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cloths and accompanierl by European foremen, are to be sent to 

 suspected places, and the author says that if only the Mission had at 

 its disposal the men necessary to finish the work at present in hand, 

 and above all to keep the ground cleared, and to hunt down the few 

 wild pigs still existing, these forming the chief source of the blood 

 supply for the fly, there is no reason to doubt that the fly in the near 

 future might be reduced to insignificant numbers. 



Although the habits of Glossina palpalis are well known, he thinks 

 it desirable to state that in Principe the fly lives almost entirely among 

 great masses of vegetation, preferably in marshy places, along the 

 banks of the rivers and streams well shaded by trees, climbing plants, 

 and tall grass. It requires for its development, however, not only 

 the shade and coolness provided by these conditions, but some mammal, 

 which it can easily attack, and which lives by preference in the depths 

 of thick bush. When the large herds of cattle, which lived half wild on 

 the north of the island, disappeared, the fly had to depend almost entirely 

 on the wild pigs, once extraordinarily abundant all over the island. 



The mammalian wild fauna of the island is limited, consisting of 

 a species of monkey, musk-cat and rats, which owing to their condi- 

 tions of life do not offer an easy prey to the tsetse. G. palpaUs 

 cannot live under prolonged exposure to strong winds and the rays 

 of a tropical sun, the latter especially interfering with the develop- 

 ment of the pupa. This explains the well-known fact that the tly 

 diminishes considerably during the dry and windy season with a 

 temperature of 70° to 75° F., and that they increase immediately 

 in the damp, rainy and hot season, with a temperature from 77° to 90° F. 

 and a cloudy sky. The rapid disappearance of the fly is thus 

 accounted for when infested areas are cleared, marshes drained, 

 water channels cleaned, and at the same time, the wild pigs hunted 

 down on a large scale. 



Cacao plantations are apparently unsuited to the fly, probably 

 on account of the methodical cleaning and cultivation practised, 

 and inasmuch as more than half the island is planted with cacao 

 trees, and as the sanitary work has been chiefly carried out in the 

 north-eastern and Avestern zones, which are still uncultivated, and in 

 which in former times the flies principally abounded, it will be readily 

 understood that the area within which the fly may live and thrive 

 is becoming exceedingly limited, even supposing that they can adapt 

 themselves to the blood of human beings, or of the few domestic 

 animals exposed to their attacks in place of their former food, the blood 

 of the wild pig. 



From June to September of 1913, among 366 persons examined, 

 five fresh cases of sleeping sickness were discovered. In October and 

 November, the period to which the present report refers, 493 persons 

 were examined, and only five, or one per cent., showed new infections 

 of Trypanosoma gambieiise, whereas in October 1912, the percentage 

 of fresh cases was TS. Dr. da Costa points out that all the patients 

 recently examined are persons who have resided in the island more 

 than two years, and that the majority of them have long been 

 suspected, although examination by the Ross-Ruge method failed 

 to reveal the parasite. Other, more modern methods are now being 

 used, and it is possible that the number of cases now discovered 

 may be affected by the adoption of better methods of diagnosis. 



