4o8 BIOLOGY AND HUMAN LIFE 



specialists, ear specialists, heart specialists, nerve specialists, 

 and so on. Another division is based on the study of particular 

 kinds of diseases, or particular periods, or particular conditions 

 that can be studied more intensively ; thus, there are specialists 

 in tuberculosis, in cancer, in diabetes, in children's conditions, 

 in childbirth, in nutrition, in the conditions of old age, in indus- 

 trial hygiene, in school hygiene, in tropical conditions, in epi- 

 demics, in mental hygiene, in mosquito extermination, in health 

 education, in diagnosis. These men and women are all doctors, 

 but they gradually drift apart so that the work which one spe- 

 cialist does in the course of a year is entirely unlike that done by 

 another. One of them may spend day after day in interviewing 

 patients ; another, in performing surgical operations ; another, 

 in giving instructions to nurses ; and many of them never see a 

 patient for years at a time. 



Various classes of helpers furnish the supports for the doc- 

 tors' daily work. We know, of course, of the nurse, of the anes- 

 thetist (who administers the anesthetic for the surgeon), and of 

 the various hospital attendants and other assistants ; but there 

 are many helpers who never come near the patient. Laboratory 

 workers are concerned with the detailed examination of mate- 

 rials for diagnosis (see page 399)— chemists, microscopists, 

 bacteriologists, physiologists. Then there are those engaged 

 in various occupations that directly aid the technicians. Speci- 

 mens have to be prepared ; apparatus has to be prepared and 

 kept in condition; various chemicals and culture media (in 

 which bacteria are grown) have to be prepared, often with ex- 

 treme pains and accuracy ; animals have to be fed and kept in 

 good condition ; records, reports, and calculations have to be 

 made. There is need for many kinds of workers that we do not 

 commonly regard as related to health promotion. A trained 

 clerical w^orker, for example, might get a job in a broker's office 

 or in a hospital office, in a cigar-factory office or in a board- 

 of-health laboratory. In any case she might have to make rec- 

 ords, conduct correspondence, or apply her arithmetic ; in some 

 cases she would be a health worker, but not in others. 



