622 



JOHN E. MUKLIN 



not given satisfactory results. In pregnancy the extra metabolism due 

 to the product of conception includes the energy used by accessory struc- 

 tures as well as by the fetus itself. Nevertheless, it is worth while to 

 estimate the difference particularly with a view to determine whether any 

 material change in energy relations occurs at the moment of parturition. 



With the dog Murlin(c) was able to show that the extra heat production 

 of mother and offspring just before parturition was very nearly propor- 

 tional to the weight of newborn pups delivered three days later. It was 

 impossible to record the metabolism nearer to parturition than this on ac- 

 count of the restlessness of the dog. Quite fortunately it happened that 

 the same dog gave two litters, one consisting of a single, the other of five 

 pups. Comparing the total metabolism on the third day before parturition 

 in the two pregnancies with that of the dog in sexual rest after lactation 

 had been stopped, it was found that the extra energy metabolism at the 

 culmination of pregnancy for^the one pup'was (551.3 505.3 =)46 cal- 

 ories or 164 calories per kilogram of the single newborn pup; and 

 (7.63.8 505.3*=)258.5 calories or 165 calories per kilogram for the 

 five new-born pups. In other words, the extra metabolism was very 

 nearly proportional to the weight of the newborn. 



46 Cal. :' 258.5 Cal. : 280 gm. : 1560 gm. 



It should be emphasized that the temperature of the cage was the same 

 on the several days compared, that the mother dog was trained to lie per- 

 fectly still, and finally that the diet was exactly the same in weight and 

 composition on all these days. 



It is interesting to observe that the extra metabolism necessary to 

 maintain the embryo (and all accessory structures of the mother's body) 

 at a time when the pregnancy is at its highest phase is very nearly equal 

 to the amount which the newborn of the same weight would theoretically 

 produce (according to the law of skin surface), the first day after delivery, 

 if exposed to ordinary room temperature and if resting (Murlin(c) ). 



If the law of skin surface is applicable to the embryo and the new- 

 born, as Eubner believes it is, we may conclude that the metabolism of 

 the uterus, mammae, etc., would almost 'exactly compensate for the differ- 

 ence between the metabolism of the newborn at room temperature and 

 the metabolism of the embryo at the temperature of the mother's body. 

 In other words, the curve of total metabolism of mother and offspring 

 would scarcely suffer any interruption at birth, if mother and offspring 

 after birth could be kept sufficiently quiet for the demonstration. If this 

 generalization should be true of the human mother and her offspring it 

 would be a matter of considerable interest and importance. 



To secure proper conditions for this inquiry, the problem was taken 

 to the Nutrition Laboratory of the Carnegie Institution in Boston, where 

 a bed calorimeter had been perfected large enough to contain mother and 

 child (Carpenter and Murlin). Three subjects were studied. The metab- 



