38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 



none on the tarsi. Recently he has more carefully examined the tarsi 

 of six species of butterflies. Xo chemoreceptors were seen on the 

 dark and hair}- tarsi of three species, but on most of the light colored 

 ones of Pontia rapce, Papilio polyxencs, and P. troilus a row of 

 supposedly olfacton.^ pores were observed on each tarsus. They are 

 ver\' plain on the tarsi of the cabbage butterfly (Pontia). A few 

 pores were also seen on the tarsi of the codling moth (fig. 5). If 

 these pores are the only chemoreceptors on the tarsi, it is not con- 

 ceivable how they can detect differences between liquids except by 

 the odors which might be emitted. If the tarsi of butterflies, which 

 are covered with a thick and hard chitin, contain contact chemo- 

 receptors, the mouth parts of insects in general should be provided 

 with such receptors. 



In other series of tests ^^linnich (61 j repeated his former ones 

 and obtained similar results. According to his scheme of measurement, 

 the total response of all the butterflies tested was 100 per cent to the 

 sugar solution used, 84.7 per cent to the quinine solution, and 51.6 per 

 cent to the salt solution. 



In his third report on this subject ^Minnich (62) says that the tarsal 

 sensitivit}- of the butterflies tested to sugar solution may be as much 

 as 256 times that of the human tongue. It is scarcely conceivable, 

 although his carefully planned and admirably controlled experiments 

 firmly convinced him that the feet of butterflies contain sense organs, 

 which, when properly stimulated, are 256 times as sensitive as are 

 the taste organs in our mouths. 



A fourth paper on this subject by Alinnich (65J deals with three 

 species of flies. It was similarly determined that these flies can dis- 

 tinguish water from paraffin oil, or from sugar solution, by use of the 

 chemoreceptors in the tarsi. Chemical sense organs were also located 

 in parts of the proboscis. These organs are more sensitive than those 

 in the tarsi to sugar solution. ^linnich believes that all of these 

 receptors serve as taste organs. Thus, according to these results, taste 

 organs, at last, seem to have. been located on the mouth parts of insects. 



In regard to the so-called taste organs of insects, the writer has 

 repeatedly stated that no one has demonstrated that they actually 

 receive taste stimuli. Minnich ( 66 j says that the proboscis of a 

 certain blowfly is clothed with hairs, some of which are long and 

 curved, and that these have been proven to be taste organs by the 

 following test : A fly, abundantly supplied with water but otherwise 

 starved, does not extend its proboscis when these hairs are touched 

 with a tiny brush wet with distilled water ; but when they are touched 



