The Living Materials 



53 



Fig. 18. Culture of undifferentiated callus from the hybrid, 

 Nicotiana langsdorffiix X. glauea maintained for many passages in 

 vitro on nutrient agar. (From White, P. E. 1989. Am. J. Bot. 

 26: 60, fig. 3, 78.) 



Fig. 19. Cultures of bacteria free crown-gall tissue from sun- 

 flower, grown in vitro on nutrient agar. 



