42 THE POPULAR SCIENCE MONTHLY. 



nutritive functions are particularly active in supporting the individ- 

 ual, the reproductive system is undeveloped, and vice versa." 



Let, therefore, on this principle, any class of organs or any parts 

 of the body be unduly or very much exercised, it requires the more 

 nutrition to support them, thereby withdrawing what should go to 

 other organs. In accordance with this physiological law, if any class 

 of organs become predominant in their development, it conflicts with 

 this great law of increase. In other words, if the organization is car- 

 ried by successive generations to an extreme, that is, to a high nerv- 

 ous temperament a predominance of the brain and nervous system 

 or, on the other hand, to a lymphatic temperament a predominance of 

 the mere animal nature it operates unfavorably upon the increase of 

 progeny. Accordingly, in the highest states of refinement, culture, 

 and civilization of a people, the tendency has always been to run out 

 in offspring ; while, on the other hand, all tribes and races sunk in the 

 lowest stages of barbarism, and controlled principally by their animal 

 nature, do not abound in offspring, and in the course of time they tend 

 also to run out. The truth of both these statements is confirmed by 

 history. The same general fact has been observed among all the ab- 

 normal classes, such as idiots, cretins, the insane, the blind, the deaf 

 and dumb, and to some extent, with extreme or abnormal organizations, 

 such as are excessively corpulent or spare, as well as of unnatural size, 

 either very large or diminutively small. 



It would seem that Nature herself is bound to put an end to organi- 

 zations that are monstrous, that are defective, and abnormal or unnat- 

 ural or imperfect in any respect. All history, we believe, proves that 

 such organizations are not prolific in offspring, and the number of 

 this class born into the world, reaching an advanced age, is compara- 

 tively not large. Such facts would indicate that there must be a 

 general law of propagation that aims at a higher or more perfect 

 standard. 



If this principle is applied to distinct classes in society, some strik- 

 ing illustrations may be obtained. Take the families belonging to the 

 nobility, the aristocracy, or the most select circles, where by inherit- 

 ance, refinement, and culture the nervous temperament has become 

 very predominant, it is found that such families do not increase from 

 generation to generation in offspring, and not unfrequently, in time, 

 they become extinct. 



A similar result has also followed the intermarriage of relations, 

 from the fact that the same weaknesses or predispositions are intensi- 

 fied by this alliance. On the other hand, in case these relations have 

 healthy, well-balanced organizations it may be that they are cousins 

 they will abound with healthy offspring, and the stock may improve, 

 and not deteriorate, from the mere fact of relationship. 



Again, if we take those families and races which for several gen- 

 erations have steadily increased most, we shall find that, as a whole, 



