38 WILLIAM PATTEN. 



ever of the appendages back of the section, and only feeble 

 movements of those on the same side in front of it. On plac- 

 ing the hand on the right side, however, all the legs on that 

 side were immediately set in motion, and continued to 

 move as long as the hand was held there, but they 

 ceased immediately the hand was removed. These 

 results could be produced repeatedly without any perceptible 

 variation. After eighteen hours, during which period the crab 

 had lain on its back on a table without attention, the reaction 

 was less vigorous, but still very prompt and decided. There 

 was no movement of the mandibles after this period in response 

 to stimulation of the gustatory spines. Unfortunately I did not 

 try this at an earlier stage; neither did I try, as I should have 

 done, heat stimulation of the appendages back of the section 

 in the left crus. These experiments are sufficiently definite, 

 however, as regards the course of the temperature impulses, 

 for they show that, starting in the cephalo-thorax, they 

 travel inward along the haemal nerves to the corre- 

 sponding crus, which they ascend to the fore-brain ; 

 from there they must descend along both crura to the 

 pedal nerves. 



If, as seems probable from this experiment, the temperature 

 centre is somewhere in the fore-brain, we ought to be able to 

 destroy all temperature reflexes by cutting both crura close to 

 the brain. This is very nearly what takes place, as shown by — 



Exp. E. — In this specimen both crura were cut completely 

 across, just back of the second pair of appendages. There was 

 much loss of blood, and all the reactions were feeble. The 

 only spontaneous movements were those of the chelicerse and 

 second pair of appendages. Five hours after the operation no 

 response could be produced by heat stimulation of the sides of 

 the cephalo-thorax, but feeble movements of the legs 

 could be produced by breathing on them directly. 

 Tliese experiments indicate the existence of subordinate 

 temperature centres in each crus (see also experiment on 

 amputated chelae, p. 16), and prove that the main tempera- 

 ture centre is located somewhere in the fore-brain. 



