TAESAL CHEMORECEPTOES OF BUTTERFLIES 203 



6. Pyrameis and Vanessa are able to discriminate through 

 their tarsi between applejuice and distilled water. Pyrameis is 

 also able to distinguish a 1 M saccharose solution from distilled 

 water and such solutions as 1 M, HCl, M/600 quinine sulphate, 

 and 1 M NaCl from either distilled water or 1 M saccharose. 



7. Distilled water itself, when applied to the tarsi, is a most 

 effective stimulus in evoking the proboscis response. 



8. The responsiveness to stimulation of the tarsi by a given 

 solution, such as 1 M NaCl, for example, may vary widely from 

 one day to another. This variability is undoubtedly conditioned 

 by changing physiological states in the animals. 



9. The removal of the antennae, labial palpi, and rudimentary 

 fore legs in Pyrameis does not affect in any significant way the 

 responses produced through contact chemical stimulation of the 

 tarsi. 



10. One very important role of the tarsal chemoreceptors, 

 perhaps their only role, is in connection with food substances 

 and water. Not only is the animal able to detect the presence 

 and exact location of such substances by means of these organs, 

 but it is also able to make some discrimination as to their nature. 

 The tarsal organs, therefore, appear to function somewhat as 

 organs of taste. 



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