184 THE STORY OF GERM LIFE. 



wise succumb earlier in the struggle is enabled to 

 live a few years longer. Whatever be our humani- 

 tarian feeling for the individual, we can not fail 

 to admit that this survival of the weak is of no 

 benefit to the race so far as the development of 

 physical nature is concerned. Indeed, if we were 

 to take into consideration simply the physical 

 nature of man we should be obliged to recom- 

 mend a system such as the ancient Spartans de- 

 veloped, of exposing to death all weakly individ- 

 uals, that only the strong might live to become 

 the fathers of future generations. In this light, 

 of course, parasitic diseases would be an assist- 

 ance rather than a detriment to the human race. 

 Of course such principles will never again be 

 dominant among men, and our conscience tells us 

 to do all we can to help the weak. We shall 

 doubtless do all possible to develop preventive 

 medicine in order to guard the weak against para- 

 sitic organisms. But it is at all events well for us 

 to remember that we can never hope to develop the 

 strength of the human race by shunning evil, but 

 rather by combating it, and the power of the 

 human race to resist the invasions of these or- 

 ganisms will never be developed by the line of 

 action which guards us from attack. Here, as in 

 other directions, the principles of modern humanity 

 have, together with their undoubted favourable 

 influence upon mankind, certain tendencies toward 

 weakness. While we shall still do our utmost to 

 develop preventive medicine in a proper way, it 

 may be well for us to remember these facts when 

 we come to the practical question of determining 

 where to draw the limits of the application of 

 methods for preventing infectious diseases. 



