590 ANIMAL PHYSIOLOGY. 
sity of its light, one color passes into another: e. g., let violet 
light be gradually increased in intensity, and the retina soon 
fails to perceive this color so strongly; but thered and green 
sensations being as yet submaximal, we perceive a color the 
result of the blending of these two with violet, and so on till 
we may get such a mixture of the sensations of violet, red, and 
green as produces white. 
Fig. 430.—When looked at with one eye, the lines are never all distinct at one time ; this is in 
Bars owing to astigmatism, but in part also to inability to accommodate perfectly ares 
‘om any defect of this kind for more than a very limited area. When viewed with both 
eyes, a number of curious phenomena may be observed, the explanation of which we 
leave the student to work out for himself (after Bernstein). 
Misconceptions as to the Comparative Size, etc, of Objects—A 
glance at Figs. 430 and 431 will illustrate some surprising 
peculiarities. On a clear day distant mountains appear nearer, 
A B Cc 
" 1 
Fig. 431.—Illustrates illusions as to size. In A the height seems at first greater than the 
breadth, though they are equal: the reverse in B; while C appears to cover a less area 
than either of the others (after Bernstein). 
