Chicken 5 



SECT. 8] CARBOHYDRATE METABOLISM 1025 



only the merest traces", said Lochhead & Cramer. They found that 

 glycogen could not be detected histochemically in the foetal liver 

 before the 22nd day. A variety of diets had no effect on the amount 

 of glycogen in the placenta and embryo, a finding quite in harmony 

 with other work, which demonstrates the remarkable independence 

 of the reproductive system against external influences. "The con- 

 stancy of the amount of glycogen deposited in the placenta and 

 in the foetal tissues generally", said Lochhead & Cramer, "con- 

 trasts markedly with the fluctuations in the glycogen store of the 

 adult liver, both in the normal and in the pregnant animal, and 

 shows up again the autonomy 

 of the glycogen metabolism of 

 the foetus." Some interesting 

 experiments on the effect of 



, . 8 ph-rul Glycogen outside embryo 



phloridzin were also made by ^ '-""'^1— Glycogen inside embryo 



these workers. 0-6 gm. of phlo- 5 ''^''''''^[~ Glycogen in embryonic llver / 



ridzin was injected daily into "Sss- /' 



the mother animals from the 



8th day of gestation onwards, 



the time when, according to °^^^|oRabbit 5 



Chipman, glycogen first appears ^.^ ^ ^^ 



in the maternal placenta. The 



result showed clearly that the placenta does not give up its glycogen 



readily to the maternal organism; thus on the 23rd day of gestation, 



a normal animal would have 4-5 per cent, of glycogen in its placenta 



and a phloridzinised one 4-24 per cent., or again 2-56 and 2-68 per 



cent, respectively. In some cases, however, there was an interference 



with growth, and the embryos were stunted; when this was so, the 



glycogen percentages were less than normal. As for the foetal liver 



after treatment with phloridzin, it had a lower glycogen content 



than normal, but yet much higher than the corresponding maternal 



liver. 



Since Lochhead & Cramer's classical investigations, the general 

 inter-relations between the liver and the placenta laid down by 

 them have been confirmed by a number of workers. Thus Clogne, 

 Welti & Pichon found in human embryos that the liver glycogen 

 increased from i-8 gm. per cent, dry weight at the 3rd month to 

 29-5 gm. per cent, at the gth month, while the placenta glycogen 

 correspondingly decreased from 2-75 at the 3rd to 1-05 at the gth 



