SECT. 12] GYCLOSES, PHOSPHORUS, SULPHUR 1241 



solid mass largely composed of cholesterol, but he did not quantita- 

 tively separate the cholesterol from the squalene or other unsaponifi- 

 able matter. 



Nitrogenous bases associated with lipoids have been reported as 

 existing in several kinds offish embryos. Thus Ackermann & Kutscher 

 isolated in 1907 as much as 2-0 per cent, (dry weight) of betaine 

 from embryos of Acanthias vulgaris, and o-oy per cent, from adult 

 fishes. The formula of this substance shows it to be related to choline: 



Choline (trimethyl /3-hydroxy 

 Betaine (trimethylglycine) ethyl ammonium hydroxide) 



CHa— COO GH^— CH2OH 



N 1 N— OH 



IgCHs 



CH3 CH3 CH3 CH3 CH3 CH3 



and it has been believed, though certainly wrongly, that betaine can 

 replace choline in the lecithin molecule. Suwa in 1909 and Kutscher 

 in 19 10 have also obtained betaine from embryonic fish muscle. 

 Later Berlin & Kutscher isolated no less than 1 2 per cent, of betaine 

 (dry weight) from the embryos of Acanthias vulgaris, and 0-5 per cent, 

 of choline, as against 0-7 per cent, of choHne in the adult muscles 

 and 0-3 per cent, in the adult liver. Nobody has any idea as to the 

 significance of these findings. 



Considerable interest attaches to the presence of scyllitol in elasmo- 

 branch fishes, for this stereoisomer of the /-inositol of animals might 

 or might not be present in the undeveloped eggs. In 1929 Needham 

 examined a number of eggs of Acanthias vulgaris and Scyllium canicula 

 for scyllitol, using a method as quantitative as possible, and found that 

 only traces were present before development, although at hatching 

 a large amount was to be found. The dogfishes, then, have to syn- 

 thesise their own particular form of cyclose, just as the birds have 

 to synthesise theirs. Fig. 401 gives a survey of the relationships 

 involved, and it will be seen from it that the cases are indeed quite 

 parallel. 



1 2-1 1. Phosphorus, Lipoids and Sterols in Arthropod Eggs 



For insect development we know next to nothing. Tichomirov's 

 balance-sheet of the silkworm &gg, made in 1882, old as it is, contains 

 the only information available. He found that the eggs of Bombyx mori 



