I. DATE OF FLOWERING AS AFFECTED BY CLIMATIC TEMPERATURE. Published Paper, from "Plant Physiology" (July 1933)
Analyses of records on the date of flowering of various members of different
genera at the Royal Botanic Garden, Edinburgh, show the following
points:
1. The actual date of flowering of any species in any one year may vary
from the average date.
2. Such aberration is referable to the temperatures obtaining during
narrow belts of time.
3. These belts of time vary between genera as to the remoteness from the
actual date of flowering, and her a are referred to the periods of activity in
gamete formation.
II. STUDIES IN THE GERMINATION OF
AIRA FLEXUOSA
It is apparent from the foregoing discussion
that light sensitive seeds are also sensitive to
temperature and substrate, being in general favourably
affected as regards their germination by fluctuation
of temperature, slight acidity of the substrate, or
presence of nitrates in weak solution. Aira flexuosa,
at least under the conditions of these experiments,
is adversely affected by fluctuation of temperature,
and practically unaffected by anid or potassium nitrate
in weak solution, although it is light -sensitive.
The seeds of Aira flexuosa require a period
of after- ripening for good germination, and in the
after-ripened condition are less sensitive to external
factors than in the un-after-ripened condition.
III. PHYSIOLOGICAL STUDIES IN BRASSICA ALBA
The tissue reaction of Brassica alba were determined by means of the "Range indicator Method".
The plants investigated were grown throughout in
a greenhouse at 45-60°F, thus eliminating possible
variation due to variation of environmental conditions.
The epidermis and epidermal hairs were throughout,
at ph 5.6.
The cortex, ground tissue of the petioles, palisade and mesophyll of the leaves were all at ph 5 °9.
The fibres of the cortex when present were at
pH. 5.2 - 4.8.
The endodermis varied from ph 5 °9 to ph 4.8,
being most acid at the base of the hypocotyl of the
older plants.
The phloem and cambium were at ph 5.9.
The xylem was constantly one of the most acid
tissues, being in general at pH 5.2 - 4.8 towards the
base of the plant, and pH 5.6 further up.
The pith was at pH 5.9 throughout.
The piliferous layer of the root varied from pH
5.6 to pH 4.8.
The tissue reactionsof hrassica alba appear to
be subject to much less variation than has been found
in other genera by other workers.
IV. THE BUFFER SYSTEM OF BRASSICA ALBA
V. The Effect of the Mucilage of the Seed -Coat in
Germination of Brassica alba
VI. The Distribution of Starch in the Radicle of
Brassica alba
