SECT. 12] GYCLOSES, PHOSPHORUS, SULPHUR 1207 



entirely of soft parts, there is none. Hence it is concluded that 

 a certain portion of oil is necessary for the formation of bone". 

 What Hatchett actually did we shall never know, for nothing 

 but the bare statement given above is contained in the place 

 referred to by Prout, and that not in a paper by Hatchett himself 

 but in one by Sir Everard Home. But in spite of our ignorance 

 of Hatchett's technique, one cannot help surmising that he had 

 attained in some measure, however feeble, an estimate of the lipoidal 

 constituents in eggs of different species, and that, in actual fact, more 

 of these substances are present 



in what Prout would call "the 

 recent egg" where bones, with 

 their calcium phosphate, have 

 to be formed than where they 

 have not. A study of Table 30 

 does not, unfortunately, lend 

 weight to this view, but the 

 analyses of eggs which included 

 reliable estimations of lipoid 

 phosphorus have been so few 

 that no conclusion, either in 

 favour of Hatchett or against 

 him, can at present be drawn 

 from them. 



Other investigations besides 

 those of Plimmer & Scott and 

 Masai & Fukutomi have been 

 made of the phosphorus in the 



Lecithin, (Riddle) 



• Yolk-sacs and contents 

 O Liquid contents of yolk-sac 

 ® Solid contents of yolk-sac 

 O Intracellular yolk 

 ^ Yolk-sac 



5 



Days-* 



Fig. 378. 



hen's egg. Thus Riddle estimated the ether-soluble phosphorus in the 

 yolk and yolk-sac of the chick during the last half of incubation, and, 

 expressing his results in terms of lecithin as per cent, of the dry 

 weight, obtained figures from which Fig. 378 has been constructed. 

 An extremely marked absorption of phosphatides from the yolk is 

 indicated during the last week of incubation, for the percentage phos- 

 phatides to dry weight in the yolk falls with a rush, and this is just 

 what one would expect from the evidence in PUmmer & Scott's 

 experiments. The phosphatide-content of the yolk-sac seems to re- 

 main stationary, if anything can be deduced from two points only, 

 and the composition of the more solid parts of the yolk would seem. 

 N E II jy 



