198 



PROBLEMS OF RELATIVE GROWTH 



the growth-gradient in Carcinus. He finds that the effect of 

 the parasite is primarily to reduce general growth of the crab 



D 



Fig. 88. — Regulation of growth of eyes of one species of Amblystoma grafted 

 to individuals of another species and of different age. All x 6. 



G, grafted eyes. 



(A) A specimen of A. punctatum with an eye from a younger specimen of the larger species, A. 

 tigrinum. 



(B) The same 40 days later, after feeding on maintenance diet ; the grafted eye has enlarged. 



(C) A similar specimen to (B), but starved since the operation ; the grafted eye has not grown. 



(D) A. tigrinum, with an eye from an older A. punctatum. 



(E) The same specimen 45 days later, after normal feeding. The grafted eye has lagged in its 

 growth. 



