REPAIR IN EVOLUTION 63 



phenomena. As the conclusion is gradually being 

 strengthened that large variations of a Mendelian character 

 deal with other characteristics than those which are racial, 

 all who rely on inherited spontaneous variations are forced 

 back on the Darwinian view that small variations can 

 gradually, if of an advantageous kind, convert one species 

 into two or more, and that all living characteristics, or 

 organs themselves, are due to such a cumulative effect. 

 It is, of course, inferred and definitely stated by Darwin, 

 that any variation in the least degree injurious would 

 inevitably be destroyed. It is this statement I propose 

 to examine, and for the purpose of such an inquiry it 

 must be clearly understood what is meant by the word 

 " disadvantageous " or injurious. 



At first sight nothing seems clearer. Why should we 

 doubt that any functional or organic failure is a handicap 

 in the biological race ? By functional trouble, of which 

 the cause is not obvious, we mean some hindrance, which 

 may be recovered from, to normal or physiological action. 

 It is due to factors which, for the most part, are unknown. 

 We do not doubt that there is a failure somewhere, which, 

 as regards certain cells, might be called organic, but often 

 we cannot do more than guess where the actual failure 

 occurs. In that advanced disorder of function which has 

 visible lesions, and destruction or irremediable alteration 

 of the individual parts of the machine, there is undoubted 

 organic disease. Can anything seem more certain than 

 the conclusion that any organism which fails in the estab- 

 lished functions of its species is as a fact severely handi- 

 capped, that the variation is disadvantageous, and cannot 

 possibly be transmitted either directly or by survival? 

 There are, however, some reasons for believing that this 

 inference is inaccurate, and that the function of disease 



