TRYPANOSOMES, TRYPANOSOMIASIS, AND SLEEPING SICKNESS 57 
were seen, but they reappeared six days later. Ten c.c. of one per cent, trypanroth was 
then given every eighth day ; the temperature lowered. The parasites decreased but 
the anaemia persisted ; March 19, atoxyl 1*5 c.c. of ten per cent, solution 
subcutaneously given ; parasites disappeared to reappear eight days later. Despite 
large amounts of trypanroth the animal succumbed to the disease. A blood count, 
March 30, reds, 1,710,000; whites, 6,600 ; haemoglobin, forty per cent.; 
trypanosomes, 24,000 per cm. 
T. dimorphon. — -This parasite has proved harder to combat with atoxyl or any 
other form of arsenic than the preceding parasites. Laveran also notes this 
peculiarity. Guinea-pigs showing a severe infection react extremely badly, they 
appear to manifest a greater tendency to toxicity than do similar animals infected with 
Nagana or other trypanosomes. The disappearance of the parasites is often less rapid, 
sometimes they never absolutely disappear, an occasional one being seen in the prepara- 
tion. In the endeavour to cause the typical reaction a fatal dose may easily be given. 
One guinea-pig out of twenty-two experimented with survived three months. This 
animal was only treated once a week with 0*3 c.c. of five per cent, solution. It 
improved considerably, but towards the last the parasites reappeared, and the animal 
succumbed. The autoagglutination of the blood-cells never completely disappeared ; 
the animal always exhibited some fever. 
Rabbits. — React better to the drug, but the effect is more transient than with 
other trypanosomes. Higher doses have to be given. The life of the animal can 
be greatly prolonged, and for one or two months the general condition is improved. 
After that time parasites once more reappear ; by increased dosage they may again 
disappear. Towards the end larger doses have to be given than at first to produce 
the effect on the parasites. Here it may be noted as applying to all species of 
animals infected with T. dimorphon that the parasite in animals treated for some 
time will hardly be recognizable ; it presents a deformed appearance, its flagellated 
extremity is shortened so that scarcely any movement occurs. Blood from such an 
animal will be declared negative unless each field is gone over thoroughly. All 
peculiar bodies present must be examined, and over any such object minutes spent to 
determine if there is any movement. This point seems rather superfluous, but our 
experience is that the ordinary careful observer usually fails to find these degenerated, 
deformed parasites, and it is probably for this reason why so many negative diagnoses 
are made. Dogs and cats infected with this parasite show only a slight retardation 
of the disease ; the numbers are greatly reduced or absent, but tend quickly to 
reappear. 
Trypan red 
This dye has been mostly used in connection with animals infected with T. equinum. 
The results tally with those of Ehrlich and Shiga, and the later report of Laveran 
and Mesnil. Some rats injected with this compound have lived as long as one 
H 
