of Edinburgh, Session 1864-65. 463 
ceed from two large solitary ganglia, one of which is situated at the 
root of the neck on the right side, the other on the left. 
In the rabbit, they proceed from four smaller ganglia, two of 
which are situated on the right side of the root of the neck, the re- 
maining two on the left. 
In the calf, the number of ganglia furnishing cardiac branches 
increase to six, these being similarly divided and situated. 
The cat, therefore, seems best adapted for physiological pursuits, 
and a series of carefully performed experiments on that animal may 
probably be the means of determining the nature and the extent of 
the influence exerted by the nerves on the movements of the heart, 
if indeed these movements, as the author remarks, are not referable 
to the ganglia situated in the heart itself, which, from various con- 
siderations, he thinks not unlikely. The heart, e. g., is known to 
contract and dilate for a considerable period after the blood, which 
is regarded as its natural stimulus, is abstracted from it. It further 
acts regularly when removed from the body and placed under a bell 
jar from which the air has been subsequently exhausted by the 
action of an air-pump. In the frog, moreover, as not unfrequently 
happens, the heart suddenly ceases to contract, if the base, where 
the ganglia are most numerous, be removed by the stroke of a 
scissors.^ 
In the second part of the investigation, the great cardiac plexuses 
are shown to resolve themselves into four minor ones. 
Of these, one occurs on the pulmonary artery, and supplies 
branches to that surface of the auricles which is directed towards 
the great vessels. It also supplies branches to the right ventricle. 
A second occurs between the pulmonary artery and aorta, and fur- 
nishes branches to the anterior coronary vessels, and to the right 
and left ventricles, particularly the latter. A third occurs on the 
posterior coronary sinus, and gives branches to the left auricle and 
ventricle, especially the latter. The fourth occupies that surface of 
the auricles which is directed towards and is in contact with the 
pericardium, and supplies branches to the inferior cava, to the 
auricles, and to the posterior surface of the right ventricle. The 
Bracket declares that if the cardiac plexus in mammals be destroyed the 
movements of the heart are suddenly and permanently arrested . — Du Sysfhie 
Nerveuse Gavglionaire, p. 120. 
