288 



Dr. J. C. Ewart. On the Development of [Mar. 6, 



or lenticular) ganglion. By Reniak,* Schwalbe,f Marsh all, J and 

 others, the ganglion of the ophthalmicus profundus has been described 

 as the ciliary ganglion, and this ganglion has frequently been regarded 

 as the ganglion of the motor oculi nerve, and hence as homologous 

 with the Gasserian and other cranial ganglia. The ciliary ganglion 

 having been shown by van Wijhe§ to be quite distinct from the 

 ganglion of the ophthalmicus profundus, the old view of Arnold has 

 been recently revived, and already van Wijhe, Hoffmann, || Onodi, 6 ^ 

 Dohrn,** and Beardff have indicated that they regard the ciliary as 

 a sympathetic ganglion. Hoffmann bases his belief on certaiu ob- 

 servations on the development of the ciliary ganglion in reptiles, 

 while Onodi has adopted this view chiefly because in the higher 

 vertebrates the ciliary ganglion receives a communicating branch 

 from the sympathetic. But Beard, while considering the ciliary a 

 sympathetic ganglion, states that in sharks he has seen nothing in 

 support of " the mode of origin for the ciliary ganglion described 

 by Hoffmann," in reptiles. 



Having examined the cranial nerves of a number of Elasmo- 

 branchs at various stages of development and growth, I am now 

 able to give an account of the ciliary ganglion and indicate its 

 nature and its relations to the motor oculi and other cranial nerves. 

 In this note, however, I shall only state the more important results 

 obtained, as the subject will be fully dealt with in a further con- 

 tribution " On the Cranial Nerves of Elasmobranchs." In study- 

 ing the ciliary ganglion in Elasmobranchs I have been specially 

 struck with its tendency to vary, not only in the same genus or 

 species, but in the same individual. Of the numerous specimens 

 examined, I have only once found the ganglion entirely absent (in an 

 adult Raia radiata), while I have occasionally (in Acanthias) found 

 two well developed ganglia on each side. Usually in sharks I found 

 the ganglion lying in connexion with the inferior branch of the motor 

 oculi, while in skates it was generally in contact with the ophthalmicus 

 profundus, or lying midway between the motor oculi and the ganglion 

 of the profundus. In form the ganglion varies extremely ; rounded or 

 conical in some cases, in others it was represented by two or three 



* ' TJntersuchungen zur Entwickelungs-Greschichte der Wirbeltiere,' 1885. 

 f ' Jenaische Zeitschrift fur Naturwissenschaft,' 1879, p. 173. 

 t ' Quarterly Jcrarnal Microscopical Science,' Jan., 1881. 



§ " Ueber die Mesoderniseginente und die Entwiekelung der Nerven des Selachier- 

 kopfes" (' Natuurk. Verh. der Koninkl. Akadeinie, Amsterdam,' vol. 22). 



|| " Weitere TJntersuchungen zur Entwickeluugsgesch. der Reptilien " (' Morph. 

 Jalirbuch,' vol. 11, part 2). 



% ' Arcbiv fur Anatomie und Physiologie (Physiol. Abth.),' 1887. 



" Studien zur TJrgeschichte des Wirbelthierkorpers," No. 10 (' Mitteil. a. d. 

 Zool. Stat, zu Neapel,' vol. 6, part 3). 



ft ' Anatomischer Anzeiger,' Jahrgang 2 (1887), Nos. 18 and 19. 



