159 



feet tied, and since this causes suffering it is difficult to feed many flies 

 from one of these animals. If a goat or sheep be tied up and hobbled, 

 from six to nine jars can be placed upon it. 1 



REARING TSETSE-FLIES IN LABORATORIES IN EUROPE. Some seven 

 years ago the first results of an attempt at rearing Tsetse-flies in a 

 European laboratory were described by Dr. E. Roubaud (1196). 



At the end of December 1913 Dr. Roubaud brought from Senegal a 

 score of living pupae of G. palpalis and G. morsitans. Cold during the 

 voyage proved fatal to the older pupae, but the younger ones hatched 

 out in the laboratory of the Pasteur Institute, Paris. In the case of 

 G. morsitans the resultant flies, placed in a Roux incubator kept at a 

 mean temperature of 24-25 C. (75-77 F.), and fed daily on guinea- 

 pigs and rabbits, lived and bred in a satisfactory manner. The G. 

 palpalis pupae produced only two male flies, which were small but well- 

 formed, and lived from 17th January to 26th February. From the 

 G. morsitans pupae there were obtained two males and six females. 

 One of the latter deposited four larvae, which were the origin of a stock 

 which was still in existence three years later, being kept at a mean 

 temperature of 24 to 25 C. (75-77 F.), and in a mean humidity of 

 of 50 to 55 per cent. In January 1915, 20 flies were alive, and it is 

 stated by the author in a subsequent paper (121) that, from start to- 

 finish, the experiment continued satisfactory for three years, the strain 

 ultimately dying out naturally owing to an unusual preponderance of 

 males and absence of females. 



The conclusion drawn by Dr. Roubaud is that it is possible to keep 

 and breed Tsetse-flies in Europe, under conditions permitting of pro- 

 longed experiments upon these insects. If the incubator be small, 

 care must be taken to see that it is properly aerated, and the humidity 

 must not be allowed to exceed 60 per cent. 



CHAPTER XVII. 



DISSECTION OF THE SALIVARY GLANDS OF TSETSE-FLIES. 



On this subject we cannot do better than reproduce the admirably 

 clear and succinct directions given by Mr. LI. Lloyd (87). 



" Workers on the transmission of trypanosomes by various species 

 of Glossina," writes Mr. Lloyd, " have hitherto been unable to agree 

 as to the part played by the salivary glands in the process. It is of 

 importance, therefore, that some method of removing the glands be 

 adopted in which the risk of contamination by gut-contents would be 

 reduced to a minimum. The usual method employed hitherto has 

 been to remove the entire viscera by means of pressure on the abdomen, 

 after either the removal of the last segment, or the severance of the 

 abdomen from the thorax. These methods are open to the criticism 

 that the gut, especially if it contains much blood, is liable to rupture ; 

 that the glands are liable to lesion ; and that it is very difficult to 

 dissect them free from fat body and gut. 

 



1 Messrs. Baird and Tatlock, of Manchester, make little wooden cages, which 

 are very light, portable and inexpensive. These cages, manufactured to the 

 specification of Sir David Bruce, are of an oblong shape, about 6 in. long, 4 in. 

 wide and 4 in. high ; two sides are covered with muslin or wire gauze, and a hole, 

 fitted with a cork, enables flies to be introduced. There are two types of cages 

 one (with wire gauze sides) intended for carrying flies, the other (with muslin 

 sides) for feeding purposes. 



