the Broad Bean and certain other Plants. 653 
( f) Winter Vetch, (g) Rye. 
Hardly any difference was noticeable in either of these plants between 
those treated with boric acid and the controls. In the case of rye, growth 
was apparently satisfactory in all the sets, though no ears were formed— 
probably on account of the unfavourable season of the year. The vetch did 
not flower either. 
Although these last few tests have only been carried out on quite 
a small scale, it seems probable that boron is able to supply some need in 
the case of several other plants besides the broad bean. Phaseolus multi - 
floras and Trifolium incarnatum in particular appear to derive especial 
benefit from treatment with a small quantity of boric acid. 
In the earlier work on boron Brenchley (11 (a)) has stated that lupins 
were particularly difficult to grow in water culture, since they tended to drop 
their leaves for no apparent reason. This is somewhat suggestive of the 
leaf-fail noticed in broad beans deprived of boric acid, and it is possible that 
lupins may be another instance of a plant benefiting from a continual 
supply of a minute quantity of boron. 
It is hoped to repeat these experiments at the first opportunity, with the 
addition of several other plants, including yellow and white lupins, in order 
to investigate the matter more completely. 
2. Pot Cultures . 
Experiments were carried out with both broad beans and barley. Tall, 
narrow, glazed pots containing 22-J lb. of soil were used in every case. 
Owing to the heavy nature of the Rothamsted soil, which renders it difficult 
to handle in pot-culture work, 10 per cent, sand was added, this mixture 
being found quite satisfactory. 
All the pots received a basal dressing of 5 grm. superphosphate, 1 grm. 
potassium sulphate, and 1-0-1*5 grm* sodium nitrate, whether or not they 
were further treated with boron compounds. 
Five or six pots were taken as the unit. 
A. Broad Beans . 
Sutton’s Prolific Longpod was used in every case and graded for each 
experiment, two plants being grown per pot. 
a. The Effect of adding Various Quantities of Boric Acid to the Soil. 
The effect of a wide range of concentrations of H 3 B 0 3 was tried in the 
two preliminary experiments; in the first case it was mixed throughout the 
whole depth of the pot, but in subsequent series it was applied as a top- 
