126 PROBLEMS OF RELATIVE GROWTH 



His results can be analysed (Huxley, unpublished) to shed 

 some light on our problem, although not so much as if the 

 experiments had been designed for that purpose. 



His results are particularly valuable in one respect, as the 

 growth-rate of the regenerating and normal limbs was followed 

 during a number of moult-stages, until the animals became 

 adult (or died). In general it appears that after amputation 

 of the fore or middle leg, the normal growth of the next pos- 

 terior legs is first depressed during the period of most active 

 regeneration ; then accelerated ; and finally, as the rate of 

 regeneration approximates to that of normal growth, sinks 

 again, usually below normal. (The rate of growth of the 

 regenerating limb also frequently sinks below normal at about 

 the same time.) The effect on the unoperated leg of the 

 opposite side of the same segment as the amputated leg appears 

 to be similar, but is less pronounced. After amputation of 

 the hind-leg, the effect on the next anterior (middle) legs is 

 of the same general form, but the initial depression is greater, 

 the later acceleration less. (I have no data for the effect of 

 amputation of the middle leg on the growth of the fore-legs.) 

 When, as sometimes happens, no regeneration occurs, the effect 

 of amputation appears to be a temporary acceleration of 

 normal growth in other legs, without any marked depression 

 at all. The effect on limbs in other segments is always identical 

 on both sides ; the effect is no greater on the side where regen- 

 eration is in progress (Fig. 68). 



Thus the effects depend partly upon the rate of growth in 

 the regenerating limb ; but there appears to be also a positional 

 effect, the depressant effect of a regenerating (rapidly-growing) 

 limb being more marked on the limb anterior to it, the stimu- 

 lative effect more marked on the limb posterior to it. This 

 fits in with the facts of normal growth in Palaemon, Maia and 

 Inachus. 



Von Ubisch (1915) carried out somewhat similar experi- 

 ments on the larva of the insect Cloe diptera. Unfortunately 

 his method of recording his results does not permit of a satis- 

 factory analysis of the question which here interests us, namely 

 the effect of regeneration on the normal growth of neighbour- 

 ing unoperated structures, but only of effects on the rate of 

 regeneration itself. However, some of his results are of 

 relevance. All operations were made directly after one moult, 

 and the final measurements made directly after the next 

 moult. He finds that when two different legs are removed, 



