20 
BOTAL HOUTIOITLTUEAL sooiett. 
" It will be remembered that Dr. Gilbert, at the above-named 
Meeting, referred to some very striking experiments conducted 
for many years at Eothamsted Park by Mr. Lawes and himself 
on permanent pasture which has been under grass probably for 
centuries. 
" Under ordinary management this herbage yielded about fifty 
species of graminaceous, leguminous, and other plants usually 
found in permanent meadows." 
" The number of species of plants was but little changed on 
those experimental plots in the park to which a complex, but 
purely mineral, manure was applied, consisting of salts of potash 
soda, magnesia, and sulphate and phosphate of lime. 
" On the other hand, salts of ammonia, nitrate of soda, applied 
by themselves, or the addition of nitrogenous manures to mineral 
fertilizing matters, greatly diminished the number of species in 
the herbage. 
" According to the particular kind of nitrogenous manure 
used, and the quantity and combination with other fertilizing 
matters in which nitrogenous manures were employed, the dimi- 
nution in the number of species varied ; but in all cases it was 
strikingly apparent, and in some instances amounted to about one- 
half of the species in the herbage from the unmanured part of the 
park, or those parts dressed with purely mineral manures. 
" Attention was further directed to the fact that not only the 
weight of the produce reaped per acre was much influenced by 
the description of the manures which were put on the different 
experimental plots, but likewise the relative proportions of gra- 
minaceous and of leguminous and miscellaneous plants in the 
produce were found to vary considerably with the manures em- 
ployed. 
" Thus, to cite only a few examples, the weight of the grami- 
naceous plants in the produce from the unmanured plots and 
those dressed with purely mineral manures, in round numbers, 
amounted to about 60 per cent, of the whole produce. .Dressed 
with salts of ammonia or nitrate of soda and other purely nitro- 
genous manures, the herbage yielded from 70 to 80 per cent, of 
the whole weight of produce in graminaceous plants ; and in some 
instances, in which both nitrogenous and mineral manures were 
employed together in abundance, the weight of the graminaceous 
plants in the whole produce amounted to nearly 95 per cent. 
" The effect of nitrogenous manures in encouraging the growth 
