1242 METABOLISM OF LIPOIDS, STEROLS, [pt. iii 



contained the following percentages of lipoid (estimation-method not 

 given) and cholesterol: 



After the diapause At hatching 



What process explains the rise in lecithin we may well enquire, 

 though at present there is no hope of an answer till more work is 

 done. The cholesterol remains constant, much as in other eggs. 

 Kaneko could not find any cholesterol esters in the silkworm egg by 

 examination in the polarising microscope, but Kitamura and Kamiya 

 affirm that the developing larva, as is the case with the chick, synthesises 

 glutathione : 



% wet wt. 

 Freshly laid eggs 0-062 



Hatching larvae o-o88 



The same remarks apply to the phyllopod crustacean Artemia salina, 

 for Hopkins obtained negative nitroprusside tests on the egg-contents 

 and positive ones on the hatched nauplii. 



Needham & Needham investigated the phosphorus-metabolism of 

 this brine-shrimp in 1929, obtaining the following figures: 



Mgm. per gm. dry weight: 



Undeveloped eggs 



Hatched nauplii* 

 % of the total phosphorus 



Undeveloped eggs 



Hatched nauplii* 



* The egg-shells left behind weigh a considerable amount and were included in the 

 weighings. They contain practically no phosphorus. 



It is clear from these figures that no absorption of phosphorus takes 

 place from outside the tgg, and that there is, as noted in Section 10, 

 a sufficiency of nuclein in the beginning for the needs of the embryo. 

 In view of Tichomirov's results on another arthropod egg, it is of 

 much interest to find the lipoid phosphorus rising. These same 



