i;.) 



a shorl Icnglli of lime ;il llic ex])t'nsc' ol" llie growth pro- 

 moling sul).staiic('s conlaiiUMl in the lissnc fragnicnl itself, 

 and ciinnol llu'i'dbrc \)v considered as a real tissue cul- 

 ture in sensu s I i- i c I i o i" i. but a mere survival. 



P2xperimenls were undt'riaken to isolate a traction of 

 the embryonic tissue juice, which contains llie actual growth 

 promoting substances. Tlie results were rather negative as 

 it proved to be imj^ossiblc by employing the ordinary known 

 chemical methods for breaking down the proteins to simpler 

 Iraclions. The results are therefore moic valuable IVom 

 the ])oinl of view, that they have contributed to characterize 

 the nature of these substances, llie experiments made here 

 cannot at all. therefore, be considered as completed but 

 each of them is a i)rol)lem in itself and need further in- 

 vestigation. Considering that these experiments are the 

 first of theii" kind, they merely indicate the line of work 

 and conti'ibule to the making of the first rough charactei'i- 

 zation of the substances. 



The conclusions of the chemical experiments may be 

 summarized thus: The gi'owth promoting substances are 

 exceedingly unstable Tlie\ are suppressed at 37 C. for a 

 few hours and completely inactivated at 56 (1. for onehoui*. 

 Shaking and filtration through Berkefeld and C h a m- 

 ber lands fillers also suppress their activity. 



Different methods were applied for preparing fractions 

 of the protein solutions. Precipitation of the globulins and 

 albumins was carried out by using salts of the heavy metals, 

 carbon-dioxide and by dialyzation. These processes caused 

 practically an inactivation of the growth ])romoting substan- 

 ces, though it can be concluded that the active substances 

 are precipitated with the globulins. The albumins did not 

 show any activating power at all. The COo method for 

 precipitating the globulins jiroved to be the most conser- 

 vative for the labile su])slances. 



Precipitation of the proteins with 95 "o alcohol, followed 

 by a quick washing with ether, proved to be the best method 



5 



