338 SCIENCE PROGRESS 



of the disastrous activity of the disease when introduced amongst 

 peoples not previously exposed to its attacks. 



On the other hand, the Jewish race is now possessed of a 

 high degree of natural immunity. Though it cannot be said 

 that tuberculosis does not attack Jews, the experience gained in 

 Out-patient Departments of Hospitals for Diseases of the Chest 

 affords unquestionable proof of the fact that pulmonary tuber- 

 culosis is of only occasional occurrence amongst them. When 

 met with in this race, moreover, the disease is rarely fatal but 

 assumes a chronic, i.e. a mild and slowly progressive form. 



The statistics at my disposal of postmortems at the 

 Children's Hospital, Great Ormond Street, demonstrate equally 

 clearly the relative immunity from tuberculosis of the children 

 of Jewish parents. It is possible that the explanation of this 

 remarkable condition lies in the essentially urban character of 

 the Jewish race. Since the Fall of Jerusalem, at latest, the 

 Jews have lived in cities. Through the Middle Ages and 

 during the last century they have successfully encountered 

 persecution and squalor in the poorest quarters of the cities 

 of Europe and have flourished despite the slenderness of the 

 resources permitted them by the ruling race, owing to their 

 thrift and their aptitude as traders, in circumstances under 

 which the less careful indigenous population has gradually 

 succumbed. As a matter of fact, whilst tuberculosis is always 

 rife amongst slum populations, the Jewish members remain 

 practically immune. In fine, one is tempted to hazard the 

 suggestion that by a rigorous process of natural selection a 

 race has gradually been evolved possessing so high a degree 

 of resistance to tuberculosis that at the present day their 

 freedom from this disease justifies the statement that they are 

 naturally immune. 



How far breast-feeding is responsible for the vigour of the 

 majority of Jewish children is open to discussion ; at all events, 

 their example is cited as a point in favour of cows' milk being the 

 cause of tuberculosis, breast-feeding being far less frequent or 

 prolonged amongst other races, notably the English. 



Enough has been said to make clear the wide distribution of 

 tuberculosis in the animal kingdom and the extreme variation 

 in susceptibility to this disease shown by races subjected during 

 longer or shorter periods to its attacks, as well as the relatively 

 high mortality from tuberculosis in early life. 



