IV 



QUANTITATIVE ASPECTS 



605 



x remains to be regenerated varies according to the amount x initially removed, 

 as shown also by the results of Ellis (1909) and others. This is probably related to 

 the fact (Abeloos, 1930: Brondsted and Brondsted, 1952) that the rate of regener- 

 ation is specific to intrinsic properties of the tissues near the point of amputation 

 rather than to the amount of loss itself. It should be noted, in parenthesis, that 



4.0 

 3.0 

 2.0 

 1.0 



.4.0 

 3.0 

 2.0 



1.0 



4.0 

 3.0 

 2.0 

 1.0 



/ Normal growth 



J I I L 



10 



_l I I I I I L 



20 30 40 50 60 70 10 20 30 40 50 60 70 



Time in days 



Fig. 2. Graphs of length/time for a 

 regenerating limb of Triturus showing 

 the normal curve of regenerative 

 growth and the effect on this of de- 

 nervating the limb at various stages of 

 regeneration. The arrows mark the 

 points of denervation and the dots 

 show subsequent growth against the 

 reference lines of the normal curve, 

 and of the projections of the standard 

 deviation for the length at the time 

 of denervation (broken lines). (From 

 Singer and Craven, 1948). 



in the whole-body regeneration of planarians, studied by these last workers, this 

 intrinsic power, as measured by the time for complete regeneration, and by the 

 frequency of successful head-regeneration, is maximal near the anterior end, and 

 so decreases disto-proximalwards, in contrast to the absolute initial rate in the 

 various appendages considered above. However further careful quantitative work 

 is required, since in the latter, also, the time required for regeneration is minimal 

 when least is removed, and measures specific, not absolute, regeneration-rate. 

 The absolute amount regenerated per unit time increases also with the number 

 removed, of a serially repeated organ, for instance the radial series of tentacles and 

 arms of the medusa Cassiopea, and the brittle-star Ophioglypha (Zeleny, 1905, 1907) 

 and the linear series of limbs of arthropods. Zeleny found that even the specific 



Literature p. 64^ 



