160 



" The complete salivary glands may be obtained without risk of 

 rupture of the gut by the following method. G. morsitans has been 

 used in the dissections. The fly is held firmly in the hand and a 

 longitudinal incision is made in the median dorsal line of the thorax 

 from the neck to the abdomen. The insect is then immersed in normal 

 salt solution and incisions are made along the transverse groove of the 

 thorax from the median incision almost to the bases of the legs. The 

 .strong muscles in the thorax which run in a longitudinal direction 

 should also be severed. A needle is now placed in the anterior end of 

 the longitudinal incision, and another in the posterior end. A gentle 

 longitudinal pull applied to the fly by these needles causes the remainder 

 of the thorax to break across. The alimentary canal breaks between 

 the pharynx and proventriculus, while the salivary glands are drawn 

 out of the abdomen quite free from fat body and with only the finer 

 twigs of the tracheal system adhering. It is now a simple matter to 

 dissect away the remainder of the thorax and head till a preparation 

 is obtained consisting of proboscis, pharynx and salivary glands. The 

 figure shows the appearance of such a preparation. The glands when 



p.b. 



Fig. 19. Preparation of salivary glands and proboscis of Glossina morsitans 

 (semi-diagrammatic), x 10. 



s.g., salivary glands ; j.d., junction of salivary ducts ; oe, oesophagus ; 

 ph., pharynx ; p.b., bulb of proboscis ; p.m., muscles of proboscis. (After 

 Lloyd, 87.) 



first withdrawn are quite transparent and exhibit an active wriggling 

 motion. They correspond exactly with the salivary glands of G. 

 palpalis as described by Minchin. 1 If the pull on the fly is not perfectly 

 longitudinal, one of the glands may break off just posterior to the 

 junction of the salivary ducts. Occasionally both the glands break 

 away at this attenuated part of the ducts. In either event the 

 remainder of the thorax attached to the abdomen is dissected off and 

 the protruding glands are withdrawn by means of fine forceps. A little 

 dissection of the anterior end of the abdomen is sometimes necessary 

 to effect this. 



" Another method that has been adopted with some success is to 

 draw the glands out of the fly by means of the proboscis. A longitudinal 

 median incision is made in the thorax as before and the cut is opened 

 out by means of needles, with which the structures in the thorax are 

 loosened. The dorsal surface of the head, the eyes and the jowls are 



1 E. A. Minchin, Report on the Anatomy of the Tsetse-fly (Glossina palpalis) : 

 Proc. Roy. Soc., London, Ser. B., vol. 76, p. 538 (1905)." 



