540 Prof. E. A. Minchin. Report on the [| Aug. 17, 
slender duct traversing the thorax. The sucking stomach in the ordinary 
condition of the fly is filled with gas, but shortly after feeding it is found 
filled with blood. 
The duct of the sucking stomach arises, as already stated above, from the 
cesophagus, at the point at which the latter communicates with the stomach, 
in such a way as to appear as a direct continuation of the cesophagus, the 
opening into the stomach having rather the appearance of a dorsally-directed 
diverticulum. At the point where the communication with the stomach 
occurs, the sides of the stomach are folded down ventrally so as to wrap 
completely round the duct, meeting below it, and forming a complicated 
system of cavities into which the fat-body intrudes. 
When the duct passes the waist,it expands rapidly to become the capacious 
sucking stomach (figs. 2 and 5, S. S¢.), which has delicate walls, provided with 
a layer of unstriped muscles disposed irregularly. 
The Malpighian tubules (7 ¢., MW. ¢., fig. 5) arise by a pair of main stems 
given off from opposite sides of the 10th limb of the abdominal intestine. 
Each of these stems very soon divides into two again. In Glossina these 
tubules are excessively long, and so entangled with the fat-body and other 
organs that it is impossible to unravel them for their whole length, but 
since they are never observed to branch again, after their origin from the two 
main stems, it may be inferred that, as in other Diptera, there are in all 
four Malpighian tubules, disposed in this case in two couples, each couple 
coming off from a common stem. When the dorsal integument of the 
abdomen is removed, it can generally be observed without difficulty that two 
of the Malpighian tubules have thickened terminations, which lie close 
alongside the heart in the pericardial sinus right and left. In some specimens 
of Glossina these two tubules are not conspicuously thickened, but their 
position is constant. In no case do they exceed the salivary glands in 
thickness. It is evident that these two tubules must be of physiological 
importance for purifying the blood in the pericardial sinus. Mr. Tulloch has 
found in Stomoxys the same two pericardial Malpighian tubules, thickened to 
such an extent as to greatly exceed in calibre the salivary glands. Mr. Tulloch 
also found, and I was able to confirm his observation, that the two pericardial 
tubules of Stomoxys were a couple, arising both from one of the two stems on 
one side of the gut. The Malpighian tubules being much shorter in Stomoxys 
than in Glossina, it was possible to dissect out the two pericardial tubules of 
the former as far as their common origin from the gut, at which point they 
were detached, stained, and mounted in Canada balsam, thus putting this 
somewhat unexpected result beyond all doubt. Whether the two pericardial 
Malpighian tubules of Glossina are also, like those of Stomoxys, a couple with 
