190 MENTAL EVOLUTION IN ANIMALS. 



rubbish, bones, stones, dry dung, &c., near its burrow ; " the 

 guanacoes which " have the habit of returning (like flies) to 

 the same spot to drop their excrement ; " horses, dogs, and 

 the hyrax, showing a somewhat similar and equally useless 

 propensity ; hens cackling over their eggs, &c., &c. So that 

 I think the evidence is abundant in support of the proposi- 

 tion that senseless or useless habits may be inherited, and 

 thus become racial characteristics, or purposeless instincts. 



Passing on, then, to Propositions III and TV, — viz., that 

 such habits may vary, and that vjhen they vary the variations 

 may he inherited — the truth of these facts has already been 

 made apparent. The paces of the horse in different parts of 

 the world are so many race-characteristics of the animals ; the 

 ground-tumblers display an inherited variation as compared 

 with the air-tumblers, and if tumblers are not allowed to 

 exercise their art, it undersjoes the variation of becominsr 

 obliterated — ^just as we shall presently see is the case with 

 many true instincts. The different dispositions of the same 

 species of monkeys on different islands, prove that the 

 ancestral disposition must have varied in the progeny, and 

 have then continued to be inherited in its varied states along 

 the several lines of descendants. 



Prom the exclusive nature of the requirement, it is not 

 easy to find many examples of inherited varieties of useless 

 habits, nor is it important that I should give a number of 

 illustrations on this head. There is abundant evidence that 

 non-intelligent and purposeless habits are inherited, and this 

 is the main point ; for that such habits, when inherited, should 

 vary, is a matter of certainty, seeing, as w^e presently shall, 

 that such is the case even with intelligent and useful habits. 

 If the latter are liable to vary in their course of inheritance, 

 a fortiori the former must be similarly liable, inasmuch as 

 they arise in a manner analogous to fortuitous " sports " of 

 structure (which are always eminently variable), and after- 

 wards have no check imposed on their variability either by 

 intelligence or by selection. 



Similarly Proposition V requires very little to be said in 

 the w^ay of proof. If among a number of meaningless habits, 

 all more or less hereditary and more or less variable, any one 

 should happen from the first to be, or afterwards to vary so 



