TRYPANOSOMES, TRYPANOSOMIASIS, AND SLEEPING SICKNESS 31 
susceptible animals. After two years and rive months it is still alive and apparently 
in good health. Its blood is still infective to rats and mice, but the amount necessary in 
order to secure an infection has had to be increased. Formerly a few drops of blood 
were required. At present 1 - o to 1*5 c.c. of pure blood is needed to infect a medium- 
sized rat ; rabbits require 3*5 c.c. of blood. The blood still preserves the characteristic 
agglutination of the corpuscles. Very occasionally a trypanosome has been found 
after long continued examination. The temperature has lost the markedly irregular 
type which characterises the disease. The animal has put on weight and has become 
accustomed to the change of climate. No symptoms of oedema, etc., have been noted. 
Blood counts : — April 8, 1905, reds, 7, 1 60,000 ; whites, 17,600; haemoglobin, ninety 
per cent. Its blood no longer causes any more agglutination than does normal horse 
serum ; the protective properties are nil. The urine is normal. 
From the above records it will be seen that observations on the disease are in 
accordance with the findings of Dutton and Todd and Laveran and Mesnil. The 
disease in horses can become chronic and the animal may live for some time, probably 
a cure will result in such a case as the above. From Goat 10 and Horse 6 cases it is 
evident that animals in which the disease is markedly chronic for some time, will 
hardly show any evidences of infection. The blood, in amounts of even i'o to 1-5 c.c, 
is non-infective, and when inoculated in larger amounts, 3-0 to 10 c.c, the incubation 
period is prolonged. 
It is not our intention to enter into a detailed description of the parasite as the 
morphological characteristics have been well pictured and described by Dutton and 
Todd, Laveran and Mesnil. The parasites have been examined in both fresh and 
stained specimens from the blood of all the species of animals used in the investigation. 
In no instance has the long form, described by Dutton and Todd and possessing a 
long thin body and a long flagellum, been seen ; in this we are in accord with Laveran 
and Mesnil. The long form is known to have been seen in the blood of animals, 
but it disappeared early in September, 1903, when the research work in Liverpool was 
begun. From a study of the films the forms described by Dutton and Todd 
(PI. I, Fig. VII, VIII), and Laveran and Mesnil (Fig. XX), are those seen by us. 
Granules have been seen in many specimens, but not so numerous as in other species 
of trypanosomes. The agglutination of T. dimorphon is a very noticeable feature. 
As pointed out by Laveran and Mesnil it is especially remarkable in the blood of 
rats and mice shortly before death, it is also well seen in rabbits and guinea-pigs under 
the same conditions. In making agglutination experiments with serum, etc, it is 
therefore necessary to avoid such blood. 
