l8o FUNCTIONS OF THE BRAIN. 



prolonged violent movements during which they are convulsively flexed, and the tips thrown 

 repeatedly toward the mouth. The right legs, meantime, becoming quiet. 



h. As soon as the crab had quieted down, the experiment was repeated, but with the ut- 

 most care not to produce too violent a stimulus. The little puffs of warm air could be so regu- 

 lated as to cause the left legs to move, while the right remained motionless. The experiment 

 was repeated many times with the same results, showing that the left side reacted much more 

 readily than the right. 



V. Respiration. — a. August 7. When at rest in the air, the gills are twisted toward the 

 left, the left gills tighdy compressed, the right ones slightly elevated. At first there was a tend- 

 ency for the left gills to move spontaneously in rhythmical respiratory movements. A week or 

 two later, the right gills frequentiy performed the normal yawning movements, or the normal 

 respiratory movements, the left gills remaining motionless. 



b. Placed in water, normal respiratory movements begin at once, except that the left gills 

 are raised higher than the right. 



c. August 26. Crab still vigorous. Repeat a and h with same results. 



d. August 27. Stimulation of gills with clam, or finger tips, does not induce respiratory 

 movements. 



VI. Equilibrium; Locomotion. — a. August 7. Crab rights itself repeatedly when placed on 

 its back in the aquarium. When righted, it constantly moves in a circle toward the left with 

 right side raised high on the legs, the left side depressed. The caudal spine turned to the 

 right, at an angle of about 20°. The crab, when righted, circulates to the left, because the 

 right legs alone make the motor movements. The circular movement continues for hours at a 

 time. August 27, condition same as a. 



b. August 7. On removing the crab from the water and placing it on its back, the left 

 legs move restlessly and aimlessly, often bending the tips into or toward the mouth. Movement 

 continues for more than an hour, liight legs remain quiet, but may move vigorously if properly 

 stimulated. 



c. At certain intervals, when in the air, all the right legs swing in unison forward, and then 

 with a vigorous stroke backward. The forward and backward movements are repeated many 

 times with great regularity, precisely as in swimming, except that the gills did not join in the move- 

 ment. The left legs never made these characteristic movements. 



d. August 19. In water the crab sometimes fails to right itself. In such cases, the swim- 

 ming movement of the right legs may continue for hours with great regularity, but without 

 sufficient force to move the animal about. The left legs are meantime passive. 



e. August 25, same conditions described in c and d are retained. 



VII. Autopsy. — August 27. Three weeks after the hemisection of the brain the crab was 

 alive and vigorous. On removing the brain, it was found that all the parts about the wound 

 were thickly incrusted with a granulated matter, which when removed showed the cut surfaces 

 of the commissures and of the crura to be very little changed. There was no indication of degen- 

 eration, or regeneration of the surrounding parts. There was a thick deposit of sepia colored 

 pigment about the wound in the forebrain. The cotton plugs were incrusted with a granular 

 matter, and they apparently had not interfered by pressure or otherwise with the action of the 

 nervous system. 



Experiment IV — A. 



August 25. Large female. Cut both crura in front of the second thoracic appendage. 

 (Fig. 113, D.T.) Immediately after the operation, the left legs moved restlessly, the right 

 remained quiet. 



I. Thoracic Reflexes. — a. Immediately after the operation, no definite crossed or un- 

 crossed thoracic reflexes could be obtained by warming the sides of the thorax in the usual way. 



