FOLIAGE-LEAVES AND THE CHLOROPHYLL FUNCTION. 535 
Trillium erectum, Linn., and T. erythrocarpum, Michx. 
The specimens used were furnished with a premorse tuberous 
rhizome, from the apex of which arose a single bud. The rhizome 
was densely charged with starch. Ordinarily the bud develops 
a stem 8 to 15 em. high, bearing at the top a whorl of three 
ovate, obovate, or oblong leaves imbricated in the bud around 
the single stalked flower. 
Effect of an Atmosphere free from CO,.—Plants grown in an 
atmosphere free from CO, exhibited a normal development of the 
leaves, which attained full size in a period of from 10 to 12 days, 
except that the lamin: were lighter in colour, due to the smaller 
proportion of chlorophyll present. The plants were not capable 
of continued existence in the apparatus, or even until all of the 
reserve material in the rhizome was exhausted, since destructive 
fermentations generally set in at this time. 
Effect of Darkness.—ln darkness the stems undergo only a 
slightly exaggerated development ; in some instances the minimum 
measurement for the species was shown. The peduncles show 
no increase in size, and the laminæ loosely retained the imbri- 
cated position held in the bud with no increase in size. These 
conditions could not be altered by the removal of any of the 
coneurrent members. 
Comment.—In light the leaves are capable of expansion so 
far as food-material is available. In darkness a minimum of 
growth ensues. 
Isopyrum biternatum, Torr. & Gray. 
Plants of this species consist of a short woody rhizome, from 
which arise stems 11 to 20 cm. in height bearing a number of 
small trifoliate leaves. Depending from the rbizomes is a dense 
tangle of fibrous roots, which are thickened in such manner as tc 
` form numerous tubers, containing a large proportion of sugar 
and starch. The proportion between the amount of stored food 
and the mass of the aerial stems and leaves to be developed at 
its cost is about the same as in the Ovalis material used. 
Effect of an Atmosphere free from CO,— Young plants on 
which were borne leaves barely emerged from the bud, and 
others still in a folded condition, showed a continuation of the 
normal development of these organs during the continuation of 
the experiment over a period of from 14 to 20 days. During 
this time many of the leaves attained full size, and exhibited a 
