No. 520] THE NATURE OF GRAFT-HYBRIDS 53 



the higher plants there goes a high degree of regenera- 

 tive power, a great contrast to the very limited capacity 

 for regeneration shown by the highly organized animals 

 where new individuals can only arise through sexual 

 reproduction. This great power of regeneration in 

 plants is accompanied by much less specialized cells and 

 a very imperfectly marked individuality of the organ- 

 ism as a whole. Any seed plant may be regarded as a 

 colony df individuals since the parts are repeated in- 

 definitely and can be made to regenerate the whole plant. 

 The power of regeneration shown by almost any part of 

 the plant, even a single cell in some cases, renders any 

 theory of a special germ plasm out of the question in the 

 case of plants, however plausible such a theory may ap- 

 pear when applied to animals. 



It is not then so very extraordinary that this regenera- 

 tion of the plant from somatic cells should be carried so 

 far as to involve cell fusions such as Winkler believes 

 preceded the formation of his Solarium darwinianum. 

 Kvon if this should not be proved, his experiments show 

 beyond question the existence of graft-hybrids of a sort 

 quite inconceivable in any animals except very low types, 

 such as corals where it is by no means impossible that 

 similar graft-hybrids might be developed. 



It is this positive demonstration of the reality of 

 "vegetative" or "somatic" hybrids which gives the ex- 

 periments of Winkler their greatest value, and it is to 

 be hoped that they will serve as a stimulus to other work 

 in the same direction which may well have a great influ- 

 ence upon the drift of biological speculations dealing 

 with the laws of heredity. 



