522 
Die iibrige Literatur tiber Muskeldefekte siehe bei 
7. R. Bine, Uber angeborene Muskeldefekte. VIRcHow’s Archiv f. Patholog. 
Anatomie, Bd. 170, 1912 und 
8. B. ABROMEIT, Beitrag zur Kenntnis der kongenitalen Muskeldefekte, Monats- 
schrift für Psych. u. Neurologie, Bd. 25, S. 440 u. 530. 
Nachdruck verboten. 
The Structure of the Vagus Nerve of Man as Demonstrated by 
a Differential Axon Stain. 
By S. WALTER Ranson. 
With one Figure. 
From the Anatomical Laboratory of the Northwestern University 
Medical School. 
For many years it has been an easy matter to demonstrate 
medullated nerve fibers. For the study of these fibers a number of 
excellent differential stains have been developed, chief among which 
are osmic acid and WEIGERT’s hematoxylin. But until very recently 
we have not possessed a similar differential stain for axons. A Gonar 
preparation shows an occasional axon here and there but the picture 
is too fragmentary to be of much service. Methylene-blue used intra- 
vitam also has a very limited application. 
Because of these limitations of neurological technique investigators, 
following the line of least resistance, have confined their study of nerves 
and fiber tracts, to an examination of their medullated fiber content. 
Attention having been focused on the medullated fibers for so long, 
it was quite natural that we should have come to assume that they 
were the only nerve fibers present in the cerebrospinal nerves (the 
olfactory excepted) and in the fiber tracts of the central nervous 
systems. Because of these limitations of our technical methods it 
would have been impossible to have differentiated axons not covered 
with myelin from the connective tissue and neurologia by which 
they are enveloped. Only through the development of a technique, 
which gives a stain of the axons as sharply differential as is the osmic 
acid stain of the myelin sheaths, has it been possible to show that 
axons devoid of myelin sheaths are present in great numbers in many 
parts of the cerebrospinal nervous system where we had supposed 
only medullated fibers were to be found (Ranson ’11, ’13). 
