PLATE XCII. 



FIG. 237. Dissection of the parts in relation with 

 the vagus nerve of the frog oil the right side. The 

 (Montagu! is ilisti'inli'd with a glass tube alxmt half 

 iin inch in width. The object is represented of about 

 twice the actual size, a. Right aorta ; B. bulbut 

 nortte ; c, posterior horn of hyoid l>one ; g.h., genio- 

 hyoid muscle ; h.;/., hyoglossus muscle ; ]>, lowest of the 

 three petrohyoid muscles ; H, ninth nerve ; G, glosso- 

 pharyngeal nerve; r, vagus ; 6, larynx ; s& h & oh., point 

 to the space occupied by the origins of the large muscle 

 (stemohyoid) winch connects the hyoid with the ster- 

 num, as well as by the omohyoid ; both of these muscles 

 have beeu cut away ( 73). 



FlO. 235. Tra 



obtained by recording 



multaneously on the same cylinder the variations of pressure in 

 the right auricle, right 

 ventricle, and left ven- 

 tricle, respectively. The 

 interval between each 

 vertical line and the 

 next corresponds to 

 about a tenth of a se- 

 cond. The second ver- 

 tical line is just before 

 the completion of the 

 systole of the auricles. 

 The contraction of the 

 ventricles falls be- 

 tween the third and 

 fourth lines. It ends 

 between the seventh 

 and eighth ; conse- 

 quently, in the horse, 

 the interval of time 

 between the auricular 

 systole and that of 

 the ventricles is about 

 o'iS sec., and the 

 duration of the ventri- 

 cular systole is about 

 0-4 sec. (After Chau- 

 veau ; tee 67.) 



Fid. 236. Septum 

 auricularum of frog, a, 

 Muscular fibres ; 6, endo- 

 cardium ; c, free edge of 

 septum ; dd, wall of ve7i- 

 tricle; e. right cardiac 

 branch of vagus ; /, left 

 branch ; h, anterior 

 nerve of septum ; t, 

 posterior nerve ; k k, 

 Bidder's ganglia; II, 

 ganglia of ventricle ; 

 69. (After Bidder.) 



