ENERGY-EQUIVALENT OF GROWTHS 



593 



From these results it is clear that an animal gaining 1000 grams 

 in fifty days needs fewer calories for this gain than one gaining 1000. 

 grams in one hundred days, the reason being, as indicated above, that 

 in the former instance the animal needs to be "maintained" for only 

 one-half-as long as the latter. The following are comparable observa- 

 tions made by Aron upon Filipino children: 



From 

 week. 



21 

 26 

 31 



From 

 week. 



4 



9 



To 



Number 



MARIA INOCENCIA. 



Increase in grams. 



Calories. 



week. of days. 



26 



31 

 35 



To 

 week. 



9 

 13 



35 



31 

 28 



From 

 3500 

 3650 

 4225 



to Per day. 

 3600 3 



4225 17 

 4811 21 



MIGUELO PRIEGA. 



Increase in grams. 



Per day. 

 17 

 24 



Number 



of days. From to 



35 3550 4175 



28 4175 4850 



Per day. Per kilo. 



350 to 375 100 to 105 



450 115 to 120 

 500 125 



Calories. 



Per day. Per kilo. 



350 to 400 100 



450 to 475 105 



Hence, during the entire period of the investigation, Maria Inocencia 

 increased in weight at the rate of 14 grams per day and consumed an 

 average of 450 calories per day and 115 calories per kilo. Miguelo 

 Priega, on the other hand, increased in weight at the rate of 21 grams 

 per day and consumed about the same number of calories per day and a 

 considerably smaller number per kilo. 



According to Rubner, the energy consumed per kilo in doubling the 

 Birth-weight of animals is always very nearly the same, excepting in the 

 case of man, namely about 4000 calories. The following data are 

 presented by Rubner in support of this thesis : 



Species. 

 Horse . 

 Cow . 

 Sheep . 

 Hog . 

 Dog . 

 Cat . 

 Rabbit 



Energy-consumption per kilo 

 in doubling the 

 birth- weight. 



. . . 4512 



. . . 4243 



. . . 3926 



. . . 3754 



. , . 4304 



. . . 4554 

 5066 



Man . 28864 



The generalized form of this relationship would be: 



E 



= a log x + b 



where "E" is the energy-consumption, "x" the weight of the animal 

 and "a" and "b" are constants which are the same for all species 

 (excepting man). Doubling of the weight would obviously always 



add an equal amount to the quotient -, that is, to the total energy- 



X 



consumption per kilo. This leads to the differential or velocity- 

 equation : 



dE E 



38 



