THE SLEEPING SICKNESS 171 



from the sleeping sickness. Unfortunately there is no 

 immunity for Europeans in the matter ; and the exist- 

 ence of half a dozen or more cases of white people 

 infected with the trypanosome, who have ultimately 

 died in England or elsewhere in Europe from sleeping- 

 sickness contracted through the bite of a fly in Africa, is 

 abundant proof that there is not, as has been supposed, 

 any special freedom from the disease for white people l 



The foregoing description of the nature and mode of 

 the infection of sleeping sickness will not cause any 

 astonishment to the layman of the present day who 

 knows anything of recent medical science. We are all 

 familiar with the danger of fly-bites, even in this 

 country, where deadly bacteria are occasionally carried 

 by biting flies, such as the horse-flies, into the human 

 subject ; and nowadays every one is more or less familiar 

 with the discovery of the minute blood-parasite which 

 causes malaria or ague and is carried by a particular 

 kind of gnat in the interior of which it multiplies by 

 a process of sexual conjugation. At the same time 

 the reader who is interested in sleeping sickness will 

 probably desire to know more about the nature of the 

 tsetze flies and some further details as to the parasite 

 spoken of as trypanosome. 



The tsetze flies form a genus called by Wiedemann 

 (in 1830) " Glossina." They are only found in Africa ; and 

 some seven species in all are known. They are little bigger 

 than a common house-fly, and much like it in colour (fig. 48). 

 They differ in appearance from the house-fly in the fact 



1 Only last year (1905) Lieut. Tulloch, of the Army Medical Depart- 

 ment, who with Professor Minchin was engaged in carrying on further 

 researches for the Royal Society on the sleeping sickness at Entebbe in 

 Uganda, became infected by the trypanosome, probably through an 

 unobserved bite by a tsetze fly, and died of the disease soon after his 

 return to England, 



