PHYSICAL FACTORS IN RACE SURVIVAL 287 



disease. Longevity has been abundantly proven by actuarial statistics to 

 be directly connected with heredity. Individuals who come of long-lived 

 parents and long-lived families have been found to have a greater life ex- 

 pectation than those who belong to families whose members have been 

 short-lived. Indeed it is a common observation that individuals, whether 

 they belong to long-lived or to short-lived families show the greater tend- 

 ency to succumb to affections, and in a manner, that is common in their 

 family, thus indicating susceptibilities that run in families. Hence, en- 

 vironment being equal, the broad means of survival, and we should also 

 note of extinction, lie in heredity. 



Under natural biological conditions, individuals with physical anomalies, 

 imperfect organs, and deficient physiological functions tend to be eliminated 

 in each generation, thus removing such physical causes of deterioration in a 

 race. Under our own civilization many such individuals are preserved and 

 often transmit to offspring these physical weaknesses. The racial gravity 

 of this fact has as yet been realized by few. Pathological heredity however 

 is now coming to be regarded as an important study, and the findings from 

 such studies always show the frequent recurrence in many family strains 

 of particular physical defects and weaknesses. Once such defects are trans- 

 mitted to offspring they go to contaminate and weaken the racial germ- 

 plasm permanently. 



Organic defects may be structural or functional, and often are both. 

 They occur in the heart, the liver, the pancreas, the kidney, and the various 

 glands of the body. Thus there may be cardiac deficiencies, hepatic de- 

 ficiencies, pancreatic deficiencies, renal deficiencies, and glandular deficien- 

 cies of various degrees of seriousness. In the great majority of cases these 

 deficiencies are clearly of hereditary origin, and their incidence is frequent 

 or rare owing to whether they are of a dominant or recessive nature, and 

 whether the inheritance factor is present on one or both sides of the in- 

 dividual's pedigree. Their hereditary transmission is abundantly supported 

 by many family studies that have been made of the occurrence of such 

 defects. 



While hereditary deficiencies in the sense organs may not always directly 

 menace human survival in our civilization, they are a source of serious dis- 

 advantage to individuals and go far to handicap them both in their enjoy- 

 ment of life and in their accomplishment. Myles Bickerton, one of the 

 most eminent of British opthalmologists, says: "We know more about the 

 hereditary diseases of the eye than about those of any other organ, for the 

 good reason that, being the most important and complicated of our sense 

 organs, its slightest defects cause marked disturbances of function." We 



