TRIFACIAL NERVE. 571 



mation in most experiments to lesion of the ganglion of Gasser and of the 

 sympathetic connections, which are very abundant at this point. These 

 sympathetic filaments are avoided when the section is made behind the gan- 

 glion. 



The explanation of the phenomena of disordered nutrition in the organs 

 of special sense, particularly the eye, following division of the fifth, is not 

 afforded by the section of this nerve alone ; for when the loss of sensibility 

 is complete after division of the nerve behind the Gasserian ganglion, these 

 results may not follow. They are not explained by deficiency in the lachry- 

 mal secretion, for they are not observed when both lachrymal glands have 

 been extirpated. They are not due to exposure of the eyeball, for they do 

 not follow section of the facial. They are not due simply to an enfee- 

 bled general condition, for in the experiment just detailed, the animal died 

 of inanition after section of the nerve, without any evidences of inflam- 

 mation. In view of the fact that section of the sympathetic filaments is 

 well known to modify nutrition of parts to which they are distributed, 

 producing congestion, increase in temperature and other phenomena, it is 

 rational to infer that the modifications in nutrition which follow section of 

 the fifth after it receives filaments from the sympathetic system, not occur- 

 ring when these sympathetic filaments escape division, are to be attributed to 

 lesion of the sympathetic and not to the division of the sensory nerve itself. 



A farther explanation is demanded for the inflammatory results which 

 follow division of the sympathetic filaments joining the fifth, inasmuch as 

 division of the sympathetic alone in the neck simply produces exaggeration 

 of the nutritive processes, as evidenced chiefly by local increase in the animal 

 temperature, and not the well-known phenomena of inflammation. 



It was remarked by Bernard that the " alterations in nutrition appear 

 more promptly in animals that are enfeebled." Section of the small root of 

 the fifth, which is unavoidable when the nerve is divided within the cranial 

 cavity, generally interferes so much with mastication as to influence seriously 

 the general nutrition ; and this might modify the nutritive processes in deli- 

 cate organs, like the eye, so as to induce those changes which are called 

 inflammatory. The following observation (W. H. Mason) has an important 

 bearing on this question : 



The fifth pair of nerves was divided in a cat in the ordinary way. By 

 feeding the animal carefully with milk and finely chopped meat, the nutri- 

 tion was maintained at a high standard, and no inflammation of the eye 

 occurred for about four weeks. The supply of food was then diminished to 

 about the quantity it would be able to take without any special care, when 

 the eye became inflamed, and perforation of the cornea and destruction of 

 the organ followed. The animal was kept for about five months ; at the end 

 of which time, sensation upon the affected s'ide, which had been gradually 

 improving, was completely restored. 



The following explains, in a measure at least, the consecutive inflamma- 

 tory effects of section of the fifth with its communicating sympathetic fila- 

 ments : By dividing the sympathetic, the eye and the mucous membranes of 



