TRYPANOSOMES, TRYPANOSOMIASIS, AND SLEEPING SICKNESS 73 
more pronounced were found in the medulla — small-celled infiltration around the 
vessels, with a dilated perivascular lymph space, filled with transudate sometimes 
containing lymphocytes. The vessels in the white matter were not so much altered 
as those in the grey. Haemorrhages were also present in far greater numbers in the 
grey matter though no pigment was seen. 
The pia and arachnoid of the spinal cord was the seat of a well-marked small- 
celled infiltration, the meshes in the connective tissue of the arachnoid being often 
altogether obliterated by it. It is worthy of note that m this region the walls of the 
larger vessels were very often normal, whilst the small ones showed marked changes. 
The spinal dura mater presented the same change as the cerebral. The 
congested vessels ran between the connective tissue, in places surrounded by a few 
lymphocytes, and here and there even small collections of lymphocytes. 
The inflammation continued along the vessels into the fissures and white 
substance of the cord. Both fissures were often indicated by a dark blue band, this 
appearance being produced by the accumulation of exudation cells alongside the 
vessels running into the fissures. The changes in the grey matter of the cord were 
also much more marked than elsewhere. The periphery of the cord was ver/ 
oedematous, and showed proliferation of the neuroglia. The grey matter was often 
intersected by a network of congested capillaries, which were surrounded by a thick 
sheath of cells (consisting of elements similar to those of the brain vessels). The 
congestion of the vessels was so great that the vascular supply of the core! was 
displayed in the sections almost like a diagram. The perivascular changes were 
irregularly distributed, now one, now another vessel showing them. Relatively, few 
white cells were found in their lumen, and but slight signs of endarteritis. The 
epithelium of the central canal was proliferated, as also the neuroglia adjacent to it. 
The most marked changes were found in sections of the spinal cord taken from 
the level of the sixth cervical down to the third dorsal segment. In the seventh 
cervical region, the artery of the left posterior horn was surrounded by a layer of 
lymphocytes, four to six deep, with a layer of red blood corpuscles of the same width, 
external to it again. At the base of the horn a haemorrhage destroyed its substance 
in half its width. In the grey commissure also an abnormal patch was seen, consisting 
of two large arteries with veins and a number of capillaries, all sheathed in 
infiltrated connective tissue. 
Fig. 8 represents a section of the cord taken two segments lower down. The 
artery of the posterior fissure is seen enclosed in small-celled infiltration in the inner 
third of its course. There is also a haemorrhage on both sides of it extending into 
the white substance of the cord, and destroying the adjacent medullated fibres, so 
that there are only a few bundles of fibres left, which appear in isolated groups in 
the haemorrhagic region. Other smaller haemorrhages are also seen in the posterior 
horns and in the grey commissure. 
K 
