PLATE XXII 



Figure I. Apiece of Malpighiau tube from Tabanus, showing 

 the way the cells are wrapped round the lumen. X 100. 



Figure 2. Malpighiaiij tubes of same in section. Only one 

 nucleus at most appears in an ordinary thin section. 



Figure 3. The alimentary canal of Culicoides kiefferi. The crop 

 is not shown, m.g., mid-gut. mp.t., Malpighian 

 tubes, co., colon, rt., rectum. X 90. 



Figure 4. The alimentary canal of Phlebotomns mi nut us. oes., 

 oesophagus, d.c., duct of the crop, lying on it. cr., 

 crop. Other letters as before. The dissection from 

 which this was drawn was stretched a little. X 180. 



Figure 5. Cells from the wall of the hind-gut of Tabaiins. ch., 

 the chitinous inner lamina. t.m., circular muscle, 

 l.m., longitudinal muscle, x 800. 



Figure 6. A section through the upper part of the rectum of 

 Tabanus. The section was a little oblique, and shows 

 the whole of one rectal papilla, and a part of another. 

 tr., trachea, mu., muscle, ch., chitinous lamina in 

 the wall. In the lower part of the section this lamina is 

 of considerable thickness. X 70. 



Figure 7. Section through the oesophagus of Culex, anterior end. 

 showing the chitinous spicules which project into the 

 interior, and the absence of cells in the wall. 



Figure 8. Section through the same, lower down, in the thorax. 

 Note the low cubical cells in the wall, and the large 

 amount of muscle externally. The chitinous lamina 

 is here not so well marked. 



