The Determinative Action of Environic Factors Upon Neobeckia acquatica Greene. 269 
and stem, whicli are formed in terrestrial cultures. These fusiform 
structures were cut into two parts by a single transverse section. The 
uppermost part bearing the active crown and other buds produced leaves 
of the broader type, but the smaller lower part, which was not so 
heavily stored with surplus food material and which had only axillary 
buds, in every case displayed nepionic leaves of the extremely narrow 
type. 
The growth of cuttings consisting of a portion of stem in water, 
from plants cultivated in the soil was marked by curvatures probably 
Fig. 7. 
Fig. 9. 
Fig. 7. Rejuvenating lateral bud of Neobeckia 
attached to stem with narrow nepionic leaves. 
Fig. 8. Cutting from a stem of Neobeckia grown 
in water. 
Fig. 9. Longitudinal section of segment of 
aquatic leaf of Neobeckia. 
Fig. 8. 
induced by illumination, and the terminal part formed a number of 
short internodes homologous with those of a submerged rosette, during 
the winter season in New York when the total illumination was low. 
With the advent of spring the formation of finely divided leaves began 
(Fig. 8), which might be considered as corresponding to those of the 
free stem of a plant rooted in the mud. The examination of these 
leaves showed the familiär structure of hydrophytes. The smaller sub- 
Flora, Bd. 106. 18 
