38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 63 



concerning their structure, although since our modern technique of 

 making stained sections was entirely unknown in his time w^e should 

 not expect his drawings to represent the finer anatomy of these 

 pores. He used the following technique : 



After cutting off the wing and washing it well in water or spirits of wine, 

 and draining off the major part by blotting paper, I immerse it in spirits of 

 turpentine for a week or two, after which it is placed in Canada balsam between 

 glass in the normal way, taking care not to heat it, as that renders the nerve too 

 transparent. In those parts which are too dark for observation, I have been 

 enabled to render them colorless by Chlorine. 



In regard to smell in insects and the function of the pores on the 

 legs Hicks says : 



Tlie delicacy with which odours are perceived by many insects argues an 

 olfactory apparatus of considerable perfection; and it seems to me not impos- 

 sible that these latter named organs [those on the legs] may be in som.e way 

 connected with the sense of smell, or perhaps with some sense not to be found 

 in the \'ertebrata. 



To summarize Hicks' three papers, he discovered these pores on 

 the b.alteres and on the bases of the wings of all Diptera examined : 

 on the bases of all four wangs of the four-winged tribes ; on the 

 trochanter and femur of all insects, and occasionally on the tibia. He 

 examined many species representing various insect orders and found 

 these pores even on the lower insects, such as the earwig. In such 

 wingless insects as the worker and soldier ants, he infers that these 

 pores are much more abundant on the legs than they are on these 

 appendages in the winged insects. Hicks suggested an olfactory 

 function for all of these pores, whether on the legs or wings, but he 

 performed no experiments of any kind. 



\\'einland ( 1890) and several others have made a special study of 

 the halteres or balancers of fiies and the sense organs on the bases of 

 these appendages. Weinland distinguishes four kinds of structures 

 on the halteres, all of which are similar in most respects and difTer 

 only in minor details. Their internal anatomy is similar to that of 

 Hicks' vesicles. Of these four structures Weinland calls only one 

 of them Hicks' papillae, and neither he nor anyone else except Hicks 

 and Bolles Lee ( 1885) has ever attributed an olfactory sense to any 

 of the structures on the balancers. 



Guenther (1901) studied the nerve endings found in butterfly 

 wings. He spent a short time on the anatomy of Hicks' vesicles but 

 failed to recognize them as the ones which Hicks first described in 

 1857. Guenther calls them sense domes ( Sinneskuppeln). He de- 

 scribes the external appearance of them as being light spots whose 



