EXPERIMENTS. l8l 



b. Several hours later. There was, in no case, any raising of the legs, or purposeful 

 thrusting away movements of the legs on either side, although faint movements of the opposite 

 legs followed a stimulation of the sides of the thorax. 



c. If the hands were placed on the margin of the thorax while the chewing movements 

 were going on, the movements on the stimulated side were inhibited. 



II. Abdomino-thoracic Reflexes. The following results are in marked contrast with the 

 above: 



a. Hand placed on the margin of the abdomen causes raising of the legs of the opposite 

 side, where they are held in a sort of tetanus, as long as the stimulus is applied. When the 

 fingers are removed, they instantly drop back on the carapace. There is no purpose in the 

 movements and it is difficult to understand their meaning. The legs of both sides may be 

 affected, but those on the side opposite to the stimulus are flexed first and to the greater extent. 



III. Leg-gill Reflexes. If the surface of the gills and operculum is touched, the sixth 

 legs at once make vigorous and well directed movements to rub the stimulated spot. If the 

 stimulation is on one side only, the sixth leg of the opposite side moves first and most vigorously 

 The fifth and fourth legs may be, to some extent, involved in the movements. 



The movements of the sixth legs, under these conditions, are remarkable. The ends of 

 the legs are rubbed against each other, and over the surface of the gills, something like the 

 "washing" movements of the posterior pair of legs in a common house fly. 



IV. Gustatory Reflexes. a. Immediately after the operation, stimulation of the jaws 

 with food caused chewing movements of both legs and jaws on the left side, but none on the right 

 Three hours later, however, vigorous chewing movements were produced on both sides. The 

 coxal chewing movements were vigorous and normal, the leg movements greatly exaggerated. 



V. Respiratory Reflexes. Stimulating the gills with clam produced no effect. 



Experiment IV B. 



Twenty-four hours later. Crab still shows remarkable vitality and spontaneity. Made 

 a sagittal cut through the cross commissures of the thorax and right crus, D,II. For a few 

 minutes after the operation, the left legs are very restless and the right are quiet. 



I. Thoracic Reflexes. a. Hand placed on the right margin of thorax produces no 

 reflexes. On left margin, retraction of the left legs. 



II. Abdomino-thoracic Reflexes. a. Hand placed on right margin of abdomen causes 

 slight movements of left legs, none of right. 



b. Hand placed on left margin causes stronger movements than before of the left legs, 

 none of right. 



c. Hand placed on the gills causes violent movement of left legs, none of right. 



III. Gustatory Reflexes. a. Immediately after the operation, no chewing movements 

 could be induced by stimulating the jaws with food. Applying the electrodes to the left jaws 

 caused movements of the corresponding legs, but no movements followed when they were ap- 

 plied to the right jaws. The right legs would not respond to any change of temperature, 

 whether applied directly or indirectly. 



b. One hour later, obtained a faint chewing movement on the left side, on stimulating the 

 jaws with clam; none on the right. 



IV. Respiratory Reflexes. After the second operation, respiratory movements of the 

 gills ceased, and for twenty-four hours no rhythmical movements of the gills could be produced, 

 either by stimulation with clam, or by placing the crab in sea water. But the next morning the 

 following curious facts were observed. The crab was found on its back in the aquarium, 

 just as it had been left the previous day. No respiration had apparently taken place during the 

 night, as the gills were covered with a light sediment. 



a. On removing the apparently dead crab from the water and stimulating the gills with 



