ABSTRACT
A number of plants grown in the full daylight of a greenhouse have been exposed daily to the radiations of an Ulviarc mercury vapour lamp for very short time intervals, varying from 10 minutes to 30 seconds in the different experiments.
Stunting and other formal and formative effects were seen with intervals of 1 minute and upwards.
Exposures of 30 seconds on seedlings of Trifolium six weeks old appear to have no stunting effect and a favourable after-effect.
Exposures of 2 minutes given to plants of Voandzeia receiving natural illumination for 7 hours or 5 hours daily have a more serious effect than when given to a plant receiving a 12-hour day.
In all Miss Ritson’s experiments the illuminations were given on only 5 days out of the week, Saturday and Sunday being omitted for convenience.
Hybrids from P. inquinans Sol. and P. zonale L’Hér.
Arachis hypogaea L., the ground- or peanut, indigenous to Brazil and Paraguay.
Voandzeia subterranea Thou., the Bambarra nut, indigenous to tropical Africa and Madagascar.
