353 
Anomalous Stem of Osmunda regalis. 
plant would still be in a debilitated condition, a weak place in the stem 
would probably result, where it would be very likely to snap off when the 
specimen was collected. 
In Osmundites Kolbei a mixed pith was found throughout the whole 
length of the specimen examined, and there is no reason to believe that it is 
not a perfectly constant and diagnostic character of the plant. Apart from 
the larger size and vertical elongation of the medullary tracheae (Figs. 4 and 6), 
it is essentially the same type of pith as that in the specimen of Osmunda 
regalis described above. It may be held, therefore, that if the normal 
differentiation of the pith of the present-day Osmunda regalis is interfered 
with by traumatic conditions, some of its elements are liable to revert to 
their earlier phylogenetic habit and are still able to give rise to tracheae 
instead of parenchyma. We have thus a return to an ancestral type of pith- 
structure that was normal in the Cretaceous fossil Osmundites Kolbei. If 
this is so, additional support is given by our specimen to the theory that the 
pith of the Osmundaceae is truly stelar in origin ; that it arose by the 
conversion of the central tracheae of an originally solid mass of xylem into 
thin-walled parenchyma; and that this transformation did not take place 
simultaneously in all of them, but some retained their tracheal characters 
long after the rest had become converted into parenchyma. 
The fact that valuable phylogenetic information may be obtained from 
traumatic variations in structure has already been pointed out in the Gymno- 
sperms, both fossil and recent, by Professor E. C. Jeffrey. 1 He has shown 
that tracheidal cells appear traumatically in the medullary rays of the 
secondary wood of Cunninghamia sinensis , in the normal secondary wood of 
which they are entirely absent. It is interesting to note that these traumatic 
ray-tracheides are to be found in tissues that are formed some time after the 
reception of the wound and in a region some distance away from it. Again, 
in Sequoia sempervirens the normal secondary wood is entirely devoid of 
resin-passages, yet such appear traumatically, as in the case above, subse- 
quent to and at some distance from the wound. Jeffrey considers that these 
facts may be taken as evidence of the descent of the plants concerned from 
abietinous ancestors in which ray-tracheides and resin-passages respectively 
occurred in the normal secondary wood. 
It would no doubt be dangerous to place any great phylogenetic weight 
upon the peculiarities of traumatic tissues considered apart and by them- 
selves. At the same time I agree with Professor Jeffrey in so far that when 
traumatic characters ‘ are supported by a considerable body of collateral 
evidence, especially if such evidence is derived from extinct species they 
1 Jeffrey : (i) Traumatic Ray-tracheides in Cunninghamia sinensis. Annals of Botany, vol. xxii, 
1908, p. 593. (ii) The Wound Reactions of Brachyphyllum. Ann. of Bot., vol. xx, 1906, p. 383. 
(iii) Comparative Anatomy and Phylogeny of the Coniferales. Pt. I, The Genus Sequoia. Mem. 
Boston Soc. Nat. Hist., vol. v, 1903, p. 441. Pt. II, The Abietineae. Ibid., vol. vi, 1905, p. 1. 
