RESEARCHES ON PROTEID METABOLISM. 151 



the dissociation of the metabolism of the cell from the meta- 

 bolism of the tissue-juices. 



J^ote. — The method employed by Schondorff for determining 

 the urea in the blood was as follows : One volume blood is treated 

 with two volumes of a solution of phospho-tungstic acid in dilute 

 hydrochloric acid, allowed to stand twenty-four hours and filtered 

 (Filtrate I.). By this means the proteids and nitrogenous extrac- 

 tives (excluding urea) are precipitated. Filtrate I. is rubbed in a 

 mortar with calcium hydrate to an alkaline reaction and filtered 

 (Filtrate II.). Filtrate II. is divided, one part being used to deter- 

 mine ammonia by a modification of Schlosing's method. In another 

 part of Filtrate II. the total nitrogen is estimated in the following 

 way: 10 grms. of crystallised phosphoric acid are weighed out into 

 a long-necked flask of one litre capacity. A measured quantity 

 (15 or 30 ccra.) of Filtrate II. is then added, and the mixture heated 

 three hours in a drying oven to 230°-26o° C. The brownish syrupy 

 residue at the bottom of the flask is then dissolved in boiling water, 

 70 c.cm. caustic soda (sp. gr. 125) and talc added to the mixture, 

 which is then heated. The ammonia which comes off is collected 

 in a measured amount of titrated H 2 S0 4 . From the nitrogen found 

 in this way, the nitrogen present as pre-formed ammonia is sub- 

 tracted. The remainder represents the nitrogen present in the 

 blood in the form of urea. 



(1) Argutinsky. Muskelarbeit und Stickstoffumsatz. Pfliiger's 



Ardiiv, xlvi., p. 652. 



(2) Die Quelle der Muskelkraft. Ibid., L, p. 98. 



(3) Ueber die Entstehung von Fett aus Eiweiss im Korper. Ibid., 



li., p. 229. 



(4) Ueber Fleisch-und Fettmastung. Ibid., Hi., p. 1. 



(5) Die Ernahrung mit Kohlehydraten und Fleisch oder audi mit 



Kohlehydraten allein in 27 von Pettenkofer und Voit ausge- 

 fiihrten Versuchen. Ibid., Hi., p. 239. 



(6) Ueber einige Gesetze des Eiweissstoffwechsels. Ibid., liv., p. 333. 



(7) Schondorff. In welcher Weise"beeinflusst die Eiweissnahrung 



den Eiweissstoffwechsel der thierischen Zelle? Ibid., liv., p. 

 420. 



(8) Jacobsthal. Versuche liber die Fettbildung bei der Reifung des 



Kases. Ibid., liv., p. 484. 



(9) Ueber die elementare Zusammensetzung des Ochsenfleisches. 



Ibid., lv., p. 345. 



E. H. Starling. 



