410 BOTANICAL GAZETTE [JUNE 
shortening it pulls down the tuber into a horizontal position, 
carrying with it also the basal part of the primary root. 
The annual prolongation of the tuber amounts only to 1™*, 
even in old specimens, but every year’s addition broadens it, 
until in old tubers it comes to a permanent diameter of 10 to 
15™™. Such tubers are 3 to 4™ long, containing the living prod- 
ucts of twenty to forty years, and die off by degrees at the 
basal-end with a smooth scar. They do not branch. The full 
grown tuber brings forth on its lower side yearly two to four 
roots, situated close together and directed vertically downwards. 
The roots are about 30™ long and 3 to 4™™ thick at the base, 
taper toward the tip, and branch there very sparingly in the 
Ist degree. They last about ten years, and twenty or more of 
Portas may be found attached to one tuber. 
 - The central cylinder is 6-archic, the narrow-celled endoder- 
mis furnished with slight 0-thickenings. The rather abundant 
cortex is almost devoid of starch grains in the swollen basal 
_ portion, but contains rather abundant starch in the thin terminal — 
Portion. ‘The latter part of the root does not show anything: : 
extraordinary. The basal region, on the contrary, shortens very 
much, the active cortex cells elongating radially. As 4 result 
I become strongly undulated, a zone of compressed cells is 
u led for a length of 3 to 5. F - 
The total shortening of the root probably cause to “about 
mainly the j a oungest roots, situated nearest the growing end of © 
net ber, exsert a pull upon the latter. This pull brings it 1 
= ee, often vertical position, with the growing point 
rend, sO that the leaf stalk or the aerial stem ci a 
ingle . ae the thizome. In this es eae sp - 
1€ contraction, the radial-longitudinal walls of the endoder- 
below the outer cortex, and the root aut becomes “ 
en ‘The: main contraction goes on during the first months of : : 
ie Ei A e of each root. Hence in Trillium, like in Scoliopy 
“to 
