186 Observations upon the supposed 



long as twelve, months) ; but the results thus obtained, or, at 

 least, remarked upon, have been authentic proofs only of their 

 extraordinary powers of life in a state of complete abstinence: 

 though, as we know they lie long in a dormant state, it is not 

 quite so surprising as at first sight it seems to be. On one 

 occasion, it is said that, instead of eating its food, a viper, con- 

 fined with a mouse introduced as food for it, was itself partially 

 eaten, and not improbably, as surmised, killed by the mouse. 

 {Mag. Nat. Hist., vol. vi. p. 457.) In its natural state, such 

 a turning of the tables upon the viper could scarcely have 

 happened: it does not, at any rate, with our present information, 

 seem within the range of the probable. But who is there that 

 has caught and caged the common female viper with young ; 

 has seen the young brought forth ; observed and noted down 

 the changes incident to sex, age, and season ; and, at the same 

 time, fixed (which is no less necessary) a certain standard of 

 their hues, from the time of production as long as they should 

 live? The habits of the viper, living in holes, and seldom 

 appearing, except when basking, prevent the making of accurate 

 observations, of which guess-work is too often allowed to take 

 the place ; and, besides, in a state of nature, it is next to impos- 

 sible to distinguish individuals for the purpose of experiment ; 

 but, though difficulty exists in ascertaining facts, that is no reason 

 for being guided by anything that is said, merely because it 

 is said, which, for the most part, seems to be the reason of its 

 acceptation. Though not without ground of objection, it may 

 be urged that the experiment of the cage, as a certain test, can 

 not be relied on ; as, being debarred from exercising its natural 

 habits and appetites, the animal might not exhibit the changes 

 common and proper to it when at large. There is something 

 in this objection. Granting there is difficulty inducing doubt, 

 yet, on the contrary, when this is granted, still it must be 

 admitted that such an experiment would form, not only a con- 

 siderable approximation to the truth, but, from the nature of 

 the animal, afford the nearest that can be made towards a 

 satisfactory determination, by observation and fact, of the dis- 

 puted point, whether there exist a black, a blue, and a red 

 species of viper; or but one species, of which these different 

 hues *, it is contended, are merely incidental to individuals, 

 owing to changes connected with sex, age, season, or, possibly, 

 to local circumstances, as the nature of the habitat, or a peculiar 

 kind of food. Making allowances, then, for the difference 

 likely to arise from the viper being confined in a cage, and 



* If specific distinctions are to be founded upon shades of colour, one 

 might make out three or four species of bass or perch, (?) which vary in 

 colour according to the nature of the habitat and food. 



