1915] Casimir Funk 343 



fat fraction and butter-milk. The fat fraction which, according to 

 these authors, contained no nitrogen and phosphorus had apparently 

 the same effect on growing rats as the original butter; rats which 

 were in a bad nutritive condition quickly recovered. Especially, an 

 infectious disease of the eyes was promptly cured. The beHef that 

 this butter fraction contained no nitrogen, was used as an argument 

 against the vitamine-theory of growth, and induced me to investi- 

 gate the butter problem more closely. 



Macallum and I (130) fractioned butter, by the method of Os- 

 borne and Mendel but further purified the butter-fat fraction in 

 the following way. The fat was dissolved in acetone and shaken 

 with a weak Solution of hydrochloric acid. From 12 k. of butter 

 23.4 mg. of nitrogen were obtained by the Dumas method, and 

 slightly less by the Kjeldahl method. The butter-fat, after its 

 subjection to this process of extraction, was hydrolyzed with weak 

 acid and again 22 mg. of nitrogen were obtained. These iigures 

 are certainly low and would suggest that the butter-fat was prac- 

 tically nitrogen-free, if there were not the possibility that some of 

 the contained nitrogenous substances were volatilized during con- 

 centration in vacuo. This possibility must be tested. 



McCollum and Davis (131) also questioned the absence of 

 nitrogen and phosphorus from Osborne and Mendel's butter-fat. 

 Osborne and Wakeman (132) again tested the purity of their butter 

 preparation and found only traces of nitrogen and phosphorus. 



Aron (133) has also observed beneficial effects of butter on 

 growth. Osborne and Mendel (134) have found that old stunted 

 rats resumed growth when the inadequate diet was changed to a 

 " complete " one. 



The possibility of a Stimulation of growth with nitrogen-free 

 butter seems to me so highly improbable that I am unable to accept 

 the Statements to that effect without further proofs. Macallum and 

 I performed some comparative experiments with crude butter and 

 purified butter, following our method on rats. The percentage com- 

 position of the diet was as follows: Casein, 20; starch, 41; sugar 

 (cane), 21; butter crude or purified, 12.4; salts, 2.6. The casein 

 was extracted for several days with boiling alcohol. Lactose was 

 avoided as it contains a small quantity of nitrogen — according to 



