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of resistance. This progeii}^ being in its turn weeded 

 out by the destructive fever, and the same process of 

 elimination of the most unfit being carried on during 

 every successive generation, the result has very 

 gradually, but none the less surely, come about, that 

 there are no longer left any members of the com- 

 munity that are susceptible to the disease, and that 

 the race as a body is now hereditarily immune against 

 it. And exactly the same result would happen in the 

 case of white men did we but send out sufficient 

 numbers in the first place to make a fair start, and 

 then give them time to work out their own salvation. 

 An acquaintance of mine, who had sufficient resistive 

 power inherent in his constitution to withstand- a 

 twenty-five years' residence on the Gold Coast, and to 

 come back to England to enjoy good health in his 

 retirement, would have been a fair sample of the sort 

 of man required to help in the foundation of an 

 immune white race. 



Now let us see how all this fits in with and 

 explains the difficult problems and apparently con- 

 tradictory facts that present themselves in relation to 

 the occurrence of septicaemia in birds. By long 

 habitude all birds, like indeed all animals, are, when 

 in health, more or less immune against the action of 

 such septic organisms and their spores as are found in 

 the air and on the common inanimate objects of the 

 earth's crust, since as we have seen, the bacilli pro- 

 pagated at a low temperature and on poor food are 

 comparatively incapable of producing much harm. 

 Consequently wild passerine birds living in a per- 

 fectly natural state appear to suffer but seldom from 

 the disease. But, as I have pointed out, the bacillus ' 

 bred amidst the environment of increased heat, such 

 for instance as the one which generation after genera- 

 tion has been passing through the intestines of birds at 

 109^ or 1 10*^, is another thing altogether; and so on 



