790 Holden . — Some Wound Reactions in Filicinean Petioles . 
aquilina and Lastraea Filix-mas , the plants were grown under glass and 
under practically identical conditions. The writer hopes to make the 
physiological aspect of the paper the subject of a subsequent investigation. 
Summary. 
1. When a fern petiole is wounded in the still meristematic apical 
zone, the plant attempts to protect the injured area by the production 
of a pad of cambiform cells, which arise by the subdivision of the cortical 
parenchyma. 
2 . In the most successful cases the wound-cambium completely covers 
the affected part with a typically meristematic tissue, as in Asplenium 
bidbiferum , A. Belanger i, Polystichum proliferum, Woodwardia orientalis 
and W. radio ans. 
3. More usually the cambial response is imperfect, consisting of the 
elongation of the cells at or near the seat of injury, with a greater or less 
number of transverse divisions of these (e. g. Lastraea Filix-mas, Poly podium 
glancum , Scolopendrium vidgare ). In Polystichum angulare , Pteris cretica , 
Lastraea reflexa , and Woodwardia virginica, elongation of the outermost 
layer alone occurs. 
4. The cambium, whether well developed or imperfect, is supplemented 
by the scab-like remains of dead cortical cells on the outside. 
5. As the petiole develops secondary changes take place, resulting 
in the thickening of the cell-walls by deposits of cellulose, ligno-cellulose or 
lignin, and in the deposit of an almost solid mass of intracellular gum. 
6. Petioles wounded in the more mature ‘ region of pinna-insertion ’ pro- 
duce cambium less readily, only those producing bulbils, of the forms 
examined, showing this mode of response in any marked degree. 
7. It is suggested that the production of bulbils may demand a more 
adaptable type of tissue, this accounting for the readiness with which 
cambium is produced. 
8. In other forms, elongation of the outer cells, together with an 
abundant deposit of gum, is the most general type of wound response. 
Transverse divisions of the modified cells are few in number or do not 
occur. 
9. Occasionally, as in Davallia polyantha , there may be an extremely 
thick deposit of cellulose on the walls of the cells at the seat of injury, 
resulting in the production of a very resistant tissue. Gum is deposited as 
in the previous cases. 
10. Plants wounded in the basal part of the petiole generally show 
no celk elongation, but thickening of varying character together with a con- 
stant deposit of gum were constant features. 
11. In only one case, an abnormal one, in which the wound was infected 
by Bacteria, was any secondary activity evinced. This resulted in the local 
