733 
In the course of these experiments, having specially in view the 
posterior longitudinal bundle and the Drrrnrs-complex, it appeared, 
that — at least for this system -— in relation to the disturbances observed 
during life one has to distinguish three different modes of traumati- 
cal lesion. 1. Total destruction of a cell-complex or bundle through 
the instrument used, with renders the structure irrecognizable, the 
tissue being totally or partly replaced by a moderate bloodextravasation. 
After this lesion invariably a total degeneration of all fibres arising 
from or passing this region occurs, if care be taken, that the specimen 
does not stay too long in Mourrers fluid. 2. Malacy of a region 
which causes in a selective way some systems of fibres to degenerate, 
whereas other systems apparently continue to be nourished and pro- 
bably also continue their function *). In view of KonnNsramM’s and 
Monakow’s findings it appears, as if the great, the middle-sized and 
the small cells of the Derrers-complex suffered unequally in their 
nourishment, if this structure happens to be involved in such a 
malacy. 3. If an extensive haemorrhage occurs and exerts compression, 
irritative symptoms appear of the same order ®) but more vehement, 
than those which are caused hy the dissolution of the medullary sheath 
and the moderate irritation, caused by this process. 
In judging about the physiological consequences, it must be kept 
in view, that every lesion after 1. and 3. is always found sur- 
rounded by a zone of malacy, and finally, that in a case with volu- 
minous haemorrhage in the brainstem the general brain-compression 
may mask completely the forced movements. . 
It is quite natural, that in different experiments the vestibulary 
P. L. B.-complex was repeatedly wounded on more than one loca- 
lity. Regarding the physiological effect it appeared, that a lesion of 
the N. vestibularis itself predominates above a lesion of its nucleus, 
and the latter again dominates above a lesion of the posterior longi- 
tudinal bundle. 
') So I found in 102, that the left longitudinal bundle passed such a malacy in 
the upper pontine region. The descending commissuro-medullary bundle was degene- 
rated and the animal had shown the physiological consequence of this degeneration; 
the ascending vestibulary-P. L. B. fibres were not degenerated. 
2) It is interesting to note, regarding the nucleus of the posteror commissure, 
tbat after E. Sacus’ experiments (Brain 1909, p. 180) direct electrical stimulation 
of this region causes conjugated deviation to the opposite side; which evidently 
corresponds to the effect, described in this paper, of the stimulation exerted on the 
nucleus of the posterior commissure by the degeneration of a number of ascend- 
ing fibres, running in the P, L. B. and ultimately arriving in this nucleus. The 
circus movement in many of my experiments was accompanied by conjugated 
deviation to the same side; both phenomena evidently being narrowly related. 
