ORIGIN OF I'HOSPHORT'S COMPOU^'DS IX HENS' EGGS 291 



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intestine can, liow(^ver, hav(> and presumably actually do have a role 

 in the suppl}^ of .the plasma i)hosphatides.The presence of phosphatides 

 in the intestinal lymph was repeatedly shown*') in experiments on dogs. 

 The amount of phosphatides reaching the hens circulation by the influx 

 of intestinal lymph could be ascertained by measuring the amount 

 of intestinal lymph produced and also its phosphatide^ content. In Fig. 3 

 we show the specific activities of the phosphatide P in the organs 

 of the hen killed 5 hours after the administration of the labelled sodium 

 phosphate. The heaviness of the shading indicates the specific activity. 

 A hen laying daily deposits about 60 mgm phosphatide P in the yolk 

 or about 3 times as much phosphatide as present in the plasma. In the 

 course of a day the phosphatide content of the plasma of a laying hen 

 must therefore be replenished three times. In view of this great strain 

 on the phosphatide circulation in the plasma it is very significant that 

 the plasma phosphatide content of a laying hen is higher than in most 

 other animals. If the laying hens plasma should show such a low phos- 

 phatide content as does a rabbit or a rat (per cc.)the plasma lecithin would 

 have to be replenished as much as 17 — 22 times a day. It is significant 

 that the high phosphatide content is maintained only during the laying 

 period and that the red cells contain less phosphatide than the plasma, 

 a behaviour not shown by the blood of any other animal investigated. 

 We find furthermore that in the course of 28 hours taken by the experi- 

 ment a much greater part of the phosphatides found in the plasma is 

 labelled than of that contained in the corpuscles. This is a significant 

 result as it demonstrates clearly that lecithin is carried to the ovary 

 by the blood plasma and not the blood cells which obtain their lecithin 

 in various ways. Labelled phosphatide could be taken up by the cell 

 membrane, possibly diffuse through the cell membrane; labelled inorga- 

 nic phosphorus which was found by us to diffuse at a moderate speed 

 into the corpuscle could lead to the formation of labelled phosphatide 

 phosphorus inside the latter, finally the lecithin could get into the cor- 

 puscles at their birth. If they are formed from labelled plasma the newly 

 formed corpuscles should become labelled as well. As to the formation 

 of labelled phosphatide from labelled inorganic P in blood, we found, 

 in experiments in vitro that such a formation actually takes place, 

 though only on very minute scale. As to the rate of formation of blood 

 corpuscles, some information on this point could be obtained by inject- 

 ing labelled plasma and investigating the radioactivity of the phosphorus 

 compounds isolated from the corpuscles after the lapse of some time. 

 If after the lapse of a day, for example, only 1% of the corpuscle phos- 

 phatides were found to be labelled we could conclude that the rate of 



(i) H. E. Hamerich, Amer. J. Physiol. 114, 342 (1934); S. Freeman and A. 

 C. Joy, loc. cit 110, 132 (1935). 



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