THE PLAY OF ANIMALS. viv 
Forms or Puay. 
There seem to be two fundamental and primitive forms of 
animal play—the play of movement, and the play of experi- 
ment. 
Play of Movement. 
“Most young things,” Hamerton says, “appear to be 
reservoirs of pent-up natural energy that finds vent in 
irrepressible gambols.” The simplest play is the gambol or 
frolic. Quite apart from direct use, insects play in the air, 
birds among the branches, dolphins in the waves, and so on, 
endlessly. And as they play the heart beats more quickly, 
the breathing is more rapid, the peripheral blood-vessels 
expand, and there ensues that happiness which is the reflex of 
healthy function. The secondary advantage is the training 
of the nerves and muscles for future work. Perhaps the 
so-called roughness of many young boys is often simply 
inappropriate play or a symptom of insufficient play. 
Everyone must remember with affection the wood-chopper 
pourtrayed in Thoreau’s Walden. “By George,” he would 
exclaim, “I can enjoy myself well enough here chopping; I 
want no better sport.” “Sometimes, when at leisure, he 
amused himself all day in woods with a pocket pistol, firing 
salutes to himself as he walked.” The idiot! you say; but 
when he was at dinner the chickadees would sometimes come 
round and peck at the potato in his fingers, and he would say 
that he liked “to have the little fellers about him.” Such 
exuberance of spirits had he, that when a thing amused him 
“he sometimes tumbled down and rolled on the ground with 
laughter.” That was primitive playfulness, and if we know 
the connection between emotion and muscular movements, we 
shall not think of it too lightly. 
When one sees beautiful sights, or hears fine sounds, or the 
like, sensory impressions travel in to our brains, of course. 
But they do not quite stop there. They set agoing other 
messages, which travel out to the heart, which beats differ- 
ently ; to the larynx, which vibrates; to the lungs even, and 
other parts—in short, internal muscular movements occur. 
As the results of these, a third set of messages travel in 
