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THE NATIONAL GEOGRAPHIC MAGAZINE 



In the advanced stages of the disease, 

 the sufferer lies about in the corner of 

 his hut, indifferent to everything going 

 on about him, but still able to speak and 

 take food if brought to him. He never 

 spontaneously engages in conversation or 

 even asks for food. As torpor deepens, 

 he forgets even to chew such food as is 

 brought to him, falling asleep, perhaps, 

 in the act of conveying it to his mouth 

 or with the half-masticated bolus still in 

 his cheek. As the lethargy becomes more 

 continuous, he wastes quickly from lack 

 of nourishment, and the end is brought 

 about either by coma or by the increasing 

 weakness. 



The mortality of the disease must be 

 reckoned as 100 per cent. It is possible, 

 but there is no definite knowledge on this 

 point, that recovery may take place in 

 the very early stages of trypanosomiasis, 

 but when once the sleeping-sickness stage 

 of the disease has been reached it is prob- 

 ably invariably fatal. 



INVESTIGATIONS BY DR KOCH 



Not longer ago than September, 1907, 

 Professor Koch, in reporting on his in- 

 vestigations made in Lake Victoria, 

 added yet another terror to the already 

 gloomy outlook on sleeping-sickness. He 

 found a large number of cases in dis- 

 tricts where the tsetse-fly was absent. 

 The majority of the cases were undoubt- 

 edly imported, occurring in people who 

 worked in the rubber industry in forests 

 along the lake shore, where tsetse-flies 

 abounded. But fifteen of the cases could 

 not by any possibility have been im- 

 ported. All were women and all were 

 wives of men employed in the rubber in- 

 dustry in a tsetse-fly area. Assuming 

 that no other biting insects than tsetse- 

 flies are capable of transmitting the dis- 

 ease, the only tenable hypothesis is that 

 these women contracted it from their 

 husbands. If Professor Koch's observa- 

 tion is correct, the prospect of eradicat- 

 ing sleeping-sickness is a sufficiently re- 

 mote one, as not only can the disease be 

 transmitted by a widely-distributed fly, 

 but it also belongs to the category of 

 venereal diseases, and experience of 



many centuries has shown the difficulty 

 of stamping out diseases of this class. 



If the natives could be induced to wear 

 some sort of light garment, they would 

 obtain a certain measure of protection ; 

 but water-side populations in Africa 

 usually go even more naked than others. 



The most recent recommendation is 

 that of Professor Koch, who asserts that 

 in the neighborhood of the Victoria Ny- 

 anza the tsetse-flies subsist almost en- 

 tirely on the blood of crocodiles ; he there- 

 fore suggests the extermination of these 

 reptiles . by the destruction of their eggs. 

 It is difficult to take this suggestion really 

 seriously, because the numbers of croco- 

 diles are so immense, their distribution is 

 so wide, and their powers of reproduc- 

 tion so great. 



the tsetse-fly 



The tsetse-flies (Glossince) comprise 

 ten species, which are confined to Africa. 

 They are sombre-colored, narrow-bodied 

 flies from about 8 to 12 millimeters long, 

 with a thick proboscis projecting hori- 

 zontally in the front of the head. When 

 the fly is at rest the wings overlap each 

 other, crossing like the blades of a pair 

 of scissors. Glossina palpalis has been 

 found from Senegal to Angola on the 

 west, through the Congo and Lualaba to 

 Tanganyika and the Victoria Nyanza, 

 and northward along the Nile to the 

 Uganda-Sudan border. The flies are 

 seldom, if ever, found above 4,000 feet 

 and always near water. A swampy 

 shore is not much to their taste ; they are 

 most commonly found along those 

 stretches of river bank or lake shore 

 where there is a beach of mud or sand 

 overhung by trees or bushes. 



Tsetse-flies do not lay eggs, like most 

 diptera, but larvae, which turn into the 

 pupa condition almost immediately after 

 extrusion. The perfect flies, both male 

 and female, are blood-suckers. They 

 feed during the dav, and by reason of 

 their exceedingly rapid flight and the 

 extraordinary softness with which they 

 alight on their victims, it is very difficult 

 to detect them until after the mischief 

 has been done. 



