1910.] A fferents of Third, Fourth, and Sixth Cranial Nerves. 455 



appeared, about 20 nerve-fibres of minute diameter remained sound, 

 three reaching the tendon. In the other muscles, the nerve-endings and 

 tendon nerves were normal. 



(B) In the 15-day experiment the results were the same as the above 

 in regard to the branches of the fifth and the sixth nerves. 



In the branch of tlie third to superior rectus, however, and in the fourth 

 nerve, as it entered the superior oblique, there were degenerate fibres to the 

 number of 70 — 80. From external rectus all nerve-endings had disappeared, 

 but one sound nerve-fibre of small calibre was present, not, however, reaching 

 the tendon. The remaining muscles of the orbit, including superior rectus 

 and superior oblique, exhibited the usual normal nerve-endings and tendon 

 nerves. 



(C) In the 50-day experiment the results agreed with the above, except 

 that in frontal nerve, at its exit from orbit, six minute nerve-fibres were 

 still sound, and in sixth nerve, at entrance into external rectus, five minute 

 nerve-fibres were still sound. In the tendon of external rectus, three 

 minute sound fibres were discovered, otherwise, all nerve-endings and 

 nerve-fibres had disappeared. In this experiment, as in the 16-day experi- 

 ment, the fourth nerve and the branches of the third nerve were entirely 

 free from any trace of degeneration. 



V. Intracranicd Severance of Fourth Xerce, Ophthalmie Division of Fifth 

 Nerve, and Sidh Nerve. — One experiment (monkey). Symptoms as in IV. 

 Period allowed tor degeneration, 50 days. 



Degerteration Results. (1) Orhital Nerves. — Complete degeneration of fourth 

 nerve and of all branches of ophthalmic of fifth and the sixth nerve. 



(2) Muscles. — In superior oblique no nerve-endings were found, but a few 

 nerve-fibres persisted sound ; some of these approached the tendon end. In 

 external rectus no nerve-endings and no tendon nerves remained. In the 

 remaining muscles of the orbit the customary nerve-endings and tendon 

 nerves were discoverable as usual, and showed no departure from normal. 



VI. Intracranial Severance of Third Nerve, Ophthalmic Division of Fifth 

 Nerve and the Sixth Nerve. — One experiment (monkey). Period allowed for 

 degeneration, 30 days. Symptoms during life were ptosis, practical 

 immobility of eyeball, great dilatation of pupil, ana'sthesia of cornea, upper 

 lid and forehead. 



Deijeneration Eesidts. (1) Orhital Nerves. — The frontal brancli of fifth 

 contained no sound fibres, the nasal branch contained two, and the lachrymal 

 branch contained a few sound fibres of minute size. 



The branch from third nerve to internal rectus contained no sound fibres, 

 but the branch to inferior rectus contained six, that to superior rectus four, 



2 N 2 



