1906. 
Andkrson. — A nivial Coloration. 
117 
such places gray rocks or white ones enable sheep to escape 
detection, even when things are fairly clear. Umbrageous 
foliage serves animals of darker hue. It is well known 
however that suggestions have been made with reference to 
the protective effect of light and shade for some animals. 
This problem has been discussed by most competent authori- 
ties, who have pointed out that the effect of light passing 
through trees is to throw a pattern on the ground that may 
serve the animal that is particularly coloured. It is suggested, 
however, that light and shade may not be simple in its origin 
and reflection, perhaps refraction of colours may lead to a 
disguise in animals that have a complementary coloration. 
It is only necessary to suggest that an animal if colour-blind 
would not be able to distinguish red from green, even though 
the light green of grass were the colour complementary to the 
red of certain animals. 
It would seem that the bright, central portions of the 
spectrum retain their characters longer and show later than 
the colours at either end. The yellow and green seem more 
persistent than the light blue and orange. The yellow and 
green seem much more penetrating. It will be seen that the 
larger question which has received attention from so many 
competent authorities has not been touched upon in the 
present paper. Sensitiveness is so different in different 
animals and animal groups, whether w^e take the power of 
seeing with a greater or smaller amount of light, or the 
ability of distinguishing objects in light that may have an 
ultra-violet character, or with rays that are of an}^ lower 
degree of refrangibility, that one cannot do more than allude 
to a subject the fringe of which only has been touched. 
Queen's College, Galway. 
