245 



embryonic tissue juice from young chicken cmbr\^os, for 

 abouL a month. In other words the culture medium for the 

 human sarcoma was cntirelj^ heterologous. 



The human tumors cultivated by Carrel and B u r- 

 rows '^^), Losee and Ebeling^ss) were either cultivated 

 in autogenic or homogenic plasma. Losee and Ebeling 

 cultivated the human sarcomatous tissue in a medium com- 

 posed of equal parts of normal human plasma and R i n- 

 ger solution and varying the quantities of extract of fresh 

 human fetal cadavers. The technique of preparing the cul- 

 tures was the same as so often described, and it is not 

 necessary to repeat it here. 



All investigators agree that the malignant tumor cells 

 liquefy the plasma medium so extensively that all further 

 growth ceases and the tissue dies. It is probably Ihe li- 

 quefaction which has complicated the cultivation of tumor 

 cells. The liquefaction depends very much upon the nature 

 of the plasma medium and the tumor cells. Human plasma 

 is liquefied much easier than chicken plasma, for instance, and 

 certain tumor tissues possess liquefj'ing properties much 

 greatei' than others. It seems to be very difficult to prevent 

 liquefaction of the plasma clot. Recently Carrel '^^) found 

 that the addition of small amounts of serum and a trace 

 of sodium linoleate to a fibrinogen-Th y ro d e-medium, 

 partly prevented the liquefaction of this medium when 

 normal fibroblasts were cultivated in it. I have tried this 

 modification myself in the cultures of sarcomatous tissue 

 — but without success. The best results of that kind I ob- 

 tained by reducing the amount of embryonic tissue juice in 

 the culture medium. 



Liquefaction of the plasma medium generally occurs after 

 a certain amount of ne\v growth has appeared, usually 

 a few^ hours after the cultures are prepared or not until after 

 15 — 21 hours. As soon as liquefaction has taken place, all 

 connection between the original explanted fragment and the 

 new growth is broken off, and on account of the change 



