28 WILLIAM PATTEN. 



olfactory organ, although there can be no doubt about the 

 character of the response when it does occur. For example, 

 some males would never respond, although repeatedly stimu- 

 lated at diflFerent times. Others would respond immediately 

 and at almost every stimulation. There was one male upon 

 which stimulation had at first no effect, but which responded 

 beautifully a short time after its mandibles had been stimu- 

 lated into action by rubbing clam upon them. Another would 

 not respond at first, but did after it had lain on its back in 

 the air for two or three hours. Again, it might happen that 

 repeated stimulation produced at first no eflfect, when sud- 

 denly the characteristic movements of the second pair of legs 

 and the chelicerse would begin of themselves. Subsequent 

 stimulation, however, failed to reproduce this response, al- 

 though the animal would start whenever the electrodes were 

 applied, showing that the current had passed through the 

 cuticula into the underlying tissue. 



It is also a curious fact that persistent stimulation of both 

 sides will sometimes produce the characteristic leg movements 

 on one side only; then suddenly both sides, or perhaps the 

 opposite side alone, respond. When the mandibles were 

 shaved or amputated on one side, the opposite side usually 

 responds first on stimulating the olfactory organ. 



In one female, in which all the mandibles of the right side 

 were amputated, stimulation of the olfactory organs produced 

 sudden raising of the second to the fifth legs on the left side, 

 and forcing of their tips toward the mouth ; the movements 

 of the second leg were most marked. The legs on the right 

 side remained motionless. This is t\\e nearest approach I 

 have seen in the female to the movements so characteristic 

 of the male under the same circumstances. In every other 

 case that came under my observation (at least 

 twenty) stimulation of the olfactory organ of the 

 female produced only slight starts of the legs and 

 abdomen. 



These experiments point toward a double function of the 

 olfactory organ. The reflex chewing movements indicate its 



