128 THE NERVOUS SYSTEM. 
What is the appearance of and changes in cerebral softening ? 
The degenerated area may be pale or red, the color depending upon 
the fact whether much or little blood is present. Microscopically the 
softened tissue is usually more or less fluid containing fragments of 
nerve fibre, degenerated brain tissue, droplets of myelin, nerve cells, 
shreds of neuroglia tissue and bloodvessels. Evidences of fatty degen- 
eration are seen by the presence of fat-drops, cholesterin crystals and 
large and small cells infiltrated with fat. 
What derangements of circulation may be present in the brain, and 
what appearances do they give rise to ? 
The brain may be hyperzemic, and on section may show an increased 
number of bloodvessels. The brain matter may be reddish in color. 
On the other hand there may be an anzemic condition in which a sec- 
tion of brain shows a decreased number of bloodvessels, and may look 
pale, with the markings between gray and white matter indistinct. 
The brain tissue may be cedematous. 
What forms of hemorrhage may occur in the brain, and what 
changes are produced ? 
The hemorrhages may be small and punctate (capillary hemor- 
rhage), or there may be the formation of clots of blood called apoplec- 
tic foct. 
Microscopical examination of a brain which is the seat of a capillary 
hemorrhage may show a distension of the perivascular spaces due to 
an escape of blood, and the brain matter may be broken down. Ad- 
jacent brain tissue may be stained by the degeneration of the extrav- 
asated blood. The apoplectic foci or clots are made up of blood and 
broken-down brain matter. . 
What various forms of inflammation are seen in the brain ? 
A simple exudative inflammation or encephalitis, chronic interstitial 
encephalitis (sclerosis), tubercular and syphilitic inflammation. 
Dest the changes produced in the brain by exudative inflam- 
mation. 
Brain tissue in the neighborhood of hemorrhages and areas of 
thrombotic and embolic softening often becomes the seat of an exuda- 
tive inflammation with exudation of leucocytes and red-blood cells. 
There is a local hyperzemia and the brain tissue is broken down. If 
the degenerated area is red from the presence of red-blood cells it is 
called red inflammatory softening, and if yellow or yellowish white 
with few red-blood cells it is called yellow inflammatory softening. 
