202 



their usual occupations. On the other hand let an 

 average Englishman, used to more cleanly feeding, eat 

 the veriest trifle of tainted meat or fruit, especially in 

 hot and mnggy weather, and his medical adviser im- 

 niediatel}^ has on his hands a case of zymotic diarrhoea 

 due to septic enteritis. Ask any Medical Officer of 

 Health what are the results on the death and sickness 

 rate among children due to the use of that modern 

 invention, the feeding bottle, with its long india- 

 rubber tube containing, as it does, a constant supply 

 of septic organisms, but which is cleanliness itself 

 compared with the putrid and disgusting dainties of 

 the Kaffir. 



This seemingly abstruse question of racial 

 immunity is after all quite easy and simple to under- 

 stand : it is purchased merely at the expense of long 

 contact with whatever disease against which the 

 immunit}^ is being slowly obtained : in other words it 

 is an outcome and example of that universal law of 

 Natural Selection and Survival of the Fittest which 

 has been so fully and ably interpreted for us by the 

 greatest of modern philosophers. 



It will not be necessary in the application of this 

 law to the previous examples to traverse the whole 

 list — let us take an}^ one of them, say the extreme 

 instance of yellow fever, where complete immunity 

 has been obtained. Here through ages and aeons of 

 ages the negroes have been continuously exposed 

 to the attacks of the special bacteria of this 

 disease, those showing the least power of resistance 

 being the first to be swept away and destroyed, and 

 being thus removed from the chance of propagating 

 a progen}^ with the like weakness of resistance. 

 On the other hand the survivors, in obedience to the 

 natural law that like tends to produce like, would 

 beget a progeny containing a certain proportion of 

 individuals with an inherited greater or less power 



