OLFACTORY SENSE OF THE HONEY BEE 331 



ganglion which is a combination of the mesothoracic, metatho- 

 racic, and the first two abdominal ganglia, innervates the second 

 and third pairs of legs, the bases of both pairs of wings, the meso- 

 thorax, metathorax, the propodeum, and the first abdominal 

 segment. 



The groups of sense cells are so located that they are constantly- 

 bathed in the blood. The large trachea (figs. 15 and 18, Tra) 

 branches profusely, and one of its branches is always near a 

 group of sense cells. There seems to be little connective tissue 

 (fig. 18, ComiT) in the leg of a bee. It appears as fine lines and 

 is found between the tracheal branches and nerves. The large 

 muscles (figs. 15 and 18, M) are so located that they do not 

 interfere with the sense cells while contracting and relaxing. 

 Hence the sense cells are so located that they are constantly 

 nourished by the blood that surrounds them and they receive 

 their supply of air from the neighboring tracheal branches, xllso, 

 the muscles are distant enough not to affect them mechanically. 



At various times while examining the superficial structure of 

 the pores in group 3 on the front wing, peculiar structures which 

 were first thought to be hair sockets were noticed irregularly 

 scattered on the tegulae (figs. 2 and 6, Tg). Cross sections 

 through these apparent hair sockets (fig. 16, L) show that they 

 have the same structure as the olfactory pores. They were ob- 

 served in only a few sections and their sense cells were never 

 seen. On account of the small size of these structures and since 

 their apertures are never distinct, they were at first not consid- 

 ered as olfactory pores, but since they are dentical in structure 

 with the olfactory pores, even if their sense cells were not seen, 

 it is evident that these structures are the external ends of olfac- 

 tory pores. 



Cross sections of stings were made in the same manner as 

 those of the legs and wings, although the slides fail to reveal any 

 sections passing through the extreme end of the lancets. 



Since the superficial appearance of the pores in groups 20 and 

 21 on the lancet (fig. 14, A, F, and G) is identical with that of the 

 pores on the shaft, it may be assumed that the internal anatomy 

 of the pores on the lancet is identical with that of the pores on the 



