book

image

Fig. 2–5. Pictures of cells (After Grew , 1671; From Katznelson, 1963). 

It must be emphasized that during the XVIII and the beginning of the
XIX centuries the notions of the cell and cellular tissue have born only a
conditional meaning. Despite the already mentioned studies of
Leeuwenhoek, Malpighi and Grew the cell has remained a hollow space
surrounded by walls. Such notion of the cell is encountered in the works
of such well-known botanists as K. Sprengel, J. Bernhardi, Ch. Brisseau
Mirbel, H. Link, etc. The latter of mentioned authors has broadened the
knowledge of the cells assuming them as structural elements that could
form tissues. He has clearly designated the double outlines of the cell
walls (Fig. 2–6).
Despite the still very vague pictures of the observed cells, the
researchers in this period have shown an interest in the development of
the living organisms after their fertilization. The views on that have
differed a lot, being in some respects even contradictory. Embryology
has been at that time at the very beginning of its development, so that
the preformists have been holding a dominant position. According to

image

Figure 2–3. Pictures of plant cells (After van Leeuwenhoek, 1922; From 
Katznelson, 1963).

The concept of the cells as hollow spaces separated by thick
walls has been preserved for long period of time. It has not
been changed easily even after the interesting and well
illustrated systematic descriptions in the anatomy of
plants of M. Malpighi (1675, 1679), N. Grew (1671, 1682),
etc. Malpighi as well as Leeuwenhoek has observed
cells in different plant parts (Fig. 2–4) but he also has fallen far
behind the idea of the cell structure. Grew has recorded
remarkable observations of plant tissue cells (Fig. 2–5). By
contrast to Leeuwenhoek and Malpighi, Grew has made a step
further by reaching to the idea that the cells are inherent to all
plant organs. He has introduced the terms parenchyma and
tissues which are still valid.

image

Fig. 2–4. Pictures of cells (After 
Malpighi, 1686; From Katznelson, 1963). 

In his famous “Micrographia” (Hooke, 1665) the structure of a plant
tissue has been recorded for the first time thus laying the basis for cell
studies. At that time neither he himself nor his contemporaries could have
even imagined the historic importance of this discovery. With the then
existing microscopes they only out of curiosity have observed and registered
the porous structure of different plant and animal tissues and organs. To
them these pores have been hollow spaces filled up with air or a liquid,
separated by bars. That is why their discoverer himself did not give them the
most suitable name — cells. The term cell wall was introduced later.
The Dutch inventor-microscopist and biologist Antony van
Leeuwenhoek has constructed an instrument with one lens resembling a
modern magnifying glass (Fig. 2–2). In his rich collection of 200
“microscopes” there were such of magnification from 40 to 270 times. With
them he has observed and described in 1674—1680 invisible to the “naked
eye” red blood bodies (erythrocytes), spermatozoa and different unicellular
organisms in a water drop. So was the world of microorganisms
discovered. Besides, Leeuwenhoek has observed that in the plant and
animal tissues there are “pores” i.e. cells (Fig. 2–3), but he has not reached
the ideas of the cellular structure (van Leeuwenhoek, 1705; see History of
Biology, 1972, 1975).

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Figure 2–2. The “microscope” of Antony van Leeuwenhoek (From 
Katznelson, 1939). 

THE CEL – BASIC STRUCTURAL AND FUNCTIONAL BIOLOGICAL SISTEM

CHAPTER 2

Section 2.1. Discovery of the Cell and First Notions of Its Essence and Structure

The discovery of the cell is closely connected with the invention
of microscope. During the XVI and XVII centuries in different European
countries (especially Holland and Italy) the art of manufacturing and polishing
optical lenses has attained a remarkable efflorescence. Except for a number
of different purposes some naturalists have got interested in using them for
observation of the inner structure of plants and animals from the surrounding
nature. Conditions for the construction of microscope have matured.
The names of several inventors of microscopes are given in the
monographs of Z. Katznelson (1939, 1963). The first perfected microscope
known to mankind as a scientific tool is the one of the English physicist and
inventor Robert Hooke (Fig. 2–1 A). Studying thin sections of cork tissue he
has noticed that they consist of empty pores separated by bars which he
called “cells” since they looked like a honeycomb (Fig. 2–1 B). Such
structures Hooke has also observed on sections from other tissues of
plants but in their case the pores have been full of plant sap.

image( a,b)

Figure 2–1. (A) The microscope of Robert Hooke by the help of which he 
has observed thin sections of plant tissue and has noticed their porous 
structure; (B) The historic “micrographia” on which can see pictures 
resembling honeycombs. The empty spaces surrounded by bars were 
named “cells” (After Hooke, 1665; From Katznelson, 1939).

When the critically minded person encounters such cases, reads or
listens to unproved information he would not hurry in trusting or which is
worse taking them as proofs for the existence of extraterrestrial life and
intelligent creatures trying to establish contact with the human
civilisation. To him it is clear that this problem is constantly subjected to
the scrutiny of the researches in that field, and if a positive result is
achieved it will be immediately announced to the entire mankind longing
for such a really sensational news.
Hoping for the discovery of a certain form of extraterrestrial life or
living creatures similar or different from the ones on the Earth,
investigations are being continued with the implementation of more
sophisticated automatic and controlled interplanetary stations. Up to now
these are only undertaken in the boundaries of the Solar system where it
is still impossible to assert definately that life either past or present is not
to be detected on some of its planets. If as a result of another triumph of
space sciences and astronautics, it is made possible to go out of its
limits and to enter new, more distant systems in the Cosmos, the
chances to answer this question will be greatly increased. Let us hope
the answer will be positive.

out from the Earth and with AIS Pioneer and Voyager show that their
atmospheres predominantly consist of hydrogen and helium which
chemically brings them closer to the Sun rather than to the planets of the
earth type.
In Jupiter’s atmosphere molecules of methane, ethane, ammonia,
acetylene, etc. have been registered. The presence of these compounds
and water vapours in its upper layers suggests a possible chemical
evolution on that planet. Titan — the biggest satellite of Saturn, raises an
exceptional interest. It is the only natural satellite in the Solar system
with a dense atmosphere containing nitrogen (90%), methane (1—10%),
certain amounts of ethane, ethylene, acetylene, etc. Its atmospheric
pressure is 1.6 times the Earth’s one. But at temperatures of minus
180°C it will hardly prove to be the lucky place for another presence of
life in the Solar system.
Uranus, Neptune and Pluto. What is typical of these planets is that
they receive less light and heat from the Sun. Being so remote from the
Earth, they are much less studied. A presence of mainly hydrogen and
helium in their atmospheres has been recorded by spectrometric studies.
The low temperatures of the order of minus 180—200°C for Uranus and
Neptune (putative data) and minus 220°C for Pluto do not raise hopes for
life on them.
The data from the flight of Voyager 2 (launched in September 1977
and reached Neptune on 1st Septembre 1989) showed conditions
exceedingly unfavourable for life on that planet. Apart from the low
temperatures, ferocious storms with speed of about 1120 km/h rage on
Neptune. Its satellite Triton which has a gas envelope (800 km thick) of
nitrogen and methane proves to be the coldest place in the Solar system
— minus 240°C.
In conclusion I would resort to the statement of Oró et al. (1990)
who have closely followed the results from the investigations of NASA on
that problem: “We have no evidence of extraterrestrial life. It is difficult
however to conceive from a scientific point of view that “intelligent” life
on Earth is a singular phenomenon in the trillions of galaxies that
comprise the observable Universe”.
Scientific truth is strict and most often boring. That is why don’t like
it a considerable number of people who are not acquainted with the
means, ways and methods for its accomplishment and are inclined to
believe fantastic stories without any scientific foundation about unproven
or altogether non-existent phenomena and events. The Tungus
meteorite exploded on July 30th 1908 in the Siberian tundra has been for
decades presented as an explosion of a spaceship from another planet.
A huge number of books, journals and newspapers sensationally report
on UFO (Unidentified Flying Objects) sometimes even trying to provide
proofs with the testimony of eye-witnesses.

ice. The long straight lines observed on its surface were mapped by the
Italian astronomer G. Schiapparelli as canals (canali) which led to the
idea that the latter are artificially built constructions by intelligennt beings
— the hypothetical “Martians”.
But here is what the studies carried out by AIS of the Mariner, Mars
and Viking series showed: low atmospheric pressure (0.006 of the
Earth’s); CO₂-atmospheric content reaching up to 95% supplemented by
minimal quantities of O₂, O₃, H₂, CO and water vapours; temperatures
ranging from plus 25°C during the day to minus 100°C in night, being
even lower in certain areas; the polar “white caps” proved to be frozen
CO₂.
Yet, the “secrets” of Mars are still not disclosed. The network of canals
photoregistered (Fig. 1–11) give grounds for assuming that in its historical
development there have been warm and rainy epochs with erosion
processes due to water, which some authors attribute an earlier existence
and development of life on that planet.

image

Figure 1–11. Taken by Viking Orbiter 1, this photograph of the Martian 
surface shows a small channel system. The channel, about 2.5 kilometers 
in width, has flow features along its length and tributaries that join the main 
channel. This and similar channels on Mars suggest that water erosion may 
have occurred during a warmer and wetter epoch in the planet's history 
(From Exploring the Living Universe, Washington, DC, 1988) 

Jupiter and Saturn. These are the two largest planets in the Solar
system with a number of satellites surrounding them. The studies carried

During this period the development of space studies has recorded
another brilliant success. Alongside the automatic interplanetary stations
(AIS), manned flights were also made possible. On April 12th 1961 Yury
Gagarin in the spaceship Vostok made the first in the world flight of man in
space. The road to space was opened.
On July 16th 1969 Apollo 11 was launched with three astronauts on
board — N. Armstrong, M. Collins and E. Aldrin. On July 21st 1969
Armstrong stepped on the surface of the Moon in the region of the Sea of
Calm. A few minutes later that he was followed by Aldrin. This historical
moment was marked by placing a plate reading: “Here men from the
planet Earth first set foot upon the Moon, July, 1969 A. D. We come in
peace for all mankind”.
After this remarkable flight the investigation of the Moon turned into a
routine research procedure. Soon after another 10 astronauts visited it.
The thorough photograph-mapping of the Moon, the excursion on its
surface by lunar modules as well as the samples taken from different
sites proved that there is no life on the Moon, in which even the NASA
(National Aeronautics and Space Administration) experts were not
convinced prior to 1960. The reasons for this negative results are
basically the lack of water, absence of atmosphere and temperatures with
drastic diurnal fluctuations from minus 160°C to plus 130°C.
Mercury. The planet situated nearest to the Sun. The high
temperatures (167°C on the average) and the absence of atmosphere
make the existence of life on it impossible for the present at least.
Venus. The “bright beauty” of the Solar system was thought to be
capable of sustaining life. The studies carried out by radiosounding
methods and AIS from the series of Mariner and Venus showed that the
temperature there is very high (466°C on the average) which does not allow
for the presence of water in liquid state. Besides, its atmosphere is almost
entirely made up of CO₂ and the atmospheric pressure is 90 times higher
than the Earth’s.
The high temperature on Venus is due to the so-caled
greenhouse effect. Sunlight reaches its surface heating its upper layer
then is radiated back in the form of heat which, stopped by its
impermeable to infra-red (heat) rays atmosphere is retained to disperse
in space. By contrast to the Earth, where CO₂ is dissolved in water and
precipitated in the soil layers as carbonates (lime-stones and dolomites),
CO₂ on Venus remains in the atmosphere. Its “clouds” consist of small
drops of concentrated (70—80%) sulphuric acid. Under such conditions
it is for now considered lifeless.
Mars. Also called the “red planet”, wrapped in mystery and raising
hopes for life existence. In 1659 the Dutch mathematician and
astronomer Ch. Huygens has noticed the permanently existing “white
polar caps“ which have been until recently taken for eternal snows and

think that there are mountains and planes on the Moon similar to the ones
on the Earth. With the help of a hand-made telescope Galileo Galilei has
watched the Moon and in 1610 has seen mountains and “seas” (thus he
has termed the large dark areas). The non-existent seas and oceans are
mapped by their traditional names — Sea of Abundance, Sea of Rains,
Ocean of Storms, etc. which were later used as benchmarks in the space
flights to the Moon.

Beginning with Sputnik 1 launched into orbit around the Earth on
October 4th 1957, humanity entered its “space age”. In 1959 with the orbital
station Luna 1 the start for investigations of the Moon has been given and,
which was later continued by a number of Soviet stations of the Luna and
Zond series and the American ones — Pioneer, Ranger, Surveyor, etc.,
some of which accomplished a soft landing on the Moon.

of the main tasks of Exobiology. The subject of this new branch of
science is the study of the origin, evolution and spreading of life in the
Universe.
This question remains still unanswered. Sensational announcements
about encounters with “Martians” or other extraterrestrial civilisations
continue to be topics mainly of science fiction books. The attempts for
establishing contacts by sending signals in space or spaceships to the
Moon or other planets of the Solar system have not yet yielded positive
results.
Despite this fact, it is hard to accept that life on the Earth is an
exception in the Universe. If however it proves to be so, then future
mankind will have to combine the joy derived from the happy incident with
the boredom of loneliness.
Based on detailed accounts some authors have expressed the
suggestion that in the numerous galaxies civilisations can be cropping up
every 10²years. According to the American astronomer H.
Shapley there are 10⁸ space bodies on which life could be engendered and exist after
that.
These assumptions raise a logical question. Since life origination is
of such a great frequency and its spreading in space after the panspermia
hypothesis is quite plausible why life is not a more frequently encountered
phenomenon? This leads to the thought that the accounts do not include
the strictly defined and concrete conditions necessary for its origination
and development. The planets of the Solar system can serve as an
example. Some of them theoretically have the possibilities for the
presence of life but as we shall see the results are far from hope raising.
The studies carried out by various methods on nearby and faraway
planets, asteroids, comets and meteorites show that molecules of CO,
NCN, NH₃, H₂S, HCHO, H₂O, etc. which could serve for abiotic synthesis
of more complex organic compounds are not rare in space. Organic
compounds of a varying composition combining H, C and N have been
registered in the interstellar space and cosmic dust. A number of high
molecular particles of various combinations of C, H, O and N,
hydrogencyanide and formaldehyde including, have also been found on
Halley’s comet. Carbon oxide (CO) has been recently detected on the
Hale-Bopp comet. These findings support the idea of the availability of
prerequisites for abiogenic synthesis in space. These prerequisites are
however only the first (space) stage of life origination. The second — the
biological stage, has proven to be much more complex.
And now let us remain in the boundaries of the Solar system and
look at Table 6. The data in it are directly connected to the prerequisites
for life origination and its further existence and propagation.
Moon. The only natural satellite of the Earth. It has been provoking
interest since antiquity. “Naked eye” observations of it have made people