402 ANIMAL BIOLOGY 



3. Health and Wealth 



It has been aptly said that health and wealth are essentially 

 synonymous, and this is amply shown by the fact that medical 

 progress is reputed to have added at least twenty years to the 

 average life span of Man during the past century — mainly years 

 of the highest efficiency from the age of thirty-five to fifty-five 

 years. It is conservative to say that the increase in longevity has 

 effected a saving of more money than has ever been expended in 

 support of every kind of scientific investigation, and this without 

 taking into account the economic value of the lives or the im- 

 mensely greater factor of human happiness which follows from 

 healthful and unbroken family life. 



The same can also be said for the leading role which medical 

 zoology has played in rendering vast regions of the tropics almost 

 as safe for human habitation as the temperate regions of the Earth 

 — regions which must offer an outlet for the rapidly increasing 

 human population. Statistics make clear that the population of 

 the world has more than doubled during the last century: what 

 it will do during the next century experts in vital statistics are 

 actively computing. But this much is certain : it is merely a matter 

 of time before regions now untenanted by civilized Man must be 

 encroached upon more and more, not only for food and other ma- 

 terials but also for a place of abode; and the first step necessary 

 to make this possible is the survey of the innumerable biological 

 competitors in the form of parasites, etc., which Man must en- 

 counter in adjusting himself to this environment. 



Again, knowledge is power — the best investment from the 

 standpoint of health and wealth is in support of research. It is 

 easy to forget that combined studies on the life history of Bacteria, 

 Fleas, Rats, and the rest have made impossible to-day such epi- 

 demics as have many times in the past swept over the world. 

 During the Christian era more people have succumbed to the 

 Plague than constitute the total population of the Earth to-day. 

 It is easy to forget that the biological forces of disease are costing 

 the United States nearly four billion dollars annually — a loss 

 largely preventable by an efficient dissemination of knowledge 

 and an efficient application of biological principles already well es- 

 tablished. Civilizations in the past have succumbed to the on- 



