ouToiN ov iMiospnoius roMrofXDS i\ hkns- e(;gs 270 



the albumin P. As 40 mgm active phosphorus wore injected and only O.OOOU mgm 

 are found in the albumen we can (ioncdude that the formation of albumen from 

 inorganic blood phosphorus in the course of the last A^i, hours which the egg 

 spent in the oviduct is a very moderate one, even when we take into account 

 that the O.OOOfi mgm active phosphorus found in the yolk passed through the 

 albumen into the yolk bringing the amount of labelled phosphorus present at 

 least temporarily in the albumen to 0.U012 mgm and that a large part of the active 

 phosphorus injected gets rapidly replaced in the blood by non-active phos])horus 

 present in the skeleton and other oigans. 



In the shell of the egg we find 10 mgm phosphorus b.\- chemical analysis (colori- 

 metric method of Fiske and Subbarow) and 0.1 mgm of the labelled phosphorus 

 administered by radioactive determination (measurements with a Geiger-counter). 

 1 % of the shell phosphoms originates thus from the labelled phosphorus adminis- 

 tered, which got into the shell in the ciourse of the last 414 hours before laying 

 the egg. 



The labelled phosphorus content of eggs layed at different time is shown by 

 the figures of the tables 4 to 6. 



In what follows we discuss the significance of these figures. That the specific 

 activity of the shell is very much higher after 0.17 days than at a latter date 

 is due to the fact that shortly after the administration of the labelled P the acti- 

 vity of the inorganic P of the plasma is very high and it is the latter which is 

 incorporated into the shell. As found by us in numerous cases the active P content 

 of the plasma decreases first rapidly and later at a decreasing rate the differenc;e 

 between the specific activity of the plasma and that of the tissues becoming less 

 and loss. The specific activity of the shell phosphoi-us is a measure of that of the 

 inorganic plasma P at the time of formation of the shell and vice v-ersa. The low 

 specific activity of the albumin P in the egg layed after 0.17 days comes possibly 

 for the following reasons. The white of the egg was already to an appreciable 

 extent formed before the administration of the labelled P. The phosphorus compound 

 of the plasma, presumably the plasma protein which mainly enters into the white 

 was at such an early date after the administration of the labelled P active onh' 

 to a small extent. The synthesis of labelled organic compounds takes some time 

 and therefore shortly after the administration of labelled P the' speoificj activity 

 of the inorganic plasma P is much higher than that of the organic P. On the other 

 hand the labelled organic P flisappeare at a slower, usually even much slower, 

 rate from the plasma than the labelled inorganic P, the latter having a unique 

 opportvmity to exchange with the inactive tissue, especially bone tissue P. 



When comparing the yolk figures with those of the albumin we have to bear in 

 mind that contrary to the albumin whic^h is formed within the day preceding the 

 la^'ing of the egg the greater part of the yolk was already present when the active 

 phosphorus was injected and therefore the labelled phosphorus of the yolk was 

 fliluted by the unlabelled phosphoi-us already present in the yolk. With increasing 

 time we should expect the amount of active phosphorus in the yolk to increase. 



Labelled P administrated at different dates 



In another set of experiments we were interested in producing strongly active 

 egg-lecithin to find out whether after feeding the latter iis dry yolk to rats, the 

 presence of active lecithin in the blood of the rats can be ascertained. This was 

 found not to be the case. In these experiments we administered to the hen on 

 several days active phosphorus which made the interpretation of the activit_\- 

 measurement of the yolk removed from the ovary rather difficult. A compaiison 

 of the activity of the shell of the yolk with its fluid interior revealcti large diffe- 



