274 THE RATE OF GROWTH [ch. 



Some writers have found the curve of regenerative growth to be 

 different from the curve of ordinary growth, and have commented 

 on the apparent difference; but they have been misled (as it seems 

 to me) by the fact that regeneration is seen from the start or very 

 nearly so, while the ordinary curves of growth, as they are usually 

 presented to us, date not from the beginning of growth, but from 

 the comparatively late, and unimportant, and even fallacious epoch 

 of birth. A complete curve of growth, starting from zero, has the 

 same essential characteristics as the regeneration curve. 



Indeed the more we consider the phenomenon of regeneration, 

 the more plainly does it shew itself to us as but a particular case 

 of the general phenomenon of growth*, following the same lines, 

 obeying the same laws, and merely started into activity by the 

 special stimulus, direct or indirect, caused by the infliction of a 

 wound. Neither more nor less than in other problems of physiology 

 are we called upon, in the case of regeneration, to indulge in 

 metaphysical speculation, or to dwell upon the beneficent purpose 

 which seemingly underhes this process of heahng and repair. 



It is a very general rule, though not a universal one, that 

 regeneration tends to fall somewhat short of a complete restoration 

 of the lost part; a certain percentage only of the lost tissues is 

 restored. This fact was well known to some of those old .investi- 

 gators, who, like the Abbe Trembley and hke Voltaire, found a 

 fascination in the study of artificial injury and the regeneration 

 which followed it. Sir John Graham Dalyell, for instance, says, in 

 the course of an admirable paragraph on regeneration!: "The 

 reproductive faculty ... is not confined to one pjortion, but may 

 extend over many; and it may ensue even in relation to the 

 regenerated portion more than once. Nevertheless, the faculty 

 gradually weakens, so that in general every successive regeneration 

 is smaller and more imperfect than the organisation preceding it; 

 and at length it is exhausted." 



* The experiments of Loeb on the growth of Tubularia in various saline 

 solutions, referred to on p. 24.5, might as well or better have been referred to under 

 the heading of regeneration, as they were performed on cut pieces of the zoophyte. 

 (Cf. Morgan, op. cit. p. 35.) 



t Powers of the Creator, i, p. 7, 1851. See also Rare and Remarkable Animals, 

 u, pp. 17-19, 90, 1847. 



