624 COMPARATIVE HISTORICAL. 



are the oculo-pupillary symptoms. Stimulation (electrical) of the peripheral end 

 produces the opposite results, pallor of the ears, owing to contraction of the blood- 

 vessels, with consequent fall of the temperature ; dilatation of the pupil, bulging of 

 the cornea, protrusiou of the eyeball (exophthalmos), and widening of the palpebral 

 fissure. At the same time, the blood-vessels to the salivary glands are contracted, 

 and there is a secretion of thick saliva. The last results are due to the vaso- 

 constrictor and secretory fibres. The vaso-motor and oculo-pupillary fibres, although 

 they lie in the same trunk in the neck, do not issue from the cord by the same 

 nerve-roots ; the latter come out of the cord with the anterior roots of the 1st and 

 2nd dorsal nerves (dog), while section of the cord between the 2nd and 4th dorsal 

 vertebra? produces the vaso-motor changes only. The nasal mucous membrane and 

 lachrymal gland are influenced by the sympathetic] 



[Division of the cervical sympathetic in young, grouting, animals results iu hypertrophy of 

 the ear, aud increased growth of the hair on that side {Bidder, W. Stirling).] 



[The vago-sympathetic nerve (dog) in the neck contains vaso-dilator fibres (really in the 

 sympathetic) tor the skin and mucous membranes of that side of the head. Weak stimulation 

 of the central end of the sympathetic causes dilatation of the blood-vessels of these parts. The 

 vaso-dilator fibres of the superior maxillary nerve probably come from the same source. The 

 centre for these nerves is in the dorsal region of the cord between the 1st and 5th dorsal 

 vertebra-, where the fibres pass out with the rami communicantes to enter the cervical sympathetic 

 (Dastre and Morat). The vaso-dilator fibres occur in the posterior segment of the ring of 

 Vieussens, and when they are stimulated after section of the 7th cranial nerve, there is a 

 " psendo-motor " effect on the muscles of the cheek and lip ( 349).] 



Irritation in the area of the splanchnic, as occurs occasionally in lead poisoning, is 

 characterised by violent pain (lead colic), inhibition of the intestinal movements, (hence 

 the persistent constipation), slowing of the heart's action, brought about reflexly, just as in 

 Goltz's "tapping" experiment ( 369). Irritation in the area of the sensory nerves of the 

 sympathetic may give rise to that condition which is called by Romberg neuralgia hypogastrica, 

 a painful affection of the lower abdominal and sacral regions, hysteralgia, neuralgia testis, 

 which are localised in the plexuses of the sympathetic. In affections of the abdominal 

 sympathetic, there may be severe constipation, with diminished or increased secretion of the 

 intestinal glands ( 186). 



357. COMPARATIVE HISTORICAL. Comparative. Some of the cranial nerves may 

 be absent, others, again, may be abortive, or exist as branches of other nerves. The facial 

 nerve, which supplies the muscles of expression in man, and is, at the same time, the nerve for 

 facial respiratory movements, diminishes more and more in the lower classes of the vertebrata, 

 pari passu, with the diminution of the facial muscles. In birds and reptiles, it supplies the 

 muscles of the hyoid bone, or the superficial cervical muscles of the nape of the neck. In 

 amphibians (frog), the facial no longer exists as a separate nerve, the nerve which corresponds 

 to it springing from the trigeminus. In fishes, the 5th and 7th nerves form a joint complex 

 nerve. The part corresponding to the facial (also called ramus opercularis trigemini) is the chief 

 motor nerve of the muscles of the gill-cover, and is, therefore, the respiratory uerve. In the 

 cyclostomata (lamprey) there is an independent facial. The vagus is present in all vertebrata; 

 in fishes it gives off a large nerve, the lateral nerve of the body (N. lateralis), which runs along 

 each side of the body close to the lateral canal. It is also present in the tadpole. Its 

 rudimentary representative iu man is the auricular branch. In the frog the 9th, 10th, and 

 11th arise together from one trunk, and the 7th and 8th from another. In fishes and amphibia, 

 the hypoglossal is the first cervical nerve. In amphioxus, the cerebral and spinal nerves are 

 not distinct from each other. The spinal nerves are remarkably similar in all classes of the 

 vertebrata. The sympathetic is absent in the cyclostomata, where it is represented by the 

 vagus. Its course is along the vertebral column, where it receives the rami communicantes of 

 the spinal nerves. In the region of the head its connections with the 5th and 10th nerves are 

 specially developed. In frogs, and still more so in birds, the number of connections with the 

 cranial nerves increases. 



Historical. The vagus and sympathetic were known to the Hippocratic School. According 

 to Erasistratus, all the nerves proceed from the brain and spinal cord ; Herophilus was the first 

 to distinguish the nerves from the tendons, which Aristotle confounded with each other. 

 Marianus (80 a.d.) recognised seven pairs of cranial nerves. Galen was in possession of a wide 

 range of important facts in the physiology of the nervous system ( 140) ; he observed that loss 

 of voice followed ligature of the recurrent nerves ; and he was acquainted with the accessorius, 

 and the ganglia on the abdominal nerves. The cauda equina is referred to in the Talmud ; 

 Coiter (1573) described exactly the anterior and posterior spinal nerve-roots. Van Helmont 

 (t 1644) states that the peripheral motor nerves also give rise to impressions of pain, and 



