418 BOTANICAL GAZETTE [DECEMBER 
meters long were amputated at the junction of stem and root. In the 
stele of the hypocotyl a vertical canal was made by inserting a small 
glass tube a few mm. and then withdrawing the tube. Into the canal 
was then inserted the root tip of a very young lupin seedling, and 
the whole preparation was then incased with gypsum and later 
placed in moist sawdust in vertical position (fig. 3). The parenchyma 
of the central cylinder offers the entering 
root the path of least resistance, so that the 
stele is often thus traversed its whole length. 
One may then make cross and longitudinal 
sections and very clearly study any changes 
in the tissues. As in the tests already 
described, no essential difference can be 
noted between the action of a main root 
and a lateral root on the tissues traversed 
by them. 
The stele of the lupin is surrounded by a 
sheath which is only one cell in width, and 
the cells of this sheath only contain starch 
in any abundance. The cross-section thus 
stained with iodin shows the cylinder 1” 
closed by a circle of starch-bearing cells. 
In cases in which the traversing root has 
pressed against this sheath, one may easily 
observe that even in cells of the sheath 
Soci collapsed by the pressure the starch 15 
Fic. 3.—The radicle of Present in undiminished quantity. oS 
the smaller seedlingisgrow- is no evidence of digestion of the starc 
ing downward through the - either on the part of the entered root oF 
central cylinder of the larger ;, SS ‘ ells the mselves- As 
seedling’s hypocotyl; the ?Y autolysis in the C she 
line-shaded portion repre. One sections farther and farther along s 
sesame. same hypocotyl, until only about 6 or a of : 
radicle remain within the hypocotyl, at - 
be observed, if the hypocotyl is allowed to remain undisturbed ws 
moment, that the radicle is gradually pressed out of the central me 
der, showing that it has encountered resistance from the tissue * 
that the latter recover from the pressure of the root. That the cf 
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