VI. 



Tissri{ iri;rrRii as a imi\'si()L()gical 



AND ANATOMICAL MinilOl). 



1. nui iHMOKS oi' tmi:mu)I)\'. 



The strains ol" lihroblasls and epithelium i^row with 

 ail astonishing reguhiiily, and are lound to respoiid promptly 

 to changes in the eoniposilion of tlie culture medium by 

 a modil'icalion of their rale ol' nuilti|)licalion. The strains 

 can therefoi'e he used as reagent I'oi" the detection ol" sub- 

 stances contained in the humors which have the power of 

 activating or decreasing the rate of cell proliferation. 



I'lom the very beginning of the researches on explamted tis- 

 sue cells, barrel") observed a constant relation between 

 the rate of growth and the composition of the medium. A 

 definite programme for investigation was followed by Car- 

 rel and his associates. Cell j)henomena such as multipli- 

 cation, growth and senility were studied. It was vStatcd by 

 C a r r e 1 that from the time of Claude Bernard it was 

 known that the life of an organism is the result of the in- 

 teractions of the cells of which it is composed and of their 

 milieu i n t e r i e u r e. In order to discover the laws by 

 which the cell growth is regulated it would be necessary to 

 modify the humors of the organism and to study the effect 

 of these modifications on the growth of the tissues. 



The works of Can- el and his pupils of the last 15 years 

 is mainly characterized as a study of the humors of the 

 body with strains of tissue cells as reagents. The work is 

 ingenious in its continuity and prospeclivity. Tne results 

 are of the greatest importance and dominated by manj^ new 

 points of view. 



It was assumed rather early by Carrel ^^), that a me- 

 dium more efficient than normal ])lasma could be found, as 



