44 
POPULAR SCIENCE REVIEW. 
ultimately remained in possession of the plot. The plots 
under observation were 2 metres 30 cents, long, 1 metre broad, 
and all as nearly as possible under the same conditions, save that 
the soil was varied, in some cases consisting of the orchnary 
soil of the garden, in others of an admixture of lime, in others 
of sand, or of sand and lime, and so forth. 
Of the 107 species under observation, all, or nearly all, 
found the most essential requisites of their existence equally 
well in all the varieties of soil ; so that, other conditions being 
equal, the nature of the soil was indifferent. The species 
which remained victors, all the others being ultimately dispos- 
sessed, were Triticum repens (couch), Poa pratensis, Foten- 
tilla reptans, Acer Pseudo Platanus (sycamore), Cornus 
scmguinea, native plants ; and Aster sallgnus^ A. parviflorus^ 
Euphorbia virgata^ and Prunus Padus, derived from other 
portions of the garden. 
It may, therefore, be inferred that the district in which 
these experiments were made would in process of time, if no 
obstacle were afforded, become covered with meadows and 
woods — meadows in the low ground and woods in elevated 
places. Again, the experiments show that the survival of 
certain plants has not been influenced by the nature of the 
soil ; thus the couch-grass was ultimately spread over all the 
plots, whether of sand, or of loam, or of lime, whether drained 
or un drained. So also with Poa pratensis and Potentilla 
reptans. So that the chemical and physical nature of the soil, 
as has been so often shown in similar investigations, plays only 
a secondary part. 
As to the action of shade, it was found by Professor Hoffman 
that low-growing plants, especially if annuals, disappeared 
rapidly, while taller-growing plants, such as couch, Prunus 
Padus, &e., survived. The survival of certain plants, then — 
couch. Aster, Potentilla, &c. — is due much less to external 
conditions than to the ‘‘ habit ” of the plant itself ; that is to 
say, to the facility the plant has of adapting itself to varying 
external conditions, and thus of triumphing over others less 
favourably endowed in this wise. 
The immediate source of victory lies in the powerful root- 
growth of the survivors, including under the general term 
“ root ” not only the root proper, but the offshoots and runners 
which are given off just below, or on the surface of the ground. 
Indeed, the latter habit of growth is more advantageous to 
plants in such a struggle than the development of the true 
root downwards would be. Among those plants where the 
roots were equally developed there were, nevertheless, inequa- 
lities of growth, dependent probably on the greater need for 
light in some species than in others, &c. 
