SECT. 7] OF EMBRYONIC DEVELOPMENT 971 



by cultivating it on a medium of abnormal pH, but in the case of 

 the chick embryo no such interference with the normal course of 

 events is possible. In 1927 I made some exploratory calculations, 

 using Meeh's formula and Rubner's constant. The calculation could 

 evidently not be exact, because we do not know how these quantities 

 vary during the embryogeny of the chick. The relevant figures are 

 shown in Tables 123 and 124. 



In Table 123 the calculated surface of the embryo is obtained 

 according to the formula : 



s - K\^m, 



where S is the surface, K Rubner's constant for the chicken, 

 10-4, and W the weight taken from Murray's data, and Voit's figure 



Table 123. 



calories 



evolved Total calories evolved 



Surface of the embryo in basal (Bohr & Hasselbalch) 



^ '■ ^ metabolism ,• '^ ^ 



Total Daily in- Daily in- Output Daily in- 



sq. mm. crements elements per day crements 



123456 



Day o — __ t 



1 — _ _ Heat _ 



2 — absorbed 



3 100-5 



198 

 380 

 586 



4 '9» 182^ i?2 24 24. 



^ 3BO 1% ^ 4 It 



' ^^ llo If, - fe 



5?o tst 11^ llo 



" 2'5io =70 =ci7 396 1^6 



3,080 570 537 156 



^3 3,750 ^ g^g 780 



H 4,490 74 y ,001 



'5 5,290 860 111 ^240 2^y 



ID 0,150 — 



''- I'Z 980 924 \f,: 250 



^''^"^ '.040 981 710 ,^„ 



19 9,280 -3 ,^-; i960 



20 10,700 



o 1050 -g 200 



420 1350 — 



Total 10,599 



of 0*943 cal. per sq. mm. surface for the chick's basal metabolism 

 is accepted. Col. 4 represents the quantity of inevitable loss on the 

 weight of embryo formed each day. Now if the number of cal. evolved 



