100 MENTAL EYOLUTIOX IN ANIMALS. 



proof of the high development to which the colour-sense has 

 attained in this class. 



All the remarks just made with reference to Birds, apply 

 5^ likewise, though not perhaps in quite so high a degree, to 

 Mammals, considered as a class. And here it becomes need- 

 ful to consider the speculation of Dr. Magnus and Mr. Glad- 

 stone, that the colour-sense of man has undergone a great 

 improvement within the last two thousand years, inasmuch 

 as before that time mankind are supposed by this specula- 

 tion to have perceived only the lower colours of the spec- 

 trum, or red, orange, and yellow, and to have been colour- 

 blind to the higher, or green, blue, and violet. Professor H^eckel 

 lends his support to this speculation ; but to me it seems a 

 highly improbable one, and this for the following reasons. 



In the first place the speculation is based merely on 

 etymological grounds, which in a matter of this kind are 

 exceedingly unsafe. For the absence in a language of words 

 denoting particular colours is, at best, but negative evidence 

 that the men who spoke the language were blind to those 

 colours; the absence of such words may quite as well be due 

 to the imperfection of language as to the imperfection of the 

 visual sense. Thus, for instance, Professor Blackie tells us that 

 the Highlanders call both sky and grass "gorm," and are 

 nevertheless quite able to discriminate between the colours 

 blue and greeiu In the next place, it is antecedently im- 

 probable, upon the general principles of evolution, that a 

 considerable change in the visual apparatus of man should 

 have taken place within so short a period as the speculation 

 in question assigns — especially in view of the fact that other 

 Mammals, Birds, and even some of the Invertebrata un- 

 questionably distinguish the higher as well as the lower 

 colours of the spectrum. Lastly, Mr. Grant Allen has taken 

 the trouble to enquire, by means of a table of questions 

 addressed to educated Europeans in all parts of the world, 

 whetlier any of the savage races of mankind now living 

 display any inability to distinguish between the colours of 

 the spectrum, and the answers which he has received have 

 been uniformly in the negative.* I think, therefore, we may 

 safely dismiss the speculation of Dr. Magnus and Mr. Glad- 

 stone as opposed to all the evidence wliich is at once trust- 

 worthy and available. But in saying this I do not intend to 



* Colour-sense^ Chapter X. 



