1 68 Journal of Comparative Neurology. 



nerve fiber terminating in the spindle constitutes the investment. 



Cattaneo also mentions a collar or ring, surrounding one 

 extremity of the spindle, which, he thinks, may be due to the 

 action of the acids, or may consist of circular or spiral fibers 

 surrounding the spindle or may be regarded as the termination 

 of the capsule. 



He emphasizes the fact that the spindles vary with the age 

 of the animal, being smaller, less prominent and with more 

 numerous nuclei in the young than in the adult of the same 

 species ; also that they vary with the species, being smaller and 

 less distinct in the guinea pig than in the rabbit, while in the 

 dog, the spindles are still larger, approaching those of man, in 

 whom are found very large and complicated end-organs. 



The nervous structure he describes as follows : Generally 

 but one nerve fiber innervates the organ, rarely two ; oftener 

 one fiber divides and supplies two or more organs. This nerve 

 fiber generally divides before entering the spindle, loses its 

 sheath of Henle as it enters, which becomes continuous with 

 the investing capsule ; these meduUated fibers then divide and 

 redivide, always approaching the periphery of the spindle, 

 either suddenly or gradually becoming non-medullated. Finally 

 the pale fibers reach the periphery, where, by finer and closer 

 ramifications, they form numerous, circumscribed reticular net- 

 works, like small tufts, sometimes well isolated, sometimes 

 closely crowded together, which cease at some distance from 

 the periphery. "These networks " he says, " show from time 

 to time nodosities which may be due to the action of the arsenic 

 acid on the nerve termination." 



The blood supply of these organs comes from the neigh- 

 boring vessels, which send generally two, but sometimes only 

 one branch to supply the spindle. These run along on either 

 side of the spindle and send off side branches at intervals which 

 anastomose with those from the opposite side, thus forming a 

 long-meshed plexus somewhat resembling that of muscle. 



The author discusses at some length the relation of these 

 organs to other sensory corpuscles, such as neuromuscular 

 spindles, Pacinian corpuscles, corpuscles of Krause, etc., de- 



