544 



PRINCIPLES OF GENERAL PHYSIOLOGY 



strychnine does not reverse the inhibitory phase of this reflex, at all events in 

 any possible dose. 



Fio. 175. ACCESSORY (SYMPATHETIC) NERVE-ENDINOS IN VOLUNTARY MUSCLE. 



A, From intercostal muscle of young rabbit. Magnified 1,700 times. 



bl. Blood vessel, partially covered by the muscle fibre. 



af. Accessory nerve fibre, which is seen to be connected with the peri vascular (sympathetic) nerve plexus. 



This fibre ends in a special structure, independent of that of the motor fibre. 

 /, Motor fibre, with branch, ending in ordinary end-plate. 



(Boeke, 1911, Fig. 49.) 



B, From a section of thes uperior oblique muscle of the cat's eye. After section of the trochlearis nerve and degenera- 



tion of the motor fibres. 



in. Degenerated motor-nerve fibres with remains of end-plate. 

 /, Accessory fibres intact. The hypolemmal ending of one is seen in profile. 



(Boeke, 1913, Fig. 10, p. 353.) 



C, Knding of fine non-medullated fibres, aj, on muscle fibre of the rectus superior oculi of the cat. These endings 



he in a granular, nucleated protrusion of sarcoplasm. The nerve fibres themselves have nuclei here 



and there. 



bl, A blood vessel, upon which a fine branch of the accessorv fibre, af, is distributed. 

 Magnified 1,800 times. 

 Silver impregnation of sections from material fixed in formaldehyde ; sometimes treated with gold afterward-;. 



(Boeke, 1911, Fig. 53.) 



The neck reflexes were also found to follow definite laws, for which the original paper of 

 Magnus and De Kleijn must be consulted. By combination of the two factors, all the complex 

 phenomena of the decerebrate reflex tonus could be explained. 



The fact that the labyrinthine reflexes are only to be obtained by changes of 

 position in relation to gravity, and the fact that they are permanent as long as 



