782 Holden. — Some Wound Reactions in Filicinea?i Petioles. 
Athyrium Filix-foemina there is a remarkable increase in the length and 
bulk of the cortical cells for a depth of from four to six cells, and these 
divide by one or more transverse walls, giving a distinctly meristematic 
character to the region, and affording a marked contrast to the cells which 
have not become secondarily active. Here, too, the suberization of the outer 
walls of the most peripheral cells has also taken place, thus affording adequate 
protection without interfering with their vitality (PI. LXXIII, Fig. 3). 
This stage of wound repair seems to be generally attained within three 
weeks of the infliction of the injury, but in the case of Asplenium Belanger i 
there was no trace of secondary activity in that period. Petioles of this 
species examined after three weeks showed a dry but in no way discoloured 
wound, and sections demonstrated that the collapse of the cells at the sur- 
face was the only response. In five weeks, however, the characteristic 
cambial development was perfectly obvious, and, apart from the slower rate 
of the early development, this species showed no striking points of difference 
from the remaining bulbiferous forms. 
One form, Cystopteris bulbifera , however, appears to stand somewhat 
apart from the rest. The cortical cells of the petiole showed very little 
secondary activity either at the apex or below, but if a young, barely visible 
bulbil were cut off there was an appreciable cambial reaction. This is per- 
haps partially explicable in the comparative slenderness of the petiole, since 
this would be obviously more weakened by wounding than one of a more 
robust type, such as Asplenium viviparum. 
The behaviour of S colop endrium vnlgare was also of some interest, as 
the cortical cells, for a much greater depth than the average, elongated, 
but on the other hand this was accompanied by a relative paucity of trans- 
verse divisions. 
As the plant develops, and the originally curled portion becomes 
straight, secondary changes are involved. In one or two cases, however, 
plants of Lastraea Filix-mas which were wounded early, whilst they were 
still completely enveloped in ramenta, and collected eight weeks afterwards, 
before the spring period of rapid uncurling and growth had supervened, 
were found to show very little further modification. It is a noteworthy 
fact that all the hardy indigenous forms appear to show a more pronounced 
activity if wounded before the first great elongation of the petiole has taken 
place, the results with Lastraea , referred to above, with Athyrium Filix-foe - 
mina, and with Pteris aquilina, being specially marked (PL LXXIII, Fig. 3). 
This second type of apical wound response, with its inadequate attempts 
at cambium formation and its inability to produce a really efficient cell- 
barrier, affords a striking contrast to the condition characterizing Wood- 
wardia radicans and its allies. 
A still further reduction is shown in the attempt at healing made by 
Polysticlmm angular e, Pteris ere tic a, Lastraea reflexa , and W oodwardia 
