382 RUTH M. HARRISON. 



minal ganglia, sf^ — st-j. Sternites five to seven, i^,t^ — /jq. Tergites four, five 

 to ten. 



Figs. 3 — 12 liave all been drawn with the aid of a camera lucida. 



PLATE 15. 



Fig. 1.— Dissection of the six posterior segments of a large male cockroach 

 X 5. 



Fig. 2 — The gland removed with the tracheal vessels associated with it. 

 X 22, 



Fig. 3. — Longitudinal sagittal section through a female cockroach in the 

 region of the gland. The nerve cord has been cut just below the fifth abdo- 

 minal ganglion. The external opening between the sixth and seventh sternites 

 is shown, also the thickened chitinous rim at the anterior end of the seventh 

 sternite. X 43. 



Fig. 4. — Transverse section through a male cockroach at the anterior end 

 of gland, showing that two lobes project forward, x 70. 



Fig. 5. — Transverse section through tiie same cockroach a little further 

 back, showing that posteriorly the lobes unite. The thickened chitinous rim 

 of sternite 7 has been cut near the posterior limit of the crescent, x 70. 



Fig. 6. — Portion of the wall of a gland from a male cockroach more highly 

 magnified. The tubes in the cells of the epithelial layer have been cut in a 

 good many cases, x 330. 



Fie. 7-— Portion of the wall of the gland from another cockroach under a 

 higher magnification. The tubes are not visible in this preparation, but the 

 hairs attached to the lining membrane are shown. This section also shows 

 some of the cells of the outer layer migrating inwards. X 400, 



Fig. 8. — A small portion of the gland after maceration in potash so that 

 only the chitinous hairs remain. The magnification in this figure is so high 

 that it was impossible to get the whole of a single hair within the field of the 

 camera. Only the attachments and beginnings of each hair were therefore 

 traced with a camera, and the free extremities had to be drawn in separately. 

 Oil imm. oc. 12. 



Figs. 9 and 10. — Longitudinal sections through a young male cockroach 

 about 1'5 cm. long. Fig, 9 is a median section showing the external openings ; 

 Fig. 10 is a section taken to one side of the middle line, showing the extent 

 of one lobe of the gland, x 105. 



Fig. 11. — An enlarged drawing of a portion of the same gland. The com- 

 paratively enormous breadtli of the cliitinous lining in the last three figures is 

 probably artificial, due to a breaking a])art in the secl.ion-cutting. x 400. 



Fig. 12. — A small portion of the wall of the gland iiighly magnified, showing 

 the tubes in tlie epithelial layer, x 9G0. 



