Scientific American Supplement, No. 430, March 29, 1884Various
Science
Scientific American Supplement, No. 430, March 29, 1884
Various
Science -- Periodicals
It is well known that many plants appear to select certain mineral soils
and avoid others, that a number of plants which prefer calcareous soils
are grouped together as _calcicoles_, and others which shun such ground
as _calcifuges_. Herr Hoffman has grown the specimen which has been
cited by many authors as absolutely calcifugic. He has obtained strong
plants upon a soil with 53 per cent. of lime, and these have withstood
the severe winter of 1879-1880, while individuals of the same species
grown on silicious ground have failed. This will modify the ideas of
agriculturists, at least in regard to this plant.
Herr Schwarz has been engaged in the study of the fine hairs of roots.
According to this author, there is a maximum and minimum of humidity,
between which there lies a mean of moisture, most favorable for the
development of these capillary rootlets, and this amount of moisture
varies with different plants. He finds that this growth of hair-like
roots is conditioned upon the development of the main root from which it
springs. In a weak solution of brine these fine roots are suppressed,
while the growth of the main root is continued. The changes of the
_milieu_ lead to changes in the form of the hairs, rendering them even
branched.
Signor Savastano has ventured to criticise as exaggerated the views of
Muller, Lubbock, and Allen on the adaptation of flowers to insects,
having noticed that bees visit numbers of flowers, and extract their
honey without touching the stigmas or pistils. He has also found them
neglecting flowers which were rich in honey and visiting others much
poorer. These observations have value, but cannot be considered as
seriously impairing the multiplied evidences of plant adaptation to
insect life.
Mr. Camus has shown that the flora of a small group of hills, the
Euganean Mountains, west of the Apennines and south of the Alps, has a
peculiar flora, forming an island in the midst of a contrasted flora
existing about it. Here are found Alpine, maritime, and exotic plants
associated in a common isolation.--_Revue Scientifique_.
* * * * *
RECENT BOTANICAL ADVANCES.
Among the most significant of the recent discoveries in botany, is that
respecting the continuity of the protoplasm from cell to cell, by means
of delicate threads which traverse channels through the cell walls. It
had long been known, that in the "sieve" tissues of higher plants there
was such continuity through the "sieve plates," which imperfectly
separated the contiguous cells. This may be readily seen by making
longitudinal sections of a fibro-vascular bundle of a pumpkin stem,
staining with iodine, and contracting the protoplasm by alcohol.
Carefully made specimens of the soft tissues of many plants have shown
a similar protoplasmic continuity, where it had previously been
unsuspected. Some investigators are now inclined to the opinion that
protoplasmic continuity may be of universal occurrence in plants.
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