of the chest in breathing , speaking , and expression. 299 
Upon stimulating the nerves after the death of this animal, 
it was observed, that the class of respiratory nerves retained 
their power of exciting their respective muscles into action, 
long after the other nerves had ceased to exert any power ; 
they were evidently of that class which retain their life the 
longest. 
It is a duty to avoid the unnecessary repetition of experi- 
ments, and I have now to make a short statement of facts, 
resting on the highest authorities : experiments made without 
reference to the views now presented to the Society. 
The division of the recurrent branch of the par vagum de- 
stroys the voice.* 
The division of the laryngeal branch of the par vagum stops 
the consent of motion between the muscles of the glottis and 
the muscles of the chest.-f 
The injury or compression of the par vagum produces 
difficulty of breathing. £ 
By the assistance of these well known facts, we complete 
the knowledge of the circle of actions which result from the 
respiratory nerves. 
The medulla oblongata and spinalis are composed of columns 
of nervous matter, which (from the different powers of the 
nerves, as they arise from the one or other of these co- 
lumns), possess distinct properties. In animals that breathe 
by ribs and a numerous class of muscles, and which animals 
have a spinal marrow, we see that a column of nervous 
* Sectis ambobus nervis recurrentibus vox perit : Arnemann, Sommerring, Mor- 
gagni . f Le Gallois. 
t Vinculo compressis nervis vagis oriuntur in bestiis spirandi difficultas, surditas, 
vomitus, corruptio ciborum in ventriculo. Sommerring, Haller, Bran de ligaturis 
nervorum. 
