J. W. Capstick and T. B. Wood 267 



this anomaly except on the grounds that the experiment at 16'9" was 

 unsatisfactory throughout. The hog was scarcely ever really quiet 

 throughout the whole fasting period with the result that the galvano- 

 ■ meter curve was less regular than usual. It should be noted that errors 

 due to the hog would almost certainly cause the observed metabolism 

 to be too high, whilst experimental errors would be indifferently high 

 and low. There was also an instrumental failure on the last day of the 

 16'9' experiment. One of the electrical heaters in the thermostat burnt 

 out and there was a great disturbance of the curve before the fault 

 could be remedied. 



The remaining points however are sufficiently consistent to enable 

 the writers to state that the critical temperature is very near to 21° C. — 

 remembering, however, what has been stated above, that the real average 

 temperature of the hog's surroundings may be somewhat different. 



This conclusion agrees very well with that reached by Tangl who 

 states that he found the critical temperature to be between 20° and 23°. 



The actual metabolism at the critical temperature is I'SO calories 

 per minute for a 300 lb. hog or 2,160 calories per day. 



The exact relation between a hog's surf;\ce area and his weight is 

 not known. Tangl accepts Voit's formula A = 9-02 IF". This gives 904 

 calories per day per square metre, which is near the value generally 

 adopted for human beings. 



The values of the basal metabolism at different temperatures have a 

 practical interest for pig breeders as they enable us to calculate the 

 maintenance ration at various temperatures. 



Table III gives the metabolism of a 300 lb. hog at intervals of 2° 

 from 0° C. to 22° C. The metabolism between 10° and 20° is taken from 

 the full curve in Fig. 4. Actual observations of the metabolism could 

 not be made at very low temperatures as the temperature of the town 

 supply water did not permit of the calorimeter being set to anything 

 below 10°. In order to get an estimate of the metabolism below 10° it 

 is therefore necessary to use the uncertain expedient of extrapolation. 



