62 Wisconsin Academy of Sciences, Arts, and Letters. 



demand made by the fearful mortality ; for this is what nature 

 is perpetually doing elsewhere ; depletion at any point being 

 the occasion of a grand rally of forces to sup))ly whatever loss 

 has been sustained, and so restore the equilibrium. It is also 

 quite possible that the lack of sustenance, instead of being a 

 natural co-operating cause of the mortality, may itself be the 

 effect of the same unnatural cause to which the other derange- 

 ments are due ; the predominance of the animal over the spir- 

 itual elements in man. For in some of the same countries in 

 subsequent times has sustenance been produced for a much 

 larger population where the mortality has been less ; and in 

 no country have the capabilities of the soil for production ever 

 yet been exhausted. 



These possibilities become more obvious and tend more 

 strongly in the direction of probabilities in view of certain 

 analogies which themselves hint, at least, at a natural law 

 capable of universal application. It is well known that the 

 insects whose term of life is but a few days are produced by 

 myriads ; animals whose term is half a dozen years, are re- 

 duced as to the number of their offspring from thousands to 

 only hundreds ; while those which live a score or mere of 

 years, are proportionately less prolific. The principle here 

 unquestionably is that the power of reproducing life is in the 

 inverse ratio to the power of maintaining it. May we not sup- 

 pose this law to extend not merely to all the various species, 

 but also to the varied conditions of the several species, includ- 

 ing that of man ? The facts of history would seem to warrant 

 an affirmative answer. 



That there is no such thing as a natural law of uniform in- 

 crease of population can be made tolerably evident to any or- 

 dinary observer. Providence works here as everywhere else, 

 according to the conditions and requirements of the case. 

 Hitherto, while there has sometimes been a rapid increase, at 

 other times this increase has been slow or has entirely ceased. 

 In many instances where, according to the natural order of 



