APPENDIX D 215 



claw, a lizard its tail, and so forth, but none of these parts can 

 reproduce the whole ; that is done solely by germ-cells. Higher 

 yet, as among birds and mammals, the power of reproducing lost 

 parts is comparatively very trifling ; important and complex parts 

 cannot be restored. Wounds and mutilations are healed, but, if 

 serious, very imperfectly, for only scar tissues replace the tissues 

 which were lost. 



We see, then, that the reproduction of lost parts, whether it 

 be on a very great and perfect scale, as when a fragment reproduces 

 a whole, as in a sponge, or whether it be on a very small and 

 imperfect scale, as when a wound is healed in one of the higher 

 animals, is a process of the same order. Now, we speak of a 

 scar in a man, for example, as an acquired character ; but who 

 would dream of speaking of all that which is reproduced by the 

 fragment of a sponge or a begonia leaf as a character acquired by 

 the fragment. Moreover, when one of the higher animals is 

 mutilated, as when a dog loses his tail, we lump together both 

 the mutilation and the tissue with which the lost part is replaced 

 {i.e. the scar) as a single acquired character. But, even if we 

 should agree for convenience to regard the scar as an acquired 

 character, surely the mutilation ought not to be so designated, 

 but should rather be termed (as I venture to suggest) an enforced 

 character. We see, moreover, that the power of reproducing lost 

 parts to a greater or less extent persists throughout organic nature, 

 but that this power is vastly greater lower in the scale than higher. 

 In other words, if we agree to regard such reproductions as ac- 

 quired, observation proves that the power of acquiring them is 

 very much greater lower in the scale {e.g. sponge), than it is higher 

 (e.g. man). 



On the other hand, there is another class of acquired char- 

 acters — perhaps the only class to which the term should be 

 applied properly — the power of acquiring which is greatest 

 among the highest animals, and, apparently, is little or not at all 

 present among the lower animals, nor in the whole of the plant 

 world. I speak of such characters as arise as a result of exercise 

 and use, as, for instance, the increased muscular power of an 



