336 BOTANICAL GAZETTE [APRIL 
the transformation has actually taken place is proven by the dis- 
covery of intermediate forms of cells. In fig. 10, which is a more 
magnified view of the lower part of fig. 8, is an element with a dis- 
tinct bordered pit on its vertical wall and several equally distinct 
simple pits on its horizontal wall. This element, therefore, is 
neither a tracheid nor parenchyma cell, but combines the pitting 
of both. Several such cells were seen, in some cases both kinds 
of pits occurring on the same wall. So far as the writer is aware, 
the anomaly of bordered and simple pits occurring on the same 
element has never been observed except in this laboratory by Miss 
Gorpon? in material of Sequoia. 
A much commoner type of transitional element than the anoma- 
lous structures just described is illustrated in fig. 13, from A. 
Veitchii. The pits on the ray tracheid are so slightly bordered 
as to be scarcely distinguishable from the simple pits of the paren- 
chymatous cells. The figure illustrates but one or two of the 
many forms intermediate between typically simple and typically 
bordered pits which may be observed on these elements. 
Conclusions 
The presence pf ray tracheids as a result of wounding in A. 
amabilis and A. concolor parallels exactly the phenomena described 
by JEFFREY for C. sinensis. The interpretation advanced by him 
is that we have here a case of the revival by wounding of 
structures ancestrally present and lost in the course of evolution. 
Owing to the closer affinity of Abies with those genera in which 
ray tracheids are abundant, his reasoning applies with even greater 
force to the observations described in this paper. Again, their 
sporadic occurrence in uninjured material of a few species of the 
genus strongly supports this view. Further support is added 
by the association of the ray tracheids with the degenerating 
cells or ‘‘ghosts,’’ and with the groups of marginal parenchyma 
cells at the ends of the annual rings. It may be concluded that 
ray tracheids were present in the ancestors of Abies, and have per- 
4Gorpon, Marjorie, Ray tracheids in Sequoia sempervirens. New Phytol. 
¥X37-9. fes..7. 1013. 
