186 JOHN BEARD. 



true spinal nerves were ever connected with branchial sense organs. 

 So far as my researches go there is a wide difference both in mor- 

 phology and development between the cranial and spinal nerves. 



The mode of development of the lateral nerve here described is, as 

 previously mentioned, in the main the same as that ascribed to it by 

 Van Wijhe. The only author who has assigned to it a different origin 

 in Elasmobranchs is Balfour, who was inclined to the view that the 

 nerve really grows backwards from the vagus ganglion. 



My own researches on Teleostei 1 led me to accept Balfour's view, but 

 since I have had the opportunity of investigating the matter in Elas- 

 mobranchii I conclude that my interpretation of the matter in Teleostei 

 was erroneous. 



No doubt the account given by Hoffmann 2 of the development in 

 Teleostei is correct. It accords well with the facts as recorded for 

 Elasmobranchs here and by Van Wijhe. 



But none the less it may not be superfluous to point out that the 

 existing accounts of the development of what I have called supra- 

 branchial nerves in Teleostei, Elasmobranchii, and Amphibians — that 

 is, the accounts given by Semper, Gotte, Hoffmann, and Van Wijhe — 

 contain in them one element of uncertainty. That is, as to how the 

 nerve thus developed from the skin acquires its connection with the 

 appropriate ganglion. 



Most of the accounts are quite silent on this point. Gotte, it is 

 true, recognised the importance of the matter, and stated that the 

 nerve in any particular case separates from the skin along part of its 

 length and grows to its ganglion. This view, however, is not in 

 accordance with the facts, and I have reason to believe that Prof. 

 Gotte has now himself ceased to hold it. 



The apparent absence of connection between the nervous structure 

 of the brain and the branchial sense organs of the head was to Balfour 

 a great objection to Gotte' s and Semper's view. He said, and to a 

 certain extent he was right, that at first there is no nerve in connec- 

 tion with the developing sensory thickening. 



This is right so far as its growing point is concerned, for there the 

 nerve has not developed. 



But, as Van Wijhe has pointed out, it is not really the case so far 

 as relates to entire absence of nerve in connection with the sensory 



1 Op. cifc. 



= Hoffmann, "Zur Ontogenie der Knochenfische," 'Archiv fiir Micr. Anat.,' Bd. xxiii, 

 p. 45. 



