64 HOMOIOTHERMISM 



the left "heat center" is more strongly developed than 

 the right in the rabbit. Barbour and Prince (1914) 

 found that local applications of heat to the heat center 

 caused diminution in the production of carbon dioxide 

 and in the consumption of oxygen. Cooling the center 

 reversed these effects. 



Effects of Decerebration and Spinal Cord Sections on 

 Thermoregulation. — The importance of the brain on heat 

 regulation has been demonstrated by the removal of the 

 cerebrum. Eogers (1919) has shown that the ability to 

 regulate body temperature is lost in decerebrate pigeons 

 when the optic thalamus has been injured. Freund and 

 Strosmann (Barbour, 1921) sectioned the cord at 

 various levels and found that, while normal rab- 

 bits withstood environmental temperatures of 6 to 31 

 deg. C. with no appreciable change in body temperature, 

 those with the cord sectioned were poorly regulated. 

 Eabbits which had the dorsal cord sectioned, could regu- 

 late their temperature fairly well between 18 and 31 deg. 

 C, but were ineffective beyond those limits. In rabbits 

 with the cervical cord sectioned a poikilothermal condi- 

 tion obtained in environments varying from 19 to 33 

 deg. C. Freund (Barbour, 1921) has found more recently 

 that if in addition to the dorsal cord operation a double 

 vagotomy just below the diaphragm is performed an 

 animal becomes poikilothermic to essentially the same 

 extent as those with the cervical cord transsected. He 

 concludes that this is likely due to the severance of the 

 sympathetic fibers. 



Garrelon and Langlos (Barbour, 1921) suggested a 

 "polypnea center." In corroboration of that idea Nico- 

 laides and Dontas (Barbour, 1921) have found that heat 

 polypnea cannot occur if the medulla is separated from 



