206 DISEASES OF THE BRAIN. 



occur which is usually designated as white (hydrocephalic) softening. 

 Small capillary extravasations are often found in the vicinity of tu 

 mors, abscesses, or along with collateral oedema. 



The form of partial anaemia of the brain, induced by diseases en- 

 croaching on the cranial cavity, is the variety most readily recognized on 

 autopsy. The pressure exercised by large extravasations of blood and 

 extensive tumors is so great that, not only the capillaries and finer 

 arteries and veins of the brain-substance, but also the larger vessels of 

 the meninges, that are subjected to this pressure, are compressed and 

 bloodless. If the disease be in one of the large hemispheres, this be- 

 comes more prominent after the skull is opened, so that on the affect- 

 ed side the dura mater appears more tense than on the other side. If 

 the dura mater be opened and turned back, we see that the surface of 

 the diseased hemisphere is remarkably even, that there is very little, 

 if any, liquid in the subarachnoid space, that the convolutions are 

 lower, the furrows shallower, and that the vessels of the pia mater are 

 not so full or are quite empty. Lastly, also, on section through the 

 brain, we cannot fail to see a decided difference in the two hemi- 

 spheres in regard to their color and as to the number of blood-points 

 appearing on the cut surface. In those cases where the falx and 

 tentorium have to a certain extent given way to the pressure propa- 

 gated to them, the falx showing a convexity toward the healthy side, 

 the tentorium being flattened, or, when the disease is in the posterior 

 cranial fossa, being more strongly curved, it is certain that the capil- 

 laries are compressed in those portions of the brain where the disease 

 encroaching on the space is located. But at the same time it is found 

 that the anaemia does not remain limited to the part first affected, but 

 extends to other parts subsequently, although to a less extent. 



SYMPTOMS AND COURSE. Anaemia limited to one portion of the 

 brain induces the so-called " herdsymptome " (page 194) ; if the anae- 

 mia be absolute,, these consist of symptoms due to complete loss of 

 excitability in the anaemic portions of the brain ; if it be not absolute, 

 there may even be signs of increased excitability, or morbid excite- 

 ment of the affected portion of the brain. In the vicinity of the 

 anaemia, often even through the entire brain, the circulation is dis- 

 turbed, so that, besides the direct symptoms of partial anaemia, we 

 may have those of more or less extensive secondary disturbances of 

 circulation. However, neither the " herdsymptome," nor the symptoms 

 of secondary disturbance of the circulation in the brain, nor a combina- 

 tion of the two, are pathognomonic of partial anaemia of the brain ; 

 on the contrary, we must distinctly state that each of these also occurs 

 in many other diseases of the brain. Not unfrequently, we can recog- 

 nize one or other form of partial anaemia of the brain, and exclude 



