573 



thalmicum of Hoffmann). I cannot say that this is unlikely, l)ut at 

 the same time from the actual sections figured by him it is not 

 rendered absolutely certain. 



The sections figured in most cases lack the third nerve, and if 

 this could not have been given in single sections either combined 

 sections should have been given or more numerous single sections. 



No doubt the mode of development described by Hoffmann is 

 satisfactory in that it harmonises the development of the ciliary 

 ganglion as a sympathetic ganglion with the mode of development of 

 the sympathetic ganglia of the trunk, but until it be shown that the 

 otic and sphenopalatine gangha etc. are formed in this manner, it is 

 rather premature to conclude that the sympathetic of the head arises 

 in the same way as that of the trunk. 



The short connective branch between the third nerve and the 

 mesocephalic ganglion seems to suggest this mode of origin, and even 

 if there be in Elasmobranchs no actual outgrowth of cells from the 

 mesocephalic ganglion as stated by Hoffmann to be the case in 

 reptiles, the two things would be exactly comparable if only one or 

 two cells during the close connection of the third nerve and meso- 

 cephalic ganglion passed from the ganglion to the nerve. By later 

 divisions these could easily be supposed to give rise to the Ciliary gang- 

 lion within the nerve itself. 



In the series of sharks at my disposal I have seen nothing to lead 

 me to the mode of origin for the ciliary ganglion described by 

 Hoffmann. I wish, however, to cast no sort of doubt on Prof. Hoffmann's 

 statements. 



It is very easy now to reconcile all the different accounts, and in 

 the following table under the heading ciliary and mesocephalic I have 

 given the names which different observers gave to these two ganglia 

 in the embryo. 



Embryo 



Ciliary. Mesocephalic. 



ciliary 

 ditto 

 ditto 

 ditto 

 ditto 

 ditto 

 ditto 

 ophthalmicum 



40 



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