366 P. R. BILLINGSLEY AND S. W. RANSON 
path without giving off collaterals, a certain unknown percentage 
of them may possibly give off such collaterals. Since in our 
enumeration the fibers were counted just below the superior cer- 
vical ganglion the possibility that collaterals had been given off 
from some of these fibers at a lower level makes it not unlikely 
that the ratio of postganglionic to preganglionic neurones as 
determined in this paper is somewhat too low. 
SUMMARY 
Careful enumerations show that the superior cervical ganglion 
in the cat contains some 123,603 nerve cells and that the truncus 
sympathicus near the ganglion contains 3851 ascending pre- 
ganglionic myelinated fibers. The ratio between these fibers 
and the cells in the ganglion is 1 to 32. We believe that this 
ratio may be taken as expressing the approximate numerical 
relations between preganglionic and postganglionic elements 
for this ganglion. 
LITERATURE CITED 
Huser, G. Cart 1899 A contribution on the minute anatomy of the sym- 
pathetic ganglia of the different classes of vertebrates. Jour. Morph., 
vol. 16, pp. 27-90. 
Lanauey, J. N. 1892 On the origin from the spinal cord of the cervical and 
upper thoracic sympathetic fibers with some observations on white 
and gray rami communicantes. Phil. Transact. Roy. Soc. Lond., vol. 
183, Series B, p. 85. 
1903 The autonomic nervous system. Brain, vol. 26, p. 1. 
Ranson, S. W. 1906 Retrograde degeneration in the spinal nerves. Jour. 
Comp. Neur., vol. 16. 
