1886.] Fhysiology. 305 
tory movements. Microscopic study of this region convinced 
him that the spot whose destruction had.this effect was a bundle 
of nerve fibers lying outside of the nucleus of the spinal accessory 
nerve and below the nucleus of the posterior pyramid. This 
result was of course very unsatisfactory. According to the pres- 
ent conceptions of physiologists nerve centers must always con- 
sist of nerve cells, and it is not conceivable that automatic stimuli 
can arise in nerve fibers. ‘If investigations had rested here this 
collection of fibers could only be looked upon as the efferent 
fibers from a center whose location had not yet been determined. 
Other physiologists have denied the existence of a respiratory 
center in the medulla, altogether holding that the centers govern- 
ing the respiratory movements are situated in the spinal cord. 
While others have described respiratory centers in the floor of the 
third ventricle, or in the corpora quadrigemina in the gray matter 
surrounding the aqueduct of Sylvius. Two interesting commu- 
nications on this subject. have appeared recently in the Central- 
" blatt f. Med. Wiss., Nos. 27 and 34, 1885. Unfortunately these 
Investigations have given different results, so that we are still left 
in doubt as to the location of the medullary center, though it looks 
as if the problem was very near its final solution. The first com- 
munication, No. 27, is by Mislawsky. He states that Gierke’s 
bundles have nothing to do with the respiratory movements. 
fourth ventricle, Destruction of this centre on both sides com- 
pletely stops the respiratory movements, while injury to one side 
attects the respiratory movements of that side alone. The efferent — 
fibers rom this center to the spinal origin of the nerves of the 
respiratory muscles Jie‘ outside of Gierke’s bundle. In No. 347 
-of the Centralblatt, Gierke replies to Mislawsky’s criticism. He 
States positively that the group of cells described by Mislaw- — 
‘Sky as the respiratory center does not exist; that the locality 
‘assigned to it, is occupied entirely by the reticular formation, 
and it is the scattered cells of this formation which Mislaw- 
“Sky -has mistaken for a definite nerve center. The disposition — 
irregular in different mammalia, and in no case was there any — 
‘ction of these cells that could be differentiated from the 
“Femaining cells of the formation. D 
. Gierke states that his latest investigations have convinced him — 
that the bundle of fibers previously described by him as the res- _ 
‘Prratory center contains in its whole extent a number of nerve — 
