Holden .- — Some Wound Reactions in Filicinean Petioles . 779 
once preserved in chromo-acetic fixative, Perenyi, or Farmer’s fluid. The 
number of forms examined in this way included the following species : 
Adiantum Capillus-veneris , A. Edgworthii , A futvum , Allosorus crispus , 
Asplenium Belangeri, A. bulbiferum , A. fontanum, A. viride , X. viviparum , 
Aspidmm thelypteroides, A thyrium Filix-foemina , Blechnum brasiliense , 
Cystopteris bulbifera , £ 7 . fragilis , Dennstaedtia punctilobula , Davallia poly- 
ant ha, Faydenia prolifer a, L astraea dilatata , L. Filix-mas , Z. reflex a, 
L. thelypteris , Lomaria chilensis , Microlepia anthurifolia , Osmunda regalis , 
Phegopteris hexonaptera , Phleb odium {P oly podium) glaucum , Polystichum 
angular e, P. prolife rum, P. falcatum , P ter is aquilina , Z\ cretica , S colop en- 
drium vulgare , Struthiopteris germanica , Woodwardia orientalis , IF. 
02m, IF. virginica. 
A large proportion of these were found to be much too hard in texture 
to microtome successfully, and consequently only sections of the apices 
of such were so prepared ; some of the less resistant forms, however, offered 
little difficulty. The material was transferred from absolute alcohol, 
through pure cedarwood oil, to paraffin, as this method caused less shattering 
than when xylol was used. The harder forms were sectioned by hand. 
The best general results were obtained by double staining with carthamin 
and picric anilin blue, or safranin and Lichtgrun ; for nuclear studies 
Heidenhain’s iron-haematoxylin with a light erythrosin counterstain was 
satisfactory. 
The microchemical investigation of the cell-walls and contents 
involved the use of special reagents, which will be dealt with in detail 
later. 
Results and Discussion. 
The change in the external appearance of the affected surfaces, apart 
from a browning of the dead cells, was, as a rule, inconsiderable. In one or 
two cases, however, notably in Pteris cretica , the petiole became distorted 
and bent at the seat of injury (PI. LXXIV, Fig. 23), and the explanation of 
this seems to be that the removal of tissue had caused a violent disturbance 
of the osmotic balance. This had resulted in the flexure of the petiolar strand 
and the consequent crushing of the cortical parenchyma on that side of the 
strand remote from the wound. 
With regard to the details of internal modification a systematic survey 
of the results obtained serves to demonstrate that, although no rigid scheme 
of classification of the various types of wound response is possible, there are 
yet certain underlying broad similarities and differences, correlated with 
the region of the wound and the texture of the petiole. Thus an almost 
solid deposit of gummy matter in the cells at the seat of injury is of practi- 
cally universal occurrence, whilst the more or less widespread thickening of 
the cortical tissue is also a very frequent feature. 
