Life and Death at
Low Temperatures
How to freeze and revive a garden snail. By Charles Platt
F ew people realize that the processes of THE PROBLEM WITH
life can restart after long periods in which FREEZING CELLS
they are ceased completely. Any backyard However, the freezing point of water forms a barrier
biologist can verify this strange fact by below which most mammals cannot go. Ice causes
performing a couple of experiments that originated catastrophic damage, although not because it
in the work of a solitary scientist named Basile “bursts” cells, as is commonly believed.
Luyet, more than half a century ago. When the water inside cells freezes, it forms
Luyet was a Swiss Jesuit priest who immigrated rigid hydrogen-oxygen bonds that exclude other
to the United States in 1929, did graduate work molecules, such as the sodium and potassium salts
at Yale, and then set up his own small laboratory that are essential for cellular functions. As the ice
in Madison, Wisc., where he toiled in isolation for accumulates, the normally beneficial impurities are
many years. squeezed out and form toxic concentrations that
He wanted to preserve living creatures in such literally poison the cell.
a way that they could be revived at any time in For a graphic demonstration of this phenom-
the future. He knew that this was possible, since enon, place some apple juice in a freezer until more
some creatures can return from days or even than half of it has turned solid. Now take a sip of
years of lifelessness. the remaining liquid, and you’ll find it is the most
The tardigrade, for instance, is a kind of worm intense juice you have ever tasted. The water that
about one millimeter long that is able to withstand was mixed with the juice has extracted itself as
temperatures down to almost absolute zero. pure ice, leaving only concentrated juice.
Reducing temperature is a logical way to preserve Luyet was well aware of the damage caused when
life, because living things are composed of cells, ice forms in cells. He tried to avoid it by freezing tiny
and chemical reactions inside cells occur more tissue samples very rapidly, so that ice molecules
slowly when they are deprived of heat. would not have time to organize themselves in a
Even human beings can withstand a moderate crystal structure. As he explained to a visiting jour-amount of cooling. To repair a brain aneurysm, nalist, “Living matter can survive freezing, but only if
surgeons may reduce normal body temperature the molecules are not ordered, but solidified where
by more than 20 degrees Centigrade ( 36 degrees they are ... in disordered or uncrystallized form.”
Fahrenheit), which slows the metabolic rate so that Unfortunately, this technique cannot be used on
a patient may remain in a state of circulatory arrest larger groups of cells, because there is no way to
for as long as one hour. Brain activity ceases during cool them fast enough. In the 1950s, three British
this period and resumes when the patient’s normal scientists who were familiar with Luyet’s work
body temperature is restored. solved the dilemma by using glycerol, a form of
