PROPERTIES OF GROWTH SUBSTANCES 



43 



and phenylalanine) into growth substance (see discussion on 

 formation). 



Urine, a Source of Auxentriolic Acid (Auxin a).— The following 

 outline of procedure is that of Kogl, Haagen Smit, and Erxleben 

 (1933, Mitt. IV). It may be followed with reference to Table 2. 



Table 2.— Concentration and Physiological Activity of Growth 

 Hormone at Different Stages of Its Preparation from Urine 



1. Concentration of the Urine. — One hundred and fifty liters 

 of mixed urine (auxin content, 300 mg.) were acidified with 

 hydrochloric acid (1:1) until the reaction was acid to Congo red. 

 The fluid was then concentrated in batches of 30 liters in a distill- 

 ing apparatus until it became a thick, dark-brown, partially 

 crystallized syrup. The residues of the five batches totaled 

 5,700 g. in weight, and these were combined for further steps in 

 purification (see Table 2). 



2. Ether Extraction of the Crude Syrup. — The crude syrup was 

 dissolved in 25 to 30 liters of water, acidified with hydrochloric 

 acid, and repeatedly shaken with an equal volume of purified 

 peroxide-free ether. The ether extracts were combined and 

 dried over sodium sulphate, then concentrated (boiled down). 

 The residue of 87 g. contained almost all the active substance 

 concentrated sixty-five times. 



