180 The Botanical Gazette. [May, 
brought out a marked differentiation just without the central 
cylinder, in the pericambium. At regular intervals, certain 
small groups of cells peripheral to the central cylinder stained 
a much darker blue than the surrounding cells. From their 
position it was judged these were the nascent tissues of the 
lateral rootlets, the darker staining indicating their greater 
activity. The mode of formation and development of the 
lateral roots from the mother root can be easily followed. 
Longisections of the rootlet coming off from various sections 
of the root were secured. These show the rootlet branching 
from the pericambium and organically connected with the 
central cylinder only, for a space surrounds it and separates 
it from the endodermis, cortex and epidermis. 
Back from the tip at varying distances in different roots of 
the same length, but averaging about 1.5, were noticed the 
beginnings of the large air-cavities. A cross-section shows 
the plerome cylinder surrounded by a sheath of thin-walled 
cells. Just without this endodermis are about six or seven 
rows of very regular cylindrical cells (fig. 2) forming loose 
tissue, with large intercellular spaces. Outside of these, be- 
tween the cells of the cortex proper, occur the radiating 2 
cavities of varying width, traversing the length of the root. 
The coloring matter of the root and root-stock, anthocyal 
in, imparts a dark-blue color, except for an inch or mor 
back of the tip. It is in solution in the cell-sap of the epider 
mal cells only; is soluble in alcohol and is turned red by dilute 
acids. It 
The running stem bears an off-shoot at its distal end. a 
has aerating spaces particularly large and abundant ne — 
periphery. The closed collateral bundles are but few we ‘a 
loose region. By far the greater number are aggregate 
the center of the stem, forming in mass a cylinder. pil 
root-stock has a structure somewhat similar to that e on: 
stem. Bundles of raphides are very abundant, espernt 
ward the periphery, outside of the cylindrical aggregatlo i 
bundles. There was no evidence of starch being stor 
the root-stock. - enlogicll 
The leaf shows perhaps the most interesting histo!os? 
see pHe. When the inflated petiole is er thro hie 2 
exa iti —2™ indi en(fig- 4)- : d 
gonal cavities o. 5-2™ in diameter are seen(hg. loose tissue : 
ing cutinized partitions are plainly visible. This 1005 
is almost impervious to water. A section placed in * 
shows a great deal of air imprisoned in the cavities. 
flated petiole refused to be infiltrated. 
d 
