GROWTH-GRADIENTS IN NEGATIVE HETEROGONY 89 



tomer can eat as flesh only 30 lbs. ; on the other hand, when the 

 animal is shaped like that of the adult Suffolk ram, from 100 lbs. live 

 weight 67 lbs. of carcase is obtained, and of this 61 lbs. is flesh which 

 can be eaten — more than double that from of the badly shaped animal." 



Phase 1 



(Smallest to largest 



new-born 



Phase 2 



(Largest newborn 

 to medium sized 



-J* 



o 



-i 



S-j 



o 

 txo 



08 



0-6 



C4 



12 3*3 12345 



Axis of limb : distal — > 



Fig. 49. — Reversed growth-gradient in organs showing negative heterogony 



(limbs of sheep). 



The figures on the abscissa represent : i, limb-girdle ; 2, humerus, or femur ; 3, radius + ulna, or 

 tibio-fibula ; 4, carpals, or tarsals ; 5, metacarpals, or metatarsals, (solid line, forelimb ; dotted line, 

 hind-limb). The ordinates denote growth-coefficients (k), those below i-o signifying negative hetero- 

 gony : they are taken relative to vertebral column weight. Size-phase 1 includes smallest to largest 

 new-born specimens (100 to 256 g. vertebral column weight) ; size-phase 2, largest new-born to half- 

 grown (256 to 690 g. vertebral column weight). The growth-gradient is at first flat, with slight 

 positive heterogony ; then steeply tilted downwards distally, upwards proximally. 



TABLE VIII 



Relative weights of parts of the skeleton of Suffolk sheep at three 

 different ages (c? Hammond, 1929; $ Hammond, 1927), reduced to 

 proportions of weight of cannon-bone taken as 100. From Huxley, 

 1931B. 



