105 



their part. The question at once arises whether the pressure 

 of this mass of growing tissue does not finally cause a rupture 

 of the surrounding wood. And in fact in the stem just men- 

 tioned the ring of first formed secondary wood , in spite of its 

 firm structure, is cracked in three places. No great weight 

 however ought to be laid on this circumstance, as the similar 

 ring of wood in old stems of Phi/tocrene shows occasionally 

 cracks of like character although no anomalous tissue is pre- 

 sent in the pith. During this continued production of phloem 

 no further addition is made to the few scattered xylem-ele- 

 ments on the outer surfaces of the cambium-strips. It is evi- 

 dent , therefore , that the cell-division of the cambium proceeds 

 in such a manner that the daughter-cell lying toward the 

 outer surface is in every case the one which retains its meri- 

 stematic qualities. 



In connection with these anomalous bands of cambium the 

 question naturally presents itself whether they can in anyway 

 be regarded as belonging to the normally oriented fibro-vascu- 

 lar bundles in the sense that the latter are ^bicollateral". The 

 term „bicollateral bundle" however has within some years 

 been very justly limited in its use^); and, as the following 

 facts will show , is in its stricter and more accurate sense not 

 applicable in the case of lodes tomentella. As already described 

 the anomalous formations group themselves into four, or more 

 rarely three, rather broad bundles. The normally oriented 

 fibro-vascular zone contains however no less than thirteen 

 distinct bundles, the arrangement of which is as follows. At 

 both ends of the ellipse stand broad bundles (It.) which come 

 from the leaves of the next node above. Each side of each of 

 these leaf-trace-bundles stand small bundles {h r, h r, a b, a b) 

 which originate in the axillary buds, and owing to the fact 

 that only one of these buds is developed to a branch while 

 the others are regularly aborted , those bundles at one end of 

 the ellipse {a b, a b) are considerably smaller than those at the 



1) cf. M. Herail, Etude de la tige de3 dicotjl^dones. Ann. d. Sciences nat. (bot.) 

 ser. VII, torn. II, p. 266. 



