ANATOMY OF THE GOUT-FLY OF BARLEY. 797 



in the midgut. From its point of junction with the midgut, the 

 liindgut passes fouwavds for a sliorfc distance near to the dorsal 

 body- wall iind thou turns backwards and runs mr n practically 

 straight tube to the anus. At its commencement the hindgut 

 is slightly swollen and bulbous; on this follows the narrow 

 finteriorly-directed region. The posteriorly-directed region is 

 dilated initil a short distiuice in front of the anus, where it again 

 becomes a n.-viio'v tube. The whole of the hindgut is lined with 

 a well-marked ohibinous intima, which is thrown into numerous 

 longitudinal folds, some of which are very pron)inent. Thei-e 

 is a well-delined ring of imaginal cells at the junction of the mid- 

 gut and hindgut. 



Salivary Glands. 



The salivary glands are two simple tubular bodies with a con- 

 tinuous central intercellular lumen. The glandular portion (as 

 distinct from the duct) begins at the level of the proventriculus 

 iind passes baclv wards to about the posterior limitof the ninth body- 

 segment, the glands lying one on either side of the gut. In about 

 the sixtli or soventli body-segment each gland turns dorsally, 

 then forwards for a short distance, then again dorsally, and then 

 backwards and ventrally to its termination near the ventral body- 

 wall. Tliese bends are always present, but their position is not 

 absolutely constant. In transverse section the gland is circular, 

 with a central star-shaped lunien surrounded by four to six gland 

 cells. At the anterior end of each gland there is a narrow ring 

 of small imaginal cells surrounding a small central lumen which 

 is continuous posteriorly with the lumen of the gland and an- 

 teriorly with that of the salivary duct. 



The duct is a narrow tube lined by a chitinous intima, its 

 walls being formed of flattened cells, of which three are usually 

 seen in any transverse section except anteriorly, where there are 

 only two. Each duct runs forwards, becoming very closely applied 

 to the ganglionic mass, and lying in the groove dividing the sub- 

 <esophageal from the supraoesophageal ganglion. Anterior to the 

 ganglionic mass the two ducts lie ventro-lateral to the cesophagus 

 and directly ventral to the lateral edges of the antennal imaginal 

 discs. As they pass forwar<l.s they approach the median line 

 finally joining, slightly posterior to the pharyngeal mass, to form 

 a single median duct which opens through the ventral wall of the 

 pharynx at the point marked X in text-fig. 3. The duct narrows 

 <;onsiderably just before entering the pharynx. 



Malpighian Tubes. 

 There are two pairs of malpighian tubes, an anterior and a 

 posterior. The anterior pair unite to form a short common tube 

 whicli narrows considerably as it passes mesially to open into the 

 left side of the gut at the point of junction of midgut and hind- 

 gut. The posterior pair of tubes forms a similar short common 

 tube opening in a cori-esponding position on the right side of the 



