Memoirs presented to the Cambridge philosophical society on the occasion of the jubilee of Sir George Gabriel Stokes, bart., Hon. LL. D., Hon. SC. D., Lucasian professor.

AND THE INFLUENCE OF A MAGNETIC FIELD ON OPTICAL PHENOMENA. 407
cules orientated in all directions, such as may be considered to exist in an effective
element of volume of the medium: and this averaging would constitute the source of
its isotropy. But there would remain a question as to whether, when a plane-polarized
wave-train is passing, those fortuitous components of the polarization of the molecules
that are not in the direction of the electric vibration of the wave-train would not
send out radiation as independent sources and thus lead to extinction of the light.
The definite features of polarization of the light scattered from a plane-polarized train
by very minute particles or molecular aggregations seems also to suggest in a similar
manner that the individual molecule is isotropic.