450 Harvey- Gibson. — Contributions to K?iow ledge of 
that occurs at the end of the aerial portion previous to the 
first bifurcation. He gives no detailed account, however, of 
the anatomy of the root. 
Nageli and Leitgeb’s researches lay the foundation of our 
knowledge of the anatomy of the roots, and as their observa- 
tions and conclusions have been called in question by more 
recent investigators, it may be advisable to summarize their 
results at somewhat greater length. Their observations were 
apparently made on four species, viz. »S. Kraussiana , 6*. 
Martensii , S. cuspidata , and S, laevigata . They commence by 
calling in question the accuracy of applying the term * root * 
to the organs arising at the branchings of the stem, and point 
out that a root-cap is absent from the apices of such organs. 
They further express the belief that these bodies are in reality 
cauline in their homology, giving them the name of ‘ rhizo- 
phores ’ ( Wtirzeltr tiger), Despite the fact that several 
authorities have brought forward evidence and arguments 
against this view, the name is still commonly employed in 
textbooks, &c., to designate the unbranched aerial portion 
of the root in such species as possess such organs. In the 
present paper the rhizophore is designated as the ‘ aerial part 
of the root/ and that portion which is embedded in the soil 
as the ‘ subterranean part.’ The rhizophores, according to 
Nageli and Leitgeb, originate on the upper side of the stem, 
near the base of the weaker branch, arching round towards 
the ground on that side. Following the system of bifurcation 
of the stem they arch alternately to right and to left, and 
occur at all the points of branching of the stem. In 5. Kraus- 
siana two rhizophores are occasionally given off, the accessory 
rhizophore arising close to the normal one from the upper 
side of the stem, but at a little distance from the branch, and 
bending round the stem on the other side. No root-cap is 
apparently developed at this stage. The rhizophore is at 
first circular in section, but later becomes elliptical, the long 
axis of the ellipse being parallel with the long axis of the 
stem. The apex of the rhizophore is occupied by a two- 
sided apical cell, giving off segments on the backwardly 
