126 THE ACTION OF THE LIVING CELL 



cytost preparation differ from those in the embryo 

 extracts in that they are not thermolabile, for, as stated 

 at the beginning of this section, the extracts used by 

 the author were autoclaved, a procedure which in- 

 activates embryo juice. 



This difference was made more strikingly apparent 

 in the following way. It will be recalled that the au- 

 thor was able to obtain the typical systemic effects of 

 cytost when extracts of charred tissues were injected 

 into cats. Such being the case, it became of interest 

 to investigate the action of such extracts upon tissue 

 cultures. To this end 10 gram portions of tissue were 

 heated in a crucible at 300° C. until a black ash was 

 obtained. This ash was extracted with 1 cc. of water 

 and filtered to remove the insoluble material, the re- 

 sulting solution being used as "ash cytost" in the ex- 

 periments described below. 



As in the previous experiments, transplants of chick 

 tissues were made from the stock cultures to a drop 

 of homologous plasma and a trace of the "ash cytost" 

 was added on the tip of a platinum needle. So far as 

 could be judged, the cultures thus prepared grew as 

 well as control cultures made with plasma and un- 

 ashed cytost. Again, when transplants were made in 

 a mixture of two parts of plasma with one part of the 

 "ash cytost," the cultures were found to be dead at 

 the end of 48 hours. When similar experiments were 

 conducted with chick tissues and ash cytost, prepared 

 from human tissues, decidedly different results were 

 obtained. The heterologous ash cytost did not appear 

 to augment growth appreciably, but it did not kill the 

 culture, as was the case with the extract of homolo- 

 gous ash. 



