PROTOZOA IN DISEASE 301 



tsetse does not affect wild but only domesticated animals, 

 especially horses ; also that it is not due to any inherent 

 venom in the fly itself, but to the communication of certain 

 flagellated germs from other diseased animals. 



From Dr. Bruce's observations it would appear that the 

 fly is viviparous, giving birth to adult larvae, a most impor- 

 tant fact hitherto unnoticed. The disease itself, he finds, is 

 due to the presence in the blood of an inoculated animal of 

 a flagellated hsematozoon furnished with a membrane or 

 ' fin,' running along one side of its body, with a flagellum 

 at one end. The appearance of this hsematozoon in the 

 blood is signalised by a rise in temperature ; the incubation 

 period is from seven to twenty days, after which period the 

 hsematozoa may be found swimming actively among, and 

 apparently ' worrying,' the corpuscles, the red blood cor- 

 puscles becoming very largely reduced in numbers. With 

 the progress of the disease, the hsematozoa increase in 

 numbers. Dr. Bruce has demonstrated that it is possible 

 repeatedly to feed tsetse on a healthy dog without producing 

 disease in that animal, showing that the fly possesses no 

 specific venom, but that if allowed to draw blood from a 

 diseased animal, or the carcase of one, it will communi- 

 cate nagana to healthy animals. The disease is invariably 

 fatal in the horse, ass and dog, but perhaps not necessarily 

 so in cattle, in which it runs a much slower course. From 

 some preliminary experiments, arsenic appears to have a 

 marked action on nagana, causing disappearance of the 

 hsematozoa, reduction in temperature, and maintenance of 

 the red blood corpuscles. 



Protozoa in Dysentery. — Certain organisms known as the 

 Amoeba coli have been described by Liisch, Grassi, Kartulis 

 and others, as occurring in the intestines of persons suffer- 

 ing from dysentery. The amoebae, when at rest, are round 

 or slightly oblong bodies, consisting of an outer pale homo- 



