THE BATTLE OF LIFE AMONO PLANTS. 
43 
duly examined. In addition to these no trifling observations, 
three “ separations ” have been carried out at regular intervals. 
These separations consist in the picking out, from a sample 
of a certain weight taken from each plot, every fragment of 
every species contained in the sample. In this way the rela- 
tive quantity and weight of each of the different plants in the 
several samples is accurately determined, and the proportion 
in the whole plot computed. The labour is enormous ; but the 
results, when fully brought out, must be most important, both 
as regards the scientific aspect of the question, the history of 
the life-struggle between plants so circumstanced, and also 
as regards the practical hints to be derived by the cultivator. 
Some experiments of a somewhat similar character, and bear- 
ing directly on the struggle for life among plants, have been 
made by Professor Hoffman of Griessen, and they are of such 
interest that we introduce here a very condensed account of 
them taken from the pages of “ The Gardener’s Chronicle,” 
1870, p. 664 
In a previous set of experiments the Giessen Professor had 
ascertained that the particular plants under observation grew 
equally well in all the varieties of soil in which they were 
placed, provided due care was taken to prevent the growth of 
intruding weeds. Having arrived at this result. Prof. Hoff- 
mann next left the several plants to themselves, with a view 
of ascertaining how they would comport themselves without 
assistance against the inroads of weeds. The result was, that 
the weeds completely gained the upper hand, as might have 
been expected from their known habit. The species which 
held out longest was Asperula cynancTiica. This plant, after 
having been grown in a bed for three years, and protected from 
weed-invasion by the use of the hoe, was then left to take care 
of itself. It held out for four years, but was ultimately 
elbowed out l3y the intruders. Acting on the principle of 
“set a rogue to catch a rogue,” Prof. Hoffmann then set 
himself to observe the results of the internecine struggle 
between the weeds themselves, thinking that the ultimate sur- 
vivors would perhaps prove to have special affinities for the soil 
in which they grew. 
Thus left to themselves the beds became so densely covered, 
that in a square foot the Professor counted 460 living plants, 
and the remnants of many others, which had succumbed in the 
encounter. Every year, in July, the plots were examined, and 
every year the number of species was found to have dimi- 
nished. Melilots, at first abundant, gradually disappeared ; 
Artemisia vulgaris succumbed after two or three years ; and 
so on, till at length only a few species were left, and these not 
only persisted, but slowly gained ground from year to year, and 
