1038 LIFE : OUTLINES OF GENERAL BIOLOGY 



numerous as the mole-hills in a badly infested field in Britain. 

 They also break down the banks of canals and streams by honey- 

 combing them with their tunnels. They are extremely costly animals. 

 The Red Pocket Gopher of the fertile Mississippi valley, whose body 

 is about seven inches in length, with three more to the tail, is so 

 destructive that an authority who ought to know says: "No animal 

 in the West is more universally disliked or more diligently destroyed." 

 They are trapped and poisoned in thousands — in thousands on one 

 plantation in one year; they have their natural enemies in weasels 

 and poisonous snakes, foxes and coyotes, hawks by day and owls 

 by night, and yet they flourish! They are not only non-social, but 

 live on positively bad terms with one another. The old ones are 

 usually found living alone. They have poor sight, heavy bodies, 

 short legs, and rather clumsy movements outside of their burrows. 

 They are, so far as we can judge, rather stupid animals. And yet 

 they flourish ! 



Thus our first question is : How do these destructive rodents hold 

 their own in spite of handicaps and enemies and man's commendable 

 retaliations? They extend from Panama to Saskatchewan, and from 

 sea-level to the timber-line at above 13,000 feet on some of the high 

 mountains of Mexico. Part of the explanation is easy enough ; they 

 have an extensive vegetarian bill of fare; their chisel-edged incisor 

 teeth are very sharp and strong; they use these teeth to help in 

 burrowing, which is mainly effected by the strong claws of the fore- 

 feet ; the working tunnels are usually less than six inches below the 

 surface, but there are interesting adaptive details, such as an 

 occasional drop of two or three feet to the living-room, the setting 

 apart of special store-chambers, and the use of short side branches 

 as sanitary conveniences. As gophers dislike the light, they do not 

 often show face by day, unless it be to make a short excursion to 

 food plants near at hand. It is obviously a great advantage to be 

 able to stuff the cheek-pockets with seeds and bulbs and pieces of 

 plants, and to take these home to be stored. The pockets are packed 

 by sideways movements of the front feet, used as hands so quickly 

 that the details can hardly be followed. In the process of unloading 

 the hands press on the distended pockets from behind forwards. 

 In adaptation to gnawing and burrowing there is a fine development 

 of muscles about the broad head, the fore limbs, and the anterior 

 body. As might be expected in burrowers, the ears are reduced to^ 

 small fleshy rims around the openings, which means, we take it, 

 that germinal variations in the direction of vestigial ear-trumpets 

 were advantageous, while individuals that persisted in having 

 prominent pinnae would be eliminated. 



Speaking of burrowing, we may cite the fact that gophers can run< 

 backwards as well as forwards in their burrows, the rather short, 

 well-innervated, tail serving as a guide when they move in that J 



