MAMMALOGY — MILLER 393 



man-malaria has wrought incalculable good, but in every instance 

 systematic work pursued first for its own sake has laid the founda- 

 tion on which the humanly useful structure could be raised. 



In some of these life histories mammals play a part. The minute 

 organism which causes the deadly Rocky Mountain fever is brought 

 to the human body by an insect, a special kind of tick, which nor- 

 mally feeds on the blood of ground squirrels, marmots, and other wild 

 animals, but which may occasionally vary its diet by sucking the 

 blood of man. A knowledge of the kinds of mammals with which 

 this tick is associated, and their distribution, therefore becomes 

 highly important from the human point of view, because the disease 

 can be avoided by keeping away from the places where these animals 

 occur, or it can be eradicated by destroying the tick carriers. A 

 similar life chain is now well known, linking up man, rat, flea, and 

 plague. Let it be broken at any link and the disease must disappear. 

 The more practicable way is to eliminate the rat or other mammal, 

 such as the ground squirrel in California or the tarbagan (a large 

 marmot) in Mongolia, which may be a suitable reservoir for the 

 plague-carrying flea — a different insect from the fleas of cats and 

 dogs. But before this work can be successfully prosecuted it is neces- 

 sary to know what mammals may harbor this particular flea and, 

 by their distribution and habits, thus become menaces to human 

 health. Here mammalogy must be called upon for its knowledge of 

 species and their ranges. The importance of this knowledge will be 

 evident when it is realized that the rat tribe, instead of being limited 

 to the two or three rats and ratlike mammals known by most people, 

 actually consists of many hundred different kinds, each with its par- 

 ticular range, its particular mode of life, and its particular possi- 

 bilities of serving as an intermediary between fleas and men. So also 

 with the ground squirrels and other carriers of plague fleas. Their 

 number, as revealed by the study of mammalogy, and the intricacies 

 of their possible contacts with man, are vastly greater than is popu- 

 larly supposed. All of this mass of information must be made avail- 

 able to those who are carrying on campaigns of health. 



Centuries ago public opinion forbade the dissection of the dead 

 human body. Dissection of animals and reasoning from analogy 

 were therefore the means by which our forefathers obtained their 

 first ideas of human anatomy and physiology. At present experi- 

 mentation on living men and women is similarly forbidden, though 

 the time is not very far past when surgeons were permitted to oper- 

 ate on criminals who might thus obtain pardon in view of theii^ serv- 

 ice to humanity. To-day, therefore, we must have recourse to physio- 

 logical experimentation on mammals other than ourselves in 

 efforts to solve some of the most vital problems with which society 

 IS confronted. As examples it is only necessary to mention the use 



