ACTION OF CYTOST 127 



These rather startling results tempt one to specu- 

 late as to the possible nature of the growth-stimulating 

 agent present in the ashed tissues. At first one might 

 be led to believe that simple inorganic salts were re- 

 sponsible for the observed effects. This seems some- 

 what attractive, in view of the experiments of Loeb 

 and Blanchard or amoebocyte tissue. They found that 

 various inorganic salts exerted a marked influence 

 upon the migration of cells from experimental amoeb- 

 ocyte tissue. The concentrations used by these authors, 

 however, was considerably greater than could pos- 

 sibly exist in the cytost-plasma media used in our ex- 

 periments. Further, in the present state of our knowl- 

 edge it is difficult to conceive of any mechanism 

 whereby inorganic salts would exert such a specific 

 action as that observed in the tissue culture experi- 

 ments. One is therefore forced to an alternative hy- 

 pothesis: that the ash cytost contains some markedly 

 heat-resistant organic compound which is not com- 

 pletely destroyed during the ashing procedure. 



Admittedly this concept seems a wild stretch of the 

 imagination, but no other postulation seems to fit the 

 empirical results of the experiments. As far as the 

 writer is aware, no organic compounds of biological 

 importance can withstand the temperature attained 

 during ashing, although my friend Dr. K. C. Blan- 

 chard informs me that he has encountered some syn- 

 thetic organic compounds such as tetra substituted 

 ureas and aromatic silicon derivatives which do not 

 suffer appreciable decomposition at such tempera- 

 tures. Of course these substances are of no biochemical 

 interest, and are simply referred to here to illustrate 

 the possibility of the existence of organic compounds 



