24 THE POPULAR SCIENCE MONTHLY 



cinoma. Among the male Arabs nine tenths of all cases of carcinoma 

 occur in the face, which is especially exposed to the rays of the sun, 

 and in the women carcinoma is more frequent in the vagina than in 

 the uterus. Carcinoma of the gastro-intestinal tract is relatively rare. 

 Also among the inhabitants of East India and Ceylon and among the 

 Chinese we find a lower cancer rate than in Europe. In Japan how- 

 ever cancer seems to be relatively frequent as far as the available 

 statistics indicate. 



Also among the Indians in the reservation of the "United States 

 cancer is considerably rarer than among the white population (J. 

 Levin). Differences in climate can therefore not be held responsible for 

 these great differences in the cancer incidence. But is it due to inherit- 

 able race characteristics or differences in mode of living, preceding in- 

 fection with other diseases ? This question we can not answer definitely 

 at the present time. Some facts however are of interest in this connec- 

 tion. W. Eenne found that among the natives of Sierra Leone cancer 

 is very rare; but since a more intimate intercourse between the natives 

 and immigrated whites has taken place, cancer has increased in Sierra 

 Leone. But even in this case we are unable to decide whether this 

 increase is due to changes in the conditions in life or to the inter- 

 marriage between whites and natives. In the United States we also 

 find that within the last fifty years there has been a considerable increase 

 in the cancer incidence among the colored population. Cancer of the 

 uterus, which was formerly rare among colored women, is now more fre- 

 quent among the colored population than among the white. Here again 

 we can not be sure how much of this increase is due to changes in the 

 mode of living, to increase in the inflammatory conditions of the uterus, 

 and how much to intermarriage. 



In the case of the relative rarity of uterine cancer among Norwegian 

 women, we again do not know whether it is due to the relative infre- 

 quency of preceding infections of the uterus or whether it is a question 

 of race. Interesting problems thus present themselves as to the relative 

 importance of race and of external conditions in the origin of cancer. 

 More definite knowledge could be gained if in statistics a distinction 

 were made between negroes and mulattoes; it would also be of interest 

 to establish the frequency of uterine cancer in the first and second gen- 

 eration of Norwegian women in this country, especially distinguishing 

 between those interspersed among the rest of the population and those 

 living in close rural communities in which the original customs are pre- 

 served. 



We mentioned already that on the whole carcinoma occurs espe- 

 cially in old age. In the United States the average of death from 

 carcinoma is 60 years for males and 58 years for females. Between 45 

 and 64 years 7 per cent, of all deaths in the male and 16 per cent, of all 



