Cy^ Shearer, Netvc Tenninations in the Selachian Cornea. 209 



following figures in regard to the arrangement of these cells in 

 the nerve chords : . 



Right Chord Left Chord 



J^ A 



Dorsal Ventral Dorsal Ventral 



68 16 55 20 



Total : 84 75 



The axis cylinders of the neurochord cells all pass distad 

 in the nerve chords, divide dichotomously in their course, and at 

 certain distances show constrictions. 



In regard to the " gross anatomy " the following discov- 

 eries may be noted : in Ccrebratithis lacteus and Linens gesseren- 

 sis there is a second commissure uniting the ventral brain lobes, 

 and in an European species of the latter genus, in addition to 

 the second, a third. There are three commissures of the oeso- 

 phageal nerves in Cerebratnlns, and four in Linens. 



On the Nerve Terminations in the Selachian Cornea. 

 By Cresswell Shearer, 



University of McGill, Montreal. 



Throughout the vertebrate body there is hardly an organ 

 whose innervation has received so much attention as that of the 

 cornea. 



Time and again as new neurological methods have been 

 discovered they have been applied to the study and re-study of 

 the corneal nerve endings. Ever since 1866 when Cohenheim 

 (i) published his celebrated paper on the termination of sensory 

 nerves in the cornea, as demonstrated by him with his gold 

 chloride method, down to the more recent researches of Dogiel 

 (2 and 3) with methylen blue, an innumerable number of pa- 

 pers have appeared. 



Despite the fact, however, that so much has been done and 

 said on this subject, little is really known about these nerve ter- 

 minations in the cornea of vertebrates lower than amphibians, 



