A468 OSCAR RIDDLE 
I may say here that the fat and phosphatid extractions were made 
with the methods recently discussed and described by Prof. 
Waldemar Koch, in whose laboratory these analyses have been 
made. At this time it seems most desirable to present only the 
amount and sort of data which is necessary to give a clear picture 
of the major differences between the two forms of yolk under con- 
sideration, and to answer the two questions just stated above. 
TABLE 2 
ey PER CENT OF SOLIDS 
NO. OF SAMPLE MOISTURE - ————— —_—_—_ 5 ; ~ 
Fat Phosphatids Extractives | Protein 
dT eee Be esearch nce pgs 47.8 A492 20.9 | 0.6 | 28.8 
Ze Ne 21? | PMG SE A BAS 7 15.3 2:0) Pays 
Seen, Gighena eee ete: 49.2 40.7 15.9 2.4 38.7 
BA RE se Ae 5 cists 88.1 36.8 Iba 3.4 43.5 
1 = analysis of fresh egg-yolk (yellow yolk) (17.670 gr.) 
2 = analysis of a resorbed ovum (1.834 gr.) 
3 = Average of three analyses of contents of (9) yolk sacs (18 da. ine.), (78.821 
4 = analysis of white yolk (6.019 er.) 
Table 2 has been so arranged as quickly and accurately to tell 
the story. Nos. 1, 2 and 4 are single and quite typical analyses. 
The several analyses of the yolk sac contents varied considera- 
bly, and therefore an average of three separate analyses of yolk- 
sacs of eighteen days incubation is here given in preference to a 
single analysis. The white yolk was taken from a great number of 
eggs under 6.0 mm. in diameter, the yolk being removed without 
‘carrying over any traces of the enveloping membranes. 
The quantitative differences in each of these chief components 
of white and yellow yolk are remarkable. Quite as striking and 
conclusive, too, are the numbers which show that when yellow 
yolk is subjected to digestive action, in either of the two situations 
named, eacn and every component approaches more nearly to the 
quantity characteristic of white yolk. 
It cannot be said, however, that these data conclusively answer 
the question we have raised as to whether white yolk is an inter- 
