292 British Association for the Advancement of Science. 
he had never found among his numerous examinations of the 
lenses of fishes, any which are perfectly spherical, as they were 
all.either oblate or prolate spheroids, so that along the different 
diameters of the solid lens, the vision would not be similarly per- 
formed. But, independent ofthis circumstance, he stated that 
‘in every solid lens there was only one line or axis in which vision 
could be perfectly distinct, namely; the axis of the optical figure, 
_ or series of positive and negative luminous sectors, which are 
seen by the analysis of polarized light. Along every other diam- 
eter, the optical action of the lens ig not symmetrical. When the 
lens is not spherical but lenticular, as in the ‘human eye and in 
the-eyes of most quadrupeds, Dr. W. considers that the apparatus 
for adjustment is the ciliary processes, to which this office had 
viously ascribed, though not on the sami scientific 
grounds as those by him discovered. One of the most impor- 
tant results of Dr. W.’s dissections, is the discovery of fibres in 
the retina. 'These fibres may be rendered distinctly visible. 
They diverge from the base of the optic nerve, and’ surround the 
foramen ovale of Sémmering at the extremity of theveye. Sit 
J. Herschel had’ supposed such fibres to be requisite’ in the ex- 
planation of the theory of vision, and it is therefore doubly in- 
teresting to find that they have been actually discovered. Sir 
D. concluded by expressing a hope that British anatomists = 
turn their attention to this subject.. 
Sir D. Brewster then éommunicated his researches on “A N ew 
Kind of Polarity i in Homogeneous Light.” - At the last meeting, 
said he, I gave an account of a new property of light, which did 
not adniit of any explanation. Since that time, I have had oc- 
casion to repeat and vary the experiments; and having found the 
same property exhibited in a series of analogous though different 
phenomena, I have no hesitation in considering this property of 
‘light as indicating a new species of polarity in the simple ele- 
ments of light; whether polarized or unpolarized. ~After detail- 
‘ing the experiments, he says, hence I conclude that the different 
sides of the rays of homogeneous light have different. properties 
when they are separated by prismatic refraction or by the dif 
fraction of grooved surfaces or gratings ;—that is, these rays have 
polarity. When light is rendered as homogeneous as possible by ~ 
absorption, or hint it is emitted in the most homogeneous state 
by certain col — it exhibits none of the indications of 
