846 THE AMERICAN NATURALIST. [Vor XXXII. 
its maximum at V and would gradually fall away towards the 
base to zero. In the opposite direction the curve will be 
sharper, because the short fibrils terminate abruptly at the 
truncated apex of the cone. The curve for yellow-green light, 
on the other hand, with its apex opposite G7, will be symmetrical 
because there is an equally long series of fibrils on either side 
of the maximum, which can respond to some extent to green 
light ; those on one side being too short, and those on the 
other too long. 
(4) If a beam of polarized white light be passed through the 
cone, the stimulated fibrils would, if luminous, appear as two 
opposite spectra, wedge-shaped in cross-section, extending the 
whole length of the cone. All the fibrils in any one transverse 
plane should have the same color, but the intensity of the color 
should gradually diminish in those fibrils that become more and 
more nearly parallel with the plane of vibration. The fibrils at 
successive levels in the cones would of course be of different 
colors, and these colors would be arranged lengthwise of the 
Fic. 7.— Section nearly parallel with the surface of the retina of ocellus II of Lycosa. 
cones in the same order as those in the spectrum. The grada- 
tion of colors in such a spectrum would be more or less abrupt, 
according to the angle of the cone and its altitude ; that is, 1t 
