GROWTH 301 



found that mesoderm was more likely than ectoderm to react to in- 

 fluences from its surroundings and become assimilated into a compound 

 organ. 



Figure 13. ii 



The two forelegs of a newt, T. taeniattts, in one of which (the lower in the 



figure) the mesoderm of the limb-bud had been replaced with tissue from T. 



cristatus. The operated leg has developed the long, rapidly growing toes 



typical o£ cristatus. (From Rotmann 1933.) 



SUGGESTED READING 

 Medawar 1945, Reeve and Huxley 1945, Weiss I949<j, Zuckerman 1950. 



