7 o THE POPULAR SCIENCE MONTHLY. 



ing for whatever is positively useful. In other words, two principles 

 are recognized as determining the character of animal forms : 1. Natu- 

 ral selection, which implies the production of such structures as are 

 useful in the particular environments m which the animal is placed. 

 2. The influence of the structure already acquired at any given period 

 of development this being determined by heredity. But heredity 

 itself represents the organized product of a permanent environment, as 

 illustrated, for example, in the hereditary blindness of fishes living in 

 Mammoth Cave ; or, better still, in the respiratory mechanism of all 

 water-breathing animals ; so that the environment is the ultimate 

 factor which determines the specific character of animal forms the 

 structure developing slowly in accordance with this influence. 



Similarly in the department of morals, two factors must be recog- 

 nized as determining conduct : 1. Those qualities of character belong- 

 ing by inheritance to the organized structure of body and brain. 2. 

 Those influences which grow out of the social environment, which are 

 constantly modifying the inherited nature, and building up a corre- 

 sponding character. In my proposition, then, to found a city in which 

 any given degree of morality, within certain limits, may be secured, 

 these limits are understood to depend on the laws of inherited charac- 

 ter ; while the modifiable morality (that which may or may not be 

 secured at the option of the founder of the city) is that which de- 

 pends on the particular environment, physical and social, determined 

 upon by the founder ; the inherited character, also, like the inherited 

 bodily organism, being subject to modification from this source. To 

 discuss this proposition in a manner commensurate with its impor- 

 tance, would take us too far afield for the present occasion, since it 

 would involve a consideration of the whole subject of the origin and 

 evolution of morals. Your attention is, therefore, invited to a few 

 only, and those the more obvious, points connected with this proposi- 

 tion of securing a given morality-rate within certain limits, inherently 

 as definable, although not as precisely defined, as in the case of the 

 proposition with reference to the mortality-rate. 



As a result of Mr. Chad wick's statement, Dr. B. W. Richardson (in 

 the address referred to) projected a city of health, which he named 

 Hygeia (and which it is scarcely necessary to premise was located in 

 Spain ! ) in which all the modern sanitary inventions and precautions 

 calculated either to promote health or to prevent disease, were 

 grouped together in a picture most delightful to the mind's eye of 

 every sanitarian. This model city, Hygeia, with some alterations and 

 additions, would furnish the material substratum of the possible city 

 of which I have spoken, and which I would name Ethica. A brief 

 glance at the general features of our model will serve to bring the sub- 

 ject fairly before us. 



First, and most conspicuously, we note that overcrowding in this 

 city of health is impossible made so by the style and location of the 



