caepenter; development of the oculomotor nerve. 151 



Direct stimulation of the short ciliary nerves, however, still caused con- 

 traction of the ciliary body and the iris. The results of Laiigley and 

 Anderson were confirmed for the dog and monkey by Marina ('98, '99). 

 These investigators consequently regard it as proved that tlie neuraxons 

 which innervate the sphincter iridis and the ciliary muscle are connected 

 ■with the cells of the ciliary ganglion. The physiological experiments of 

 Langendorff ('94) and Bernheimer ('97) point to the same conclusion. 

 The former found that some time after death, when stimulation of the 

 third nerve proximal to the ciliary ganglion was without result, excita- 

 tion of the short ciliary nerves produced contraction of the iris. Bern- 

 heimer demonstrated that lesion of the oculomotor nerve in the monkey 

 leaves the iris still active. 



The physiological behavior of the ciliary ganglion of birds affords ad- 

 ditional proof of the lack of similarity between its cells and those of the 

 ciliary ganglion of mammals. Langendorff (:00) states, on the author- 

 ity of Consiglio (:00), that, after the ciliary ganglion of birds has been 

 subjected to the action of nicotin, stimulation of the third nerve is still 

 followed by constriction of the pupil. He himself found that, in birds 

 which have been bled to death, the neuraxons of the third nerve, the 

 stimulation of which causes closure of the pupil, retained their irritabil- 

 ity considerably longer than did tliose of mammals subjected to the 

 same treatment. For these reasons he regards it improbable tliat an 

 intercalation of sympathetic cells occurs, as in mammals, within the 

 ciliary ganglion. 



The fact that fibres emanating from the cervical sympathetic ganglia 

 have no effect on the movements of the pupil in birds was established 

 by Jegorow ('87), and has recently been confirmed by Langley (:03). 

 In mammals, several observers have shown that stimulation of the cer- 

 vical sympathetic nerve causes dilatation of the pupil (Hensen und 

 Volkers, '68; Nawrocki und Przybylski, '91; Anderson, :03). The 

 radially placed dilator muscle of the iris of birds is exceptionally well 

 developed (Geberg, '83 ; Koganei, '85 ; and others). 



B. Observations, 

 a. Methods. 

 For the purpose of examining the main trunks of the eye-muscle 

 nerves and their larger branches, dissections of the heads of adult fowls 

 were made. Soon after death, the orbital cavities were opened by cut- 

 ting through the conjunctiva and connective tissue, and the whole head 

 placed in the picro-aceto-platino-osniic mixture of von Rath, the formula 



