MORPHOLOGY OF EYE MUSCLE NERVES 71 



migration of cells derived from the mesocephalic ganglion along 

 the oculomotor nerve is not very convincing. 



Carpenter ('06) finds evidence of free cell migration from the 

 mesocephalic ganglion into the loose mesenchyma and towards 

 the oculomotor anlage in the chick. Guthke ('06, p. 43) on the 

 other hand, asserts that the ganglion of the profundus nerve 

 (which he erroneously calls the ciliary ganglion) has absolutely 

 nothing to do with the oculomotorius which has no connections 

 with the profundus ganglion in Torpedo. 



Belogolowy ('10, p. 275) infers, in agreement with Carpenter 

 ('06), that the cells, which in the chick migrate from the brain, 

 probably participate in the formation of the motor neuroblasts 

 of the ciliary ganglion; and he is of the opinion that neural 

 crest cells play an important part in the formation of the accom- 

 panying cells. 



Several have inferred the participation of the mesenchyma in 

 the addition of cells to the oculomotor anlage. Indeed that has 

 always been the orthodox assumption of the derivation of the 

 neurilemma of the nerve. Held ('09) was in doubt as to the 

 actual origin of the neurilemma nuclei of the oculomotor, but 

 regards them as belonging to mesenchymatous cells of unknown 

 origin. There can be no doubt of the close association of mesen- 

 chymatous cells in all early stages of the histogenesis of the 

 nerve, and it seems not unlikely that they contribute to the 

 formation of the sheath cells of the nerve. In fact Gast ('09) 

 confirms the assertion of His, Jr., and Romberg ('90) that neuro- 

 cytes migrate freely through the mesenchyma toward the nerve 

 anlage. 



Thus, in the derivation of its cellular elements, the oculomotor 

 of Squalus resembles a spinal somatic motor nerve. Part at 

 least of its component cells are of medullary origin ; some of them 

 maj^ be mesenchymatous; and, finally, the nerve has close asso- 

 ciation with cells derived from a cerebro-spinal ganglion, the 

 mesocephalic or profundus ganglion. 



g. What is the fate of these cells? The fate of these cells ap- 

 pears even less certain than their derivation. The opinions have 

 been expressed that at least some of the cells — whether derived 



