SECT. 4] HEAT-PRODUCTION OF THE EMBRYO 



737 



and when divided by the estimated surface area of the mother, the 

 calories per square metre of body-surface for mother alone were 

 practically the same as those found by the other method. But they 

 were not quite the same, and the difference between them was always 

 greater towards the end of pregnancy than at the beginning — a fact 

 for which Sandiford & Wheeler offered no explanation, but which 

 may be due to the fact that 

 the heat-production per unit 72 



time per unit mass of foetal 

 tissue is probably not the 

 same throughout develop- 

 ment. The general trend of 

 all that has already been said 

 works strongly against the 

 assumption that it is. The 

 various curves which have 

 been mentioned are shown 

 in Fig. 1 64 taken from Sandi- 

 ford & Wheeler's paper. 

 Curve A represents the calo- 

 ries for each kilo (in this in- 

 stance not rising very much) , 

 curve 5 the basal metabolic cd -io 

 rate calculated during the -2 0.94 

 course of pregnancy by t ^_^^ 

 dividing the total calories 

 put out each hour by the 

 sum of the surface areas of 

 mother and foetus, and com- 

 paring the result obtained 



with the Dubois normal of the mother, 36-5 calories. Curve B' shows 

 the basal metabolic rate calculated in the usual way, using the Dubois 

 surface area and the normal standards. Curve C shows the calories 

 per square metre per hour calculated in the same way as for curve B, 

 and curve C shows the calories per square metre per hour obtained 

 by dividing the total calories each hour by the Dubois surface area 

 obtained by using the total weight of mother and foetus in the usual 

 manner. Curve D represents the total calories per hour eliminated, 

 i.e. the raw data of heat given up to the calorimeter. 



.5? 1.68 



og 

 ro-e64 

 " 1. 

 ■5g.60 



f2 56 



52 



I1.38 

 s_ o 



+ 10 



0-78 



^ 6 8 10 2 4 

 Lunar months 



Fig. 164. 



