Hardesty, spinal Nerves of the Frog. gj 



Biihle ('98) show that in the spinal gangHa of the frog there are 

 from two to five times as many cells in a spinal ganglion as 

 there are fibers in the dorsal root. Of this excess of cells 

 many are no doubt latent ganglion cells, others are of the Dog- 

 iel spinal ganglion cell of Type II, but still others may be mul- 

 tipolar cells. Multipolar cells have been observed in spinal 

 ganglia by Kolliker ('93), Disse ('93), Lenhossek ('94), Spirlas 

 ('96), Dogiel ('97) and Cajal and Oloriz ('98), and the possibili- 

 ty presented by Scheme IV is that some of these multipolar 

 cells are of the sympathetic type which have developed within 

 the spinal ganglion. Such a cell (b) is assumed to be under 

 the control of one of the medullated sympathetic fibers {c) 

 which have been observed to pass from the sympathetic system 

 to end in the spinal ganglia — an arrangement which would 

 give an excess of at least two fibers in the nerve trunk. 



Another barely possible arrangement might be noted : Al- 

 though histological evidence for the frog is lacking, certain ex- 

 perimental evidence brought forth chiefly by Steinach ('95) and 

 Horton-Smith ('97) seems to indicate that there are in the dorsal 

 root certain fibers of intra-spinal origin which when stimulated 

 produce disturbances in the domain of the sympathetic system. 

 This evidence might be interpreted to mean that some of these 

 fibers, instead of passing through the spinal ganglion, terminate 

 in the spinal ganglion and control some of the multipolar cells 

 there of presupposed sympathetic type. Such a fiber might 

 break up into a number of branches and thus control a 

 number of these cells each of which would send a process to 

 the periphery and thus an excess of fibers in the nerve trunk 

 would be produced. 



Against the probability that the multipolar spinal ganglion 

 cells play the role above assigned them, it must be stated that 

 Dogiel ('97) who has made a careful study of these cells in 

 mammals, in the maze of fibers present, was unable to follow 

 any of their processes outside the bounds of the ganglion. He 

 suggests that they are either cells of a sympathetic type or are 

 modifications of his spinal ganglion cells of type II. 



