138 DISEASES DUE TO PROTOZOA 



The cerebrospinal fluid is increased. The base of the brain is pale, 

 the dura mater sometimes adherent to the bone, the gyri of the brain 

 may be flattened. The pia arachnoid is thickened in places, some- 

 times adherent to the brain. 



The brain substance is sometimes firmer than usual, but may be soft 

 and edematous. 



There is usually congestion of the brain. The ventricular fluid is 

 increased. 



The findings of the cord are similar. Sometimes there are haemor- 

 rhages also. 



The Cauda equina may be surrounded by gelatinous tissue. 



Sometimes there is ascites and pericardial fluid in excess. 



The lungs may show pneumonic changes. 



MICROSCOPIC. 



Mott did not find it easy tc differentiate true trypanosome findings 

 from those due to terminal affections caused by diplococci, streptococci 

 and colon bacilli, but the following were generally agreed upon : — 



Cerebrospinal system. 



A round-celled infiltration surrounding the vessels of the pia 

 arachnoid of the brain and cord, best seen in the membranes where 

 there is excess of cerebrospinal fluid, and in the brain around the 

 vessels of the medulla, pons, cerebellum, and those entering the base. 



There is a growth in size, and then a proliferation of the neuroglia 

 elements. 



Round cells are found later in the meshes of this proliferated glia, 

 which are : — 



(i) Lymphocytes. 



(2) Plasma cells of JMarschalko, having a nucleus at one end of the 

 cell, probably derived from lymphocytes. 



(3) Morula cells of Mott, large, round or oval cells with an eccentric 

 blue nucleus, probably degenerate cells of IMarschalko. 



(4) Some mononuclear leucocytes. 



(5) A few polymorphonuclear leucocytes. 



The lymphocytes are probably produced by proliferation of endo- 

 thelial cells about the perivascular lymphatic space. 



The ependyma of the lateral ventricles may show proliferation and 

 dense fibrous formation. 



There is atrophy of the dendrons and diminution of the Nissl 

 bodies, and alteration of the nucleus, which becomes large, clear and 

 eccentric. The changes are more marked in the cerebral cortex and 

 medulla than in the cord. 



The cells of the posterior spinal ganglion show chromatolysis. 



