28 INITIATIVE IN EVOLUTION 



exactness the area of pressure of these on the ground, and anyone 

 can see it who has a canine friend of the fox-terrier type. Long- 

 haired dogs display it less neatly outlined. An instance such as 

 this cannot be excluded from the evidence forthcoming because 

 it is correlated with the useful " character " of lying in a certain 

 attitude. Such a phenomenon, many similar to which will be 

 seen later, had at any rate an origin de novo at some time in the 

 ancestral stock, and in some way. To discover these is part of my 

 business. The boldest neo-Darwinian will not claim that this 

 arrangement of a dog's hair arose by selectional processes within 

 the germ either in the initial or completed stages. 



Correlation. 



The term " correlation " is somewhat scornfully said by 

 Weismann to be " unquestionably a fine word," and it has indeed 

 in biological writings a very varied set of meanings. I will not 

 vex the reader with a reference to our old friend Mesopotamia, 

 but mention what Dr. Vernon in Variation in Animals and Plants 

 says of the term, referring to the relation between stature and 

 head -index in man : " Such a statement must vary according to 

 the notion of the observer as to what does and what does not con- 

 stitute correlation." 1 The most approved and precise meaning 

 of the loose term in question is that associated with the work of 

 the biometricians, and a few examples from Dr. Vernon's book 

 will show how far this conception of correlation is removed from 

 the literal application of Professor Thomson's formula. Dr. Vernon 

 treats of such phenomena as the correlation of the long heads of 

 greyhounds with length of legs, contrasting them with the shortened 

 heads and legs of bull -dogs. He describes also the correlation in 

 man between the stature and length of forearm from elbow to tip 

 of middle finger, correlated measurements of crabs, of external 

 structures of prawns, the tufts of Polish fowls correlated with 

 perforations in the skull, also certain constitutional peculiarities 

 with colour of skin. These few cases are enough to give an idea 

 of the more precise and fairer acceptation of the term, but while 

 these form a useful subject for minute study it may be remarked 

 that they agree also with Lamarckian factors as to their origin and 

 development. They are much more in line with Darwin's use of 

 the word and are strangely reminiscent of the well-known example 

 of the Irish elk with its great head and horns which was brought 

 forward in favour of Lamarckism by Herbert Spencer. They 



1 p. 74. 



