5i8 THE POPULAR SCIENCE MONTHLY. 



cesses. The real significance of such aberrations would reveal the dif- 

 ference between natural appetites and abnormal (artificially acquired) 

 appetencies, and teach us the necessity of applying the tests of that 

 distinction to all persuasive instincts, and occasionally to otherwise un- 

 explained aversions. 



But even M-ithin those limits a critical study of our protective in- 

 tuitions would surprisingly show in how many respects the hygienic 

 reforms of the last two hundred years could have been anticipated by 

 the simple teachings of our senses. For the wards of instinct a tem- 

 perance sermon would be as superfluous as a lecture on the folly of 

 drinking boiling petroleum, for to the palate of a normal living being 

 — human or animal — alcohol is not only unattractive, but violently re- 

 pulsive, and the baneful passion to which that repugnance can be 

 forced to yield is so clearly abnormal that only the infatuation of the 

 natural depravity dogma could ever mistake it for an innate appetite. 

 In defense of the respiratory organs, Nature fights almost to the last. 

 The blinded dupe of the night-air superstition would hardly assert that 

 he finds the hot miasma of his unventilated bedroom more pleasant 

 than fresh air. He thinks it safer, in spite — or perhaps because — of 

 its repulsiveness. " Mistrust all pleasant things " was the watchword 

 of the medieval cosmogony. Long before Jahn and Pestalozzi dem- 

 onstrated the hygienic importance of gymnastics, children embraced 

 every opportunity for outdoor exercise with a zeal which only per- 

 sistent restraint could abate. Sexual aberrations are a consequence, 

 oftener than a cause, of disordered health. Instinct has always op- 

 posed the abuse of drugs, the delusions of asceticism, the suicidal fol- 

 lies of fashion. Instinct has never ceased to urge the reforms which 

 our times have at last reached by such circuitous roads, and the study 

 of its pleadings and protests might shorten those roads for the leaders 

 of future generations. 



On the other hand, it must be admitted that perverted appetites 

 can become as irresistible as the most urgent natural instincts. Nor 

 can it be denied that in some exceptional cases Kature fails to advise 

 us of perils which her warning could easily avert, though we should 

 remember that her standards of expediency are not always our own, 

 and that, as a rule, instinct asserts itself at the fittest times, and with 

 an urgency proportionate to the importance of its mission. 



The exceptions, thus far only partly explained, may be summed up 

 under the three following heads: 1. Perverted Instincts. — The 

 physiology of certain abnormal propensities is as obscure as the origin 

 of sin. There is no doubt that the innate aversion to any poison known 

 to modern chemistry can, by persistent disregard, be turned into a 

 morbid appetency, vehement and persistent in proportion to the viru- 

 lence of the poison. The most plausible hypothesis suggested in expla- 

 nation of that fact seems to be the conjecture that, in adapting itself 

 to the exigencies of abnormal circumstances, the constitution of the 



