LIVINGSTONE'S ACCOUNT OF THE TSE-TSE 21 



were placed, only fifty yards distant, contained not a 

 single specimen. This was the more remarkable as we 

 often saw natives carrying over raw meat to the opposite 

 bank, with many Tse-tses settled upon it." 



This account makes clear one of the most remarkable 

 points in the natural history of this species of Glossina, 

 namely, the very sharply marked areas which it inhabits ; 

 this must depend upon the presence or absence of certain 

 factors in its environment, but has not yet been thoroughly 

 explained. 



After noting the symptoms of "fly disease " Livingstone 

 continues : " These symptoms seem to indicate a poison 

 in the blood, the germ of which enters when the proboscis 

 is inserted to draw blood. The poison germ, contained 

 in a bulb at the root of the proboscis, seems capable, although 

 very minute in quantity, of reproducing itself." The words 

 which I have put in italics were written by Livingstone 

 about fifty years before the discovery of the Trypanosome 

 by Bruce, and some years before the first discovery of 

 micro-organisms of disease by Louis Pasteur ! ^ 



The genus Glossina was founded in 1830, when Wiede- 

 mann described a new species of fly from Sierra Leone, 

 and in the same year another species was described from 

 the Congo by Robineau-Desvoidy : this is the one which 

 is now known as Glossina palpalis. It is interesting 

 that the first scientific description of a Tse-tse was not 

 that of the one so long known to natives in South 

 Africa ; this was not named until 1850, when Gordon 

 Cumming's travels made the fly well known in England. 



Glossina palpalis frequents forested and humid country, 

 and is not found so far south as its more widely distri- 

 buted relative morsitans. The great river courses and 

 lake shores in the tropics furnish the shade and humidity 



1 In 1857 Pasteur first showed that fermentation was due to micro- 

 organisms ; in 1865 he showed that silkworm disease was due to micro- 

 organisms. In 1876 the first '• bacterium " (of anthrax) was isolated 

 by Koch. 



