Huber-DeWitt, Neiiro-teiidtnoiis End-organs. 191 



" mehr zusammenhangende Masse von Sehnensubstanz. " In 

 such regions, the tendon looks even more hke embryonic con- 

 nective tissue than in places where the fasciculi are smaller, stain 

 more deeply and possess more nuclei. Cattaneo has noted that 

 the neuro-tendinous end-organs vary in size and in the complex- 

 ity of the nerve ending with the different species of animals 

 studied, being larger in the rabbit than in the guinea pig and 

 larger than either in the dog, whose spindles approach in size 

 and complexity those found in man. That they also vary with 

 the age of the animal, Cattaneo mentions, being smaller and 

 less complex, the younger the animal, This fact we have ob- 

 served, especially with regard to the cat, having investigated the 

 end-organs in numerous young kittens, in which they were uni- 

 formly much shorter, the capsule thinner and the nerve ending 

 simpler than in the adult cat. 



Concerning the blood supply of these organs, we have noth- 

 ing to add to the observations of Cattaneo. 



Nerve Structure. — As Golgi stated, the nerve destined to 

 supply these organs can be readily distinguished from ordinary 

 motor nerves as it passes through the muscle, the fiber being 

 large, rarely branching and the internodal segments shorter 

 than those of the motor nerve, as it approaches its termination. 



Although in general, we agree with the writers quoted that 

 the neuro-tendinous end-organ is usually supplied by one nerve, 

 which divides at a variable distance from the organ, yet we 

 hardly think it so unusual for two or more independent nerves 

 to innervate one spindle as we are led to believe from the em- 

 phasis placed upon this fact by Cattaneo and others. The nerve 

 fibers, as said before, may divide first after entering the spindle, 

 or may divide at variable distances from the organ, into two or 

 more medullated fibers, which, as they enter the spindle, lose 

 their sheath of Henle, which becomes continuous with the cap- 

 sule of the spindle, but retain their medullary sheath for a time. 

 The nerve usually enters the end-organ near its center, more 

 rarely toward its muscular extremity. 



The nerves which innervate the neuro-tendinous end-organ 

 usually approach it from the muscular side, often turning 



