258 THE INCOME OF ENERGY 



ing. These several operations, beginning with 

 the bleeding of the rabbit, should take not more 

 than fifteen minutes. 



After two hours interrupt the experiment, 

 pour the solution through a sieve, stir into the 

 filtrate solid ammonium sulphate to saturation, 

 filter off about 10 c.c., add to the water-clear fil- 

 trate an equal volume of absolute sodium hydrate 

 (70 per cent), stir thoroughly with a glass rod, 

 and let the precipitated sodium sulphate settle. 



Add to the clear liquid drop by drop 2 per 

 cent cupric sulphate solution. No biuret reaction 

 will be obtained, but the liquid will show at once 

 a pure blue color. 



Eepeat the test, with the same quantitative 

 relations, upon the reserved 5 c.c. of the blood- 

 peptone solution : a purple color will be obtained. 



Hence the not inconsiderable quantity of pep- 

 tone in the blood covering the pieces of intestine 

 has disappeared. ' 



Eub the pieces of intestine with sand to a 

 pulp, boil with as little water as possible, saturate 

 with ammonium sulphate, and test as before. 



No biuret reaction will be obtained. Hence 

 the peptone which disappeared from the blood- 

 peptone solution is not stored ill the intestine. 1 



1 NEUMEISTER: Zeitschrift fiir Biologie,1890, xxvii, pp. 324- 

 327. 



