Holden. — Some Wound Reactions in Filicinean Petioles. 785 
as lignificatlon would obviously interfere with their growth, but where the 
elongation is slight in amount or absent, the explanation does not seem at 
all clear. 
The inner layers were also occasionally of cellulose, but more com- 
monly showed distinct evidences of lignification, giving a pink colour with 
phloroglucin after acidification with HC1. The depth of the coloration 
indicates a very imperfect lignification, the walls being of a ligno-cellulose 
rather than a true lignin nature. In other cases the lignification had 
become much more pronounced, giving the typical bright red phloroglucin 
coloration and in some of the smaller petioles extending throughout the 
cortex. 
The modified cells, especially in the immediate vicinity of the wound? 
were coloured yellow or yellow-brown by the deposition of tannin-like 
substances in their walls, and, as this interfered to a certain extent with the 
action of the various reagents, it was, as a rule, removed by gently warming 
the sections with eau de Javelle. Zimmermann (37, p. 143) cites Mangin 
as stating that treatment with this liquid causes lignified elements to give 
the cellulose reactions, but in the experience of the writer, if reasonable care 
is observed, this is certainly not the case in the Filicineae. 
As a test of the reliability of the phloroglucin reaction after treatment 
of the tissues with eau de Javelle, several series of microtome sections of 
a wounded petiole of Lastraea reflexa were employed. 
Half of these were acidified with HC1 and then treated with phloro- 
glucin solution, whilst the remainder were first decolorized with eau 
de Javelle and then similarly treated. The coloration, apart from the 
yellowness of the walls of the most peripheral cells, was identical in each 
case, the xylem elements being bright red, whilst the imperfectly lignified 
cortical tissue was stained pink. The walls of the modified cells are 
abundantly pitted, though the pits themselves are not large ; they are 
shown very clearly on swelling with caustic potash (Plate LXXIII, Fig. 8). 
(ii) With regard to the reactions of the tissues in the regions below the 
apex, the same variability is noticeable in the different forms, but to a less 
degree. 
A section of a wounded area produced just below the curled apex 
in Asplenium bulbiferum exhibited a slight elongation of the cortical cells, 
accompanied by a large number of cambial divisions, this resulting here 
and there in the production of a small tabulate cell. There was not, how- 
ever, any attempt at the production of a complete new growth. The cells 
at the periphery showed what seemed to be slight traces of suberization, but 
the tests for suberin gave results which could only be described as extremely 
inconclusive (PI. LXXIII, Fig. 5). 
Similar cambial activity, to a perhaps slightly less extent, was per- 
ceptible in the middle of the fully unfolded pinna-bearing region of all the 
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