What do spots on the pages of old books, corrosion of gas pipes and
the Black Death have in common? They are all caused by microbes – minute
organisms which have fascinated us ever since the Dutch merchant Anton
van Leeuwenhoek discovered the invisible but teeming world of ‘small life’
in the 17th century. Leeuwenhoek described his pioneering observations
in more than 400 published papers and became an international celebrity,
receiving many visits from the notables of his day, including King James
II.

One of the reasons for Leeuwenhoek’s success was that he made his own
microscopes and kept his methods secret. But as lens-making techniques improved
and microscopes became more widely available, others got in on the act
and they became something of a craze. During the 18th and 19th centuries,
many important discoveries were made by gifted amateurs armed with nothing
more than a basic microscope, curiosity and a bucket of pond water. Even
today it is still possible to excite the scientific world if you take your
bucket to the right place – the first descriptions of square and triangular
bacteria were published only in the 1980s.

Scientific study of the microbial world was placed on a firmer footing
at the end of the 19th century by the French biologist Louis Pasteur. His
work helped to establish the principle that specific microbes cause specific
diseases. There are still a lot of them out there: tuberculosis, rabies,
AIDS, yellow fever, malaria, cholera and typhoid. But concentrating only
on harmful microbes misses out a large part of the picture. Most microbes
live quiet lives: they pass their time breaking down and recycling organic
material or taking nitrogen from the air and turning it into water-soluble
salts which plants can use as nutrients. From a human perspective, these
activities are not as dramatic as syphilis or food poisoning, but the whole
web of life, including our own, depends on them.

And then there are other sorts of microbes. The irritating ones damage
our monuments, clog up ship’s engines and spoil wine. The useful ones make
antibiotics, clear oil spills and give a cheese its distinctive flavour.
And then there is the one that you can buy at the supermarket and eat.

The thing that can be frustrating about this fascinating microbial world
is that all the players have names like Cephalos-porium acremonium and sorting
the interesting snippets from the technical detail is difficult. But help
is at hand. In this book Bernard Dixon, microbiologist turned journalist,
gives us a ‘meet the microbes’ portrait gallery. Each of the 75 vignettes
in the book introduces an important microbe and its friends, puts it in
historical perspective and explains its significance in nontechnical language.
The portraits are arranged in five groups: microbes that shaped the world,
sprang surprises, still threaten us, we depend on and may shape our future.
The book can be read straight through or dipped into. Either way, even for
those with some knowledge of microbes, it contains a lot of interesting
and entertaining information. And as an introduction to the world of microbes
I can think of no better book.

John Lee is a lecturer in Pathology at the University of Sheffield

Academic administration needs good scientists to provide informed opinion
for important decisions and to ensure that a wider perspective is transmitted
back to science faculties in common language. Yet it often succeeds in removing
some of the best scientists from their chosen field of scholarship and placing
them in an unfamiliar situation in which opportunism and political finesse
are assets as important as intellectual ability. This is what happened to
molecular biologist Robert Sinsheimer, whose autobiographical account, The
Strands of Life, is the latest in the Sloan Foundation’s Science Book Series.

By supporting the publication of the series, the foundation aims to
encourage public understanding of science. In contrast to most popular science
books, this series has emphasised scientific enterprise – the ways in which
science is actually done – rather than simply explain the results. Several
excellent contributions among the 17 volumes published include Advice to
a Young ÐÓ°ÉÔ­´´ by Peter Medawar, The Youngest Science by Lewis Thomas
and What Mad Pursuit by Francis Crick.

The foundation was endowed by Alfred Sloan (1875-1966), president and
chairman of General Motors for more than a quarter of a century. Under Sloan,
General Motors overtook Ford in car sales in the 1920s, and eventually became
the largest business corporation in the world. Success brought huge financial
rewards to Sloan, who became a philanthropist. He endowed centres for advanced
engineering and management at Massachusetts Institute of Technology, the
Sloan-Kettering Cancer Center in New York and the foundation that bears
his name.

Sinsheimer has had an interesting career. After graduating from MIT
he was diverted into radar research for four years during the Second World
War, but then obtained his PhD in biophysics from MIT in 1948. His understandable
frustration at having to spend four years in a research endeavour alien
to his main interests remains palpable.

Faculty positions at Iowa State University and then the California Institute
if Technology (Caltech) followed. During this time he pursued studies of
the small bacteriophage fC, which was to play an important part in the unfolding
story of molecular biology. Sinsheimer was involved in the discovery of
circular DNA – a finding quite contrary to accepted dogma at the time –
and also in the first test-tube synthesis of infective DNA. This result
was widely reported in the media and produced an example of how easily public
misconceptions of science arise. Several reports called fC a ‘dwarf virus’,
referring to its small size. As a result, people suffering from dwarfism
wrote to Sinsheimer wondering if his research might lead to a cure. The
5386 nucleotides of fC became the first complete DNA to be sequenced (by
Fred Sanger’s laboratory in Cambridge in 1977) and Sinsheimer is justifiably
proud at having put fC on the map.

A successful scientist, Sinsheimer served on many committees and became
chairman of biology at Caltech. Then, in 1977, he became chancellor of the
University of California at Santa Cruz. It is clear that he took this position
somewhat naively, expecting to be able to continue his research. About half
the book is concerned with the political manoeuvring of the next ten years.
It makes salutary reading. Although Sinsheimer puts a brave face on the
experience and was clearly good at the job, I had the strong impression
that he wished he had stayed in the laboratory. His obvious delight at getting
back into the lab on retirement is evident.

This is an interesting and well-written book by an outstanding scientist
who followed the path to academic administration. Sinsheimer’s experiences
highlight an enduring dilemma. The premise of the Sloan Foundation series
is that an understanding of scientific enterprise brings with it insight
into the nature of scientific discoveries. This is just as true for scientists
as for nonscientists and this book contains much that both will want to
think about.

John Lee lectures in pathology at the University of Sheffield.

Although Galen was able to establish the intellect in its correct position,
his understanding of the functions of the heart was not so satisfactory.
A full 1500 years were to pass before the inspired and elegant experiments
of William Harvey broke through the muddle and established the concept of
the circulation of the blood, correctly identifying the heart as a tireless
pump.

This understanding of the activity and function of the heart leads quite
quickly to a feeling of surprise that an organ can be so active for so long,
and a desire to measure just how ‘active’ the heart really is. Indeed, Harvey
himself was the first person in the history of physiology to use a quantitative
argument, when he calculated the volume of blood expelled by the heart in
half an hour and used the large number so generated (much larger than the
entire volume of blood in the animal) as evidence to support the existence
of a circulation.

One way to gain some insight into the workings of the heart is to compare
its activity in a wide variety of animals, and in fact a large amount of
information on this topic is now available. It turns out that many parameters
of interest can be related quite simply to body weight. Thus, for example,
the size of the heart scales linearly in mammals, that is, it is a constant
fraction of body weight (about 6 per cent). The advantage of this approach
is that when an equation has been constructed for a variety of different
species, one can examine the data for a particular species and see how ‘normal’
it is when compared with all the rest. When applied to Homo sapiens, this
exercise is quite revealing.

If we look at the resting frequency of the heartbeat in mammals, we
find that it is inversely related to body weight. In other words, the larger
the mammal the slower the resting heartbeat and vice versa. An elephant’s
heart, for example, plods along at a rate of about 30 beats per minute,
while a shrew’s heart manages the scarcely credible rate of 800 beats per
minute (more than 10 per second). Unlike the heart size, frequency scales
non-linearly with body weight, which means (in this case) that the heart
rate changes less fast than the body weight. The elephant is 10 000 times
heavier than the shrew, but its heart rate is only about 30 times slower.

In standard physiology textbooks, the typical human being weighs 70
kilograms and seems to be male (the ’70-kilogram man’). If we resolutely
ignore the other issues raised by this point and apply this weight to the
mammalian heart-rate equation, we obtain a result of 83 beats per minute,
quite close to the true value. In other words, when humans are compared
with a variety of other mammals, we see that our hearts beat at roughly
the expected rate for our body weight. From this we can deduce that our
hearts pump roughly the expected amount of blood per minute for our body
weight.

Now, there is another body of data, largely obtained from collections
of animals in zoos, which shows that lifespan can also be related to body
weight. The equation describing this equation indicates an upper limit for
lifespan, because animals in captivity have adequate food, are relatively
free from disease and are not subject to predation. If we put our 70-kilogram
man into this equation, we find that it predicts a human lifespan of only
27.6 years. In other words, when compared with other mammals, humans actually
live three or more times as long as is expected on the basis of their body
weight (an observation which remains essentially unexplained).

Combining this finding with those for the heart, we arrive at the conclusion
that although the human heart beats at a rate expected from the body mass,
it has to do this for three or more times longer than in other mammals.
Over a 75-year lifespan, this amounts to an extra 2076 million beats or
an extra 145 million litres of blood pumped. Perhaps it is only to be expected,
then, that diseases of the heart are common among humans (even without taking
into consideration the many environmental influences which are known to
be damaging to the heart), and we can be grateful that the design of our
hearts incorporates such a large reserve. I wonder what the story of human
civilisation would be if we all signed off at 28? We can only agree with
Woody Allen, who aptly summed up the situation in Hannah and Her Sisters.
‘The heart,’ he said, ‘is a very resilient little muscle.’

John Lee works in the department of pathology at the Royal Victoria
Infirmary, Newcastle upon Tyne.