Salt: Grain of Life by Pierre Laszlo Mary Beth Mader

Author:Pierre Laszlo, Mary Beth Mader
Format: epub
Tags: Cooking/History
Publisher: Perseus Books, LLC
Published: 2011-12-19T05:00:00+00:00

five biology

The ocean is salty, and its saltiness keeps increasing with the bite of time: rainwater dissolves and sweeps away mineral salts from soils, and rivers then carry them to the sea. Conversely, water evaporation, a distilling, pumps pure water into the atmosphere. In this way, salinity gradually increases.

Life on Earth goes back to marine organisms, some of which still remain relatively primitive. The earliest forms, single-celled beings, both differentiated and shielded themselves from the marine medium with a membrane. Reproduction into an identical cell has tended to preserve within each cell the composition of the primeval ocean, hundreds of millions, if not billions, of years old and less rich in salts than the present-day ocean.

Thus the cell membrane is not only the cell consciousness, preserving the memory of long bygone eras. It also sieves the chemicals that pass through it; it has to maintain the integrity of the intracellular environment, which for marine organisms, as I just noted, is less salty than the external environment.

In fact, there are two kinds of organisms: those whose intracellular contents adapt to changes in the outer salinity (osmoconformists) and those able to maintain their internal composition invariant in the face of salinity fluctuations (osmoregulators). Jellyfish and crabs live in environments of varying salinity and belong to the first category. Fish belong to the second. Freshwater fish and saltwater fish thus need differing adaptation mechanisms. A species such as the salmon, shuttling between both sorts of waters, has evolved for itself sophisticated means for acclimation.

In human beings, the relation of salt to thirst, which intuitively we may believe to be simple and elementary, actually attests to a complex physiology in which the kidneys and the brain both play a role. In addition, organisms take advantage of the differences in salinity between intra- and extracellular environments for other ends, one of which is the nerve impulse.

I will then discuss the strange case of extreme halophiles, that is, single-celled organisms that manage to live in environments with very high salt concentrations. And I will quote, in closing, a description of the Great Salt Lake by an early French traveler writing in the mid-nineteenth century.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.