72 
ROYAL nORTTCULTUHAL SOCrKTY. 
grasses ; whilst the ammonia-salts would seem to be at least 
as appropriate as the nitrate. As already explained, the rich- 
ness of the unmauured soil — of which, from the great root- 
development, it was obvious that the plants had full possession, 
and from which they were enabled to obtain nearly all that 
was essential for the fullest growth which the limitation of area 
and season admitted of — must be taken as accounting for the 
absence of more definite and consistent results from the different 
manures. 
Diagram 16. Plant ago lanceolata. — As already intimated, of 
all the twelve species, the Plantago gave the most growth above 
ground. Even without manure the dry substance produced was 
equivalent to about 8 tons per acre, representing an assimila- 
tion of more than 3 tons of carbon ! There was even less pro- 
duce by mineral manures than without manure. The nitro- 
genous manures, however, gave increase, and more when com- 
bined with mineral manures, though, from the very large produce 
over the limited area without manure, there was not room for 
much increase under any circumstances. The percentage of mi- 
neral matter in the dry substance was throughout comparatively 
low ; and, consistently, whilst many of the plants were unripe, 
many were freely seeding. The amount of constituents removed 
from the soil by these plants must have been very great ; but to 
this point we shall recur. 
Diagram 17. AcliiUea Millefolium, — This plant, although it 
proved inferior in assimilative capacity to the Plantago, so far, 
at any rate, as growth above ground is concerned, probably 
formed more matter below the surface than the Plantago ; and it was 
second to it, among the twelve species, in amount of above-ground 
growth without maiiure. "With its complete possession of the 
ground, and the soil so rich, it gave, however, no increase what- 
ever above ground under any of the manured conditions. The 
percentage of mineral matter, however, was higher under every 
manured condition ; and hence it may be gathered that at the 
time of the final cutting the manures had chiefly encouraged in- 
creased root-development, and that, if the season had been pro- 
longed, this increased resource would have borne result in increased 
growth above as well as under the surface. 
Diagram 18. Carum Carui.- — Of all the twelve species, this 
biennial gave by iar the smallest amount of produce above 
ground, but in its fleshy roots (a storehouse for future develop- 
