1914.] NATURAL SCIENCES OF PHILADELPHIA. 295 



the olfactory organs; and (3) to determine morphologically the 

 relative sensitiveness of different species of Hymenoptera to odors. 

 The study of the behavior of normal ants and hornets under experi- 

 mental conditions is used as a basis for correctly interpreting the 

 observations on these insects made abnormal for the purpose of 

 obtaining data which concern the first two objects in view. 



Many entomologists have had something to say about the seat of 

 the organs of smsU in insects, but most of the views are purely 

 speculative. A few have done extensive and thorough experimental 

 work to determine the location of this sense. However, since they 

 have failed to study sufficiently the behavior of the insects investi- 

 gated, the responses observed have misled them in determining the 

 seat of the olfactory organs. It is now generally believed that the 

 antennae bear the organs of smell, but as all the antennal organs are 

 coverecl with a hard membrane the objection has been raised that 

 such organs cannot receive olfactory stimuli. Hicks (1857) dis- 

 covered some peculiar organs on the bases of the wings and on the 

 legs of insects and suggested that they have an olfactory function. 

 The writer (1914) made a comprehensive study of these organs in 

 the honey bee. He experimentally proved that they have an olfac- 

 tory function and for this reason called them olfactory pores. The 

 present paper embodies the results of a comparative study on 

 Hymenoptera in much the same manner as pursued on the honey bee. 



To obtain material for the study of the disposition of the organs 

 described by Hicks, adult specimens were used. The legs and wings 

 were pulled off at their articulations, and the thoraces and abdomens 

 Avere slit open. These parts were put into a cold saturated solution 

 of caustic potash, where they remained one to three days, depending 

 on the size of the material. When removed from this solution the 

 material was washed thoroughly in water and then was decolorized 

 with chlorine gas in the following manner: A small quantity of 

 potassium chlorate was put into a small wide-mouthed bottle. All 

 the parts belonging to a specimen were loosely wrapped in a small 

 piece of cheesecloth which was suspended in the neck of the bottle. 

 Then a pipetteful of hydrochloric acid was dropped upon the 

 potassium chlorate in the bottom of the bottle. At once chlorine 

 gas was liberated which soon bleached the dark colored specimen. 



To obtain material for the study of the internal anatomy of the 

 organs herein discussed, pupal insects were mostly used. The 

 appendages and bodies of the pupae were cut into small pieces, which 

 were immediately dropped into Carnoy's fluid (equal parts of abso- 



