424 



THE CENTRAL NERVOUS SYSTEM. 



The circulation of the hypophysis must be regarded as sinusoidal, 

 In the glandular portion of the hypophysis of the dog, Berkley (94) 

 found small varicose nerve-fibers belonging to the sympathetic sys- 

 tem. From the larger bundles, which follow the blood-vessels, are 

 given off single fibers, or small bundles of such, which end on the 

 glandular elements in numerous small nodules. 



F. GANGLIA. 



In the course of peripheral nerves are found numerous larger and 

 smaller groups of nerve-cells, known as ganglia. The neurones of 

 these ganglia are in intimate relation with the neurones of the cen- 



Fig. 338. Longitudinal section of spinal ganglion of cat. 



tral nervous system, and may, therefore, be discussed with the lat- 

 ter. According to the structure and function of their neurones, the 

 ganglia are divided into two groups (i) spinal or sensory ganglia 

 and (2) sympathetic ganglia. 



The spinal ganglia are situated on the posterior roots of the 

 spinal nerves. Certain cranial ganglia namely, the Gasserian, 

 geniculate, and auditory ganglia, the jugular and petrosal gan- 

 glia of the glossopharyngeal nerves, and the root and trunk ganglia 

 of the vagi are classed with the spinal ganglia, since they present 

 the same structure. The spinal and sensory cranial ganglia are 

 surrounded by firm connective-tissue capsules, continuous with the 

 perineural sheaths of the incoming and outgoing nerve-roots. From 



