2G2 THE PATHOGENIC FLAGELLATES 



the neck. Examination of the blood and organs for bacteria by micro- 

 scopic and cultural methods produced no result. At this time it was 

 my custom, when starting on a study of a new disease, to make a care- 

 ful daily examination of the blood of the living animal, enumerating 

 the number of the red and white blood corpuscles and estimating the 

 percentage of the various varieties of leukocytes. After a few days of 

 this blood examination it was noted that there were sometimes to be 

 seen a peculiar stained body, having something of the appearance of 

 an artistic dolphin, lying among the red blood corpuscles. It must be 

 remembered that the trypanosomes are usually found in very small 

 numbers in cattle, so that it is only after a long search that a single 

 one can be found. It was thought at first that this small, peculiarly 

 shaped object was an accidental appearance due to the stain, but 

 thinking that if the body was a parasite, it might show motion, several 

 ■specimens of fresh blood were examined. A long search was rewarded 

 by finding a very active body wriggling and twisting about with great 

 'energy and dashing in and out among the red blood corpuscles. It 

 was the first time the writer had seen a trypanosome, and, as then 

 there was little or no literature on the subject of these parasites, it was 

 difficult to know how to place it. It seemed it must be a filaria, but 

 ihaving compared the description and drawing of the rat trypanosome 

 in Lewis' book with my parasite, it was concluded it was a trypano- 

 some. But there was no proof that the parasite was the cause of 

 nagana; it occurred only in small numbers in the blood of the cattle, 

 and the rat trypanosome lives as a harmless guest in healthy animals. 

 Therefore the blood of infected cattle was inoculated into horses and 

 dogs. The disease in the horse and dog is much more acute than in 

 the ox. 



"In a few days the blood, especially of the dog, was found to be teem- 

 ing with thousands of trypanosomes. It therefore began to appear 

 probable that this parasite might be the cause of nagana. At that time 

 there was no suspicion that this disease among the native cattle, occur- 

 ring in kraals situated many miles from the 'fly country,' was the same 

 disease as that known to travellers as the tsetse-fly disease. The 

 work at this time was being done on the summit of a mountain called 

 Ubombo, some 2000 feet above the surrounding low country. The 

 low country to the east of the mountain, was known to be infected with 

 the tsetse fly, and having often read, in Livingstone's and other books 

 of travel and hunting, about this disease, it was determined to take a 

 few animals into this 'fly country' and see what the disease was like. 

 Two young oxen, a horse, and several dogs were taken into the heart 

 of the 'fly country.' After being there a fortnight the animals were 

 brought back to the top of the mountain and examined in the usual 

 way — their temperature taken, their blood examined, and any symp- 

 toms that might occur noted. It was found that the blood of these 



