168 THE KINGDOM OF MAN 



As already indicated, it was found by Bruce, on 

 recording the cases of sleeping sickness brought into or 

 reported in Entebbe, that there were certain " sleeping- 

 sickness areas" and other areas free from sleeping sick- 

 ness. The theory now took shape in Bruce's mind that 

 the trypanosome first gets into the blood, and then 

 after a time, makes its way into the cerebro-spinal 

 system, only then producing its deadly symptoms. Very 

 generally, when once in the blood, the trypanosome 

 multiplies itself, and sooner or later apparently, in 

 some cases, even after two or three years gets into 

 the cerebro-spinal fluid. It is probable that it may 

 be destroyed by natural processes in the human body 

 before this final stage is reached ; and thus the infected 

 person may recover and escape the deadly phase of the 

 disease. But nothing certain is known, as yet, on this 

 head. Later observations show that the trypanosome is 

 found alive and in large quantity in the lymphatic glands, 

 especially those in the region of the neck in infected 

 persons. These glands were known to be enlarged in 

 persons suffering from the disease. 



Colonel Bruce's next step was to ascertain the mode 

 in which the trypanosome is introduced into the blood. 

 Naturally he looked for a kind of tsetze fly, such as 

 carries the trypanosome in the nagana disease of horses 

 and cattle already studied by him in Zululand. It 

 is a fact that the Glossina morsitans and Glossina 

 pallidipes, which are the tsetze flies of the " fly-dis- 

 tricts " where nagana disease is rife, are unknown in 

 Central or Western Africa ; and also it is a fact that 

 no tsetze fly had been observed in the neighbourhood 

 of the Victoria Nyanza when Colonel Bruce began his 

 enquiries. He employed, through the good-will of the 

 native chiefs and rulers, a large number of natives to 



