218 THE NERVOUS SYSTEM. 



nective-tissue sheath, called the epineurium. The separate 

 funiculi are surrounded by similar fibrous sheaths, the 

 perineuriwn, continuous with the epineurium. Within the 

 funiculi is a delicate connective tissue, the endoneurium, pene- 

 trating among the individual nerve-fibres. 



The larger blood and lymphatic vessels are situated in the 

 perineurium and send capillaries into the endoneurium. In 

 the small terminal nerves the epineurial covering consists of 

 a layer of flattened connective-tissue or endothelioid cells, 

 called the " sheath of Henle." 



Nerve-terminals. 



The axis-cylinders of nerve-fibres at their distal terminations 

 lose their coverings and divide into fine terminal fibrils, or 

 " teleneurites." Some of these terminals are situated in the 

 gray matter of the nerve-centres, and are distributed in a 

 manner analogous to the dendrites ; others are distributed 

 throughout the tissues of the body (somatic terminals), and 

 are often associated with special structures exhibiting great 

 diversity and specialization of function and form ; some of 

 them being highly developed and complex organs, such as the 

 eye and ear. 



From a functional standpoint these somatic terminals can 

 be divided into two classes, afferent and efferent. 



The afferent nerve-terminals have sensory functions and 

 initiate nerve-impulses which travel along the fibres to the 

 nerve-cells. 



The efferent terminals receive impulses (motor, secretory, 

 trophic, etc.) from the nerve-cells and impart them to the 

 organs with which they are associated. 



In general, the function of the somatic terminals is con- 

 nected with the transformation of other forms of energy into 

 the particular mode of molecular energy which constitutes 

 nervous force ; and with the retransformation of the latter into 

 ordinary modes of motion. 



Classes of nerve-terminals: Only the nerve-endings found 

 in man are here considered ; other terminals of similar gen- 

 eral type occur in other animals. 



The first division of teleneurites is into those situated in 



