CONTENTS. 



xxi 



of Rohinia hispida sending down roots on dead stem of 

 Robinia pseudo-acacia. Actual descent of woody fibres in 

 the palm — virtual descent of these fibres in the trunk even 

 of Exogens ; Dr Lindley's opinion as to this point. 



LETTER XIV 145 



Evidence continued. Unequal growth of the woody layers in 

 the same tree in different years and on different sides of the 

 trunk — these differences directly related to differences in 

 the number of the plants emanating from the buds, to the 

 vigour of the plants, and their position on the tree. The 

 development of the cambium into wood dependent on the 

 buds and their produce, i.e., on the leaves, and that in a 

 way not referable merely to supplies of elaborated sap fur- 

 nished by the leaves. The wood not wholly developed in 

 situ. An actual as well as a virtual descent, in some way, 

 of woody tissue from the leaves. Holly-and-chain piece. 



LETTER XV 155 



Dr Carpenter's objections to the theory. Partly general, partly 

 special. In as far as general, various — these considered. 

 Argument founded on an elm, referred to by him, con- 

 sidered. Argument founded on the structure and consti- 

 tution of the cactus considered. 



LETTER XVI 167 



Dr Carpenter's special objections to the theory considered. 

 These twofold — 1st, that the buds and cambium -layer, 

 and their respective produce, are merely continuous pro- 

 ducts, and an extension of the existing tree. 2ndly, that 

 the buds of trees are not co-ordinate with the seeds, and 

 that only the produce of a seed can be regarded as an indi- 

 vidual being. The former objection taken up and discussed. 



LETTER XVII 177 



Dr Carpenter's second special objection taken up and considered. 

 The seed itself, in a like sense as the bud, merely an ex- 

 tension or a continuous product of the parent plant. The 

 bud can evolve all that the seed can. No real difference 

 between two trees, e.g., two willow trees, raised, the one 

 from a seed, the other from a bud. Exceptions taken to 



