ON THE HISTOLOGY OF THE CRANIAL AUTONOMIC 
GANGLIA OF THE SHEEP 
F. W. CARPENTER 
From the Zoological Laboratory, University of Illinois, under the direction of 
Henry B. Ward, No. 19 
TEN FIGURES 
Both anatomical and experimental methods of investigation 
have established the fact that the autonomic nervous system of 
vertebrates consists, on its efferent side, of two sets of neurones. 
The first of these, the preganglionic neurones, have their cell- 
bodies in the central nervous axis, and send their neurites outward 
by way of the ventral roots of cerebro-spinal nerves to the auto- 
nomic ganglia. In the trunk region these preganglionic fibers 
pass from the spinal nerves in the white rami communicantes 
to the ganglia of the sympathetic trunks, or to ganglia more 
distally placed. In the cranial region, preganglionic fibers leayv- 
ing the brain by the third, seventh and ninth nerves end in the 
ciliary, sphenopalatine, otic, submaxillary and sublingual ganglia, 
which constitute the autonomic ganglia of the head. 
The efferent nervous impulses which thus reach outlying gan- 
glia of the body are carried onward to peripheral tissues (involun- 
tary muscle, glands) by the postganglionic neurones. These are 
multipolar nervous elements, the cell-bodies of which lie in the 
autonomic ganglia. ‘Their distally directed neurites are in mam- 
mals, as a rule, nearly or quite devoid of myelin. 
By employing modern methods of neurological technique, such 
as those introduced by Golgi, Ehrlich and Cajal, it has been 
possible to demonstrate very satisfactorily the nature of the end- 
ings of the preganglionic fibers in the autonomic ganglia of the 
trunk region. These ganglia, according to the terminology pro- 
posed by Langley, belong to the sympathetic and sacral subdivi- 
447 
