Three cases of Sleeping Sickness and one case of Trypanosomiasis dying in Liverpool have been histologically examined. The central nervous system of the sleeping sickness cases showed the changes described by different observers, Mott, Low, the Portuguese Commission and others. One case exhibited an intra-pial hæmorrhage of the spinal cord, extending from the sixth cervical segment to the third thoracic segment, about 7 mm. board. In another case there Occurred four larger hæmorrhages, besides numerous smaller ones, in the grey substance, chiefly affecting the posterior cornua and the thoracic part of the cord. Microscopically the brain and spinal cord showed small celled infiltration around the vessels, consisting for the most part of lymphocytes, Some plasma cells and phagocytes, between which were a Varying number of red cells in different stages of disintegration. The intima of the vessels showed a proliferation of the endothelial cells. Red and white blood corpuscles were often seen in the vessels walls. Here and there the blood vessels were filled with White blood corpuscles resembling a thrombosis. It is most striking that the small celled infiltration is much more marked in the grey substance of the nervous centres, especially in the large grey ganglia, than in the peripheral parts. Very numerous capillary hæmorrhages of different sizes were present in these situations. Infilteration around the vessels of the membranes and in the tissues of the pia and arachnoidea was observed. Around the infiltrated vessels degeneration of the fibres and an excess of glia cells were seen, sometimes exhibiting the picture of red softening. The ganglia cells showed an irregularly distributed degeneration, central and Peripheral chromatolysis and also partial pyknosis.