86 



blood, this percentage was made up as follows : mammalian, 9-1 per 

 cent. ; non-mammalian, 4 1 percent. ; non-recognisable, 14-1 percent. 



In a second experiment, 183 G. palpalis were caught at a spot on 

 the Lake-shore where the insects " swarmed," and both crocodiles and 

 birds were abundant. Immediate " naked-eye " examination showed 

 that " blood in a more or less digested state " was present in 59 per 

 cent, of the captured flies. On subsequent microscopical examination, 

 it was found that " out of the original 183 flies examined, 52 (28 per 

 cent.) contained blood which was recent enough to show the red 

 corpuscles. Out of these 52, 7 (13 per cent.) were from mammalian 

 blood, whilst non-mammalian blood was present in 35 flies (67 per 

 cent.)." In the latter " reptilian blood was twice as frequent as the 

 blood of birds." 



In the Proceedings of the Royal Society of 6th August 1914 we find 

 the results of other investigations, made by Sir David Bruce, Major 

 A. E. Hamerton, Captain D. P. Watson and Lady Bruce, on the food 

 of Glossina morsitans in Nyasaland. The most important paragraphs 

 in this short paper (20) are given below. 



" Five hundred flies, freshly caught in the Proclaimed Area, were 

 killed by chloroform and the gut of each was roughly dissected out, 

 smeared on a slide, fixed by osmic vapour and alcohol, and subsequently 

 stained by Giemsa. The flies were all caught in the bush, away from 

 the paths, the fly-boys proceeding in single file and catching the flies 

 with gauze nets as they circled round, or settled on the boys or the grass. 



" The proportion of male flies to females caught was roughly two to 

 one. But only 30 females were used in the present experiment, the 

 majority being sent to the breeding-station at Chunzi. 



" Of the 500 flies examined, 288, or 57-6 per cent., were found to 

 contain mammalian blood in a recognisable state. No measurements 

 were made of corpuscles, which in most cases were much altered by the 

 digestive processes, but the small type of cell appeared to predominate, 

 such as occurs in the hartebeeste, waterbuck and other antelope. 



" In only three cases were nucleated red corpuscles found, and in 

 two of these there was only a small proportion of nucleated blood mixed 

 with a large amount of mammalian. In the third case the blood was 

 all nucleated. Thus, of those flies which contained recognisable 

 blood, only 1 '0 per cent, contained nucleated blood. From measure- 

 ments, it seems highly probable that in all three cases the blood was 

 avian, not reptilian 



" In no case was vegetable matter noted in the intestinal contents. 



" From experiments with flies in the laboratory, it was found that 

 blood is recognisable in stained specimens for two to three days after 

 a feed, but not beyond the third day. Hence it may be inferred that, 

 roughly, half the flies examined had fed within, at most, three days of 

 their capture, and that therefore the flies feed naturally at least once 

 every six days." 



Another series of investigations upon the bionomics of Glossina 

 morsitans was made in Northern Rhodesia, from May to July 1914, 

 by the late Mr. R. A. F. Eminson. The following particulars, with 

 reference to "an examination of the gut contents of captured flies in 

 various conditions of environment," are extracted from a summary 

 of a report by Mr. Eminson to the British South Africa Company (50). 



" During May 1914, 300 flies were examined .... and 

 recognisable blood was found in 43 ; of these, 41 contained mammalian 

 and 2 non-mammalian blood, so that the latter amounted to 5 per 



