MAN'S FIGHT FOR SURVIVAL 611 



are lost. When a cell is killed, substances which in life could not pass 

 in or out by osmosis can easily do so, with the result that it loses the 

 salts and sugars essential for life, as well as its turgor, aad becomes 

 limp. It is dead, for it no longer has the ability to regulate its outgo 

 and intake. 



Causes of Disease 



The causes of disease are many. These may be listed as food 

 deficiencies, endocrine maladjustments, hereditary deficiencies, un- 

 favorable environmental factors, bad health habits which result in 

 body poisons, diseases of middle and old age (wearing out of the 

 machine), parasitic diseases, and infections. Health examinations 

 of some 1500 men entering Cornell University showed that over 50 

 per cent had defective eyes, over 25 per cent bad posture, over 

 22 per cent skin disease, 22 per cent enlarged thyroid glands, and over 

 20 per cent flat feet, all of which physical handicaps are correctable.* 

 Wood's estimate made in 1918 of 16,000,000 school children with 

 physical defects or ailments either preventable or remediable has not 

 changed greatly in recent years. These conditions in children and 

 young adults are largely due to lack of proper care in running the 

 human machine. Improper diet, overfatigue, poor posture, over- 

 stimulation through drugs or alcohol, heedlessness of warning symp- 

 toms — these are the most frequent causes of bodily illness. Dr. Vin- 

 cent, former president of the Rockefeller Foundation, recently stated 

 that more than 80 per cent of the illnesses of man could be avoided 

 if people were willing to obey the laws of health and live as well as 

 they knew how to live. The running of the human machine is up 

 to the individual and it is only through his willingness to take care 

 of himself that an individual health program can be established. 



Unfavorable Environmental Factors 



In the past this factor has been overstressed. There is no doubt 

 that overcrowding, unsanitary conditions, and lack of a pure water 

 supply help to raise the death rate. Tuberculosis, for example, is 

 closely correlated with social conditions. Factors which lower the 

 bodily resistance also, such as fatigue, exposure to conditions of wet 

 and cold, poor ventilation in working and living quarters, are all 

 menaces to health, but the old idea that the products of decomposi- 

 tion of animal and vegetable material cause disease is untrue. A few 



» Smiley and Gould, A College Textbook of Hygiene, Macmillan, 1926, p. 3. 



