EXPERIMENTS. 179 



This animal was then used for the following successful experiment. At the time the second 

 operation was made, the crab was in such good condition and its normal action had been so 

 little altered that it was not felt that confusion might result from this attempt to economize 

 material. 



Experiment III B. 



The second operation was performed August 6, 5 P. M. The autopsy, three weeks later, 

 showed that the left crus was sectioned close to the spinal cord, and all the thoracic cross com- 

 missures severed. (Fig. 113, C.I.) At the anterior end, the left crus was cut so that a small piece 

 of the left cerebral hemisphere remained attached to it. But only a very few cerebral cells, if 

 any ; could have been connected with the crus. 



I. Gustatory Reflexes. a. Immediately after the operation, the chewing reflexes were 

 inhibited. Five minutes later, excellent reflexes, including the chelicerae, were obtained on 

 both sides; but the two sides were not coordinated. 



b. August 7, 9 A. M. On stimulating right jaws with clam, obtain prompt and vigorous 

 chewing movements of the jaws, but with moderate, or normal chewing movements of the legs. 



On stimulating left jaws, obtain at first the same results, but the leg movement gradually 

 grows more energetic till it is absurdly exaggerated in rapidit^ and range, and finally becomes 

 much confused, the legs moving wildly back and forth, and often clashing with one another. 

 This rapid movement may be followed by a spasmodic bending of the tips of two or three ap- 

 pendages into the mouth, where they are held in a trembling tetanus or rigor. All the left legs 

 are involved in this movement, except the left chelicera, whose nerve was cut a short distance 

 from the brain. 



Repeated these experiments several times on August 10, 14, and 26, obtaining in each case 

 essentially the same results. 



II. Thoracic Reflexes. a. August 7. On placing the fingers on the left side of the 

 thorax, there is no response, and if the left legs happen to be making the chewing movements, 

 the latter are not in the least disturbed. 



b. Later. Fingers placed on the posterior, ventral surface of the left side cause no move- 

 ment beyond a slight start when the contact is made, and uneasy opening of the chelae. But 

 on touching the anterior quarter of the ventral surface, rapid movements of the second and 

 third left legs are produced. These movements at first do not last long, and are inconspicuous 

 when compared with the movements that may be produced on the opposite side. But on the 

 following days they became distinctly purposeful, repelling movements. 



c. August 7. On placing the hand on the right ventral side of the thorax, all the right legs 

 move furiously back and forth in unison, while the left continue their chewing movements as 

 before. 



d. August 10. Hand placed on the right side of thorax causes active, purposeful thrusting 

 away movements of the right legs. 



e. August 25 and 27. Repeated a, b, and d, with same results. 



III. Abdomino-thoracic Reflexes. a. Placing the fingers on right margin of abdomen 

 caused back and forward movements of all the right legs (except chelicera) and with very 

 marked thrusting away movements of the sixth leg. No movements of the left legs. 



b. Hand placed on the left margin caused obscure movements of the right legs. 



c. Hand placed on either side of the margin of the abdomen caused faint, rhythmical con- 

 tractions of the gills of both sides, but movements of the right gills are the strongest. 



d. August 26. Repeated a, b, and c, with same results. 



IV. Temperature Reflexes. a. August 25. On breathing gently on the ventral surface 

 of the quiescent crab, that had been lying on its back in the air for some time, a general muscular 

 spasm is instantly produced. All the legs are waved about, but the left legs are thrown into 



