THE NUMBER, SIZE AND AXIS-SHEATH RELATION 
OF THE LARGE MYELINATED FIBERS IN THE 
PERONEAL NERVE OF THE INBRED ALBINO RAT— 
UNDER NORMAL CONDITIONS, IN DISEASE AND 
AFTER STIMULATION 
M. J. GREENMAN 
The Wistar Institute of Anatomy and Biology 
In a study of regenerated peripheral myelinated nerve fibers 
and their controls (Greenman, 713) the question arose as to 
whether peripheral myelinated nerve fibers undergo changes in 
sectional area or changes in the axis-sheath relation during ex- 
cessive physical exertion or in diseased animals. 
Tashiro (13) reported that resting nerve fibers, in vertebrates 
and invertebrates, warm blooded and cold blooded animals, give 
off CO.; that nerve fibers increase their production of CO, about 
21% fold when stimulated by an electrical, chemical, thermal or 
mechanical stimulus. 
He concludes (1) that the nerve fiber has a metabolism and 
that this metabolism is modified by the state of excitation, (2) 
and that the increased CO, production accompanying stimula- 
tion can be used as a new criterion for protoplasmic excitability. 
The experiments here described were conducted for the pur- 
pose of measuring, if possible, any morphological changes which 
might take place in a nerve fiber by reason of some general patho- 
logical conditions or by reason of activity and also of obtaining 
some information as to the origin of the myelin, its significance or 
the influences which increase or diminish it. 
In these experiments the observations have been confined to 
the large myelinated nerve fibers of the right and left peroneal 
nerves of the inbred albino rat. 
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