MOEPHOLOGY OF BRAIN AND SENSE ORGANS OF LIMULUS. 11 



shows that the reflex in each leg and mandible is due solely to 

 the stimulation of its own gustatory organs^ and that it is 

 entirely independent of the reflex in the adjacent appendages, 

 either of the same or opposite side: this, however, does not 

 apply to the chelicerse. 



(4) If the shaved mandibles be rubbed on their outer ante- 

 rior surface, movements are rarely produced ; but they are 

 fairly well marked whenever a piece of clam is touched against 

 the smooth concave surface of the inner mandible (fig. 3,^. b.). In 

 performing this experiment, the shaved orunshaved mandible, 

 it is immaterial which, is gently raised with a pair of forceps, 

 care being taken not to touch the animal with the fingers, and 

 a very small piece of clam rubbed on the smooth surface in 

 question. Immediately the inner mandible is retracted by the 

 muscle shown in fig. 3, m. i. m., and then the whole mandible 

 begins its rhythmic movements. This proves that, besides 

 those organs in the spines, the smooth inner surface 

 of the inner mandible contains a second set of 

 gustatory organs, which when stimulated produce 

 reflex chewing movements. 



(5) The results of the following experiments may be stated 

 in this way : — Destroying a certain number of gustatory organs 

 in one or more mandibles suspends the reflex in the mutilated 

 appendages. The reflex may be partially restored by destroy- 

 ing a corresponding number of sense organs in each of the 

 remaining mandibles. 



The following experiments were performed successively on 

 the same individual : — (a) A healthy crab that was known to 

 be very sensitive to gustatory stimulation was deprived of a 

 part of its gustatory organs by shaving off" all the gustatory 

 spines on the mandibles of the right side. Ten days after, on 

 equal stimulation of both sides, the shaved appendages 

 remained perfectly motionless, while the unshaved 

 ones began the normal chewing movements. But the 

 shaved mandibles could be made to act when vigorously stimu- 

 lated, {b) When the mandibles on the left side also were 

 shaved, the reflexes were impaired for some time. However, 



