TRYPANOSOMES, TRYPANOSOMIASIS, AND SLEEPING SICKNESS 87 
giant cells. In some glands the lymphoid tissue was reduced to smaller or broader 
bands, between which were lightly stained strips of finely reticulated connective tissue 
having in its meshes a varying number of blood cells and large hyaline cells 
packed with pigment and very numerous free pigment granules. 
The long-bone marrow sometimes presented the appearance of red marrow. 
Microscopically it occasionally showed slight gelatinous degeneration. 
In animals having large numbers of trypanosomes present in their peripheral 
blood at the time of death trypanosomes were easily detected in the sections of the 
organs (Fig. 10). 
They were found both singly and in groups in the lumen of the vessels 
along with numerous leucocytes. Oidy in the spleen, however, were they found 
outside the vessels among the tissue cells. For staining the trypanosomes we used a 
modification of Laveran's method, which we found to give the best results for tissue 
imbedded either in paraffin or celloidin. 
The section is stained in a mixture ot 
1 c.c. Borrel blue 
4 c.c. Eosin (1 in 1,000 solution) 
6 c.c. Distilled water. 
Stain for half-an-hour or a little longer. The section will now be ot a dark- 
blue colour. Wash for a short time in distilled water, and differentiate with orange 
tannin (Unna), wash again well in water till it appears purple-red in colour, then pass 
rapidly through absolute alcohol into xylol and mount in neutral Canada balsam. A 
very easy method of dehydrating is to use aniline oil. The sections after differentia- 
tion with orange tannin and washing with water are fixed upon the slide. The excess 
of water is removed by blotting paper, and pure clear aniline oil is added two or 
three times for a very short time. After removing the oil, the sections are passed 
through xylol and mounted in the balsam. Both methods by careful management 
give the same good results. The protoplasm of the trypanosome is stained orange, 
and the chromatin of a red-violet colour. 
The flageilum is unstained. Thin sections are needed to get good results. Thick 
sections stain blue throughout. 
GAMBIAN HORSE TRYPANOSOMIASIS 
For studying the lesions caused by T. dimorphon in the organs of experimental 
animals, microscopical examinations were made of monkeys, dogs, rabbits, guinea- 
pigs, and rats. 
Microscopically, the leptomeninges of brain and spinal cord were very highly 
congested in all the more chronic cases, showing dilated capillaries in a meshwork of 
large dark veins. Cross sections showed the same congestion, especially in the grey 
matter, in which were also a varying number of haemorrhages. The cerebro-spinal 
