148 Royal Society. 



Jan. 17.—Prof. William Allen Miller, M.D., V.P., in the Chair. 



The following communication was read : — 



"Anatomical and Physiological Observations on the Organ of 

 Vision, for the purpose of ascertaining the alterations caused by sec- 

 tion of the Optic Nerve." By Augustus Waller, M.D., F.R.S. 



The author begins by referring to experimental researches already 

 published by him on the effects produced on the nerves of living 

 animals by section at diiferent points in their course ; and he briefly 

 recapitulates the chief results of these experiments, as follows, viz. — 



1 . Section of a spinal nerve on the distal side of its ganglion is fol- 

 lowed by degeneration of the part of the nerve beyond the section, 

 whilst the part still connected with the ganglion retains its integrity. 



2. Section of the posterior root of a spinal nerve induces no change 

 in the trunk or branches of the nerve beyond the ganglion, nor in 

 the portion of the root which remains connected with the ganglion, 

 whereas the part of the root attached to the spinal cord, but discon- 

 nected with the ganglion, becomes disorganized. His conclusion 

 from these experiments, which have been varied in different ways, is 

 " that the spinal ganglion is the centre of the nutritive power of the 

 nerve-fibres adherent to it." From other experiments, he concluded 

 that the anterior spinal roots derive their nutritive influence from 

 the spinal cord ; and he has little doubt *' that every nerve-fibre is in 

 connexion with a nerve-cell, which exerts over it a peculiar influence 

 which enables it to retain its structure," &c. He does not think it 

 proved, however, that all ganglia exert an influence both in a cen- 

 tral and peripheral direction like those of the posterior spinal roots, 

 and indeed experiments have shown that certain ganglia, such as the 

 superior cervical of the sympathetic, exert their sustaining power on 

 the nerve-fibres connected with them, in one direction only. 



The investigation of the effects of section on the optic nerve, 

 which forms the subject of the present communication, promised to 

 yield interesting results on several grounds, and especially as calcu- 

 lated to throw light on the relations of the fibres of the nerve to 

 those of the opposite one in the optic chiasma or commissure, and 

 on the question as to the manner in which they are connected with 

 the brain. 



After some observations on the structure of the optic nerve, the 

 author describes his experimental procedure. To see the nerve 

 whilst operating, and thus be assured that the section was effected 

 at the desired point, he began by dislocating the eyeball forwards 

 from its socket, while the animal was under the influence of ether. 

 This operation he found could be effected in the rabbit, by simply 

 pressing the eyelids widely apart, and was unattended with any 

 serious disturbance of the functions of the organ. In dogs the 

 operation is more difficult, and occasions more injurious effects. 

 When the eye is dislocated, its axis is inclined downwards and in- 

 wards, and the optic nerve can be reached without difficulty ; so that 

 it may readily be cut at any desirable distance behind its place of 

 entrance into the eyeball, and may even by moderate traction be 

 broken off immediately before the chiasma. 



