192 



PROBLEMS OF RELATIVE GROWTH 



rate in the same conditions ; and they then grafted limb-disks 

 and eye-rudiments from one species to the other. The main 

 important finding is that the organ retained their specific 

 growth-rates even on the bodies of their new hosts, provided 

 that conditions were equalized by keeping both species at the 

 same nutritive level (which was most simply accomplished by 

 giving both the maximum amount of food they would take). 

 Under these conditions, the transplanted organ attained the 

 same size which it would have had if left in the body of its own 

 species ; tigrinum organs grew just as fast as normal though 

 on the slow-growing bodies of punctatum, punctatum organs 

 just as slow as normal though on the fast-growing tigrinum 

 bodies (Fig. 85). On the other hand, this inherent growth- 



-n 



to 



^0 



60 



70 



80 



DAYS AFTER OPERATION 

 A 



Fig. 85. — Graph showing the growth of normal 



(A) Growth of tigrinum eye grafted on to punctatum, compared with that of a normal tigrinum 

 eye, and that of the normal punctatum eye of the host. 



