190 D WIGHT E. MINNICH 



the animal was held very close to a substrate of wet cotton and 

 the leg was greatly extended, was more of this segment affected. 

 Clearly, therefore, the sense organs under consideration must 

 be located in that part of the leg comprising the distal end of the 

 proximal segment of the tarsus and the four distal segments of 

 the tarsus. 



h. Local stimulation of tarsi. In order to verify further the 

 location of the cheyioreceptors under consideration and the 

 nature of the stimulus effective for them, the following experi- 

 ment was performed. A butterfly was placed in a holder as 

 shown in the photograph reproduced in figure 5. The substrate, 

 however, consisted of a small screen platform mounted on wood, 

 instead of that shown in the figure. Between the legs of one side 

 and close to the animal's body, a pin was stuck into the wood 

 to limit the range of the leg movement as much as possible. 

 Local stimulation was then applied by means of a needle bearing 

 on its end a small cotton swab, 1 cm. long and 0.1 cm. in diameter, 

 soaked in applejuice. 



The swab was first held 1 mm. anterior to the proboscis. 

 If the animal failed to respond in one minute, as it always did, 

 the swab was shifted to a position 1 mm. from the ventral 

 surface of one of the tarsi. Here it was also held for one minute 

 or until a response occurred. If no response occurred in one 

 minute, the swab was placed in contact with the tarsus. I 

 endeavored to maintain the swab in continuous contact with the 

 tarsus and to confine the contact to the four distal segments. 

 Movements of the leg, however, frequently prevented the reali- 

 zation of these conditions. Thus, contact might be lost for an 

 instant or the proximal segment might make contact wdth the 

 swab. But the tibia was kept free from any contact stimulation. 



Three butterflies were experimented upon, and, with one 

 exception, two trials were made on each of the four ambulatory 

 tarsi of each specimen. The total number of trials for each 

 position of the swab was thus twenty-three or twenty-four. 

 The butterflies were the same specimens that had served in 

 experiment 2, table 1, and experiment 2, table 2, in the course 

 of which the antennae, labial palpi, and rudimentary fore legs 



