582 PROF. D. T. MACDOUGAL ON THE GROWTH OF 
constructed, and allowed to rest on a metal bench covered with a 
layer of moist sand to a depth of 5 em. This dark chamber was 
placed in such a position that the sun’s rays did not strike it, 
and was attached to a simple pulley, by which it might be raised 
and lowered to allow an occasional examination of the plants. 
Awakening plants with bulbs 4 to 6 em. long., when placed in 
this chamber, showed a greatly exaggerated development of the 
bud-scales, a rapid elongation of the scapes and petioles, during 
5 to 8 days, attaining a length nearly double the normal. The 
daily increase of these organs in some instances amounted to 
12cm. The lamine in some instances were carried completely 
or almost completely through the unfolding stage, but were 
rarely able to attain a full extension, or area much in excess of 
the folded condition, and owing to the absence of the directive 
influence of light assumed various positions with respect to the 
horizontal. The process of decay did not begin until 15 to 20 
days after the beginning of the experiments, and if the plants, 
after unfolding, were brought into diffuse light with gradually 
increasing intensity the normal appearance was finally resumed. 
The colour of the etiolated leaves was of the customary waxy 
yellow, upon which the reddish-purple colour areas characteristic 
of the external tissues were boldly apparent. The spathe ex- 
hibited great variety of reaction, but in general it did not attain 
full development. This was the invariable result if this member 
alone was enclosed in a covering excluding light; and although 
not responsive to the directive action of light or gravity, it 
assumed an upright or outwardly recurved position in darkness 
(see Plate XIX. fig. 3). 
If plants with mature leaves were placed in the dark chamber, 
a renewed activity of the petioles occurred lasting 2 or 3 days, 
and in 4 or 5 days the lamine began to bleach and decay. 
Effect of Diffuse Light—Plants grown in a diffused light 
exhibited features of development in general analogous to those 
shown in darkness. Elongation of the petioles and scape, 
dwarfing of the spathe, especially the overarching hood, occurred. 
Still more marked, however, was the restriction of the area of 
the laminz, corresponding to the intensity of the light. 
Removal of concurrent Members.—In order to determine how 
far the diversion of food from certain members and its concen- 
tration in one might affect its development, recourse was had to 
the removal of two of the three aerial members of plants grown 
