1046 



CARBOHYDRATE METABOLISM 



[PT. Ill 



The balance sheet of the frog's development given in Table 129 

 shows that the average frog embryo gains about 2 1 per cent, in wet 

 weight, and loses about 32 per cent, of its dry weight, while 41 per 

 cent, of its glycogen disappears, but only 7 per cent, of its total 

 carbohydrate. 



o day 8 days Diff. 



I 2 3 



4-16 5-22 + 106 



399 

 5-9 



4-42 + 0-43 

 II +15-2 



5-4 + 2-1 

 809 + 1-41 



Average +4'62 



Result (20-8 °/o) 



Table 129. Balance sheet of the developing frog embryo 

 (Rana temporaria). 



Dry weight 

 (mgm.) 



o day 8 days DifT. 



■9 

 63 



3 



38 

 33 

 £6 



313 



1-30 



105 

 I-5I 



Glycogen 

 (mgm.) 



o day 8 days 



7 8 



0135 0079 



DiflF. 



9 

 -0056 



Total carbohydrate 

 (mgm.) 



o day 8 days Diff. 



Investigator 

 13 

 Faur^-Fremiet 

 &Dragoiu(i923) 



29 — — 



31 

 062 



-0-65 

 (32-4 °/o) 



— — — Faur^-Fremiet 



& Vivier du 

 Streel (1921) 



— — — — — Bialascewicz 



(1908) 



— — — — — Bialascewicz & 



Minc6vna(i92i) 



— — — — — Bonnet & Barth^- 



lemy (1926) 



— — — — — Williams (1900) 



— — — — — Haensel (1908) 



— — 00402 0-0373 —0029 Needham (1927) 



— -0056 — — -0029 

 (41-5 °/o) (7-2°/ J 



Method used 



14 



Bierry-Gru- 



Pfluger 

 Hagedom- 

 Jensen 



The amount of total carbohydrate found, using the Hagedorn- 

 Jensen method, is rather less than the amount of glycogen found by 

 the Bierry-Gruzevska method, though very Uttle less than the amount 

 of glycogen found by the Pfliiger method. This contradiction does 

 not invalidate the arguments given above, for the values in each 

 case are probably relatively exact. It is also hkely that the total 

 carbohydrate estimations are nearer to the absolute values than the 

 glycogen ones, for the estimation methods for glycogen have never 

 been very good, and are still under discussion. Thus Asher & 

 Takahashi have criticised Pfliiger's method severely, and the newer 

 method of Rona & van Eweyk, which unfortunately nobody has 

 used on the frog embryo, gives much lower results than the older 

 ones. 



On the whole, therefore, the results of the chemical investigators 

 agree very well with those of the histochemical ones. But it is wrong 

 to conclude, when glycogen is seen to be disappearing histochemically, 

 that it must be destined for combustion purposes. It may only be 



