282 Dr. Waller's Microscopic Examitiatiofi of the 



followed from their exit from the cranium and spine, until their 

 immersion into the tongue. After removing the mucous mem- 

 brane of the surface, we may easily trace, by means of the scal- 

 pel, with the naked eye the distribution of the principal trunks 

 nearly on the median line, giving off' numerous branches, and 

 finally proceeding much diminished in size nearly to the two 

 tubercles on each side. By immersion in alcohol or naphtha, 

 the nerves become whiter and still more distinct. The cervical 

 and cranial pairs then appear unconnected with each other 

 during their course; and Burdach is of opinion that no com- 

 munication is ever found to exist between these two pairs of 

 nerves, the first of which he terms the hypoglossus, and re- 

 gards as a pure motor nerve, and the other the glossopha- 

 ryngeal, which he looks upon as destined entirely to the mu- 

 cous membrane. 



My observations do not allow me to adopt this opinion 

 entirely, as I have seen with the naked eye and with the mi- 

 croscope numerous communications, almost ofa plexiform na- 

 ture, between these trunks at their entrance into the tongue. 

 I have therefore preferred to adopt the terms of cranial and 

 cervical pairs, which are independent of all theoretical ideas. 

 I consider the cervical as destined principally to the muscles, 

 and the cranial to the mucous membrane, where I shall pre- 

 sently describe them. When the muscles have been divested 

 of their papillary membrane, we are able to trace without diffi- 

 culty, the various ramifications and nervous loops among the 

 muscular fibres, where we see the nervous fibres nearly reduced 

 to a single tubule, forming numerous loops or meshes, running 

 either across or parallel to the striated muscular fibres. These 

 nervous trunks and fibres appear all to be derived from the 

 cervical nerve. Instead of completely removing the mucous 

 membrane, which often renders the examination difiicult, 

 from the blood which issues from the divided vessel, we may 

 remove a small portion of the membrane, which when done by 

 tearing it away, will frequently be unattended by loss of blood. 

 The surface thus exposed is usually found covered with a dense 

 plexus of nervous I'amifications, which appears to belong to the 

 muscular system. Sometimes in spreading out the tongue 

 we separate from it a kind of investing sac of cellular tissue, 

 nearly as transparent as glass. The microscope detects in* 

 this numerous muscular fibres, generally accompanied with 

 nerves and capillary vessels. The nervous fibres are usually 

 accompanied with a satellite capillary vessel closely joined to 

 them. To complete this brief account of the microscopic 

 muscular appearances, I will mention that the circulation may 

 be easily observed in these muscular capillaries, and that a 



