64 DWIGHT E. MINNICH 



EXPERIMENTS WITH LOCAL STIMULATION OF INDIVIDUAL TARSI 



Three butterflies were kept for five days after hatching with- 

 out access to food or water. At the close of this period, they 

 were subjected to a series of trials in which various chemical 

 stimuli were applied locally to individual tarsi. The stimuli 

 were applied on small cotton swabs ca. 1 cm. long and 1 to 2 mm. 

 in diameter, the swab consisting of a bit of absorbent cotton 

 wound on the end of a dissecting needle. Care was exercised to 

 keep the cotton chemically clean while being handled. As a 

 further precaution, swabs used to test the effect of dry cotton 

 alone were heated prior to each experiment, in order to drive off 

 any excess moisture. 



The butterfly to be tested was placed in a holder (fig. 2) with 

 the four ambulatory feet resting on a small platform of wire 

 screen. In this position, the specimen was closely observed for 

 one minute, this constituting the preliminary trial. In no case 

 was any sign of response observed. Immediately following the 

 preliminary trial, a dry cotton swab was appUed to the ven- 

 tral surface of the distal end of the ambulatory tarsus which 

 it was desired to test. Except for a very few partial extensions 

 this also failed to elicit any response. The dry swab was then 

 replaced by a swab saturated with distilled water, and to this the 

 animal almost invariably responded. Upon completion of the 

 trial with distilled water, the specimen was returned to its cage 

 for a minimum interval of fifteen minutes, after which another 

 tarsus was tested in the same manner. This procedure was con- 

 tinued until each of the four ambulatory tarsi had been tested 

 twice. 



On completing the trials described above, the butterfly was 

 placed on absorbent cotton saturated with distilled water, where- 

 upon the proboscis was immediately extended. In this situation — 

 presumably drinking in water continuously — it was allowed 

 to remain as long as it would. After two or three minutes, how- 

 ever, the proboscis was recoiled, and the animal either crept 

 away or was removed. Some minutes later, it was replaced on 

 the wet cotton, and thus given a second opportunity to drink, 

 but in no case was there any response. 



