Medical Officers of the Army of India.
45
NOTES.
Note A.—Rate of Evolution of Bubbles of Gas from the Flowers of Ottelia.
In plants in situ in tanks, bubbles are discharged from the flowers at rates which are principally deter-
mined by exposure to sunshine, number, and vigour of the leaves, and number of flowers in bloom. In healthy
plants under such circumstances from 15 to 54 large bubbles may be discharged from a flower per minute,
so that the total diurnal discharge must in some cases be very great. In uprooted plants in jars the dis-
charge is much more limited, only 4 or 5 bubbles being given off per minute, but even then the total diur.
nal discharge may be very considerable (vide Note B).
Note B.—Selected Examples of Experiments on Gaseous Evolution from the Flowers and from the Plant
generally in Ottelia.
Experiment I.
Two plants, each with one maturing flower, were set side by side in separate glass jars full of water, ex-
posed to similar conditions of lighting. A collecting tube was fitted over each flower. All the leaves were
now carefully removed from one plant, while they were allowed to remain intact in the other. During
the course of the day both flowers expanded alike, but whilst a very large evolution of gas occurred in that
belonging to the plant which retained its leaves, hardly a trace of evolution was present in the other.
Experiment 2.
Two plants, each of which had a single maturing flower, were exposed, as in the previous experiment,
with collecting tubes fitted to the flowers. One plant had 8 leaves, the other had 29 leaves. During
the same period the flower belonging to the plant with 8 leaves discharged 58 c. c. of gas, whilst that
belonging to the plant with 29 leaves discharged 148 c. c.
Experiment 3.
Two plants, each with 8 leaves, were exposed side by side, as in the previous experiments. Both origin.
ally had a single maturing flower. In one this was allowed to remain; in the other it was removed, and
the cut end of the scape firmly ligatured. Collecting apparatus was now applied to each plant. In the
case of the plant deprived of the flower this consisted of a simple general collecting apparatus; in the case
of the other plant a general collecting apparatus was also employed, but, in addition, a tube was fitted to the
flower, so as to collect the gas evolved from it apart from that evolved by the rest of the plant. During the
course of the day an evolution of 42 C. C. of gas took place in the flowerless plant, and of 58 c. c. from the
other, of which 55 c. c. were discharged by the flower, and 3 c. c. only by the rest of the plant.
Large numbers of similar experiments, varied in different ways, were carried out with results corrobora-
tive of those given above as examples.
Note C.—On the Arrangement and Mutual Relations of the Anthers and Stigmas in Ottelia.
The anther lobes are adnate, and each is originally bi-lobed, due to the presence of a deep furrow along
the external surface, which indicates the line of future dehiscence. On the occurrence of dehiscence the
pollen' is thus extruded on either side of the stamen.
The stigmatic surfaces consist of the hairy margins of the two elongated lobes into which each style
divides superiorly. The lobes are applied to one another, and, as a rule, their edges are directed outwards
and inwards. In this case the outer edge of each stigma is in direct relation to the outer dehiscent margin
of an anther lobe, and due to the alternation of the arrangement of the styles and filaments; each stigma
is in special relation to the pollen of a distinct anther lobe—the two stigmas connected with each style
receiving pollen from distinct anther lobes belonging to distinct stamens. When this arrangement prevails,
the pollen is applied almost entirely to the outer edges of the stigmas, the inner edges being turned
towards the centre of the mass, and removed from direct relation to the anthers. In certain cases,
however, the edges of the stigmas, in place of being directed outwards and inwards, are directed laterally,