46 



N. E. McINDOO 



All the olfactory pores studied are more or less flask-shaped 

 structures, although the width of the flask is often equal to its 

 height, and the mouths of such flasks are quite flaring; this is 

 particularly true for the pores in the legs (fig. 5 D and E) of 

 Bombjrx, but in the wings (fig. 5 A and B) of the same insect the 

 pores are more flask-shaped. 



Fig. 5 Cross sections, showing internal anatomy of olfactory pores of Bombyx 

 mori, X 506. A, from front wing; B, from hind wing, showing dome (D); C 

 and D, from trochanter; and E, from femur. Con, chitinous cone of olfactory 

 pore; D, dome; Hyp, hypodermis; N, nerve; NB, nerve branch; NF, nerve fiber; 

 PorAp, pore aperture; SC, sense cell; SF, sense fiber; Tr, trachea. 



Cones are usually present and are of three types : The external 

 boundary of the most common type (fig. 5 E, Con) is convex, 

 that of the second type (fig. 8 C) is almost flat, and that of the 

 third type (fig. 5 A) is concave. The first type is found both 

 in the legs and wings while the other two types are found in only 

 the wings; only the first and second types are present in the 

 wings of Achroia, the second type being the more common. 



The sense cells (fig. 5 A and E, SC) are more spherical and 

 therefore less spindle-shaped than those found hitherto in other 



