238 



MR. MORLEY ROBERTS ON THE FUNCTION OF 



cases, whereas the theory of inherited advantageous variations, 

 whether continuous or discontinuous, can be made responsible 

 for the whole of the*phenomena. As the conclusion is gradually 

 being strengthened that large variations of a Mendelia.n 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 a,n 

 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 enquiry 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 un- 

 doubted organic disease. Can anything seem more certain than 

 the conclusion that any organism which fails in the established 

 functions of its species is as a fact severely handicapped, that 

 the variation is disadvantageous and cannot possibly be trans- 

 mitted either directly or by survival? There are, however, some 

 reasons for believing that this inference is inaccurate and that 

 tiie function of disease in evolution is of much greater import- 

 ance than that of mere elimination. But pathology has very 

 naturally been neglected as a study by biologists. On the views 

 generally held, it has seemed sufficient to recognize that disease 

 destroyed organisms which obviously left offspring, if it left 

 them at all, that were handicapped even more heavily than their 

 parents. It has been understood that their elimination was only 

 a matter of time and that neither their virtues nor their failures 

 could influence the race. 



If there is one thing more than another which has struck me 

 when attempting to study these questions, it is that too many 

 men of science appear to believe that any serious investigation 

 of other branches than their own is for them a waste of time. 

 The physiologist ignores the pathologist, who in his turn is far 

 too likely to fix his eyes on morbid phenomena which cannot be 

 properly appreciated save by those with a knowledge not only 

 of normal function but of the general physiology which underlies 

 it. The same can be said of most workers in science, but in no 



