the Broad Bean and certain other Plants . 
665 
weight, and for the dry weight from + 1*09 to + 0-37. The only conclu¬ 
sions that may be considered justifiable are therefore those relating to the 
boron injury; beneficial effects in pot culture, though apparent to the eye 
in some cases, must be regarded as questionable. 
3. Field Experiments . 
A. Broad Beans. 
Three plots, each of area acre, were laid out in triplicate. All 
received a basal dressing of 3 cwt. superphosphate, 1 cwt. sulphate of potash, 
and J cwt. sulphate of ammonia per acre. In addition, three plots received 
20 lb. H3BO3, and three 8 lb. H 3 B 0 3 per acre ; the manures were applied as 
a top-dressing at the time of sowing. Owing to unfortunate weather con¬ 
ditions and a lack of uniformity in the seed sowing and the soil, the results 
regarding possible beneficial effects from the dressings were inconclusive, 
though no injury was apparent. However, in the three plots which were 
strictly comparable, a 10 per cent, increase over the control was obtained in 
the yield of pods, harvested when green, from the plots receiving 8 lb. boric 
acid per acre. 
B. Barley . 
A similar series of plots were sown with barley. The mineral dressings 
were the same as for the broad bean plots, except that i-J cwt. per acre of 
sulphate of ammonia was supplied. The manures were applied as a top-dress¬ 
ing just before sowing. No injurious or beneficial effects were evident from 
either of the dressings, and any differences in the yields from the various 
plots were well within the limits of experimental error. 
III. General Discussion. 
As boron is of such importance to the broad bean, the question natur¬ 
ally arises as to the part played by the element in the plant meta¬ 
bolism. It may be regarded on the one hand as an element similar in 
function to C, H, O, N, S, P, &c., the only difference being the very small 
quantity of boron required ; or, on the other hand, it may be classed as 
a catalytic agent not of itself directly useful, but able to aid some plant 
function in an indirect manner. Such a catalyst may even be essential for 
the normal functioning of the plant; for example, Bertrand (4 (d)) has shown 
that the manganese in laccase is an oxygen carrier necessary for the 
functioning of the enzyme. 
Agulhon (1 (a)) recognizes a class of elements which he terms 4 particu- 
liers 1 ; these he considers are characteristic of certain groups of individuals or 
of life under certain conditions, and may be subdivided into two groups, 
(1) of nutritive, (2) of catalytic function ; boron he regards as an example 
