244 



NcilluT L a 111 h c r I and 1 1 a ii c s 309)^ Carrel ^e)^ c a r- 

 r c 1 and B u r r o \v s, oi" L o s c t' and E b e ling 3«3) observed 

 any biological characlerisUcs wliicli were not also found 

 Tor normal lissiie cells. According to Lam be r I and lla- 

 nos, sarcomatous lissue grows as a type wbicli may be 

 regarded as cbaraclerisUc lor tissues ol" mesenchymal origin. 

 The outgrowth of carcinoma cells assumes a shcel-Uke form, 

 only one cell in thickness. This is characteristic for normal 

 epithelium as well. Both sarcoma and carcinoma cells cul- 

 tivated in vitro were found by Lambert and Ilanes^"^) 

 rapidly to absorb carmin particles placed in tiie pla.sma. 



All investigators agree as to the difficulties in cultivat- 

 ing the malignant tissue cells in vitro. Carrel ■^'5) stated 

 that sarcomatous tissue grew^ as well during a few days as 

 normal fibroblasts, but afterwards the rate of growth became 

 less rapid and the tissue could not be kept alive for more 

 than about two months. The life of the cultures of malig- 

 nant tissue cells is short, and may be due to technical 

 factors. 



L o s e e and E b e 1 i n g ^^^) were able to keep the human 

 sarcomatous tissue alive in cultures for 52 days. K i a^ r and 

 F i s c h e r*) kept a human glio-sarcoma in an active con- 

 dition of life for more than two months. 



The technique of cultivating the various tumor cells, 

 varied according to the nature and origin of the tumors. 

 For the cultivation of chicken tumors, the technique was 

 simply exactly the same as used for the cultivation of normal 

 tissues. Homogenic culture media could be used. The mouse 

 and rat tumors were often cultivated in mixtures of chicken 

 plasma and plasma or serum from the respective animal. 

 K i it' r and F i s c h e r*) cultivated the human glio-sarcoma 

 to begin with in a mixture of 20 per cent chicken plasma 

 in extract of the sarcomatous tissue and human serum. 

 Later, the same strain of sarcoma was cultivated in chicken 



*) Kiaer, S. and Fisctier, A. Unpublished experiments. 

 *) Unpublished experiments. 



