280 ^ TAYLOR— ON THE PRODUCTION OF 



to division of soft-bast cells and the causing of the cells so formed to 

 line up in a radial manner around the cork-bounded cavity. When 

 the injection caused the death of a strip of bark, this was segregated 

 by a cork-cambium that sometimes took a peculiar step-like course, 

 running between the hard-bast strands of the successive annual rings. 



Since this work was begun as a continuation of that of Dr. Rumbold's 

 with a view to the amplification and confirmation of her findings, it 

 is necessary to compare the conclusions to which we have come. 



The most important new point is the discovery of the same modifi- 

 cations in uninjected trees as she had found in injected ones. This 

 ehminates the necessity for explaining them on any such basis as that 

 propounded by her on page 491 of her paper (3). They are probably 

 a normal wound-reaction of the species. 



On page 486, heading 5, she states that "The wounded tissue was 

 abnormal in that its position was reversed from the one in which it is 

 customarily seen. " So far as the writer could determine from the mater- 

 ial at hand the direction of xylem formation from the xylem-cambia was 

 the same as from ordinary cambia, that is, from the inner face of the 

 cambium. 



The overgrowth wound- or callus-tissue that was formed at the 

 sides of the wounds was perfectly normal in position. In some cases 

 the ingrowing margin was so bent over that there is produced the appear- 

 ance in transverse section of a finger of wood largely surrounded by 

 bark, and new tissue being formed on the face turned toward the trunk 

 as well as outside. This, being merely a mechanical matter, can hardly 

 be interpreted as a physiological reversal of orientation. As for the 

 special xylem formed from the xylem-cambia in the soft-bast, this also 

 the writer cannot consider to be reversed in position. A reversed 

 relation of the xylem and phloem would imply that it was produced 

 on the outside and not on the inside of the formative meristem, inside 

 here meaning in the direction of the pith. Instead of this, it is quite 

 evident that the meristem was outside and that the elements were 

 produced on its inner face. A point emphasizing this is the relative 

 position of what appears to represent spring and autumn wood in these 

 abnormal patches, the "spring" wood being innermost. 



On page 487 she states that " Quick killing was not followed by stimu- 

 lation other than the formation of normal wound tissue (callus) to cover 

 the wound. " The overgrowing side callus which she used in her Figure 

 2 to illustrate this could hardly be expected to show the abnormal areas. 

 The writer failed to find them here in all specimens that he examined. 



