48 



N. E. McINDOO 



and B from the hind wing. At once it is seen that instead of 

 the surfaces of the wings being smooth, as is generally beheved, 

 thej^ are more or less corrugated, the elevations being formed by 

 the veins and the depressions usually by the flexible chitin be- 

 tween the veins. The position of a vein on one side of a wing 

 seldom corresponds exactly to the position of the same vein on the 

 other side of the wing, and consequently it is difficult to identify 



Fig. 7 Semidiagrammatic drawing of an oblique section through femur, 

 trochanter and coxa of Bombyx mori, showing internal anatomy at this loca- 

 tion in leg, and groups nos. 8, 10 and 11 of olfactory pores, no. 10 being shown 

 partially from a superficial view, X 106. BlSin, blood sinus; Hr, hair, called 

 S. trichodea on antenna; Me, muscle; A'^, nerve; NB, nerve branch; SC, sense 

 cell; Tr, trachea. 



the veins in cross-sections; but after making a study of the 

 serial sections this difficulty was alleviated. The identification 

 of the veins then makes it easy to recognize the groups of pores. 

 The sections illustrated passed through groups nos. 2 and 4 

 on the front wing" and nos. 6 and 7 on the hind wing. The sense 

 cells {SC) lie in thickened portions of the hypodermis and are 

 constantly bathed with blood. The nerve fibers {NF) spread 

 out fanlike from the nerves and unite with the sense cells. It 

 is to be noted that a nerve (iV) and one or more tracheae {Tr) 



