EXPERIMENTAL STUDIES ON THE THALAMUS 29 



nystagmus has disappeared. (This, however, may be more 

 apparent than real, because of the smaller amplitude of the 

 movements of the eye as compared with those of the head.) 



d. Intersegmental reflexes persisted until the body tempera- 

 ture fell to 33° and disappeared at 31°. 



e. The typical spread of reflexes was obtained with a body tem- 

 perature of 33°. 



/. Inhibition of the preening reflex by mechanical vibrations 

 of the wall of the cage was elicited at a body temperature of 32°. 



In order to illustrate these changes a series of four photographs 

 are inserted to show the influence of these temperature changes 

 on the equilibratory mechanism. These photographs were made 

 at two-hour intervals, from the same bird at body temperatures 

 of 33°, 26°, 22°, and 39°. 



6. Sections of the brain stem are figured in this bird which had 

 lost the power of maintaining its body temperature. Destruc- 

 tion of the cerebral hemispheres and major part of the thalamus 

 abolishes the ability to maintain and regulate a normal body 

 temperature. 



