109 



also given, showing the relative positions of the anomalous 

 formations at different points in the stem. The cambial acti- 

 vity in regions m, m. in cross-sec a where the secondary me- 

 dullary rays were produced gradually ceases and the two strips 

 of cambium which lay along the sides of the old ellipse e are 

 continued upwards in the node by four separate bands as in 

 cross-sec. h , the one lying next the tendril being often some 

 what smaller than the rest. These bands then unite by the 

 extension of their cambial activity into two new strips as in 

 c, lying along the sides of the new ellipse e^ , and, between 

 the bundles of anomalous phloem, two new secondary medul- 

 lary rays m^ m} are produced at right angles to those of the 

 next older intermode m m. 



It may strike the reader as strange that the course and 

 relations of the mensiematic tissue have thus been traced , and 

 that mature elements whether primary or secondary connected 

 with such meristem have been left quite out of consideration 

 In fact, however, as we have seen, no primary elements of 

 the nature of fibro-vascular bundles are present in the case of 

 the anomalous cambiums since these arise through successive 

 parallel divisions in ordinary cells of the pith. Furthermore 

 at the points of union between the normal cambium and those 

 of the pith , the secondary tissue given off is mostly of a paren- 

 chymatous character, and for this reason to secure greater 

 definiteness it has been necessary to trace the course of the 

 meristematic rather than the mature tissue. 



The connection just described between the inner and outer 

 cambiums of the /oi^e.^-stem suggests the possibility that the 

 anomalous meristem may arise merely by the gradual exten- 

 sion of the normal; that the divisions of the latter may be 

 communicated from cell to cell of the parenchyma which fills 

 the openings in the fibro-vascular ring which occur at every 

 node between the insertion of the petiole and the axillary 

 bud; and that, having thus penetrated to the pith, the cam- 

 bium spreads itself vertically into the internodes. Such a pro- 

 pagation of cambial cell-division through parenchymatous tissue , 



