410 BLOOD DISEASES. 



Sometimes two will unite and swim off as one body. Evans 

 thought that they joined heads and tails ; others thought that 

 they fastened with their tails in opposite directions. 



The disease is not contagious or infectious in the ordinary 

 sense, but can be communicated by subcutaneous inoculation, 

 and by the introduction of blood containing the parasites into 

 the stomachs of healthy animals. 



Steel differed from Evans as to the exact classification of the 

 parasite, maintaining that it resembled the spirillum of relapsing 

 fever in man. Notwithstanding this error, it must be admitted 

 that he did good work when the disease broke out in British 

 Burmah in 1885, confirming its communicability by inoculation 

 of blood containing the parasites to the dog, horse, mule, &c., 

 that the disease was relapsing in its nature, that the parasite 

 appeared as the temperature rose, and disappeared during the 

 non-febrile periods ; and he concluded as follows : — " That 

 relapsing fever of mules is invariably a fatal disorder, charac- 

 terised by the periodical occurrence of attacks of high fever, 

 during which a special organism closely resembling the spirillum 

 of relapsing fever in man is found in the blood. This organism 

 is one-sixth of the size of a blood corpuscle in width, and three 

 to six times in length, &c. All observers conclude that the 

 parasites are not always present in the blood of the diseased 

 animal, but come and go in successive broods." 



Seeing that Evans and Steel differed in opinion as to the 

 exact classification of the surra organism, Evans referred the 

 matter to the late Dr. Timothy Lewis, who concluded that it 

 resembled, but was not exactly like, that which he had dis- 

 covered in the blood of rats, now called Trichomonas Zevnsi. The 

 matter was further referred to Crookshank. — (" Journal of Eoyal 

 Microscopical Society," part 6. — " Flagellated Protozoa in the 

 blood of diseased and apparently healthy animals.") He says, 

 page 916 : — " In the face of these conflicting opinions, Dr. Evans 

 was good enough to place in my hands for investigation some 

 preparations of the organism in the blood as well as material 

 from the lungs and intestines of a camel that had succumbed to 

 the disease. 



" On examining a stained preparation with a power of 200 

 diameters, a number of the parasites could be distinguished in 

 the field of the microscope, and with a 1/12 and 1/18 O.I. (oil 



