance. 
On the other hand, it is certain that young birds will 
take on the song of their foster-parents—a fact which 
points to the conclusion that the details of song are normally 
learned by imitation. It is also well known that adult birds 
are extraordinary plagiarists, often combining in a single 
song four or five phrases imitated from their neighbours. 
Now, although song is mostly restricted to the adult male 
birds and to the time of courtship, this is not invariably the 
case. Young skylarks, robins, and thrushes, and others sing 
apparently for the pleasure of it; and we may regard these 
as cases where the youthful play is the means of acquiring 
more perfect imitative power before the critical time of life 
arrives. 
Singing in chorus, as in starling and linnet, American rice 
troupial and goldfinch, seems also to approach play. 
Mr Hudson, in his Naturalist in La Plata, has some 
interesting observations on the song-flight and chorus-singing 
of the crested screamer or chakar, a bird about the size of 
our heron. 
“The chakar . . . . so ponderous a fowl, leaves its grass 
plot and soars purely for recreation, taking so much pleasure 
in its aérial exercises that in bright, warm weather, in winter 
and spring, it spends a great part of the day in the upper 
regious of the air.” And as it soars it sings. 
He once came upon an enormous congregation around a 
lake, arranged in well-defined flocks, averaging about five 
hundred birds in each. “ Presently one flock near me began 
singing, and continued their powerful chant for three or four 
