CONSTANT DIFFERENTIAL GROWTH-RATIOS 15 



bar-eye mutant of Drosophila melanogaster (Hersh, 1928) ; 

 the linear dimensions of certain Molluscs (Nomura, 1928 ; 



30" "To 



/o 



40- 



30- 



20- 



10 



-— — ---»t-. 



10 



20 



30 



40 50 60 



mm 



Fig. 6. — Increase in relative width of abdomen with increase of carapace 

 length in the shore-crab, Carcinus maenas : above, female ; below, male. 



The ordinates represent °_?5 — \ O/ • f he abscissae represent carapace length in mm. 



carapace length /<J ' 



Nomura and Sasaki, 1928) ; the tail of the mouse Phenacomys 

 (Taylor, 1915) ; the dimensions of the casques of Hornbills 

 (Banks, unpublished) ; the weights of various organs of the 



