3S8 London Philosophical Society. 



retina, its arachnoid, pulpy or most sensible lamina is co- 

 vered on the side which is toward the vitreous humour by 

 a more consistent, vascular, and less sensible portion, while 

 the anterior part is exquisitely delicate and fine, tends to 

 confirm this theory. It receives also additional confirma- 

 tion from the circumstance, that the transparent retina thus 

 laid over the black pigmentum, and more especially over 

 the tapitum, exclusively occupying this part in some of the 

 inferior animals, must form the most perfect reflector." 



"Thus doubtless it is that that portion receives no im- 

 pression from the image, and that the anterior extren)ity 

 of the nerve, which is in all cases the most sensible, is 

 alone impressed by a natural and correct picture of the ex- 

 ternal object, and transmits it to the sensorium." 



" The physiological fact also, that the anterior part of 

 the retina cannot be impressed even by a single direct ray 

 from without, — and that, unless it receive the image re- 

 flected, reverted, and in its natural position from the 

 posterior part, as I have described, it must be apparently 

 useless, — is almost a decided confirmation of the theory 

 I have suggested." 



" A confirmation of this theory, however, still more de- 

 cisive than these, yet remains. It appears that posterior- 

 ly the retina is entirely insensible where the optic nerve 

 enters, as at that part we have no sense of vision." 



" Consistently -with the theory just delivered," Mr. W. 

 concludes, " that we have from this circumstance a de- 

 cided proof that the posterior part of the retina is utterly 

 insensible, since, at the entrance of the nerve where it 

 exists in the greatest quantity, it can be demonstrated to 

 be so ; and, that vision is wantinp; at this spot precisely 

 because, where the nerve enters. There is no choroides to 

 reflect the rays to the sensible interior portion." 



Thus he conceives the optic imace is reverted. It af- 

 forded us much pleasure to hear it intimated, that com- 

 parative vision will form the subject of another paper, as 

 probably an attentive examination of this organ in the more 

 simple (if we may be allowed the term) animals may throw 

 some light on so interesting and important a branch of 

 Physiology. 



May. — Mr. Clarkson has this month delivered two 

 Lectures on Phv;.iognomy. His object in giving them was 

 10 define accurately the expressions of Physiognomical Cha- 

 racter, and to prove that they formed, if accurately studied, 

 a species of universal character 5 thus paving the way for 



the 



