SECT, i] PHYSICO-CHEMICAL SYSTEM 355 



1-15. Carbohydrates 



The carbohydrates of the eggs of the lower animals have been less 

 investigated than anything else — a summary of our quantitative 

 knowledge concerning them is shown in Table 46. The presence of 

 glycogen in insect and mollusc eggs was noted by Bernard and in 

 those of arachnids by Balbiani. For the reasons mentioned above, 

 it is difficult to know how trustworthy the figures for carbohydrates 

 are, so bad have the methods been in the past. Faure-Fremiet & du 

 Streel's figure for the glycogen of the frog's tgg must surely be too 

 high, for most of the other workers are agreed on a value of about 

 2 gm. per cent, wet weight. In the case of animals other than 

 amphibia, the figures are too scattered to permit of any generaUsa- 

 tion: thus, though glycogen was not found in herring's eggs by 

 Steudel & Osato, Gori did note its presence in Torpedo eggs, and the 

 eggs of the reptiles Vipera aspis and Elaphis quadrilineatus, in addition 

 to free carbohydrate. Steudel & Osato pointed out that many histo- 

 logists such as Goldmann had published results concerning the fish 

 egg which might lead one to suppose that very large amounts of 

 glycogen were there. That this was not found by chemical methods 

 ought to induce, they felt, a more cautious attitude towards histo- 

 chemical work than was customary; indeed, much of what is called 

 glycogen histochemically can certainly not be glycogen. Greene's 

 carbohydrate figures for the eggs of the king-salmon Oncorhynchus 

 tschawytscha, from Cahfornian rixers, were of special interest, for, 

 throughout the maturation period, the carbohydrate content of the 

 egg remained the same. The duration of the fast did not affect it 

 at all. 



Quahtative investigations of carbohydrate in eggs have been made 

 by Anderlini on the silkworm egg and by Konopacki, who observed 

 the presence of glycogen microchemically in the perivitelline fluid 

 of the frog's tgg. As has already been mentioned, a carbohydrate 

 group is undoubtedly contained in the mucoprotein of the amphibian 

 egg-jelly, and von Furth's analysis of the egg-cases of the squid Loligo 

 vulgaris showed that their protein also contained a carbohydrate, but 

 whether these play any part in the sugar supply for the developing 

 embryo remains an obscure point. Haensel found an amount of glucose 

 in the frog's tgg which is shown in Table 46, but he also tried the effect 

 of keeping the eggs in solutions of various mono- and di-saccharides, 



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