210 Journal of Comparative Neurology. 



shape, as may be seen in the figure. The ultimate endings of 

 the spindle-nerves in the muscle-spindles of the snake seen by 

 us, do not all present the same configuration ; yet the type is 

 essentially as above described. Sihler, as he himself has stated, 

 was not able to make out clearly the ultimate ending of the 

 nerves in the muscle-spindle of the snake ; in some few in- 

 stances, however, he was able to make the following observa- 

 tion : " Es giebt namlich auch Spindeln, wo die Querstreifung 

 des Muskels im Spindelmantel nicht verloren geht, wo bloss im 

 inneren des Muskels ein Streifen der dunkeln Substanz sich 

 findet. In solchen — freilich seltenen — Spindeln konnte ich 

 mehrere feine Nervenzweige von myelinhaltigen Nerven ab- 

 gehen sehen, und glaube ich kaum, dass optische Schnitte der 

 Henle schen Scheiden mich getauscht haben. " The nerve fibers 

 mentioned by Sihler may be the branches of the intrafusal, non- 

 medullated fibers above referred to, his stain not bringing to 

 view the ultimate endings. Other writers, who have given ob- 

 servations on the simple muscle-spindle — designated by Kersch- 

 ner as '• Kiihnische Organe " — (Kiihne, Bremer, Mays, Trinch- 

 ese and Cattaneo) have given no definite observations on the 

 ending of the spindle-nerves. 



Tortoise. The preparations of muscle-spindles made from 

 these reptiles, were obtained from the vasti muscles. A one per 

 cent, solution of methylene blue in normal salt was injected 

 into the abdominal aorta, and the muscle exposed about an 

 hour after the injection, cut into strips and placed on a slide 

 and examined from time to time, until the endings of the spin- 

 dle-nerves seemed stained. The tissues were either fixed in 

 ammonium molybdate and sectioned, the sections being further 

 stained in alum cochineal, or were fixed in ammonium picrate 

 and teased, cleared and mounted in glycerine-picrate. The 

 general structure of the spindles is very much as previously 

 described. The intrafusal muscle fibers, from two to eight in 

 number, are surrounded by an axial sheath, periaxial lymph 

 space and capsule, each intrafusal fiber being further surrounded 

 by its own connective tissue sheath, which is partly fused to the 

 axial sheath, or connected with it by bands or septa of fibrous 



