740 



THE RESPIRATION AND 



[PT. Ill 



indicated on Fig. 1 66 a by the small crosses, so that in this other breed 

 the peak, if there was one, occurred before birth. That there had been 

 one Wood had no doubt, for if the curve had been simply continued 

 in an upward direction with decreasing age, the embryo of a few 

 grams would have been radiating heat to the intensity of a red-hot 

 body. The descending metabolic rate curves must, indeed, in all 

 cases, come from a peak, and not from some indefinitely high level. 



80 



70 



a 60 



s 



a- 



K. 50 



40 



30 



Subsequent work by Deighton on other breeds of pigs has carried 

 further the work reported in Wood's paper, and has demonstrated 

 that in some cases the peak occurs after birth, in other cases, before 

 it. Russell, who hoped to find an extra-uterine peak in the rabbit, 

 which is born relatively early, and an intra-uterine peak in the 

 guinea-pig, which is born relatively late, found a curve for the 

 former animal which resembled that of the Berkshire pig. Ginglinger 

 & Kayser, however, did succeed in finding such a post-natal peak in 

 the case of the rabbit, as may be seen from Fig. i66 ^. They contrast 

 the curves given by the pigeon (showing neither chemical nor physical 

 heat-regulation at birth) with the rabbit (which shows chemical regu- 



o 



o 



o 



o 



X 



J-— i^— — — ~ 



/ X ^^^^. 

 ^ ^^~^ ^^^:»- 



X " ^ - .^^ _ 



