TRYPANOSOMIASIS EXPEDITION TO SENEGAMBIA 
39 
from Horse I were, from the commencement of the infection, precisely similar in appear- 
ance to those occuring in that horse. Stumpy forms were at first more frequently 
met with in these rats, but as the parasites increased in the blood more long and 
dividing forms were seen. About a week before death amoeboid forms were also 
seen in the peripheral blood of these rats. Chromatic stippling was only 
occasionally seen in the parasites. 
The parasites which first appear in the blood of rats and mice inoculated from 
horses in an early stage of the disease are morphologically identical with the small 
forms seen in the horse (Plate I, Fig. 6). Many of these small forms are seen in 
all stages of longitudinal division (Plate I, Fig. 8). As the disease in the experi- 
mental animal progressed, long and stumpy forms were seen, and the smaller tadpole- 
shaped parasites tended to disappear. Rounded forms can be seen in the blood of 
many rats in a late stage of the disease. 
Still another variety of parasite has been seen occasionally in the peripheral 
blood of rats inoculated with the horse trypanosome and also in the blood of horses 
either one, two, or three days before death. 
In shape, like either the stumpy or long form, it differs from them by its very 
feebly staining protoplasm. This type corresponds very closely to the ' hyaline ' 
forms described by Plimmer and Bradford. 
