IV. 



THCMori: I'OR lISSrH CTLTIYATION 



The oiilliiirs ol' llu' im-lliod lor cultivaling (issue eells 

 in vitro are very imieli llie same lo-day as described l)y 

 Harrison-"' in 1!)()7. Before llial lime many investiga- 

 tors had ah'eady Ihoiighl ol' the possibility of growing tis- 

 sues outside the organism, but nothing really came of it. 

 Harrison -1'^ demonstrated thai embryonic tissue of the 

 frog, transplanted into coagulable lymph, was able to develop, 

 in a normal way. At lliat time (barrel was interested in 

 cicatrization of wounds and decided to develop a teclinitpie 

 which could be ai)])lied to the cultivation of adult (issues. 

 B u r r o w s studied the techni(|ue in H a r r i so n"s labora- 

 tory and together with Carrel they developed the beautiful 

 tcchnic|ue for tissue cultivation which gradually has been 

 modified and imi)roved. But in the headlines the lechni(|ue 

 is the same to-day. 



Insteaa of using the lymj)h as Harrison did. Bur- 

 rows and Carrel used |)lasmti from the same or from 

 different species. It was soon found by Carrel and Bur- 

 rows in what direction this line of research should go. 

 It was observed that the tissue could be kept alive and 

 actively growing by making secondary and tertiary cultures. 

 The little fragmen( of explanted tissue was able to emi( 

 new cells when cut out of the old culture medium, washed 

 in Ringer's solution and i)laced in anew fresh plasma. 

 C a r r e Is thought was that senescence was an unneccessary 



