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Trypanosomiasis is spread. It is within the knowledge of all 

 here that the great scourge of certain parts of Africa is the 

 Tsetse-fly {Glossina inorsitans) which kills off buffaloes, oxen, 

 and horses by tapping the blood-vessels of these beasts for 

 purposes of refreshment, and leaving behind certain Protozoa 

 known as Trypanosoma, which prey upon the corpuscles of 

 the blood, and sooner or later reduce the victim to an 

 emaciated condition which ends in death. 



Much controversy has raged over this subject ; that is to 

 say, as to the real nature of the disease called Nagana, or fly- 

 disease — whether it was contagious in the ordinary way, or 

 due to some irritant or morbid matter ejected by the fly. 

 The natives believed that the diseased condition only followed 

 actual fly-bites, and told how the fly avoids the neighbour- 

 hood of human excrement, and was therefore absent from 

 the immediate vicinity of the settlements. Explorers from 

 the sixteenth century onward noted the effects of these fly- 

 bites, and many imagined the proboscis had a poison-gland 

 at its base, like the sting of the wasp. There were not 

 wanting those, however, who held that the fly was a mere 

 accidental concomitant of the disease, and neither a cause 

 nor an agent in its dissemination. One is surprised to find 

 Edward Newman in this company, and declaring with great 

 conviction in the " Entomologist " for December, 1870, tha.t 

 the Tsetse was " a myth," He says, " I have always protested 

 against the importation of a myth like the Tsetse into the 

 domains of science ; the mixture of truth and fable in matters 

 of science is always to be deprecated." The last statement 

 embodied a very proper sentiment for any naturalist to hold or 

 express, but so far as the Tsetse was concerned, I think the 

 mass of the evidence then available strongly supported the 

 views of the explorers and natives that the fly was at least an 

 agent. However, in the year 1895, Surgeon-Major Bruce, of 

 the Army Medical Service, was sent by the Governor of Natal 

 to Zululandto investigate the Tsetse-fly Disease, or Nagana ; 

 and his report gives a description of the fly, and describes 

 his experiments upon it in relation to the native big game 

 and such domestic animals as the horse, donkey, dog, and 

 cattle. He traced out the distribution of the disease. The 

 Tsetse-fly is not greatly unlike our Clegg {H amatopota 

 pluvialis) ; but, unlike the majority of Diptera, it does not lay 

 eggs. These are retained not only until they hatch, but 

 until the larva is nearly as large as the abdomen of the parent 

 and full-fed. They are extruded as active yellow larvae 

 ready to pupate as soon as they have found a suitable hiding- 



