Microscopic manoeuvres

By the first decade of this century anyone who had received a scientific or medical education would have been familiar with the idea of the cell. Well before the first world war, the compound microscope with its sub-stage condenser lens was in widespread use, and there was a general appreciation that both animals and plants were composed of tissues and that these tissues were made of elementary physical units: roughly spherical, membrane-bounded, nucleated cells. Such cells were also understood to procreate, amazingly, by a process of direct reproduction: they divided themselves in half ("binary fission")- the central truth of the modern cell. That the nucleus harboured visible and distinctive chromosomes, bearers of heredity, was a further part of canonical biological truth.

Most of us would attribute this important knowledge to the celebrated originators of the cell doctrine, Matthias J. Schleiden (1804-81) and Theodor Schwann (1810-82). In The Birth of the Cell , Henry Harris, a physician and cancer researcher (formerly regius professor of medicine at Oxford), does not disagree, but finds the story more complex than "received wisdom" suggests. Harris is determined to trace through a circuitous literature the evolution of the idea of binary fission.

To the 19th-century minds whom Harris explores, the idea of generation, propagation, the increase in numbers of organisms, growth in general, was unthinkable and undescribable without resort to dichotomising sexuality; proliferation implied sexual encounter. Even so remarkable a scientist as Christian Gottfried Ehrenberg (1795-1876), who saw binary fission and documented it extensively in so many different microscopic beings that he grouped them into a family Theilmonade ("monads that undergo division"), tended to disregard the evidence of his own senses. According to Ehrenberg, "Theilungs" ("directly-dividing beings"), must reproduce sexually: "The reproductive apparatus of the monads consists of very numerous concatonated granules scattered throughout the whole body and a relatively large round glandular body which divides when the organism as a whole divides. This glandular structure is obviously quite analogous to a masculine testis and the granules closely resemble eggs." Both the green chloroplasts and the brownish plastids clearly seen by Ehrenberg were interpreted by him to be eggs; infusoria - the name he gave to more or less all the little beings that grow in plant or animal infusions ("whether open to the air, or covered cold or warm") - Ehrenberg took to be hermaphrodites that contained both male and female features in the same body.

Perhaps it is Harris's wide knowledge, not only of European history but also of Europe's languages and literatures, that stimulated his impatient dissatisfaction with the textbook version of the discovery of the cell. Whatever it was that led him to replace trite half-truths with the whole truth, we are the fortunate benefactors of his scepticism. He has written an original, detailed and unique piece of meticulous scholarship, well illustrated (especially with portraits of his protagonists) and easily readable. This small book will interest anyone concerned with any aspect of cell biology and should also reach a wider circle. Readers are likely to be astounded at the behaviour of 19th-century investigators, at the pushy political manoeuvring - by Schleiden and Schwann, for example - to ensure the glories of one's own legacy. The widespread, indefensible nationalism, the unabashed anti-Semitism, protectionism, "ad hominism", and unbridled ambition make us moderns realise that if these egregious practices in science have not diminished they have at least become less overt. Particularly notable was the French-German conspiracy in the late 19th century to minimise contributions by speakers of less influential languages: Czechs, Poles, Italians, Dutchmen and Englishmen.

Another well-read physician, Leonard Warren, from the United States, has written a related tale of 19th-century biological science, a biography of Joseph Leidy (1823-91). Both books emphasise the lack of justice in science with respect to credit given where it is due.

Leidy did not lack fame in his time. A president of the Academy of Natural Sciences of Philadelphia and a founder of the National Academy of Sciences, he made contributions in comparative anatomy, palaeontology and parasitology. He discovered the benign, indeed requisite cellulolytic protists responsible for the ingestion of wood by dry, damp and subterranean termites. He was also the first to recognise the Trichinella nematode as the cause of trichinosis transmitted by undercooked pork. And he named hundreds of New World animals and some fungi and bacteria.

Unlike most of the famed Europeans credited with contributions to cell theory who freely speculated, pontificated and congratulated themselves, Leidy remained close to his original material. None of his observations has been shown to be mistaken or exaggerated. Devoid of any trace of self-aggrandisement or over-generalisation, his works run from about the age of 12 and continue unabated until the year of his death.

He may also be claimed to be the founder of the forensic use of the microscope: a murderer confessed that blood was really human, and not from a chicken as he had claimed, after Leidy noted that its red cells lacked the requisite nuclei of avian blood. And in 1851 Leidy transplanted human tumour tissue under the skin of a frog and determined, five months later, that the tumour had acquired a new blood supply and was thriving.

Though hardly known today, Leidy was once dubbed the greatest naturalist America has produced. In 1923, he was commemorated with these words: "Dr Leidy's vision covered all nature, from the mammals and gigantic reptiles of the past to the world of small things which are revealed to the eye by the highest powers of the microscope; and I never knew anyone who carried on so varied a series of observations without confusion."

In over 30 years of working with Leidy's original descriptions of termite hindgut microbes, my students and I have seen no reason to doubt the accuracy of his descriptions. Especially impressive have been his gorgeously detailed teaching charts and drawings, some of which are reproduced here; they remain an inspiration to serious scholars and nature lovers. He would surely have been delighted to know that the ubiquitous, fancy, spore-forming bacteria he named Arthromitus cristatus are well known to thousands of biologists who have lost all contact with his beloved grassy-green, sky-blue, natural world. These days Leidy's Arthromitus are famous as laboratory weeds, called Bacillus (eg Bacillus anthracis or Bacillus cereus ). We would all of us have so loved to have discussed mutual interests with Leidy. The next best thing, and it is indeed very good, is to savour this marvellous and profound biography that has returned Leidy, the naturalist, teacher, American scholar and gentle man, to the land of the living.

Lynn Margulis is professor in the department of geosciences, University of Massachusetts, Amherst, United States.