28 NERVOUS SYSTEM. 



tissue, interlacing in every direction ; but it contains also 

 numerous elastic fibres, adipose tissue, a net-work of arteries 

 and veins, and " nervi-nervorum" which are to these struct- 

 ures what the vasa-vasorum are to the vessels. The adipose 

 tissue is constant, being found even in extremely emaciated 

 persons. 1 



The vascular supply to most of the nerves is rather scan- 

 ty. The arteries break up into a plexus of very fine capil- 

 laries, arranged in oblong, longitudinal meshes surrounding 

 the fasciculi of fibres ; but they never penetrate the peri- 

 nerve and come in contact with the ultimate nervous ele- 

 ments. The veins are rather more voluminous, and follow 

 the arrangement of the arteries. It is not certain that the 

 nerves in their course contain lymphatics ; at least these ves- 

 sels have never been demonstrated in their substance. 



Branching and Course of the Nerves. The ultimate 

 nerve-fibres in the course of the nerves have no connection 

 with each other by branching or inosculation. A bundle of 

 fibres frequently sends branches to other nerves and receives 

 branches in the same way ; but this is simply the passage of 

 fibres from one sheath to another ; the ultimate fibres them- 

 selves maintaining throughout their course their integrity 

 and individual physiological properties. This view with 

 regard to the course of the fibres in the nerves is held by 

 nearly all anatomists. Some, however, assert that branch- 

 ing and inosculation of individual fibres sometimes occur in 

 the course of nerves ; a but this statement is not sufficiently 

 confirmed, in view of the very general opinion to the con- 

 trary. It has long been known, since the researches of Savi, 

 Robin, "Wagner, and others, that in the electric organs of 

 certain fishes, the large nerve-fibres break up into numerous 



1 SAPPEY, Recherches sur la structure de T envelope fibreuse des nerfs. Journal 

 de Panatomie, Paris, 1868, tome v., p. 47, et seq. 



8 SCHDLTZE, in STRICKER, Handbuch der Lehre von den Geweben, Leipzig, 1 868, 

 S. 119. 



