SECT. 7] 



OF EMBRYONIC DEVELOPMENT 



965 



energy retained in a given amount of spatial intracellular and extra- 

 cellular organisation. It is difficult to form a clear picture of this 

 fraction of the energy. It is to be distinguished from Lapicque's 



90000 



80000 



70000 



60000 



50000 



40000 



30000 



20000 



10000 



gm. 

 cals. 



.(iLjin) 



TANGLS 

 Ea = 22940 cala. 

 / CREa = 805cal8. , 

 ^ SEa = 3600 cals.) 



Energy added to embryo 

 b_y coupled reactions etc. 

 i.e. would have gone away 

 as heat •'"■•• 

 othermic reacti{ 



Energy 

 corresponding 

 to simple 

 storage 

 (same sub- 

 stances but, 

 unorganised 



PCals 



Energy 



brought into 



the embrv! 



by simple 



storage 



Energy present in 

 the unused raw V.'t 

 materials at the fi. 

 end of development '^ 

 (spare yolk) 



J 



Fig. 259. This diagram represents the changes between o and 20 days' incubation. For 

 chicks allowed to hatch naturally U' will be larger ; thus chick weight in % of egg- 

 weight is 68 (Jull & Heywang; Upp), 66 (Jull & Quinn) or 64 (Halbersleben & 

 Mussehl) according to the breed (see p. 249). 



"epictesis", which is rather the work done by a secretion process, 

 and it more resembles Shearer's conception of the work done in 

 keeping the parts of cells and tissues together as physical systems. 

 If this expense may be said to be in adult life of a definite though 

 small magnitude, then, evidently, as the structure and organisation 

 grows in embryonic life, this quota must also grow. In other words, 

 the more organisation you have, the more molecules you maintain 

 oriented a little differently from the position they would otherwise 



