534 PROF. D. T. MACDOUGAL ON THE GROWTH OF 
with storage material. From the upper nodes of the rhizome 
arose a score or more of leaf- and flower-stalks in all stages of 
development. Plants of the second species (obtained from 
Texas) were furnished with a scaly bulb 1 to 2 cm. long, and 
1 cm. in diameter in the thicker portion. From each of the 
axils of a few of the upper scales arose a solitary leaf-stalk, with 
lamine in various stages of development. 
Effect of an Atmosphere free from CO,.—Plants placed entirely 
inside the apparatus described above, in such position that pro- 
tection was afforded from the rays of the mid-day sun, offered 
in connection with the reactions in darkness exactly the opposite 
results from those obtained by Jost with Mimosa. The diffuse 
light caused a slight elongation of the stems, although still of 
such intensity as to cause the daily movements of laminz. ‘These 
periodie movements continued in an apparently normal manner 
during the entire continuation of every experiment—13 to 20 
days. At the expiration of this time the mature lamine were 
healthy, and their further existence corresponded closely to that 
of similar organs in the open air. The younger leaves carried on 
normal development, the lamine acquiring the power of carrying 
on the nyctitropic movements at the usual time, but contained 
less chlorophyll perhaps than corresponding members in the 
open air. After the completion of the experiment, both the 
younger and the older leaves continued unchanged, and plants 
which were under observation during a period of 90 days offered 
no marked divergence from the normal forms. 
Effect of Darkness.—The leaf-stalks exhibited a slightly exag- 
gerated elongation, and the lamine attained only an incomplete 
stage of development, remaining in a folded position. A similar 
behaviour of O. Deppei and O. lasiandra was observed by Jost (5). 
Removal of concurrent Organs.—The removal of concurrent 
buds or members in no wise altered the development of those 
remaining, whether in darkness or in air free from CO,. 
Comment.—Plants of this type, of which Isopyrum is also an 
example, are able to carry on leaf-development in a perfectly 
normal manner at the expense of stored food. Furthermore, it 
18 Seen that the existence of the chlorophyll and the motility of 
the pulvini are entirely independent of the food-forming processes 
in the leaf. This latter conclusion is confirmed by the observa- 
tions of Jost, in which the pulvini of Mimosa, Acacia, and 
Phaseolus retained motility for many weeks in darkness. 
