>y)f 



of fibroblasts. The rate of growtli of the fil)roblasls which 

 have been cullivaled in a niediuni containing 7 per cent 

 ascitic fluid is shown in fig. 18. At the same passages as in 

 the control culture, namely 7, 10, 12, 14 and 17, subcul- 

 tures were made in a medium containing about 50 per cent 

 ascitic fluid and the dots A, B. C, D and E, indicate the 



26 



24 



• 22 

 b 



<^ 20 

 a' 

 "i 18 



16 

 14 

 12 



10 





1 2 3 4 5 6 T 8 9 10 11 12 13 14 15 16 17 18 19 20 



Passage 



Fig. 47. 

 The rate of growth of the non-immunized strain and subcultures. The dot- 

 ted line represents the rate of growth of fibroblasts in homogenic culture 

 medium. The solid lines (A, B, C, I) and H) represent the rate of growth 

 of the subcultures of the non-immunized strain in a medium containing 

 50 per cent ascitic fluid. 



rate of growth. It may be seen that the rale of growth in- 

 creased markedly instead of decreasing as in the control 

 cultures. These two strains w^ere no longer identical. There 

 was ahvays a sharp difference in their response to the same 

 amount of the same foreign protein. It was certain, that 

 the one of the strains had become adapted to the presence 

 of the foreign protein, while the other was still influenced 

 by its inhibiting power. 15 



