786 Holden . — Some Wound Reactions in Filicinean Petioles . 
bulbiferous species examined with the exception of Cystopteris bulbifera 
and Adiantnm Edgworthii , but gum did not begin to make its appearance 
until the lapse of from four to five weeks (PL LXXIII, Fig. 6). 
In one case, however, in which a plant of Woodwardia radicans had 
accidentally been kept without water, the gum deposit was abundant 
within a fortnight, and there were practically no traces of either cell- 
elongation or cambium formation. 
Two specimens of Woodwardia orientalis were also somewhat excep- 
tional in that for a considerable depth the affected tissues after division 
became suberized (PI. LXXIII, Fig. ir). 
That actual suberization and not merely a deposit of tannin in the 
tissues had occurred was amply demonstrated by the following reactions : 
1. The cell-walls were insoluble in hot or cold concentrated H 2 S 0 4 . 
2. They were only dissolved with difficulty by a strong solution 
of chromic acid. 
3. They stained readily with cyanin, with alkannin, and with fresh 
chlorophyll solution after removal of the tannin with eau de Javelle. 
4. They stained brown-violet with chlor-zinc-iodide after treatment 
with KOH solution. 
5. They were doubly refractive with polarized light. 
It was at first a source of difficulty to understand how the suberization 
could be so complete, and the cells yet retain their contents after three 
months apparently but little affected. 
Staining with cyanin, alkannin, and chlorophyll, however, showed the 
presence of abundant pits in the walls, these showing especially well where 
the walls had been cut tangentially, and doubtless serving to ensure 
protoplasmic continuity. 
An abundant deposit of gum was a general feature in all the remaining 
cases, but there were certain differences apparent in the mode of repair. 
In Atkyrium Filix-foemina , Lastraea reflex a, and most of the remain- 
ing species there was a certain amount of cell-elongation, with an occasional 
transverse division in a few forms, but this was seldom pronounced. It was 
always accompanied by an increase in the thickness of the walls, this 
usually being of a ligno-cellulose character. 
The species of a more horny nature, such as Pteris cretica , Blechnum 
brasiliense , and Polypodium glaucum , varied somewhat, specimens occasion- 
ally showing some elongation, but more commonly contenting themselves 
with a thickening of the walls and a dense aggregation of gum. The modi- 
fied walls in these also were often slightly lignified, and in one or two 
instances the lignification was strongly marked. In Lomaria chilensis and 
Phegopteris hexonaptera the lignification extended throughout the petiole in 
the wound area. Osmunda regalis and Struthiopteris germanica as a rule 
behaved similarly to the above forms, but in one or two instances, in the 
