I 2 I 
Rhodesian district we have under review. Short and long forms were 
present in this animal, the classification of 200 being ‘ tadpole ’ lO per 
cent., ‘ stumpy ’ 70 per cent., and ‘ long ’ forms 20 per cent. The first- 
named measured between I0‘5 and 1475/^, the ‘stumpy’ from 15 to 
i8'25/u, and the ‘long’ forms between 18 and 27'25/U. In some of 
these latter, a flagellum measuring from 3 to 5/u. which appeared quite 
free of cytoplasm, was seen. The structure of these several forms 
was essentially the same as that of those already given. 
In sheep and goats only the ‘ tadpole ’ forms were seen. These 
measured from 975 to I4‘5/U in length and from i to i75/« in w'idth. 
In no particular could they be held to differ from those in bovine 
blood, and in the films examined only one form was seen which might 
possibly be regarded as ‘ stumpy.’ It has been noted that none of 
these animals died whilst under observation, and this may account 
for the non-detection of any but ‘ tadpole ’ forms. It is also to be 
remembered that in sheep. Case No. XXXIII, and goat. Case No. XL, 
the organism which appeared was of the ‘ tadpole ’ variety, whereas 
the guinea-pig from which they were inoculated had shown ‘ long ’ 
forms, and ‘ stumpy ’ ones were present at the time of inoculation. In 
none of our inoculated dogs were forms longer than 16/^ seen. Most 
were of the ‘ tadpole ’ variety, but forms corresponding to ‘ stumpy ’ 
were encountered towards the end of the disease. We reserve the 
description of the organisms encountered in the naturally infected 
animals till later. 
In rabbits, in the films made from our single case, only ‘ tadpole ’ 
forms were seen. 
Guinea-pigs are the most satisfactory animals for revealing the 
dimorphic variations of this trypanosome. It has been noted that the 
average period of duration of organisms was ten days. During the 
first four days, ‘ tadpole ’ forms are almost exclusively present, giving 
place between the fifth and eighth days to ‘ stumpy ’ and ‘ long ’ ; 
whilst at death, and on the two or three days previous, ‘ stumpy ’ forms 
predominate. 
The ' tadpole and ‘ stumpy ’ forms correspond to the descriptions 
given, while that of the ‘ long ’ form is based on its appearance in these 
animals. We do not hesitate to say that in many of these, 
particularly the so-called male forms, a flagellum whose length 
sometimes exceeded 10^ was seen free from cytoplasm. These forms 
