SUSPENDED ANIMATION
Our leading newspapers, with rare exceptions, never report the
discoveries announced at our scientific societies. But they often
seek to astonish their readers with silly stories of monsters said to
have been seen in tropical forests, ghostly "manifestations" and such
rubbish transmitted to them at a high price by crafty "newsmongers,"
and do much harm to themselves and to the public thereby. On the other
hand, foreign newspapers do occasionally report the proceedings of
their local Academies–and then "our own correspondent" telegraphs to
London with a flourish, a confused report of what he has read and
ignorantly imagines to be "a startling discovery" because he knows
nothing whatever of the subject. Thus shortly before the recent
war–the confirmation by a French experimenter of the fact, long since
demonstrated, that the seeds of plants can survive exposure to very low
temperature, was announced with ridiculous emphasis by one of these
"fat boys" of journalism _pour épater le bourgeois_.
A temperature very near to that of the total absence of that molecular
movement or vibration which we call "heat," can now be attained by the
use of liquid hydrogen, which enables us, by its evaporation, to come
within a few degrees (actually three!) of that condition known as the
"absolute zero." We divide into one hundred equal steps or degrees the
column of liquid (mercury, spirit, or other liquid) of a thermometer
as it expands from the shrunken bulk which it occupies when placed in
freezing water to the full length which it attains when the water is
heated to boiling point. This is called the centigrade scale, or scale
of a hundred degrees. But, as we know by the records of travellers in
the Arctic regions and by the experiments made in laboratories, there
are "degrees" of coldness or diminution of heat which are much below
that of freezing water, and can be measured by the further shrinking of
the column of liquid in the thermometer, so that we record "degrees
below zero centigrade," each of the same length as those above it and
corresponding to the same "quantum" of decrease or increment of heat.
As we pass from the temperature at which water is solid to that much
lower or diminished state of hotness at which mercury becomes solid,
the shrinking column of the thermometer (in which a liquid is used not
rendered solid by this amount of cooling) falls through 39 degrees of
the centigrade size, so that we say that mercury freezes at minus 39 or
at 39 degrees below zero of the centigrade scale. The conclusion has
now been reached that the absolute zero or cessation of all heat in a
body is represented by a fall of no less than 273 degrees below zero
on the centigrade scale. Hydrogen gas becomes a liquid at 252 degrees
below zero centigrade, and a solid at 264 degrees. If we start our
counting of those degrees or increments of heat, of which there are
100 between the freezing and boiling points of water, at the absolute
zero or condition of total absence of heat, we must say that hydrogen
"melts"–that is, passes from the solid to the liquid state–at 11
degrees (absolute), and boils at about 20 degrees (absolute), whilst
water does not melt until 273 degrees (absolute) of temperature are
reached, and boils at 373 degrees above the absolute zero.
It is the fact that, from the year 1860 onward, numerous observers have
experimented on the influence of very low temperatures upon seeds, and
have uniformly shown that the power of germination and healthy growth
of the seeds is not destroyed by exposure to very low temperatures. The
celebrated Swiss botanist, De Candolle, published the first careful
observations on this subject in conjunction with Raoul Pictet, who had
devised an apparatus for producing exceedingly low temperatures. Pictet
in 1893 exposed various bacteria and also seeds to a temperature of
nearly 200 degrees below zero centigrade without injury to them. They
"resumed" their life when gradually restored to the normal temperature.
Pictet concluded that since all chemical action of the kind which goes
on in living things requires a certain degree of temperature for its
occurrence, and that this is demonstrably considerably higher than
minus 100 degrees centigrade, we must suppose that all chemical action
in living things (as in nearly all other bodies) is annihilated at 100
degrees below zero centigrade. Accordingly he maintained that what we
call "life," or "living," is a manifestation of chemical forces similar
to those shown in other natural bodies, and liable to interruption and
resumption by the operation of unfavourable or favourable conditions
as are other chemical processes. In 1897, Mr. Horace Brown and Mr. F.
Escombe published, in the Proceedings of the Royal Society of London,
an account of experiments in which they exposed seeds of twelve plants
belonging to widely different natural orders to a temperature varying
from 183 degrees to 192 degrees below zero centigrade for a period
of 110 consecutive hours (about four days and a half). As a result
the germinative powers of the seeds showed no appreciable difference
from that of seed not subjected to cold, and they produced healthy
plants. The low temperature was obtained by the use of liquid air
in a vacuum-jacketed flask (like the well-known "thermos" flasks),
into which the seeds were introduced in thin glass tubes. Professor
M'Kendrick had previously shown that the putrescence of meat, blood
and milk by bacteria infesting them was temporarily arrested, but
not permanently so, by exposing those substances for one hour to a
temperature of 182 degrees below zero centigrade. It appeared that the
putrefactive bacteria present in those substances were not destroyed
by that degree of cold, but returned to a state of activity when the
normal temperature was restored. Professor M'Kendrick also showed that
seeds would germinate after exposure to like treatment.
All this is ancient history, twenty years and more in the past. The
experiments of a French observer, mentioned at the beginning of this
chapter as foolishly trumpeted in a London paper, were of service as
confirming the extensive and careful work of his predecessors. It is
only when our old well-bottled discoveries have, however tardily, been
brought before the Paris Academy of Sciences and sent back to us by
the Paris correspondents of news agencies as "startling novelties" and
"amazing discoveries" (twenty years old), that any attempt is made to
mention them in the London daily Press. And then they are announced
without any reference to their true history. This habit of culling
stale morsels of information from the proceedings of foreign academies
points to the fact that there is incompetence both in the purveyor and
publisher of such scraps. If our newspaper editors must publish scraps
about scientific novelties, they should employ educated assistants
to see that they do not make themselves ridiculous. The scraps which
come round to our newspapers from Paris are usually plagiarized from a
French newspaper by some one who has a very imperfect knowledge of the
subject to which they refer, and adds his own blunders to those of the
original reporter.
The action of extreme cold in arresting life in such minute organisms
as plant seeds and bacteria without destroying the possibility of
the resumption of those chemical and physical changes when warmth is
restored, is dependent on the fact that those chemical changes can
only proceed in and by the aid of liquid water. When thoroughly frozen
the chemical constituents of minute organisms and seeds–which until
frozen were living and undergoing continuous, though perhaps slow,
change–become solid, and can no longer act on one another or be acted
on by surrounding chemical bodies equally reduced in temperature.
They may be compared to the solid dry constituents of a Seidlitz
powder–one an acid, the other a carbonate. So long as they are dry
they remain–when mixed and shaken together–inert, without action
on one another. Even if one is dissolved in water and then frozen
solid and mixed in a powdered state with the other at an equally low
temperature the mixture remains dry and inert. Nothing happens so long
as the low temperature is maintained. But if we raise the temperature
above the freezing-point–so as to liquefy the solution–chemical action
will immediately ensue. With much fizzing and escape of gas the two
chemicals will unite. The effect of cold on living matter is of this
nature. It is a real "suspension" of the changes which were–however
slowly and quietly–going on before complete solidification of the
protoplasm by freezing. A frozen seed and frozen bacteria are in a
state of "suspended animation."
It is not the fact that absolutely all chemical union and change
whatsoever is prevented–that is to say, arrested or suspended–by
extreme cold, although the union with oxygen and other such changes of
the essential material of living things, which we call "protoplasm,"
and most other chemical changes are thus arrested or suspended. The
most striking exception is that of the most active of all elements,
the gas fluorine, which becomes a liquid at 210 degrees below zero
centigrade, and in that condition attacks turpentine if brought into
contact with it at the same low temperature with explosive force. Even
solid fluorine combines with liquid hydrogen with violent explosion.
It seems certain, however, that elements or chemical compounds brought
into the solid (not merely liquid) condition by extreme cold cannot act
chemically upon other bodies in the same solid condition, even when
they would at normal temperatures so act with the greatest readiness,
because they are then either liquid or gaseous.
The conception of an arrest of the changes in organisms, which we call
life, followed by their resumption after a greater or less interval of
suspense, was long ago suggested and discussed before we had knowledge
of the action of low temperatures. The winter-sleep of some animals
and the "comatose" condition sometimes exhibited by human beings
had led to the notion of "suspended animation." But a careful study
of hybernating animals and of human instances of prolonged "coma"
satisfied physiologists nearly 100 years ago that the processes of
life–the beating of the heart and the respiration–were not actually
and absolutely suspended in these cases, but reduced to a minimum. The
chemical processes connected with life were still very slowly carried
on.
Again, a great deal of interest and discussion was excited in the last
century by the drying up of delicate yet complex aquatic animalcules,
such as the Rotifers (the wheel animalcules described in our last
chapter) and Tardigrades (bear animalcules), and the fact that after
their preservation as mere dust for many months dried on a glass-slip
they could be revived and made to return to life by wetting them with a
minute drop of water, whilst the whole process of revival was watched
under the microscope. Letters were published in the "Times" in the
"fifties" by the Rev. Lord Sydney Godolphin Osborn, describing his
observations and experiments on these animalcules.
The yellow slime-fungus called "flowers of tan," after creeping as
a naked network of protoplasm over the "spent tan," thrown out from
tan-pits, will in dry weather gather itself into little knobs, each
of which is as hard and brittle as a piece of sealing-wax. Yet (as I
have repeatedly experienced in using material given to me by the great
botanist, de Bary) a fragment of one of these hard pieces, if carefully
guarded in a dry pill-box for two or three years, will when placed on
a film of water at summer-heat gradually absorb moisture and expand
itself into threads of creeping, flowing protoplasm, nourish itself,
and grow and reproduce. It was formerly suggested in regard to these
cases of resuscitation after drying, as also in the case of seeds which
germinate after being kept in a dry condition for many years, that
really they were not thoroughly dried, but were sufficiently moist to
allow of very slow oxidation and gas exchange, which it was said was
so small in amount as to escape observation. There was a plausible
comparison of the condition of these dried organisms to that of
hybernating mammals, desiccated snails, and comatose men. It was held
that here, too, the life-processes were not absolutely arrested, but
reduced to an imperceptible minimum.
This view of the matter was connected, no doubt, with a traditional
assumption that life was an entity–an "anima animans"–which entered a
living body, kept it continually "going" or "living," and if driven
out from it could not return. Curiously enough, Mr. Herbert Spencer
seems to have been (perhaps unconsciously) affected by this traditional
view, since he defined life as "the continuous"–that is the important
word–"adaptation of internal to external relations." This definition
prejudiced the view of some distinguished physiologists on the question
of "suspended animation," and I remember a very warm dinner-table
discussion with Michael Foster and other friends, some twenty-five
years ago, when I put forward the view that so long as the intimate
structure–in fact, the chemical structure–of the protoplasm of a living
thing is not destroyed, it does not "die" though all chemical change in
it may be arrested. I compared the dried seed and dried animalcule–as
I would now compare the frozen seed and the frozen bacteria–to a well
wound watch which is stopped by the intrusion of a needle between the
spokes of its balance wheel, or, better, by the cooling on the wheel of
a tiny drop of soft wax so as to clog it. The works of the watch are
rendered absolutely motionless, but it is not "dead." As soon as the
needle is removed or the tiny speck of wax melted by a gentle warmth
it resumes its movement. It is, as we say, "alive again." So, too,
the frozen or dried organism is absolutely motionless. No chemical
movements can go on in it. They are stopped by the solidity set up by
freezing, or in the case of simple "desiccation," by the absence of the
moisture necessary for bringing the chemical molecules into contact.
If protected from destructive agents, the mechanism remains perfect
for just so many years or centuries as that protection lasts. Whenever
the frozen organism thaws or the dried organism becomes wet, the
life-processes are resumed, the seed germinates, the bacteria grow and
multiply.
Thus we see what are some of the points of interest and importance
raised by the old experiments of Pictet, M'Kendrick, and Horace Brown,
the results of which were the same as those announced as Parisian
novelties. I have yet to say a few words as to the reason why we cannot
produce "suspended animation" in higher organisms or in man by the
application to them of extreme cold. Further, the influence of extreme
cold on the possible passage, through space, of living germs from
other worlds to this earth–a possibility suggested by the late Lord
Kelvin–requires some consideration in connection with the striking
experiments with phosphorescent bacteria described ten years ago by Sir
James Dewar.
[Illustration: Young stages of growth or Veliger larvæ of marine
snails, showing the ciliated band or velum which is identical with the
wheel apparatus of the Rotifers or Wheel animalcules.]