ON THE MIXED HERBAGE OF PERMANENT MEADOW. 
1303 
growing competitors. It is not, however, safe to assume that the intrinsically 
strongest, the hardiest, or the most prolific, whether in seed or offshoot, will, in virtue 
of any one of these endowments, necessarily be the victor under all circumstances. 
The factors are so numerous, so complex, and so interdependent, that the “survival 
of the fittest ” depends not on any one quality, but on a capacity for adaptation to a 
combination of conditions some favourable, others detrimental. 
The idea of a natural alternation, or rotation, as broached by M. Bureau de Lamalle 
(previously referred to at p. 1212), is not strictly applicable to the case before us. That 
there is some such alternation is evident. It is not, however, the regular rhythmic 
process assumed by M. Bureau, but a phenomenon influenced by the many varying 
circumstances to which reference has been made, and it is, therefore, in itself very 
variable.* It is to be borne in mind that in the Rotbamsted experiments, even in the 
case of the unmanured plots, there are some artificial conditions introduced. Thus, 
the cutting of the crops interferes with the normal course of the vegetation, whilst the 
removal of them from the land induces a gradual exhaustion. Further, the variations 
of season from .year to year will have their varied effect, accordingly as the condition 
of the herbage is affected by such artificial treatment. It fact, it will be seen that 
variations of season have a most potent influence on the result, not only under the less 
artificial conditions of the unmanured, but also under the more artificial ones of the 
manured plots. 
In most cases we are without data for ascertaining the duration of life of a perennial 
plant, especially when it is subjected to cutting; but we know that there is a limit, 
and that, when this is reached, one plant will die, and another will take its place; and 
so we may have a fluctuating relative predominance of Gramineae, of Leguminosse, or 
representatives of other families. 
The Manured Plots. 
We now come to discuss the results due to the increased luxuriance induced by 
characteristically different conditions of manuring. We must refer to Part I., pp. 293— 
300, for the previous history and general character of the area selected for experiment, 
for the arrangement of the plots, for the detailed description of the manures employed, 
the mode of their application, &c. At p. 300, et seq., will be found a discussion of the 
results obtained on each individual plot, so far as the amounts of total produce, of' 
nitrogen, and of mineral matter yielded, are concerned ; and it will be convenient now 
to consider the botanical results obtained on the different plots, in the same order as 
to plots as in discussing the so-designated agricultural results. 
It is, therefore, proposed to consider the effects produced by ammonia-salts alone ; 
nitrate of soda alone; mixed mineral manure alone (including potass); superphosphate 
* The remarks of Mr. Darwin, on the “ struggle for existence,” chapter 3 of the ‘ Origin of Species,’ 
should he consulted with reference to the points raised in this section. 
8 D % 
