CIRCULATION. 467 



is made to inhale chloroform. The superior laryngeal and the trigeminus 

 nerves, especially the latter, convey the stimulus to the nerve-centres. 1 



The stimulation of the nerves of special sense, optic, auditory, olfactory and 

 glosso-pharyngeal nerves, also sometimes slows and sometimes quickens the 

 heart. 2 



Sympathetic. The reflex action of the sympathetic nerve upon the heart 

 is well shown by the celebrated experiment of F. Goltz. 3 In a medium-sized 

 frog, the pericardium was exposed by carefully cutting a small window in the 

 chest-wall. The pulsations of the heart could be seen through the thin peri- 

 cardial membrane. Goltz now began to beat upon the abdomen about 140 

 times a minute with the handle of a scalpel. The heart gradually slowed, and 

 at length stood still in diastole. Goltz now ceased the rain of little blows. 

 The heart remained quiet for a time and then began to beat again, at first slowly 

 and then more rapidly. Some time after the experiment, the heart beat about 

 five strokes in the minute faster than before the experiment was begun. The 

 effect cannot be obtained after section of the vagi. 



Bernstein 4 found that the afferent nerves in Goltz's experiment were branches 

 of the abdominal sympathetic, and discovered that the stimulation of the cen- 

 tral end of the abdominal sympathetic in the rabbit was followed also by reflex 

 inhibition of the heart. 



The stimulation of the central end of the splanchnic produces a reflex rise 

 of blood-pressure and, perhaps secondarily, a slowing of the heart. 5 In some 

 cases acceleration has been observed. 6 According to Roy and Adami splanch- 

 nic stimulation sometimes produces a combination of augmentor and vagus 

 effects, the augmentation appearing during stimulation and giving place 

 abruptly to well-marked inhibitory slowing at the close of stimulation. 7 



The results of stimulating various abdominal viscera have been studied by 

 Mayer and Pribram. One of the most interesting of the reflexes observed by 

 them was the inhibition of the heart called forth by dilating the stomach. 8 



The stimulation of the cervical sympathetic does not give any very constant 

 results on the action of the heart. 9 



B. THE CENTRES OP THE HEART-NERVES. 



Inhibitory Centre.- It has been already mentioned that the brothers 

 Weber 10 localized the cardiac inhibitory centre in the medulla oblongata. The 

 efforts to fix the exact location of the centre by stimulation of various parts, 

 either mechanically, by thrusting fine needles into the medulla, 11 or electrically, 



1 Dogiel, 1866, p. 236 ; Kratschmer, 1870, p. 159 ; Franck, 1876, p. 227 ; Simanowsky, 1881. 



2 Couty and Charpentier, 1877, p. 563. 8 Goltz, 1863, p. 11. 

 * Bernstein, 1863, p. 818 ; 1864, pp. 617, 642. 5 Asp, 1867, p. 150. 

 8 v. Bezold, 1863, p. 252 ; Asp, 1867, p. 172 ; Sabbatini, 1891, p. 219. 



7 Roy and Adami, 1892, p. 258. 



8 Mayer and Pribram, 1872, p. 107 ; Simanowsky, 1881. 



9 Bernstein, 1864, p. 630; Aubert and Koever, 1868, p. 240; 1869, p. 95; Bernstein, 1868, 

 p. 601. 10 Weber, 1846, p. 45. 



11 Eckhard, 1878, p. 187 ; Klug, 1880, p. 516 ; Laborde, 1888, p. 400. 



