Physiological Properties of Lipins of Egg Yolk, ioi 



junction with the left half. We compared the onset of negativity 

 at the sinoauricular junction with the right and left halves of the 

 sinus, and found the junction to precede in negativity. It must 

 be borne in mind, however, that in the exposed heart, automaticity 

 and conductivity may sometimes be abnormal, and a fairly long 

 series of observations will be necessary in order to determine 

 without question, the normal origin of the impulse. We have 

 arranged for a supply of large turtles in order to continue the work, 

 but shipment of these to northern points can be made only in late 

 spring or summer. Since our work is thus temporarily delayed 

 and since we feel the observation, if it can be confirmed by other 

 experiments, is of fundamental importance, we have been led to 

 make a report of this single experiment at the present time. 



6 1 (878) 



Further observations on the physiological properties of the lipins 



of the egg yolk. 



By E. V. McCollum and Marguerite Davis {by invitation). 



[From the Laboratory of Agricultural Chemistry of the University of 



Wisconsin.] 



We have continued our former studies 1 which have shown that 

 rats which have grown as far as possible on a diet of casein, dextrin 

 and inorganic salts, can make a new growth when small amounts 

 of the ether extract of butter or of egg is added, while they are 

 unable to do so when lard, olive oil, lecithin or cholesterin is added 

 instead of the ether extracts mentioned. These have since been 

 fully confirmed by Osborne and Mendel who have obtained similar 

 results when unsalted butter 2 or purified butter fat 3 was employed. 



We have now observed that ether, or petroleum ether extract 

 of boiled eggs possesses the same physiological property of inducing 

 a new growth as does the extract previously described. The 

 active principle, whose chemical nature is still unknown, is there- 

 fore resistant to heat, and is soluble in petroleum ether as well as 



1 Journal of Biological Chemistry, Vol. 15, p. 167 (1913). 



2 Osborne and Mendel, Journal of Biological Chemistry, Vol. 15, p. 311 (1913). 

 3 Osborne and Mendel, Journal of Biological Chemistry, Vol. 16, p. 423 (1013). 



