1910] CURRENT LITERATURE 69 
plete failure to indicate the magnification used in the figures. This makes com- 
parisons on the part of other workers difficult or even impossible. 
In spite of the exceptions taken in various respects to the work of the Anglo- 
Japanese authors, it must be conceded that their line of investigation is one of 
great promise, and it is to be hoped that they will feel encouraged to continue it 
with a greater attention to definiteness in anatomical characterization —E. C. 
JEFFREY. 
Vascular anatomy of Gleichenia.—BoopLer and HILEy,° from the study of 
the anatomy of Gleichenia pectinata and allied species, reach certain theoretical 
conclusions as to the origin of the tubular medullated stele. They report the 
result of the examination of the node and internode, as well as the branching stem, 
of certain species of Gleichenia, particularly G. pectinata. It is not surprising that 
they reach substantially the conclusions which have been published already by the 
senior author in earlier contributions. The published results in this case, how- 
ever, appear to indicate a certain modification of the position originally held by 
Boop Le, to the effect that in all cases the pith is a part of the stele and is 
not derived by inclusion of the fundamental or ground tissue from outside the 
central a for the authors in this article use the term solenostelic, borrowed 
ro NE-VAUGHAN and employed by him in the sense of a tubular stele 
with acai as well as external phloem and inclosing fundamental tissue as a 
pith (a meaning stated by GwyNNE-VAUGHAN himself to be equivalent to the 
reviewer's siphonostelic with internal phloem). Although the English writers 
in this instance concede apparently the arrival of the solenostelic condition as the 
final result of the modification of the pithless protostele, they express the opinion 
that the pith appears first as the result of the transformation of some of the tracheids 
into a central mass of parenchyma, a condition followed by the appearance of 
ramular gaps in the stele as the result of branching, leading to the intrusion of 
phloem from the outside of the stele and ultimately of the fundamental tissue 
itself. Only at the end of the process do the leaf gaps appear and become patent. 
These views are all the more remarkable because in the same article the 
authors concede that the islands of parenchyma occurring in the petiolar strands 
of certain representatives of the Gleicheniaceae are derived from the cortex by 
inclusion, and were originally surrounded both by internal phloem and internal 
endodermis. The condition in which the included parenchyma is separated 
from the vascular tissues of the petiole by neither endodermis nor internal phloem 
is a result of progressive degeneracy. It appears almost an extreme example of 
the perversity of the human mind to explain the occurrence of central parenchyma 
in the leaf trace in a node diametrically opposite to that adopted for the appear- 
ance of a pith in the vascular tissues of the stem. If the fundamental tissues may 
be included in the leaf trace, there appears to be no reason why a similar process 
should not lead to the formation of pith in the axis. The adoption of this hypoth- 
6 BooDLE and Hirey, On the vascular structure of some species of Gleichenia. 
Annals of Botany 23:419-432. pl. 29. 1909. 
