346 Sheath Colls and Axone Sheaths in the Central Xervous System 



parallel with the contour of the liber. At least after the manipulation 

 in making the preparations, lines of adjacent lamellas often appear col- 

 lapsed upon each other, giving a resemblance of heavier lines running 

 obliquely in the sheath. Often this collapse may be so great as to give 

 openings in the framework, and sometimes, especially nearer the center 

 of my sections of the cord, where fixation is perhaps less perfect, almost 

 the whole framework may appear clotted against the axone or massed, 

 axone and all, at one side of the section of the fiber. A partial collapse 

 of this kind often occurs near the periphery also and gives rise to the 



Fig. 7. Small areas from the outer portion of a transverse and of a 

 longitudinal section of the spinal cord of an adult hog. Benda neuroglia 

 method, a ^ axone; aZ = axolemma; p = peripheral membrane; n = neuro- 

 glia nucleus; nf ^ neuroglia fibers; sc = seal-ring cell as seen in adult; d=: 

 sheath with collapsed framework. Detail of figure may be better observed 

 with hand lens, x 550. 



appearance indicated in fiber d, Fig. 7. Again, in the less collapsed 

 condition, one of the lines of collapse may appear in the longitudinal 

 section to run slantingly from the axone to the periphery of the fiber 

 (c. Fig. 7) suggesting one of the Schmidt-Lantermann clefts of the 

 usual osmic preparations of peripheral fibers. 



The framework of the medullary sheaths of the peripheral nerve fibers 

 appears not only somewhat heavier than that of the fibers in the spinal 

 cord, but also its arrangement is more varied and generally more com- 

 plex. The form of the reticulated framework may be said to consist of 



