454 Miss Tozer and Prof. Sherrington. Receptors and [May 18, 



contained three degenerated fibres and the branch to superior rectxis 

 contained seven degenerated fibres. The fourth nerve showed a considerable 

 number of degenerated fibres, and so likewise did the sixth nerve. 



(2) Muscles. — The muscles supplied by the third nerve exhibited no 

 departure from the normal, either in respect to their intra-muscular nerves, 

 their tendon nerves or their nerve-endings of receptive (sensorial) and motor 

 type respectively. In the superior oblique and external rectus a number of 

 receptive nerve-endings of normal appearance were seen and many normal 

 tendon nerves. In this experiment the partial degeneration of fourth and 

 sixth nerves was, it can scarcely be doubted, due to accidental partial injury 

 of them at the time of severance of the ophthalmic divisiou of the fifth, close 

 to which they lie. And this supposition is abundantly supported by the 

 results of the experiments mentioned in succeeding sub-sections. The fil)res, 

 extremely few in number, found degenerate in certain of the branches of 

 third may have come from the ophthalmic division of fifth. 



III. Intracranial Severance of Fo^irth Nerve, and also of Ophthalmic 

 Division of Fifth Nerve. — Two experiments (monkey). Period allowed for 

 degeneration, 28 and 50 days respectively. 



Degeneration, Eesults. (1) Orbital Nerves. — In the frontal and nasal 

 liranches of fifth nerve a few fibres (maxinmm 10) of small diameter 

 were undesrenerate, otherwise their degeneration was absolute. The fourtli 

 nerve was completely degenerate, no sound fibres remaining. The sixth 

 nerve and the branches of the third nerve contained no degenerate fibres, 

 except that the branch from tlie inferior division of tliird to the inferior 

 ()l)li([ue muscle exhibited 10 degenerate fibres. 



(2) Mvscles. — In superior oblique muscle no nerve-endings were found, 

 and in one case no sound tendon nerves at all ; in the otlier case, five sound 

 fibres of minute diameter were found in the tendon. All the muscles, except 

 superior oblique, exhibited the usual nerve-endings, and the usual number of 

 tendon nerves perfectly sound. 



IV. Intracranial Sevrrancf of Ophthalniir Division of Fifth Nerve and of 

 the Sixth Cranial Nerve. — Throe experiments, including one witli D)-. E. E. 

 Laslett (monkey). Symptoms as in 11, combined with external strabismus. 

 I*eriods allowed for degeneration, 15, 16, and 50 days res])ectively. 



JJcf/cneraiion Jlesi'lts. (A) In tlic 1 G-day experiment. (1) ()rliif((l Nerves. — 

 No sound fibres were (hstected in tlie nasal, frontal, and lachrymal branches 

 of fifth nerve, nor in the sixth nerve at its entrance into the orbit. Con- 

 versely, in the branches of the third nerve and fourth nerve, no nerve-fibres 

 at all were degenerate. 



(2) MiiKcles. — In external rectus, although all nerve-endings had dis- 



