NO. 2 RECOGNITION AMONG INSECTS McINDOO 47 



parallel ridges. The chitinous layers of the two surfaces are held 

 in place by many chitinous supports. The peduncle of the scale is 

 hollow and its cavity is connected with those between the chitinous 

 supports. According to his drawings the above characteristics hold 

 good for both the ordinary scales and scent scales. 



Leoni (1898) observed that Pier is napi and Colias hyale emit a 

 delicious odor from the dorsal surface of the wings, 



Kohler (1900) does not attribute a great significance to the scent 

 scales, because while present on the wings of 78 species of Lyccena, 

 they are wanting in 32 species of the same genus. He also says that 

 the name androconia is not appropriate, because he has observed a few 

 scent scales in a female belonging to this genus. 



Guenther (1901) found that some of the scales on the wings are 

 innervated while others are furnished with gland cells, however, he 

 believes that all of the scales are probably innervated. 



Illig (1902), who has prepared a comprehensive monograph on the 

 morphology of the scent-producing organs of insects asserts that the 

 peduncle of each scent scale arises from a flask-shaped socket in 

 which the neck of the flask is quite wide. The inserted end of the 

 peduncle is open and it extends through and slightly beyond the bot- 

 tom of the flask. A large gland cell lies just beneath and against 

 the base of the flask. Many chitinous ridges running parallel the 

 full length of the scale lie on the dorsal surface, whereas the ventral 

 surface is smooth. The two sides of the scale are firmly held in 

 place by many chitinous supports. The interior of the peduncle and 

 the cavities between the supports are filled with a netlike contents or 

 matrix. In the feathered type the scales are tipped with hollow hairs 

 while in the other types myriads of small pores are found between the 

 parallel ridges. These pores run through the chitinous layer and 

 communicate with the internal matrix. The secretion from the gland- 

 cell passes through the matrix in the peduncle and into the matrix 

 which fills the cavities between the supports, then it slowly but 

 gradually finds its way to the exterior, either through the hollow 

 hairs at the tip or through the pores which are widely distributed 

 over the dorsal surface of the scale. 



Freiling (1909) has also carefully worked out the finer anatomy 

 of various scent-producing organs of insects. The large gland cell ' 

 at the base of each scent scale has a conspicuous nucleus, many 

 vacuoles and some of them have a reservoir. From the reservoir runs 

 a canal to the base of the peduncle where the secretion passes through 

 definite canals through the matrix of the peduncle into the matrix 

 4 



