Scientific Proceedings (114). 



The cold stimulus was unable to evoke more than a very weak 

 response. This inability to reduce the blood volume and thereby 

 diminish the flow through the body surface helps to account for 

 the very rapid loss of body temperature. In the second cord dog 

 the regulation appeared somewhat better; this experiment was, 

 however, performed seven days after operation instead of one or 

 two days, as in the other experiments, and there may have been 

 time for some readjustment of the development of the mechanism. 

 This increase in blood solids from 18.1 to 18.9 per cent, in forty 

 minutes did not, however, suffice to prevent the rapid fall in body 

 temperature. 



Dogs made poikilothermic by cervical cord section are deprived 

 of reactions which may be set up between the temperature sense 

 nerve endings and the circulation. The shifting of water from 

 the blood to the tissues is evidently such a reaction. It is therefore 

 concluded that the r61e of the nervous system in the reaction 

 against cold is to convey impulses from the temperature sense 

 nerve endings to "heat centers" which in turn, besides shivering 

 and vasoconstriction, incite blood thickening. Hemo-concentra- 

 tion lessens the water available either for heat dissipation by 

 evaporation or for providing blood bulk enough to flood the 

 peripheral vessels. 



92 (1674) 



The effects of environmental temperature changes upon blood 



concentration. 1 



By H. G. BARBOUR. 



[From the Department of Pharmacology, Yale University School of 



Medicine.] 



Experiments upon normal dogs, kept at rest in hot and cold 

 baths up to the neck, have shown regular changes in total blood 

 solids. Blood solids were determined simply by weighing a sample 

 of 15-16 drops shed freely from the ear vein and drying to 

 constant weight. 



Exposure to hot baths for various intervals is illustrated by 

 Table I, to cold baths by Table II. 



1 From investigations aided by the Elizabeth Thompson Science Fund. 



