I ^(i Orthoplasy 



with the rise of instinct, with the origin of structures 

 lacking in apparent utiHty when full formed or when only 

 partly formed, with correlated variations, coordinated 

 muscular groups, etc., with mental and social evolution. 

 It would seem to be a legitimate resource in the following 

 more special cases. 



(i) In cases where there is possible correlation between 

 the organ or function whose origin is in question and a 

 modification which is of acknowledged utility: the latter 

 serves as screen to the undeveloped stages of the former. 

 This is notably the case where intelligence comes into play ; 

 it screens all sorts of characters of very varied utility. 



(2) In cases of ' convergence * of lines of descent : 

 certain accommodations, common to the two lines which 

 converge, compel the indirect selection of variations of 

 the same sort in the two lines, so that they are brought 

 constantly nearer to each other; so in many cases of 

 resemblance due to similarity of function. (This is noted 

 by Poulton, as is also resemblance due to similarity of 

 habit and attitude, in the art ' Mimicry,' in the present 

 writer's Dictionary of Philosophy and Psychology.^ The 

 unlikelihood of two or more independent origins of the 

 same species or character by natural selection alone has 

 often been pointed out (cf . Poulton, Charles Darwin, p. 56). 



There are many cases in the animal world of ' analogous ' 

 organs which are yet not ' homologous,' — organs of 

 divergent origin but of common function, and possibly 

 of common appearance, — the rudiments of which may 

 have owed their common and * indirect ' selection to a 

 single more general utility. 



(3) In cases of divergent or * polytypic ' evolution : 

 a single common character being equally available as 



