172 BOTANICAL GAZETTE [SEPTEMRER 
portion. They undergo very soon a considerable longitudinal — 
contraction in the thickened basal portion, which is usually? 
to g™ long. After having attained a certain intensity, this com 
traction manifests itself externally by a shriveling of the root 
surface. I noticed, however, that these roots of the second st 
are not in all individuals developed in the same degree, li 
specimens, for instance, which were located at a considerable 
depth, these roots differed very slightly from those first formel 
On the other hand, in individuals which were placed very super 
ficially I found the roots exceptionally thick and exceeding) 
numerous. 
~“— The contraction amounts to about 4o per cent. within the 
Space of 5™" in the swollen basal portion. It diminishes ® 
intensity towards the thin terminal portion, where no contraction 
at all takes place. The whole contraction of the root amoul\” 
to about 15™™ or even more, the contractile region having ong 
inally an average length of about 5°. Of these facts E if 
myself by marking and measuring the roots during their dere? 
opment in the earth. For this purpose the plants were cultivate 
in specially constructed culture-cases, furnished with bea 
windows, which could be removed thus permitting access t0 = | 
roots. The active contractile tissue is here, as in other 18 
of similar structure, the cortical parenchyma, The cen 
of vascular bundles with the endodermis is passively eaten 
and the same holds good for the epidermis and ent 
one or two layers of parenchyma immediately below se = 
These passive layers of the outer cortex very ce A 
folded, and form transverse wrinkles. During 0%” 
which process lasts in the whole root about three or fou 
ametet, ? 
outermost layers of the active parenchyma after @ time? 
and become tangentially compressed by the innet wees 
finally a rather wide area of crushed cells is found * 
a few layers of the still turgescent innermost cells. In 
dermis, as well as in the exodermis, there is also 4 Z 
