SECT. 12] CYCLOSES, PHOSPHORUS, SULPHUR 1245 



I gm. of dry substance gave 3-53 mgm. of nucleoprotein phosphorus 

 and no phosphoprotein phosphorus. Fertilised but undivided eggs 

 yielded 3-95 mgm. per gm., and embryos at themorula stage 3-80 mgm. 

 per gm., again with no phosphoprotein phosphorus. 100 mgm. of 

 total nitrogen were associated with 3-6 mgm. of nucleoprotein 

 phosphorus in the unfertilised egg, 4-1 mgm. in the fertiUsed but 

 undivided egg, and 4-05 mgm. in the morula. From these data, which 

 agreed well among themselves, Masing concluded that there could be 

 no synthesis of nuclein during the period covered by his experiments. 

 Moreover, as has already been mentioned (p. 1157), he isolated the 

 purine bases from his material, and could not find any increase or 

 decrease. 



Shackell's work, which was published not long after Masing's, 

 confirmed it. He estimated the ether-soluble and water-soluble 

 organic phosphorus under much the same conditions as Masing, and 

 observed no change in either. He was also unable to find any increase 

 in the nucleoprotein phosphorus, as determined by the protein residue 

 left after treatment in a standard peptic digestion. 



Both these papers were severely criticised by Robertson & Wasteneys 

 in 1 9 1 3, who considered that Masing's material must have been greatly 

 contaminated by the spermatozoa. If this had been the case, his 

 values for the just-fertilised eggs would have been too high, and would 

 perhaps have obscured a real rise in nuclein phosphorus. They also 

 affirmed that the conditions under which his eggs had developed had 

 been inadequate, and that his extraction methods were faulty. Nor 

 did they fail to bring much the same criticisms against Shackell. 

 Later writers, such as LeBreton & Schaeffer, have followed Robertson 

 & Wasteneys in their opinion of the work of Masing and of Shackell, 

 but it must be remembered that Masing published a defence of his 

 methods against the American workers, in which he pointed out that 

 contamination with excess spermatozoa could not explain his results, 

 some of which were derived from unfertilised eggs. Robertson & 

 Wasteneys' own data were very erratic and difficult to interpret as 

 they only estimated alcohol-soluble, water-soluble, and insoluble 

 phosphorus, i.e. mixtures of compounds. They concluded that "the 

 proportion of phosphorus which is present in the form of lecithin, etc., 

 in Strongylocentrotus eggs diminishes progressively as development 

 proceeds". Nothing could be said on the basis of their experiments 

 about the nucleoprotein phosphorus. 



