SECT. 12] GYCLOSES, PHOSPHORUS, SULPHUR 1239 



tion. This again would agree with what goes on in the hen's egg. 

 The only other researches which have been carried out on the lipoid 

 and sterol metabolism of the amphibian egg are those which have 

 involved histochemical methods alone (e.g. Yamaguchi, who found 

 cholesterol esters in the liver of the toad at hatching) . Doubtless the 

 most important of these are the memoirs of Konopacki & Konopacka, 

 and of Hibbard, but it is difficult to tell whether what they call 

 "hpoid" is the same thing as the material known to chemists. It is 

 interesting that Rosenheim finds cholesterol prepared from frog's eggs 

 to be richer in ergosterol than similar products from any other source. 

 According to Kamiya, no glutathione is synthesised during the 

 development of the frog's egg. 



12-10. Lipoids, Sterols and Cycloses in Fish Eggs 



As regards the fishes, we are almost completely ignorant of what 

 happens to the phosphorus distribution during embryonic growth, 

 but some unpublished work of Rosenheim, Girsavicius, Ashford & 

 Stickland indicates that in the fish egg events occur very Hke those 

 in that of the hen and the frog. In 1928 they obtained on the trout, 

 Salmofario, the following figures: 



% of the total phosphorus 



Ether-soluble phosphorus ... 

 Total water-soluble phosphorus ... 

 Inorganic phosphorus 

 Organic water-soluble phosphorus 

 Nucleoprotein phosphorus... 



If these are compared with those previously given for the frog by 

 Plimmer & Kaya and for the hen by Plimmer & Scott and others, 

 the correspondence will be seen to be considerable. It is evident, 

 however, that in these experiments the ichthulin or phosphoprotein 

 of the trout's egg came out into the watery extract. When this is taken 

 into consideration, it will be seen that the fall in lipoid phosphorus, 

 the rise in inorganic phosphorus, and the probable fall in phospho- 

 protein phosphorus, parallel events in other eggs. 



For cholesterol there is a solitary observation of McClendon's that 

 the unsaponifiable substance soluble in petrol ether formed i-2 per 

 cent, of the dry weight of the eggs of the brook- trout, Savelinus fonti- 

 nalis, and i-6 per cent, of the dry weight of its hatched larvae — an 

 increase of 33 per cent. This fraction crystallised, he says, into a 



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