627 
simple. The second kind 3- to 6-seriate, up to 150 cells in height, 
often composite and consisting of 3 stories. The absolute height of 
the first kind of medullary rays smaller than that of the latter. 
Between 2 multiseriate medullary rays mostly some 1-seriate- The 
medullary rays laterally separated by 1 to 4 rows of fibre-tracheids 
often adjoining vessels. The cells of the 1-seriate rays resembling 
those of the {-seriate stories. 
Description of the elements. 
I. Vessels. R. 25 to 80 uw, T. 20 to 70 u. Elliptical and circular 
cylinders or multilateral prisms with rounded edges. Transverse walls 
placed very obliquely, showing scalariform perforations with 50 to 
125 horizontal rungs. The scalariformly perforated part of the trans- 
verse walls sometimes 500 u in length. Walls 1.5 u thick ; — with 
numerous transversely elongated bordered pits, when adjoining each 
other; — with very numerous elongated bordered pits, when adjoining 
fibre-tracheids ; —- with a few simple and numerous elongated one- 
sided bordered pits, when adjoining wood parenchyma cells and 
upright ray-cells; — with unilateral bordered pits, when adjoining 
procumbent ray-cells. 
II. Libre-tracheids. R. 20 to 30 u, T. 25 to 35 u;4- to 8-angular. 
Walls thick 6 to 8 u; — with numerous elongated bordered pits, 
when adjoining vessels or each other; these pits more numerous on 
the tangential than on the radial walls; borders of pit-chambers 
circular or somewhat elongated in a vertical direction, e.g. 5 by 6 u. 
UI Wood parenchyma cells. Those adjoining vessels mostly elon- 
gated in the direction of the circumference of the vessels. Walls 
thick 1.5 uw; — with a few simple, and numerous elongated 1-lateral 
bordered pits, when adjoining vessels ; with elongated 1-lateral bor- 
dered pits, when adjoining fibre tracheids ; — with simple pits when 
adjoining each other or ray cells. Contents : sometimes a few starch 
grains and some red brown mass on the transverse walls. 
IV. Cells of medullary vays. Walls thick 1.5 u or more; pits the 
same as in the wood parenchyma cells. 
A simple comparison shows, that there is a coincidence in almost 
every particular, such as cannot be the outcome of accidental cir- 
cumstances and as in classifying systematic botany must needs lead 
to identification. As leading features in this comparison we consider 
the very oblique transverse walls of the vessels, with their scalari- 
form perforations; the groundmass of the wood consisting of fibre 
tracheids; the excessive scarcity of woodparenchyma and the oc- 
4+1* 
