208 THE feATE OF GROWTH [ch. 



under exceptional circumstances and in transient phase. Undoubtedly 

 many of Huxley's instances shew increase by compound interest, 

 during a phase of rapid and unstinted growth; but I find many 

 others following a simple-interest rather than a compound-interest 

 law. 



Relative weights of claw and body in fiddler-crabs (Uca pugnax). 

 (Data abbreviated from Huxley, Problems of Relative Growth, 

 p. 12) 



In the common stag-beetle {Lv^anus cervus) we have the following 

 measurements of mandible and elytron or wing-case: which two 

 organs make up the bulk of, and may for our purpose be held 

 as constituting, the "total length" of the beetle. Here a simple 

 equation meets the case; in other words, the length of elytron or 

 of mandible plotted against total length gives what is to all intents 

 and purposes a straight hne, indicating a simple-interest rather 

 than a compound-interest rate of increase. 



Measurements of iS stag-beetles (Lucanus cervus)* (mm.) 



* Data, from Julian Huxley, after W. Bateson and H. H. Brindley, in P.Z.S. 

 1892, pp. 585-594. 



