925 



arising from the anterior part of the spinal cord, and passing through 

 the first intervertebral foramen, the author (following Burdach) 

 names the hypoglossal. Section of the glossopharyngeal nerves 

 does not cause any perceptible loss of motion or of common sensa- 

 tion, and this fact, together with its distribution to the fungiform 

 papillae, leads the author to consider this nerve as the nerve of 

 tasting. On the other hand, when the hypoglossal nerves are 

 divided, the tongue is no longer sensible to mechanical irritation, 

 and its motions are entirely abolished. Simultaneous division of 

 the right and left glossopharyngeal nerves is followed by the death 

 of the animal in a few days, and the same effect ensues after division 

 of both hypoglossals. This result, which takes place more speedily 

 in summer than in winter, the author is disposed to ascribe to a 

 disturbance of the mechanical process of respiration, in which, as is 

 well known, the muscles of the frog's mouth and tongue take a 

 large share. 



To ascertain the changes which take place in the nerve-fibres 

 after division of the trunks to which they belong, the operation was 

 confined to the nerve of one side only, and the fibres of the unin- 

 jured nerve of the other side served for comparison. These changes 

 ensue more speedily, and go on more rapidly in summer than in 

 winter, commencing usually in about five days. The pulp contained 

 in the tubular nerve-fibres, originally transparent, becomes turbid, 

 as if it underwent a sort of coagulation, and is soon converted into 

 very fine granules, partly aggregated into small clumps, and partly 

 scattered within the tubular membrane. These granules are at first 

 abundant, and render the nerve-fibre remarkably opaque ; but in pro- 

 cess of time they diminish in number, and, together with the inclosing 

 membrane, at length disappear, so that at last the finest ramifications 

 of the nerves which go to the papillae, or those going to the muscular 

 fibres of the tongue (according to the nerve operated on), are 

 altogether lost to view, in consequence of the destruction and eva- 

 nescence of their elementary fibres. The disorganization begins at 

 the extremities of the fibres, and gradually extends upwards in the 

 branches and trunk of the nerve. The other tissues of the tongue 

 remain unaltered. When the cut ends of the nerve are allowed to 

 reunite, the process of disorganization is arrested, and the nervous 

 fibres are restored to their natural condition. The author ascribes 

 the disorganization and final absorption of the nerve-fibres to an 

 arrestment of their nutrition caused by interruption of the nervous 

 current, and considers his experiments as affording most unequivocal 

 evidence of the dependence of the nutrition on the nervous power. 



February 28, 1850. 

 PETER MARK ROGET, IM.D., Vice-President, in the Chair. 

 The following papers were read : — 



1. "Sequel to a Paper on the reduction of the Thermometrical 



