132 THE SALAMANDER 



4. Spinal cord. 



The medulla oblongata merges imperceptibly into the spinal cord^ 

 which passes right along the body to the tip of the tail, passing 

 through the neural canal of the vertebral column. It remains fairly 

 uniform in diameter as far as the sacral region, where a slight 

 swelling is noticeable in that part of the cord giving off the sacral 

 nerves. From this point to the tip of the tail the cord gradually 

 diminishes in size. 



Segmental nerves are given off corresponding with each vertebra, 

 and arise, with the exception of the first, by both dorsal and ventral 

 roots. The details of their course and distribution will be considered 

 in a subsequent section. 



In transverse section the spinal cord is eccentrically placed in 

 the neural canal towards the ventral side. It is approximately oval 

 in shape with a small central canal lined by epithelium, around 

 which is grouped the grey matter. The white matter lies towards 

 the periphery of the cord. There is a well-marked V-shaped groove 

 dorsally — the dorsal fissure or sulcus longitudinalis dorsalis. It is 

 shallow, however, and does not extend far in a ventral direction. 

 The ventral fissure^ or sulcus longitudinalis ventralis^ is much deeper 

 and reaches nearly to the central canal. It is particularly noteworthy 

 that the A. spinalis ventralis lies well within the ventral fissure, thus 

 tending to open it still farther. 



CRANIAL NERVES (PI. X) 



I. Historical. 



The earlier workers, e.g. Funk and Rusconi, have very little to 

 say with regard to the cranial nerves. In 1 840 Vogt gave an account 

 of the vagus nerve and hypoglossal which, however, is not very accu- 

 rate. Three years later Fischer ( 1 843) published an adequate descrip- 

 tion of all the cranial nerves except the IVth, which he failed to find. 

 He did not observe the branch from the oculomotorius to the M. 

 rectus superior — in fact he states definitely that it does not exist. He 

 also omits any description of the branchial branches of the Xth nerve. 

 Apart from these omissions he is surprisingly accurate, and is fre- 

 quently more correct than some of his successors. In the same year 

 Bendz (1843) published an account of nerves IX, X, and hypo- 

 glossus, but his work contains a number of errors and is not so 

 accurate as that of Fischer. 



In 1 89 1 von Plessen and Rabinowicz gave a description of the 



