52 



PROBLEMS OF RELATIVE GROWTH 



It can at once be seen (Fig. 31) that the growth of the older 

 eyes slowly approaches the normal growth-curve (see also 

 Figs. 85 to 87, and especially 88). 



2.0 



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arm 



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BODY LENGTH 



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90 mm 



Fig. 31. — Regulation of eye-size in eyes of one species of Amblystoma grafted 



on to another. 



Dotted lines, curves for two cases when embryonic eyes were grafted to a host of the same stage 

 of development as the donor. Solid lines, curves for two cases when eyes were taken from an older 

 larva and grafted on to a younger host larva ; in this case the eyes hardly grow at all until they 

 reach the correct relative size. 



We thus are driven to the conclusion that though the eyes 

 of the two species have different specific growth-intensities, 

 and therefore different coefficients of growth-partition when 

 both are present in the same body, there is for each body-size 



