We can open or
shut a fruit by drying or wetting it. The internal causes are related to
the arrangement of the tissues, and we may say that the opening of fruit
can be easily explained by the contraction of the ligneous fibers under
drying influences. M. Leclerc shows by experiment that the fibers
contract more transversely than longitudinally, and that the thicker
fibers contract the most. This he finds is connected with the opening of
dry fruits.
Herr Hoffman has recently made some interesting experiments upon the
cultivation of fruits.
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.
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