(>(; 



for ()l)l;iininj^ the jfrcwth pronioliiiff .siil)sl;in('('s Tlu- siil)- 

 slanccs oljUiiiied by Ihis int'lhod were alinosl as aclivc as 

 llu' nalivc solulion. 



The amino acids IVom llic iiydroly/cd cinhryonic lissue 

 juice showed no loxic eiri-c-l on the ril)i-ohhisls in vilro, as 

 has been slated lor ainino-acids in general by H u r r o w s 

 and X e y ni a ii n 'o). 



X'arious indirect methods were seU'cled, so as to endea- 

 vour to obtain some ini'ormation as to the classification of 

 Ihe active substances. 



The embryonic lissue juice as well as the adull plasma 

 was hydroly/.ed and the amino-acids determined {[uanlila- 

 liMJy ad modum \' a n Slyke "'^\ so as lo make a (|ualila- 

 live as well as a (luantilalive comparison between lUe amino- 

 acids in the blood-plasma which have no activaliuiJ effect 

 at all, and the embryonic lissue juice which contains the 

 growth i)romoling substances. The results were rather in- 

 constant and not clear. 



Differenl adsorjjtion experiments w'cre undertaken, in or- 

 der to find new and more conservative methods tor the 

 study of these substances. Blood coal was generally used 

 as adsorbent in a concentration of about 10 fyo- The adsorp- 

 tion was investigated under influence of different hydrogen 

 ion concentrations of the tissue juice. It was observed that 

 at Ph. 7.0 Ihe supernatant fluid from the adsorbent (blood 

 coal; possessed almost all the activating power of the 

 tissue juice, in spite of the fact that almost 50 "o of the 

 total nitrogen of llie solution was adsorbed. At l)oth sides of 

 the neutral point, the supernatant fluid, when brought back 

 to Ph. 7,0 after the adsorption, remained inactive. 



The substances adsorbed are those belonging to the big- 

 gest molecules. The dialysable substances, the amino-acids, 

 remained unadsorbed at the differenl hydrogen ion con- 

 centrations. 



In other experinu'uts it was tried to displace the sub- 

 stances once adsorbed bv washing the adsorbent with va- 



