COMPARATIVE. HISTORICAL. 7 21 



lateral facial atrophy has been observed. Irritative phenomena in the distribution 

 of the splanchnic nerve, especially as a result of lead-poisoning, are attended 

 with severe pain (saturnine colic) , inhibition of the movements of the intestine 

 (and, therefore, obstinate constipation), reflex inhibition of the action of the heart 

 (in the sense of the percussion-experiment of Goltz) . Among the forms of irritation 

 in the distribution of the sensory nerves of the sympathetic are the painful affection 

 in the hypogastrium and sacral regions designated hypogastric neuralgia, hysteral- 

 gia, neuralgia of the testicle, which are localized in the respective plexuses of the 

 sympathetic. In connection with affections of the abdominal sympathetic obsti- 

 nate constipation is at times observed, and, in addition to irritation of the splanch- 

 nic, there may be deficient secretion on the part of the intestinal glands; at other 

 times increased secretion from the intestinal mucous membrane. With respect to 

 all of these subjects, however, there is as yet considerable obscurity. 



COMPARATIVE. HISTORICAL. 



Some of the cerebral nerves behave like the anterior, and others like the 

 posterior roots of the spinal nerves. In selachians the nerve-branches arising as 

 posterior roots supply upon the head the muscles of the visceral skeleton. In the 

 vertebrates some of the cerebral nerves may be entirely wanting; others may be 

 abortive or become branches of other nerves. Cetaceans possess no olfactory nerve. 

 The facial nerve, which in man is the mimetic and the respiratory nerve of the 

 face, grows smaller and smaller in the lower classes of vertebrates, in conjunction 

 with reduction in the size of the facial muscles. In birds and reptiles it innervates 

 the muscles attached to the hyoid bone or the superficial muscles of the neck 

 and the nucha. In amphibia (frog) , the facial is no longer present as a separate 

 nerve. The branch equivalent to it is derived from the ganglion of the trigeminus. 

 In fish the fifth and seventh nerves form a common complex. The portion cor- 

 responding to the facial (also designated opercular branch of the trigeminus) is 

 especially the motor nerve of the muscles of the gill-cover and, therefore, proves 

 itself to be a respiratory nerve. The cyclostomata (lamprey) possess an inde- 

 pendent facial nerve. The vagus is present in all vertebrates. In fish and tad- 

 poles the great lateral nerve of the abdomen is derived -from it, passing in the 

 middle line of the body along the lateral canal. Its diminutive analogue in man 

 is the auricular branch. In the frog, the ninth, tenth and eleventh, and also the 

 seventh and eighth nerves arise from a common trunk. In fish and amphibia the 

 hypoglossus is the first spinal nerve. In the amphioxus cerebral and spinal nerves 

 are not to be distinguished from each other. In them also the posterior roots 

 supply the muscles of the viscera. In other respects the spinal nerves in all 

 classes of vertebrates exhibit marked uniformity. The sympathetic is wanting in 

 cyclostomata, being replaced by the vagus. In the remaining fish its course is 

 along the vertebral column, where it receives the communicating branches of the 

 spinal nerves. In the region of the head its anastomoses with the fifth and tenth 

 nerve, are especially conspicuous in fish. In frogs, and in still greater degree in 

 birds, these anastomoses with the cerebral nerves are more extensive. 



The vagus and the sympathetic were already known to the school of Hip- 

 pocrates. Herophilus (307 B. C.) was the first to distinguish the nerves from 

 the tendons, which Aristotle still confounded. He was aware of the decussation 

 of the optic nerves. According to Erasistratus all nerves originate from the brain 

 and the spinal cord. He distinguished motor and sensory nerves. Marinus 

 (80 A. D.) was the first to describe seven pairs of cerebral nerves. Galen already 

 possessed a comprehensive knowledge of the functions of the nerves. He, as well 

 as Rufus of Ephesus (97 A. D.), was familiar with the embarrassed breathing 

 following section of both vagi. He observed aphonia after ligation of the recur- 

 rent nerve. He was familiar with the accessory nerve and also with the ganglia 

 connected with the abdominal nerves. He did not place the olfactory nerve in 

 the same category as the other cerebral nerves. Achillini (died 1525) discovered 

 the true olfactory filaments. Fallopius placed the glossopharyngeus in an inde- 

 pendent position. The cauda equina is mentioned in the Talmud. Goiter (1573) 

 described accurately the anterior and posterior roots of the spinal nerves. Van 

 Helmpnt (died 1644) announced that the peripheral motor nerves are also sensitive 

 to pain; and Caesalpinus (1571) stated that interruption of the circulation in a 

 part renders it insensitive. Thomas Willis described the portion of the accessory 

 nerve derived from the spinal cord, as well as the principal ganglia (1664). The 

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