53o A MANUAL OF VETERINARY PHYSIOLOGY 



Flourens observed that the sympathetic ganglia were sensory 

 in different degrees, but always less so than the nerves of the 

 cerebro-spinal system. He frequently noticed that stimulation 

 of the semilunar ganglion of the rabbit caused acute pain, while 

 stimulation of the cervical ganglion was unnoticed. Many ob- 

 servers following Flourens record the same fact regarding the 

 sensory character of the semilunar ganglion when stimulated. 

 Colin, in his observation on the degree of sensibility of the 

 sympathetic ganglia in horses, oxen, dogs, and rabbits, agreed 

 with Flourens that these tissues were endowed with different 

 degrees of sensation, and that the semilunar and thoracic were 

 more sensitive than the upper cervical. He found that the 

 rapidity with which a painful reaction showed itself depended 

 on the strength of the stimulus, weak stimuli taking several 

 seconds before any evidence was given. He also found that 

 if the gastric, splenic, hepatic, and intestinal arteries were 

 pinched with forceps, stretched, or damaged, great pain was 

 shown. These facts enable the pain of colic, and especially 

 intestinal twists, to be explained, though why horses can carry 

 in their intestines stones, sand, gravel, and calculi, week after 

 week and month after month, without causing pain is still 

 unknown. 



Pathological. 



The absence of alcoholism and syphilis in the lower animals 

 reduces the incidence of nervous affections. It cannot truly be said 

 that worry or anxiety are absent among them, and that hence 

 nervous affections are not so frequent. Nervousness is charac- 

 teristic of all horses, while if the existence of anxiety is denied the 

 lower creation, one only has to witness what occurs when their 

 young are taken from them. We have seen that the brain is rela- 

 tively lowly organised in the inferior animals, while the cord is 

 relatively highly organised. Brain trouble is consequently not so 

 frequent as disorders of the cord, but these are known so imper- 

 fectly that no useful purpose would be served by attempting their 

 discussion. 



