232 



Presents. 



[Apr. 5, 



Here again with the utmost uniformity on each stimulation of the 

 second dorsal the left pupil, and this one only, became widely dilated, 

 whereas stimulation of the other roots was entirely negative in respect 

 to the pupil. 



I ascertained in this experiment that a strength of current which 

 would suffice to excite the muscles of the limb or trunk to action, would 

 frequently fail to cause any dilatation of the pupil when applied to the 

 second dorsal. Somewhat stronger, but yet barely perceptible on the 

 tongue, the current at once caused the pupil to dilate. Occasionally 

 also if the second root had been stimulated repeatedly, the iris failed 

 to respond, probably from mere exhaustion of the nerve. 



Circumstances such as these would, I think, account for the absence 

 of the pupil-reaction in my first experiment, and also in the experi- 

 ment related by Professor Yeo and myself, where the second dorsal 

 root was really under stimulation. 



The general result of these experiments is to show that in the 

 monkey, and presumably also in man, the dilator fibres of the iris, 

 contained in the cervical sympathetic, are derived from the anterior 

 root of the second dorsal nerve. 



The Society adjourned over the Whitsuntide Recess to Thursday, 

 May 24th. 



Presents, April 5, 1883. 



Transactions. 



Amsterdam: — K. Akademie van Wetenschappen. Verhandelingen. 

 Afd. Natuurkunde, Deel XXII. Afd. Letterkunde, Deel XV. 

 4to. Amsterdam 1883. Verslagen en Mededeelingen, Afd. 

 Natuurk. 2e Rks. Deel XVII. Afd. Letterk. 2e Rks. 

 Deel XI. Register. Deel I-XII. 8vo. Amsterdam 1882. 

 Jaarboek, 1881. 8vo. Amsterdam. Processen-Verbaal, 1881- 

 £2. 8vo. Prijsvers : Tria Carmina Latina. The Academy. 



Brussels : — Academie Royale des Sciences. Bulletin. 3e Serie. 

 Tome IV. No. 12. Tome V. No. 1. Tables Generales du 

 Recueil des Bulletins. 2e Serie. Tomes XXI-L. 8vo. Bruxelles 

 1883. The Academy. 



Musee Royal d'Histoire Naturelle. Annales. Tome X. Les 

 Arachnides de Belgique. Par Leon Becker. Partie I et 

 Planches. 4to. Bruxelles 1882. The Museum. 



Dijon : — Academie des Sciences. Memoires. 3e Serie. Tome VII. 

 8vo. Dijon 1882. The Academy, 



