922 GENERAL METABOLISM [pt. iii 



Cols. 5 to 9 deal with the egg as a whole. Col. 5 gives the apparent 

 protein nitrogen in the whole egg for the intermediate periods; it is 

 obtained by considering the period "5th-to-6th-day", for instance, 

 as if it were 5-5 days, and taking the average of the values for the 

 5th and 6th days. Col. 6 performs an exactly similar service for the 

 true protein nitrogen in the embryo. It will be clear that, since 

 Col. 5 is for the whole egg, the subtraction of Col. 6 from it will give 

 figures for the remainder, the non-embryonic part of the egg. The 

 result of doing this is shown in Col. 7, which represents the protein 

 nitrogen in the remainder of the egg for the intermediate periods, 

 corrected for the lipoid nitrogen outside the embryo, but still in- 

 cluding the false protein nitrogen inside the embryo. Cols. 8 and 9 

 perform this final adjustment. Col. 8 shows the lipoid and purine 

 nitrogen inside the embryo, calculated for the intermediate periods, 

 and Col. 9 the true protein nitrogen in the remainder of the egg 

 at any given moment during development. 



Cols. 4 and 9 are now the ones on which attention must be focused. 

 If Col. 4 is expressed as a percentage of Col. 9, we shall be finding 

 what 100 mgm. of true protein nitrogen outside the embryo hand 

 over during each interdiurnal period to the embryo. We shall have 

 the milligrams absorbed each day in percentage of what each day 

 remains to be absorbed. 



It is clear from a summary inspection of the figures in Col. 10 that 

 this value is not very illuminating. It only shows the gradual in- 

 crease in size of the embryo. But if now this value is expressed as 

 percentage of wet and dry weight, we shall be calculating what 

 100 mgm. of protein nitrogen hand over to 100 grams of embryo 

 throughout development, and we shall be able to observe the varying 

 intensities of the progress. Cols. 11 and 12 simply give the weight 

 data of Murray and Needham calculated for the interdiurnal periods. 

 Cols. 13 and 14 give the final results. 



They are shown graphically in Fig. 250. It is seen that the ab- 

 sorption of protein, in the first few days of development very rapid, 

 falls off exceedingly between the 6th and loth days, to rise again, 

 however, to a high peak on the 15th or i6th day. After that point 

 it again falls to about its previous level. The most interesting thing 

 to notice is that, as far as protein is concerned, there is no correlation 

 whatever between absorption and combustion. The peak of protein 

 combustion (see p. 993), which occurs between the 8th and the 9th 



