702 



TBE NERVES. 



be, there is never any fusion of tlie nervous ramuscules, but simple aggrega- 

 tion of their fibres, which always preserve their independence, characters, 

 and special properties. These anastomoses, then, differ essentially from 

 those of arteries, and never permit two trunks to mutually supplement each 

 other when the course of one is interrupted. 



The nerves destined to the organs of vegetative life, and which arise 

 from the two subspinal chains in whose formation nearly every pair cf 

 nerves concui-s, comport themselves in their distribution in a slightly 

 different manner. They are enlaced around arteries, forming on these 

 vessels very complicated plexiform networks, and yet the fibres composing 

 them are as absolutely independent as in the anastomoses above described. 



Termination of the Nebves. — This point should be examined separately 

 in the case of the motor and the sensitive nerves : that is, in the muscles 

 and the integumentary membranes. The distinction, however, is not quiteso 

 absolute as this, for the muscles always receive some sensitive tubes with 

 their motor filaments. 



In entering the muscles the motor nerves divide their branches, still 

 appearing as double-contoured tubes. It was at one time believed that these 

 fibres formed loops ("Valentin) in the interior of the muscle, and returned 

 to their starting point. This opinion has become obsolete since the 

 ultimate termination of the nerves has been studied by Eouget, Krause, 



Fig. 334. 



?^i#ffffiP^€^'^€:' r/' 



iruSCULAE FIBRES, WITH TERMINATION OP MOTOR NERVE ; FROM THE 

 GASTROCNEMIUS OF THE EANA ESOOLENTA. 



a, Terminal pencil of a dark -bordered nerve-fibre ; 6, Intramuscular naked axis- 

 cylinder ; c. Nucleus of the neurilemma ; t?, Clavate extremities of the nerve ; e. 

 Spaces cf the muscle-nuclei ; /, Terminal knob of nerve, with central fibres and 

 vesicular dilatations of the nerve 



Kiihne. Kolliker, Engelmann, Conheim (Beale), and others. What is known 

 of this subject is as follows : — The voluminous, double-contoured nerve-tubes 

 which, more or less, cross the direction of the muscular fibres, soon divide 

 and form pale tubes on whose track are disseminated the nuclei. These 

 tubes contain an axis-cylinder and a medullary layer. They pass on to a 

 muscular fibre in the following manner : the nucleated sheath of the nerve- 

 tube spreads, and is confounded vpith the sarcolemma ; the medulla suddenly 

 stops, and the axis-cylinder expands to form a minute granular mass named 

 the terminal motor-pJate. Is this plate situated without or within the 

 sarcolemma ? This question is differently answered by histologists ; but, 



