II E S P I R A T I N I N T II E C II B L MA. 3:i 



The above experiments led us, irresistibly, to the conclusion, that their must be 

 a chiasm of the two superior laryngeal nerves, and it only remained to prove, with 

 the scalpel, the presence of this branch, A. careful series of dissections on large 

 turtles of various species and genera, satisfactorily proved that we were not mis- 

 taken. In every case the nerve was readily found, and the physiological prediction 

 as to its existence verified in the most absolute manner. 



The discovery of a new nerve in turtles, and upon ground over w.hich the accurate 

 knife of Bojanus had passed, called for a still more rigorous testing of our previous 

 results. For this purpose the following experiments were made. 



The first of this second series is of unusual value, owing to circumstances which 

 arose incidentally. 



Exjperimeiit. — Snapping turtle, weight nineteen and three-quarter pounds. We 

 cut down on the middle line of the hyoid bone and divided it throughout its length 

 with a hair-saw and nippers. When this operation is done with care, it exposes to 

 the operator enough of the cricoid fenestrum to enable him to cut the communicating 

 nerve at its central part. Next, both recurrent nerves were divided at the middle 

 of their course. The section, and after stimulation of the right nerve, had no effect 

 on the glottis, which we thought singular. Section of the right superior laryngeal 

 nerve was satisfactorily made as usual, the nerve being readily exposed and 

 divided. To our surprise, the right glottic lip became paralyzed almost totally, 

 the left side moving in respiration as usual. This result was opposed to all our 

 former experiments. After a rigid examination of the conditions of this last 

 experiment, and finding in them no explanation of the contradiction which it 

 offered, we dissected, with scrupulous care, the whole track of the pneumogastric nerve 

 and its branches to the larynx, as well as that organ itself. The following appear- 

 ances were noted : On the left mucous lip of the glottis, a small white patch of 

 diseased tissue. The inner end of the right upper hyoid cornu was enlarged to douhle 

 its normal size; thus of necessity stretching the right superior laryngeal nerve where 

 it crosses the cornu at its inner end. On the left side the superior laryngeal nerve 

 was perfect up to the point at which it gave off the interlateral communicating 

 branch. This latter nerve, lying on the cricoid fenestrum, was involved in a mass 

 of diseased tissue, which extended between the trachea and the body of the hyoid 

 bone, from its lower part to a point about one-quarter of an inch above the 

 fenestrum. This disease, doubtless, affected the communicating branch, so as to 

 cause partial paralysis of the right glottic lip to follow section of the corresponding 

 superior laryngeal nerve. Had the interlateral branch been completely destroyed, 

 section of one laryngeal nerve must have produced entire paralysis of the glottic lip 

 on the side operated upon. 



This observation, which at first promised to cast doubt upon those which 

 preceded it, thus proved at last the most conclusive evidence of the correctness of the 

 view to which we had arrived. An accident of disease or injury had so altered the 

 communication between the two superior nerves of the larynx, as to make unneces- 

 sary the section, which would under ordinary circumstances have followed as the 

 third step in the experiment, 



