THE ROOT-SYSTEM OF IMPATIENS ROYLEI. 503 
stem, except for a curvature in the wound-region and a counter curvature т 
the upper half of. the internode, maintained its vertieal position. This injury 
was most probably inflicted during digging, and the plant became buried 
rather obliquely, almost to the cotyledonary node. There was a profuse 
development of adventitious roots. 
Above the injury the roots arose, as usual, on the same side as the wound. 
They developed in large numbers from the upper side of the lip of tissue 
that projected above the tear, but in growing they took a curved form over 
the lp and round the stem. As in previous examples, this seemed to 
be an attempt to compensate for a deficient food-supply ; in this case, 
however, one root attained a length of nearly eleven centimetres, and so 
reached the soil-level. Below the wound, at the cotyledonary node on the 
side inclined towards the ground, the roots already developed penetrated 
the soil and produced lateral roots, and thus inereased the food-supply to the 
plant. 
EXPERIMENTAL Work. 
1. Experiments on Seedlings. 
Attempts were made to induce root-development in the hypocotyl between 
the soil-level and the cotyledonary node. Very young seedlings were taken 
before the appearance of the foliage leaves, and were treated as follows :— 
(а) The hypocotyl was completely buried in a cone of soil. 
(b) The hypocotyl was surrounded by soil to a point half-way between 
the original soil-level and the cotyledons. 
(c) The hypocotyl was pegged down so that it lay horizontally along 
the soil. 
(4) The hypocotyl was pegged down as in (6), but it was also buried 
under a layer of soil. 
In all cases the soil was kept moist and the plants left undisturbed until 
the cotyledons withered. 
Results. 
‚ (a) One seedling only showed roots slightly above the original ground- 
level, but the roots were indistinguishable in appearance from the primary 
lateral roots. Their occurrence was not at all abnormal, for, as previously 
stated, primary lateral roots of hypocotyledonary origin occur in untouched 
specimens. 
(b) Negative results. 
(с) & (4) Negative results, but the hypocotyl became swollen and did not 
elongate. 
