50 Dr. C. W. Saleehj [Feb. 14, 



These exceptions are furnished by what may be called the racial 

 poisons. Alcohol, for instance, is a substance, certainly poisonous in 

 all but very small doses, which is carried by the blood to every part 

 of tlie body, and may and does injure its racial elements. Thus a 

 true racial degeneration may be "caused. Other poisons, such as those 

 of certain diseases, act similarly. 



We must therefore note, in passing, a biological factor of his- 

 torical importance, hitherto scarcely recognised by historians. Certain 

 of our diseases, and especially consumption or tuberculosis, are at 

 present making history by their extermination of aboriginal races. 

 Minute living creatures, which we call microbes, are introduced into 

 the new and favourable environment constituted by the blood and 

 tissues of human races hitherto unacquainted with them, and the 

 consequences are known to all. But, further, it has lately been sug- 

 gested as highly pro])able, by Professor Ronald Ross, that the fall of 

 Greece, that incalculable disaster for mankind, was due to the inva- 

 sion not of human foes, but of the humble living species wliich are 

 responsible for the disease miscalled malaria. Malaria, like alcohol, 

 produces true racial degeneration, its poisons affecting those racial 

 elements of which the individual body, as biologically conceived by 

 Weismann, is merely the ephemeral host — recalling the great line of 

 Lucretius, " Et quasi cursores, vital lampada tradunt.'" To lame the 

 runner is not to injure the torch he bears — acquired characters are 

 not transmitted ; but the racial poison makes dim the lamp ere he 

 passes it on. 



But, leaving poisons out of the question, races of men and animals 

 do undergo change, progressive and retrogressive, in consequence of 

 the action of another factor than that advanced by Lamarck ; and 

 this is the factor of " natural selection," so termed by Charles Darwin 

 in 1858, exactly half a century ago ; or "survival of the fittest," to 

 use Herbert Spencer's phrase. If, of any generation, individuals of a 

 certain kind are chosen by the environment for survival and parentage, 

 the character of the species will change accordingly. If what we call 

 the best are chosen, their goodness will be transmitted in some degree, 

 and the race will advance ; if what we call the worst are chosen, their 

 badness will be transmitted in some degree, and the race will de- 

 generate. 



Now in the case of all species other than man the only possible 

 progress is this racial or inherent progress, which is dependent upon a 

 choice or selection of the best for parents, and is comparable in some 

 measure, as Darwin showed, with the change similarly produced by 

 the selective breeding, or " artificial selection," of the lower animals 

 by man. But in the case of man himself, there is a wholly different 

 kind of progress also attainable, which is not inherent or racial progress 

 at all, but yet is real progress ; and which has the most important 

 relation to the inherent or racial progress that may be achieved by 

 the process of natural selection, or the choice of parents. The dis- 



