76 H. V. NEAL 



at least, sympathetic in all forms from fishes to man seems, on the 

 basis of anatomical, histological, embryologidal and physiological 

 evidence, indisputable. But the presence of bipolar ganglion 

 cells, like those of cerebro-spinal ganglia, in the ciliary ganglion 

 of many vertebrates has led to the general acceptance of the 

 view of its double nature, a view first advanced by Krause 

 ('82). 



But the presence of bipolar ganglion cells within the ciliary 

 ganglion by no means demonstrates its morphological com- 

 parability with cerebro-spinal ganglia, since ontogenetic evidence 

 shows that the entire ganglion — whether derived from the mid- 

 brain or the mesocephalic ganglion — has not a genetic but merely 

 a secondary relation to the anlage of the oculomotor, a fact em- 

 phasized by Gast ('09). 



While Dohrn ('91) claimed an exclusively medullary deriv- 

 ation of the ciliary ganglion in Selachii, Gast ( '09) , working upon 

 the same material — in fact the same sections — concludes that 

 they are exclusively derived from the mesocephalic ganglion. 

 These diametrically opposite conclusions indicate how obscure 

 the phenomena of migration are in sections of embryonic mate- 

 rial. Carpenter ( '06) , working upon chick embryos, infers a double 

 derivation of the cells of the ciliary ganglion. 



Von Kupffer ('95), Johnston ('05), and Belogolowy ('10b) have 

 attempted to associate the ciliary ganglion genetically with the 

 'thalamic nerve. ' Johnston says (p. 244) that ''since the profun- 

 dus ganglion is distinct from the ciliary and is formed from a dif- 

 ferent part of the neural crest, it seems altogether probable that 

 the ciliary ganglion permanently represents the N. thalamicus. " 

 Belogolowy 's discovery of an anastomosis between the oculomotor 

 nerve and the transient ganglion of the ' thalamic nerve ' likewise 

 seems to him to prove the homodynamy of the latter with the cili- 

 ary ganglion of vertebrates. In drawing this conclusion Belogo- 

 lowy fails to take into account the fact that the ciliary ganglion 

 of vertebrates is a derivative of the mesocephalic or profundus 

 ganglion. It is not at all clear that the complicated anastomoses 

 between the branches of the eye-muscle nerves in reptile embryos 

 and their peculiar relations with branches of the trigeminal nerve 



