835 



wood parenchyma in the form of thick-walled, isodiametric cells, or cells 

 somewhat stretched radially, irregularly quadrangular, which appear not 

 infrequently with somewhat bent walls {kg). These represent the begin- 

 nings of a wood body, which is being formed under slight pressure. By 

 their increase they gradually compress all the thin-walled, first-formed 

 tissue, retaining the character of phloem parenchyma {ok) and representing 

 the first closing of the wound. When the meristematic zone is formed in 

 loops, round masses of wood parenchyma are produced, enclosing the brown 

 dead cell complexes of the original tissue. Gradually the whole tissue {ok) 

 is pressed back between i and 2 by cells similar in character to those marked 

 {kg), which store up starch. 



Under favorable conditions, the scion also participates in closing the 

 wound. In the present drawing, a bud is shown with the bark shield, but 

 without any wood. The cut £ is a cross section only through the bark 

 shield. The bud belonging to this, which must be imagined in the direction 

 (0), lies above the plane of the section; in this section only the large central, 

 vascular bundle {gh), which extends to the bud, and a smaller one adjacent 

 to it have been drawn. The third, smaller bundle, present in every unin- 

 jured bud cushion and likewise traversing slantingly the axis of the branch 

 on the other side of the central bundle, has been cut away here in removing 

 the bark shield; this does not affect the outgrowth of the bud. On the 

 other hand, the absence of the central vascular bundle will always signify a 

 failure in budding. The bark shield with the rapidly drying bud bracts can 

 grow further without the vascular body but in my experience it has never 

 happened that an excessively luxuriant overgrowth tissue from the bud had 

 formed adventitious buds and in this way compensated for the dead bud. 



To be sure, the formation of adventitious buds takes place in many 

 bud grafts, as is shown in the following Fig. 200 of an herbaceous bark 

 graft of Aesculus rubicunda on Aesculus Hippocastanum, but up to the 

 present I have found this bud formation only on luxuriant overgrowth 

 edges of the stock. The bark strips {ne) have produced such strong new 

 structures that they have thereby been pushed out from the scion like wings. 

 Numerous adventitious buds (a) stand on the edge. 



In the budded rose (Fig. 199), the whole inner surface of the bark 

 shield {E) has already produced new wound tissue, sometimes more, some- 

 times less, according to the age of the mother cells. The cambial zone of 

 the bundle, lying below the phloem fibre groups {b), has formed the new 

 cells very abundantly, as is shown by the protruding tip {z). The new 

 structure on the inner side of the shield bears the character of bark tissue 

 and is already distinguished by numerous crystals of calcium oxalate, while 

 the cambial zone {c), which begins to form new wood elements, appears in 

 later stages of the coalescence in connection with the cambial zone {cc) of 

 the bark strips. As soon as this union takes place a continuous cambial ring 

 is formed again about the whole circumference of the tree. The cambial 



