36 SCIENTIFIC ILLUSTRATIONS [Cap 



seize a man's hand, it must be killed before it will quit its hold. 

 The magnitude of the horse terrifies it as little as the address of 

 the dog, which last is fond of hunting it. This ferocious dis- 

 position prevents the hamster from being at peace with any 

 animal whatever. It even makes war with its own species. 

 Whether the creature prides itself, like the cantankerous man, 

 on being very brave because of all this unnecessary biting and 

 lighting we have no means of knowing. p. 



Capacity Determined by Sphere. 



Lyell mentions that when companies were formed in England 

 to work the mines in Mexico, some of the English miners who 

 were sent out, being fond of field-sports, brought greyhounds 

 with them, to have the pleasure of coursing on the Mexican 

 mountains, which abound in hares. They found, however, to 

 their great mortification, that the dogs were quite unable to 

 come up to the hares of Mexico. This is explained by recollect- 

 ing that these greyhounds, being transferred from the low and 

 flat lands of England to a mountainous country raised several 

 thousand feet above the level of the sea, and thus experiencing 

 a considerable diminution of atmospheric pressure, became short- 

 winded, and incapable of running down their game. But in the 

 course of a few years, their offspring which were born and 

 brought up in the new country, having their chests and' res- 

 piratory systems adapted to this elevated situation, proved 

 themselves in running down hares fully equal to their parents 

 in England. s. 



The Capricious Disposition. 



The genus Guenon comprises about thirty species of monkeys. 

 Geoffrey Saint-Hilaire says : " They have a singular aptitude in 

 passing from gaiety, which is otherwise their usual state, to melan- 

 choly, from melancholy to joy, and from joy to anger in a few 

 seconds, and from the slightest causes. We see them ardently 

 desirous of obtaining a certain object, testifying the liveliest 

 pleasure if allowed to possess it, and almost immediately after 

 throwing it away with indifference, or breaking it in a fit of rage. 

 We also see them delighting in the society of another animal, 



