32 



condilions cluMiiical or physical wliicli icsull in a prof^ros- 

 siw ilisappcarancc ol" [hv epillu'lium in culluiH-s, wiic-n t'ihro- 

 blasls arc prcscnl. Is liic cause lo he lound in the cells 

 Ihemsclves, in a cerlain clirrei"eiu-e in liie physiological cha- 

 raclcr of Iht two cell types, oi- in the c(jn(iili()n ol' (he cul- 

 lure-mcdiaV 



One would inia<^ine Ihal expei'inicnlal radiology would 

 have ail exceedingly good iiiclhod in tissue cullivalion lor 

 sludying the ray energy on the vaiMous isolated tissue cells. 

 Ill short, there can scarcely he found any prohlem in ex- 

 pcrimenlal medicine that could not take advantage of the 

 tissue cultivation method, es])ecially now when it has l)een 

 shown that also other tissues can he grown |)ui-e in vitro, 

 and. what is inori' important, that a dedijfei-enlialion of these 

 tissues does not occur luider the experimental condilions; 

 but that they remain in the same stale of development as 

 they were in the animal from which the cells and the 

 tissue juice necessary foi* the growth are taken. 



When the technique for cultivating tissue cells was de- 

 veloped, several investigators expected much of the method 

 to study the character of the malignant cells. 



The question was therefore quickly taken up hy most 

 investigators, but the results were rather disappointing. Al- 

 ready as early as in 1910, shortly after the technique has 

 been developed, C arret and B u r r o w s. "*^) ■ ') ^s), later 

 Lambert and Hanes ^o^j ^^7^ worked intensly on the cul- 

 livalion of malignant tumours in vitro. — The technical 

 difficulties for keeping the tumour cells growing over long 

 periods of lime were rather great. It was stated by Carrel 

 and Burrows, that no actual characteristics were found, 

 that were not also found of some normal tissue cells. 

 Not until within the last few years these (jueslions have 

 again been taken up by several investigaloi's. 



The realization of many of the said lu'ohlems will mainly 

 depend ujion an inqjrovemeni in tlie techni(|ue. an under- 

 standing of tlie value of this line of in\esliuali()ii and the 



