NEKYOTJS SYSTEM AND GENERAL SE^SATIOIT. 53 



favour of the view, that the sympathetic is nothing more than 

 a cerebro-spinal nerve. In the cyclostomes among fishes, the 

 sympathetic is either wholly, or in major part, replaced by the 

 par vagum, the eighth pair ; the same thing occurs among ser- 

 pents, in which, moreover, branches proceed directly from tha 

 spinal cord to the viscera. It is a remarkable anatomical fact 

 also, that in man and the mammalia, the lachrymal gland, 

 arid several other organs of secretion, such as the mammae, 

 are supplied with nerves directly from the cerebro-spinal sys- 

 tem, not mediately from the sympathetic. 



[ 113. "The nerves which the sympathetic supplies to the 

 viscera, are the instruments of their sensations and motions, 

 It is, for example, easy to demonstrate by experiment, that the 

 peristaltic motions of the intestines in the rabbit, dog, and 

 other animals, is powerfully and permanently increased by the 

 stimulation of the solar plexus, or of any particular branch 

 proceeding directly to the intestines. By other experiments of 

 the same kind, the motory power of other fibres, and their in- 

 fluence upon the viscera, can also be shown : the heart is ex- 

 cited by stimuli applied to the inferior cervical ganglion, and 

 also, but in a much inferior degree, by irritating the superior 

 thoracic ganglion. It has even been said, that the great vas- 

 cular trunks of the thorax and abdomen have been seen to 

 contract under the influence of stimuli applied to the thoracic 

 ganglia. Stimulation of the cervical ganglia induces contrac- 

 tions in the oesophagus ; and movements of the stomach follow 

 excitement of the four inferior cervical pairs, and of the two 

 superior thoracic ganglia. Many branches of the sympathetic 

 and other nerves minister to the motions of the small intestines. 

 Stimulation of the lower lumbar and superior sacral nerves is 

 followed by powerful contractions of the great intestines, urin- 

 ary bladder, uterus, and oviduct. The greater splanchnic nerve 

 having been stimulated in the horse, the ductus communis 

 choledochus has been seen to contract, and in birds this fact is 

 easily demonstrated, and very remarkable. In the same way, 

 motions have been observed in the ureters, on applying stimuli 

 to the abdominal ganglia, and to the roots of the abdominal 

 spinal nerves. The bladder receives its nerves principally from 

 the sacral portion of the sympathetic ; the vas deferens, and 

 vesiculae seminales, contract upon the two inferior lumbar 

 ganglia being stimulated. 



