II COLOUR-VARIATION 61 



of slight importance, and that I am losing much time 

 in bringing them before you. Truly, if we were to 

 view the things in the light of Linnaeus nimiinn 

 ne crede colori such would be the case ; but recent 

 facts have gone to show that colour variation is not 

 merely what it seems to be, a variation in pigment 

 deposits ; there are more important variations which 

 underlie or accompany it, and these are of much 

 interest in showing that colour variation is of greater 

 import than might be thought at first glance. These 

 variations are of chemical order, and, so far as I know, 

 little has yet been done to investigate this delicate 

 matter beyond a short but excellent paper by Pro- 

 fessor Armand Gautier. 1 The author begins by re- 

 calling some instances which have a remote relation 

 to this matter, and some of which are familiar to all. 

 It is known, for instance, that when a mare has once 

 given birth to a mule, it may happen that in after years 

 her foals, produced after the usual impregnation from 

 a stallion, present peculiarities which belong to asses. 

 It seems that the single fecundation by the ass has in 

 some manner impregnated the whole maternal organ- 

 ism upon which it has stamped itself. Similar cases 

 are to be observed in the human race as well as 

 among horses or dogs, and these show that a foreign 



1 Du Mecanisinede la Variation des Etresvivants, dr-'<:., \\\Hommage 

 a Monsieur Chevreul a V Occasion de son Centenaire. F. A lean. 1886. 



