350 Prof. Mialland Mr. R. Shelford on the Structure and 
granular masses are frequent. ‘Towards the middle of 
the stomach the epithelium becomes regularly columnar. 
There are no protrusions or granular masses, but a finely 
granular secretion is poured forth. Beyond this zone 
the epithelium becomes cubical, and the granular masses 
reappear. Protrusions also occur, though not so fre- 
quently as in the upper portion. ‘Towards the lower end 
of the stomach the epithelium becomes thin and flat. 
The Malpighian tubules and the beginning of the chiti- 
nous intima of the proctodzeum show that the stomach 
passes into the intestine at a place where there is no 
change in the diameter of the tube. In young larve 
there seem to be no granular masses in the epithelium, 
which is uniform and irregularly columnar throughout the 
stomach; Watney’s buds are very numerous. In starved 
larve the epithelium becomes unusually folded, and 
the protrusions are frequent, while the granular masses 
and the secretion in the cavity of the stomach are more 
copious. The cell-outlines are less clear than usual, and 
the epithelial cells appear to be more distinctly grouped 
into bundles than in normal larvee. 
The intestine (fig. 18b) may be divided into two tracts, 
colon and rectum. In the beginning of the colon the mus- 
cular layer, and especially its annular fibres, gradually 
increase in strength, while the epithelium and chitinous 
intima become folded. <A circular valve occurs at the 
end of this section of the colon. Then the muscular wall 
thins out again, and fora variable length the intestine 
becomes flexible and capable of dilatation. A con- 
siderable oval enlargement, filled with food, is often seen 
somewhere in this portion.* The epithelium beyond the 
muscular thickening is at first cubical, but gradually 
becomes thin and flat. At the beginning of the rectum 
the muscular wall again becomes thickened. ‘The epi- 
thelium and chitinous intima are, as usual, strongly 
folded. ‘The anus has been described above (p. 345). 
Salivary glands (fig. 18a). A pair of convoluted sali- 
vary glands lie along the cesophagus and the beginning 
of the stomach. Large nucleated cells, which form a 
single epithelial layer, bulge into the narrow and irre- 
* Phalacroccra illustrates the remark of Balbiani (/oc. e7t., p. 71) 
that the folds of the intestinal epithelium vary with the phase of 
digestion. 
