210 Prof. L. Hill, Mr. D. Hargood-Ash, and Dr. J. A. Campbell 



in the vein was the controlling factor, and not conduction hy the skin from 

 tissues affected by the changes in the hand. 



Pain in the hand was intense during the first few minutes if the tempera- 

 ture of the water was below 14° C. This pain may probably be due, in part, 

 to the extreme contraction of the tissues, and disappeared probably because 

 the fluids escaped up the arm from the contracted tissues in the hand, thus 

 relieving pressure. In our metabolism experiments already referred to, we 

 used water warmer than 14° C, to avoid the influence of pain. Pain i& 

 known to raise metabolism. 



In our numerous experiments, with the hand in cold water, we were unable 

 to obtain from day to day constant results for a given range of temperature, 

 probably because so many bodily conditions, e.g., vascular, are variable. 



The double fig. 2 gives the results of an experiment in which the hand was 

 placed in hot water (43 - 2° C), fig. 2, A, recording the change in temperature of 

 bath and control, and fig. 2, B, recording the changes in temperature of the 

 skin over the median vein at the point of the elbow. In this experiment 

 the heat gained by the hand in 20 minutes was 6 kilo-calories, and the rate of 

 gain, after this had become constant, O120 kilo-calories per minute. 



In these experiments with hot water the fall of temperature in the water 

 of the bath was considerably greater during the first minute or so after the 

 hand was immersed, and it was difficult to tell how long this effect, which 

 was probably due to the heating up of the hand, lasted. If this effect 

 was only temporary, and the heat gained depended only upon the tempera- 

 ture of the water, we should expect that different experiments would give 

 curves parallel to each other over the same range of temperature. This, 

 however, did not occur. 



To obtain more certain information on this point it was decided to 

 immerse the hand in hot water as before, but, instead of allowing the 

 water to cool, to supply a constant amount of heat equal to that lost by the 

 water, so that if the heat absorbed by the hand at a given temperature 

 proved to be constant, the experiments could be repeated at different 

 temperatures to obtain a curve. However, the heat absorbed by the hand 

 at a given temperature was not found to be constant, similar variations 

 being obtained as with cold water ; varying bodily conditions were probably 

 responsible. 



We also carried out numerous experiments with the flat-coiled thermo- 

 meter, when the hand as far as the wrist was heated by the summer sun's 

 rays. The temperature of the skin over the median vein was increased 

 several degrees after the hand had been exposed for a few minutes. In these 

 cases the blood in the vein may have been heated in the hand by conduction 



