54 



a. Experiments ivilli llie /alli) r(>iuj)(>nenls of the extract. 

 TIh' c'llVcts of Ihc" Intly rxtracls of the tissue jiiico on 

 tlu' ribi'ohlasls were absoliilrly lu^galixc; thr same was fouiul 

 lo he the ease with regard lo tlie tissue juice after the 

 fatty suhstaiices had l)een removed. The fat extractions were 

 done with the dry tissue juice in Soxlels apparatus. 

 Petroleum ether was used. The tissue juice was extracted 

 for 21 hours. After the evaporation of the ether the fatty 

 substances were ex])osed to cold acetone. A |)art of it was 

 dissolved and a ]Kirt remained undissolved, lioth of the 

 aceton'3 soluble and of (lie uns()hd)le some kinds of sus- 

 pensions in Ringer solution were prepared and added 

 to the culture medium. Some of these substances were also 

 saponified with XaOll and in lliis foi-m added to the cul- 

 ture medium. All the sul)stances iuid a toxic effect upon 

 the tissue cells. 



7. Adsorb tion experiments. 



Experiments were undertaken to add indifferent sub- 

 stances as adsorbents to the embrj^onic tissue juice as adsor- 

 bendum. to see if it was possible to adsorb substances 

 which in one way or another were Ves])onsible for the 

 growth promoting power of the juice — and afterwards to 

 submit the adsorbed and unadsorlied sul)stances to a che- 

 mical analysis. 



Numerous experiments of this kind were undertaken. Dif- 

 ferent substances were used as adsorbent, such as animal 

 charcoal, blood coal, mastic, gum arabic, barium sulphate, 

 powdered agar and gelatine, stroma of tissue cells and 

 fibrin. Of all of these the ])lood coal was most suilal)Ie and 

 frequently used. The adsorbtion experiments showed often 

 verj- different and rather inconstant results, j)robably due 

 to the fact, that the tissue juices and plasma can not very 

 well be standardized. They vary much, which can be seen, 

 for instance, by tlie different amounts of totally nitrogenous 

 substances they contain. In experiments of this kind the 



