122 EDWARD F, MALONE 



The discovery of two different types of cells in the sympa- 

 thetic vagus nucleus was not accidental; I was led to look for 

 this difference on the following grounds. In the first place, I 

 had recently shown that all cells concerned in transmitting effer- 

 ent impulses to striated muscle possess a fundamental similarity 

 of structure, whether the axone of the cell be in direct relation 

 to the muscle or whether the cell act on the muscle through the 

 mediation of one or more efferent neurones. This observation 

 naturally strengthened my belief in the significance of the rela- 

 tion of cell character to cell function. In the second place, I 

 had observed the striking difference between the cells supplying 

 striated and those supplying smooth muscle. Since in a recent 

 paper Molhant had shown that all fibers of the vagus supplying 

 heart and smooth muscle arise from the sympathetic vagus 

 nucleus, I concluded that in cells having such diverse functions 

 there must exist a fundamental difference in histological charac- 

 ter. As was anticipated, two different types of cells were found; 

 the evidence in favor of ascribing to the cells of one type the 

 innervation of heart muscle, and on the other hand, to cells of 

 the other type the innervation of smooth muscle, will be con- 

 sidered later. 



The material available consisted of two complete series. The 

 first was a series of the brain of a lemur, while the second was of 

 the brain of macacus rhesus. Both brains were fixed in 95 per 

 cent alcohol, and after the usual treatment with absolute and 

 chloroform, were imbedded in paraffin. Serial sections were 

 stained in a 1 per cent aqueous solution of toluidin blue (Griibler), 

 differentiated in 95 per cent alcohol, dehydrated in absolute, 

 cleared in xylol, and mounted in Canada balsam. Series of brains 

 of other forms will have to be prepared and studied before I 

 feel justified in committing myself upon many points, and the 

 present article has therefore been limited, especially as to the 

 exact location and distribution of the different types of cells. 



The efferent fibers of the vagus nerve arise from two distinct 

 columns of cells. From the nucleus ambiguous arise the fibers 

 which supply striated muscle, while from the so-called dorsal 

 motor nucleus arise fibers which innervate heart muscle and 



