ON THE MIXED HERBAGE OF PERMANENT MEADOW. 
1305 
their amount on the unmanured, or on any other plot, being the resultant of the actual 
amounts on two different plots, may show quite different relations between one species 
and another, from those indicated either in the columns of percentage, or in those of 
actual amount. These distinctions should be borne in mind; otherwise, illustrations 
drawn from the tables may be taken to be repetitions which are in reality not such. 
2. Ammonia-salts, alone; Plot 5. 
On this plot 400 lbs. of ammonia-salts have been applied per acre, per annum, 
each year, from 1856 up to the present time. Formerly (and in Part I.) we estimated 
that this amount of the ammonia salts supplied about 82 lbs. of nitrogen ; but of late 
years they have occurred in commerce in a state of greater purity, and the quantity 
of nitrogen now supplied may be 88 lbs., or probably for the whole period 86 lbs. 
It is obvious that, under the condition of this experiment, any increased growth would 
be dependent for its necessary mineral constituents (sulphuric acid and chlorine excepted) 
on the supplies derived from the soil itself. The result has been a rapidly-decreasing 
amount of produce, and of increase over that without manure, in the later as compared 
with the earlier years. The details show that there was also a reduced amount of mineral 
matter taken up in the later years. Indeed, in the later years there has been actually 
less of some important mineral constituents taken up than on the unmanured plot, 3. 
Table LXY., p. 1306, shows the botanical composition of the herbage of plot 5 :— 
the percentage, and the actual amount per acre, of the different species and groups, 
and the increase or deficiency of each compared with the unmanured plot, 3. 
The change in the flora of this plot (5), under the influence of a relative plethora of 
nitrogen, and exhaustion of available mineral constituents, has been very great. 
Unfortunately, the evidence available relating to the period of the experiments prior 
to the first complete separation-year (1862) is not such as to enable us to speak as 
definitely as might be desired as to the relative predominance of grasses, Leguminosse, 
and Miscellanea, during that period. Starting from 1862, the table shows, in the main, 
a very great increase in the percentage of the grasses, a very small amount of, and an 
immaterial change in, the Leguminosse, and on the whole a very great reduction in the 
percentage proportion, and especially in the actual amount, of miscellaneous species. 
The second separation-year was, however, a very marked exception in these respects. 
In that year, the grasses were in unusually small, and the Miscellanea in unusually 
large, proportion. The autumn, winter, and spring had been very changeable, whereby 
early vegetation was much checked ; the usual maturing period was also very change¬ 
able. The consequent restricted growth of the grasses was, of course, an element in 
favour of such Miscellaneae as could take advantage of the climatal and manurial con¬ 
ditions. The percentage of total grasses was, in 1862 rather more than 86, in 186/ not 
quite 72, in 18/2 nearly 85, and in 18 77 more than 94. In neither year did the 
Leguminosse contribute l per cent. But the Miscellanese gave less than 14 per cent, 
in 1862 ; more than double, or nearly 28 per cent., in 186/; less than 15 per cent, in 
18/2 ; and less than 6 per cent, in 18 77, 
