64 



cause ol' the ralher inconslant rcsulls ohiained here, but 

 doubtlessly expciiiiK'nlal arraii^emeiils similar lo those iiien- 

 lioiied heri' will be iiiori' iiscl'iil lliau llu' inere <luinical 

 analysis which at the present time is too a<f^ressive lor ihe 

 delicate growth promoting substances. 



SLALMAR\' AND DISCLSSIOX. 



The culture medium lor cullivalion ol" tissue cells in 

 vitro is apprehended in two parts namely 1; the sui)poi'ling 

 apparatus and 2) the growlh pi-omoting sul)stances. 



The sui)porling ap|)aratus of the plasnui cultiu'e is i*e- 

 presented in the fibrin. This can be substituted by certain 

 other indifferent substances such as spider-web, glass-wool, 

 silk- and cotton threads and almost any indifferent material. 

 It is impoiianl to know, thai there e.xisis a cerlain relalion 

 between the amounts of fluid and suj)porting material. NMien 

 the liquid phase is held by capillary suction to the frame- 

 work the best conditions are established for an outgrowth 

 of the cells. 



The second component of the culture medium is essen- 

 tial for the indefinite growth of tissue cells in vitro, namely 

 the growlh ])romoting substances. These are not found lo be 

 present in the plasma from young or old animals in any suffi- 

 cient quantity to keep the cells living permanently outside the 

 body. Whereas they are found to be present in the tissue 

 cells themselves, preferably' in certain tissues such as em- 

 bryonic tissue, spleen, liver, leucocytes from adult animals 

 and in certain sarcoma. Here il musl. naturally, be under- 

 stood, thai we are only dealing with the cullivation of 

 tissue cells in homologous media, i. e. media derived from 

 the same species of animal as the tissue cells. The cultiva- 

 tion of cells in heterologous media is entirely another matter 

 and the investigation on this field is rather new and unsuf- 

 ficiently worked out to ])ermit any conclusions being drawn. 



A fragment of tissue explanted in a protective solution 

 (Ringer, L o c k e s or Lock e-L e w i s) is able to live for 



