132 
Holden . — Further Observations on the Wound 
the deeper wounds also appear normally to have no effect, although, as in 
the case of the petiole illustrated in Fig. 3, iv, disintegration of the bundle 
may occur, but this is comparatively rare. In the few instances in which 
there is an obvious reaction, the vascular bundles affected either abut on or 
are adjacent to the wound surface. The traumatic response is always con- 
fined to the non-specialized constituents of the bundle, such as the starch 
sheath and the conjunctive parenchyma, the only exception noted during 
Fig. 4. i. Diagrammatic transverse section of wound area, showing pad of thickened cortical 
cells at wound surface and also isolated masses of thickened tissue on the flanks of the bundles. 
Local elongation of the cortical elements occurred at D, and the tissues of the vascular strands were 
affected at A and c. ii. Affected portion of C, showing effect of wound on starch sheath and con- 
junctive parenchyma, 'iii. Tracing from ii. The dotted area represents the cells which were 
discoloured by tannin, iv. Affected portion of C. i x 12 ; ii, iii, and iv x 500. 
the present observations being that shown in Fig. 3, iv, in which the endo- 
dermis had elongated at one point. With regard to the starch sheath, this 
may simply develop thicker walls, or may become both elongated and 
thickened. These stages are well illustrated in Fig. 1, vi and vii. The 
wound in this particular case had caused the total destruction of some of 
the vascular strands and the partial destruction of two others (Fig. 1, ii, B 
and C respectively). Of the strand B only a portion of the starch sheath 
