322 N. E. McINDOO 



(PorW) of the surrounding flask, but it is evidently somewhat 

 different in composition from the surrounding chitin (Ch), since 

 it generally stains less deeply with iron hematoxylin and eosin 

 or with safranin and gentian violet. The apex of the cone is 

 hollow and extends to the neck of the flask. The sense cell 

 (SC) lies beneath the mouth of the flask. It is bipolar, long, and 

 slender, and comparatively large. The peripheral pole or sense 

 fiber {SF) of this cell runs into the hollow of the cone, pierces 

 the bottom of the cone, and enters the lowest portion of the trans- 

 parent pore aperture. The inner pole or nerve fiber {NF) of 

 the sense cell joins a nerve cord. The nucleus (SCNuc), with 

 its several dark staining bodies or nucleoli (ScNucl), is always 

 conspicuous. While the cytoplasm (Cyt) in the poles is almost 

 invisible, it is easily seen at either end of the nucleus, for here it 

 stains rather deeply (AgCyt). 



The flasks may be short and thick or long and slender, depend- 

 ing on the thickness of the chitin. In the legs they are generally 

 short and thick (figs. 16, A-C, and 17) and have a short neck. 

 Occasionally the basal portion of the flask is short, making a 

 long neck whose walls are slightly evaginated (fig. 16, D). In 

 the wings and sting the basal portion of the flask is short, but the 

 neck is usually long and narrow (fig. 16, I-K; figs. 19-21, 23), 

 and its walls rarely have a small evagination. In the femur and 

 tibia the pores never pierce the thickest portion of the chitin, 

 but in the trochanter, wings, and sting this may or may not be 

 true. 



The cone is always present. Its size and shape depend on the 

 size and shape of the basal portion of the flask. With safranin 



and passes through group 6; the circles at the top represent the slits cut cross- 

 wise. C, two more pores from group 6, but here the slits are shown in longitudi- 

 nal section. D, three pores from trochanter of third leg. E, F, two sense cells 

 from two different sections of group 2 on the front wing; the^chitin is cut obliquely. 

 G, a sense cell from group 5 on the hind wing. H, two sense fibers entering pore 

 apertures belonging to group 2 from front wing; the chitin is cut obliquely. I, 

 three pores from group 3 from front wing entering pore apertures. J, five pores 

 from group 4 on the hing wing, showing how sense fibers enter pore apertures. 

 K, a typical pore and a sense cell from group 5 on hind wing. L, three pores and 

 their sense fibers from a cross section of the tegula. Drawn with the aid of a 

 camera lucida. 



