—-_ 
1893. ] The Roots of Ranunculacee. 9 
articles dealt more with general plant anatomy than with 
meristematic structure, the first article® dealing particularly 
with root structure. After stating that certain arrangements 
of tissues are only found in certain organs, he takes up each 
organ and studies the modifications of the fundamental struct- 
ure for that organ, as found in the various classes, orders, 
genera, etc., of plants. He points out the distinction between 
root and stem structure, as based on the arrangement of the 
fibro-vascular bundles, the former normally having radial 
bundles, the latter collateral ones, though older roots of dicot- 
yledons take on an arrangement similar to the stem struct- 
ure. He was not the first, however, to call attention to the 
change taking place in tha roots of dicotyledons, since Ni- 
geli as early as 1858® had shown that the older roots of many 
dicotyledons possessed a different structure from the younger 
roots of the same plant, and that the condition of the younger 
roots of dicotyledons was the permanent condition of the 
roots of monocotyledons. 
The first important generalization concerning meristem 
structure to receive immediate consideration of other work- 
ers was made by Nageli and Leitgeb.7 They found that in 
vascular cryptogams the several zones of tissues of both stem 
and root were derived from a single apical cell situated in 
the vegetative point. All vascular cryptogams studied showed 
this structure, and they assumed that phanerogams would 
present a similar development at the growing point, and in 
young roots they asserted that all the tissues could be traced 
to a single apical cell as their origin, but in older roots later 
growth concealed this primary structure. Before this time 
Otto Nicolai® had said that the vegetative point in phanero- 
gams was a group of cells, which, by means of successive 
division, formed on one side the root cap and on the other 
the body of the root. 
In 1868 Hanstein® declared that in phanerogams, the ini- 
tial at the vegetative-point is never of a single cell, but of a 
5 Ann. des Sci. Nat. V. xm. 
® Sur l’accroissement de la tige et de la racine dans les plantes vasculaires. 
Beitrege zur wissensch. Bot. 1858. 
a fe tetera und Wachsthum der Wurzeln. Beitreege zur wissensch. Botan. 
3 
® Das Wachsthum der Wurzel, 1865. 
aaa Scheitelzellgruppe im Vegetationspunkt der Phanerogamen. Bonn. 
