102 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



extends to the nerve cell but begins a little distance 

 from it. It consists of fat and neurokeratin. The 

 latter, on burning, gives an odor of burnt bone. It 



Ranvier's node. 



Axial cord. 



Medullary sheath. 



Nucleus. 



Ranvier's node. 



Fig. 70. Medullated nerve fibers from a rabbit, varying in thick- 

 ness and showing internodal segments of different lengths. In the fiber 

 aUhe left the neurilemma has become slightly separated from the under- 

 lying structures in the region of the nucleus (Bohm and Davidoff). 



is this sheath that gives the white color to nerves and 

 the white matter of the brain. In osmic acid prep- 

 arations, oblique fissures appear in the medullary 

 sheath dividing it into sections known as Schmidt- 



