42 THE POPULAR SCIENCE MONTHLY. 



saiilt.* The gopher is singularly exempt from the dangers en- 

 countered by the species which normally dwell on the surface, 

 and its needs are totally different from its purely terrestrial kin- 

 dred. How is it, then, that the form remains unchanged ? Clearly 

 the selectionist has to assume either that advantageous variations 

 do not occur, or that there is some controlling element limiting 

 the process of variation which absolutely prevents the accumula- 

 tion of these chance modifications to a profitable end. Variations 

 do occur in the shape of individuals. They seem to be about as 

 plastic as other vertebrates in this regard. Here we must throw 

 out the idea that the failure to produce advantageous modifications 

 is due to the lack of variety on which selection can work. We 

 are therefore reduced to the question-begging of which many 

 naturalists now avail themselves in considering this process, and 

 are compelled to say that there is a certain rigidity in the organi- 

 zation of the animal which prevents the accumulation of bene- 

 ficial variations. This explanation is substantially like that of 

 the doctor in Moli^re's play, who explained that " opium put peo- 

 ple to sleep because of its soporific virtue " ; but this does not 

 suffice in the present case. It is worth while to note in this con- 

 nection that, although the habits of the gopher have varied little 

 with their peculiar habit of life, they have invented, as before 

 noted, the very sufficient and ingenious custom by which they 

 discharge the surplus earth from their burrows at the least ex- 

 penditure of force and time. This peculiar intellectual adapta- 

 tion appears to me one of the most interesting features connected 

 with the life of this interesting animal. 



To the question, sometimes raised, whether in the existing profusion of books 

 and newspapers, making the direct taxing of memory less necessary than for- 

 merly, the powers of that faculty may not be depreciated, it may be answered 

 that, though we no longer depend upon the memory as our only register of facts, 

 we still use it more than the ancients did. Our knowledge travels over an im- 

 measurably wider area, we have more to remember, and with continued advance- 

 ment of civilization a good memory becomes more needful for the work of life. 

 Our general intelligence and powers are improving, and memory is sharing in the 

 general advancement. 



* The only peculiar modification of the gopher's shell which can be deemed the product 

 of selection with reference to its peculiar habits is the share-like projection of the plastron 

 or lower shell, which is directed forward, and possibly serves in a slight way to divide the 

 earth at the bottom of the burrow over which it crawls. My friend Mr. S. W. Garman, 

 who has kept one of these creatures in captivity, has observed that the animal, by tilting 

 the body downward at the anterior end, can project this share under the edge of a stone or 

 into the crevices between two boards, and exercise a considerable amount of disruptive 

 power by this process. If these creatures made their burrows in stony ground, it might 

 be possible to conceive the structure as advantageous, but as they work altogether in fine- 

 grained soils, I can not conceive that this curious projection is of any functional value. 



