Marcello Malpighi

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[b. Crevalcore (Italy), March 10, 1628, d. Rome, December 30, 1694]

A pioneer in the use of the recently invented microscope, Malpighi located the capillaries that carry blood from the arteries to the veins. He also identified sensory receptors (papillae) of the tongue and skin and capsules of the kidney and spleen. He showed that there is no such thing as black bile, which since ancient times had been believed to be one of the four humors (fluids) of the human body, together with yellow bile, blood, and phlegm.

The Italian microscopist Marcello Malpighi (1628-1694) was the first to see the capillaries and was a founder of histology, embryology, plant anatomy, and comparative anatomy.

On March 10, 1628, Marcello Malpighi was born at Crevalcore near Bologna. He attended the University of Bologna, where he graduated in philosophy and in medicine in 1653. Malpighi became a lecturer in logic at Bologna in 1655 but left in 1656 to be professor of theoretical medicine at Pisa. There he met Giovanni Borelli, a mathematician who had recently turned his attention to the analysis of movement in animals.

Malpighi returned to Bologna in 1659, where he was made extraordinary lecturer in theoretical medicine. Through Borelli's influence, Malpighi was elected to the first chair in medicine at Messina in 1662, but in 1666 he returned to Bologna to become professor of medicine, and he remained there for the next 25 years.

By 1667 Malpighi's work had already aroused the interest of the recently formed Royal Society in London, and one of its secretaries wrote to him suggesting that he communicate his results to the society. Malpighi responded favorably, and most of his later books were published in London. He was elected a foreign member of the Royal Society in 1668.

Malpighi was also a successful physician, and in 1691 he became the personal physician of Pope Innocent XII in Rome. Malpighi died on Nov. 29, 1694, in Rome.

Discovery of Capillaries

In September 1660 Malpighi began to study the structure of the lungs, and within nine months he had communicated the results of these studies in two letters to Borelli in Pisa, who published them under the title De pulmonibus observationes anatomicae (1661). Malpighi presented "a few little observations that might increase the things found out about the lungs." These observations included the first descriptions of the air sacs (pulmonary alveoli) in the lungs of a dog and of the pulmonary capillaries in the frog and tortoise.

Having convinced himself of the presence of direct connections between the arteries and veins in the lungs of the frog and the tortoise, Malpighi was prepared to speculate that the same was so in other animals: he was unable to see such anastomoses in the dog's lung, perhaps, because these "small vessels escape the senses on account of their smallness."

Histological Studies

The science of the study of the structure of tissues was established by the classical microscopists, and Malpighi's contributions were among the most important. He published four tracts in 1665. The first one described the presence of "red globules of fat" in the blood vessels of the mesentery of the hedgehog. This is one of the earliest descriptions of the red blood cell, although Malpighi did not realize the significance of his observation. In other tracts he described the papillae of the tongue and the skin and suggested that these may have a sensory function. The layer of cells in the skin now known as the Malpighian layer was also described. The last tract of 1665 concerned the general structure of the brain. Malpighi showed that the white matter consists of bundles of fibers which connect the brain with the spinal cord. He described the gray nuclei that occur in the white matter.

Malpighi's De viscerum structura execitatio anatomica (1666) gives a detailed and fairly accurate account of the structure of the liver, spleen, and kidney. Malpighi dissected the tissue under the microscope, and he identified small particulate masses or "lobules," resembling bunches of grapes, in the liver. Each lobule was composed of "tiny conglobate bodies like grape seeds" connected by central vessels. Having seen these lobules in the livers of several species, he concluded that the lobule was the fundamental hepatic unit. He believed that the lobules were supplied by fine blood vessels and that their function was secretory. Malpighi realized, therefore, that one function of the liver is as a gland and that the bile duct must be the passage through which the secreted material (bile) passes: the gall-bladder was, therefore, not the site of origin of bile. He was also able to prove in an animal experiment that the gallbladder is only a temporary store for bile on its way to the intestine. Malpighi speculated that bile might be useful in the process of digestion.

Although Malpighi was fond of describing many structures as "glands," he realized, from his study of the blood supply to the spleen, that this organ is not a gland but a contractile vascular organ. He was the first to describe the lymphatic bodies (Malpighian corpuscles) in the spleen.

Whereas other anatomists believed that the outermost part of the kidney was structureless, Malpighi showed that it is composed of many little wormlike vessels (the renal tubules) which he called "canaliculi." Although he could not demonstrate any continuity between the convoluted canaliculi and the straight tubules in the central mass of tissue (medulla), he predicted that such a continuity exists. Malpighi's description of how he discovered the glomeruli in the outer part of the kidney is vivid: "In all kidneys which up to this time I have been able to get, I have detected a number of very small glands [that is, Malpighian corpuscles, or glomeruli]. In order to see these glands, black fluid mixed with spirit of wine should be injected through the renal artery. And when the kidney is sectione…. one will see these same innumerable glands attached like apples to the blood vessels, the latter swollen with the black liquid and stretched out into the form of a beautiful tree." Malpighi realized that the "glands" were connected to the "extreme ends of the arteries" and to the veins but did not observe the true nature of the "glands," that is, that they are composed of a tuft of capillaries. He speculated that their function was to secrete the urine.

Malpighi's detailed description of the medulla of the kidney showed how the canaliculi converge on the pelvis and enter the ureter. In pathological specimens he observed the formation of kidney stones in the pelvis.

Insect Anatomy

Malpighi's memoir De bombyce (1669), on the silk-worm moth, was the first detailed account of the structure of an invertebrate. Prior to his study, it was still believed that such small creatures were devoid of internal organs, and he himself was surprised to find that the moth was just as complex as higher animals. He not only discovered the trachae and spiracles, the system of tubes and holes through which insects breathe, but also correctly guessed their function. He was the first to describe the nerve cord and ganglia, the silk glands, the multichambered heart, and the urinary tubules, which still bear his name.

Embryological Studies

With his microscope, Malpighi was able to study much earlier stages of the embryo than had hitherto been possible. His results were communicated to the Royal Society in two memoirs: De formatione pulli in ovo (1672) and De ovo incubato (1675), which placed embryological study on a firm basis of sound observation. He saw the heart within 30 hours of incubation and noticed that it began to beat before the blood reddened. He described the development of the dorsal folds, the brain, the mesoblastic somites, and structures which were later identified as gill arches. However, Malpighi believed that he had seen the form of an embryo in an unincubated egg. A possible explanation is that the egg, being 2 days old, had been "incubated" in the hot Italian August sun. This observation was used, not by Malpighi himself as much as by his followers, to support the doctrine of preformation, that is, that the whole adult was present in the egg and had only to be "unfolded" by a suitable stimulus.

Plant Anatomy

Some of Malpighi's most extensive writing, beautifully illustrated, is on plants. Malpighi and his contemporary Nehemiah Grew became the confounders of plant anatomy by their systematic studies on the microscopic structure of plants. Malpighi's book Anatome plantarum was published in two parts in 1675 and in 1679. His illustrations frequently show the plant cell with its wall, first described by Robert Hooke in 1665.

Malpighi's interest in the structure of plants began when he noticed the broken branch of a chestnut tree which had fine threads projecting from the surface. Upon examining these with his lens he was struck with their resemblance to the air tubes of insects. Although he wrongly concluded that they served the function of breathing, his enthusiasm for the study of plants had been awakened. His drawings of the stems of higher plants distinguished between the annular rings of the dicotyledon and the scattered bundles of the monocotyledon (the terms dicotyledon and monocotyledon were introduced in the early 18th century). He suggested that material required for growth of the plant was formed from the sap by the leaves, but the erroneous idea that the sap circulated, as blood did, was originated by other writers.

Malpighi's work on the development of plants is just as significant as that on the development of animals. He made drawings of the embryo sac and endosperm and gave a superb account of the germination of seeds in which he differentiated between those later called monocotyledons and dicotyledons. He was the first to describe tubercles on leguminous roots, and he showed that some galls contained a grub. He traced the grub back to an egg and onward to an insect, of which he illustrated the egg-laying apparatus.

Further Reading

Some biographical information on Malpighi is in Howard B. Adelmann, Marcello Malpighi and the Evolution of Embryology (1966), and in Circulation of the Blood: Men and Ideas, edited by Alfred P. Fishman and Dickinson W. Richards (1964). For background see Charles Singer, A History of Biology to about the Year 1900 (1931; 3d rev. ed. 1959).

Additional Sources

Malpighi, Marcello, The correspondence of Marcello Malpighi, Ithaca N.Y. Cornell University Press, 1975.

Malpighi, Marcello (1628–1694), Italian physician and anatomist. Malpighi was born in Crevalcore, near Bologna, on 10 March 1628. He graduated in medicine and philosophy at the University of Bologna in 1653, and he taught logic at the same university until 1656, when he was called to the chair of theoretical medicine at the University of Pisa. Three years later he returned to Bologna, lecturing in theoretical and practical medicine. From 1662 to 1666 he held the chair of primary professor of medicine at the University of Messina. He then returned once more to Bologna, where he taught practical medicine until 1691, the year in which he moved to Rome in the capacity of chief physician to Pope Innocent XII. He died in Rome on 30 November 1694. These institutional settings are of a special importance in understanding his development as an anatomist, physician, and natural philosopher. Although he was trained at Bologna in the traditional course of scholastic disciplines, he also attended with other select students the private dissections and vivisections conducted by the university professor Bartolomeo Massari. In his time at Pisa he met Giovanni Alfonso Borelli (1608–1679), professor of mathematics there, and their ensuing collaboration was crucial in bringing Malpighi closer to corpuscularianism (the idea that the visible properties of matter derive from the interactions of minute particles of matter), to mechanical philosophy (the view that every natural phenomenon can be explained through matter and motion), and to Galileo's natural philosophy. In Messina he found a congenial environment for his investigations on marine animals and the sensory organs. Finally, from 1667, correspondence with Henry Oldenburg and the relationships that he established with the Royal Society brought Malpighi into closer contact with English experimental physiology.

Malpighi's works display a wide range of interests. In De Pulmonibus (On the lungs; Bologna, 1661), composed in the form of two letters addressed to Borelli, he announced his discovery of capillary circulation and gave a detailed account of the vesicular structure of the human lung. In Epistolae Anatomicae de Cerebro ac Lingua (Anatomical letters on the brain and the tongue; Bologna, 1665) and in De Externo Tactus Organo (The external organ of touch; Naples, 1665), he made his discovery of the sensory receptors of the tongue and cutaneous papillae part of a far-reaching project in neuroanatomical research. De Viscerum Structura (The structure of the internal organs; Bologna, 1666) and De Structura Glandularum Conglobatarum (The structure of the conglobate glands; London, 1689) present Malpighi's main theoretical view of the gland as the building block of the body's mechanical structure. In De Bombyce (On the silkworm; London, 1669) he investigated the anatomy of insects, and he gave an accurate description of the development of the chick in De Formatione Pulli in Ovo (The development of the chick in the egg; London, 1673), adding new evidence in support to the preformationist hypothesis, that is, the idea that the organism is already present and fully developed in the seed or egg. In Anatomes Plantarum (Anatomy of plants; London, 1679), Malpighi made use of the microscope and its related techniques in the study of animal and vegetable anatomy with great dexterity and profit. In De Polypo Cordis (On the polyp of the heart; 1666), he argued that the examination of pathological states, natural anomalies, and monstrosities could shed light on the normal functioning of organs and on the general processes of nature, thus laying the foundations for a research program centered on localizing the anatomical seats of disease.

From an anatomical point of view, Malpighi's work is a clear example of experimental investigation conducted in the wake of William Harvey's discovery of the circulation of the blood. Philosophically speaking, the main influence comes from Galileo's redefinition of matter, motion, and nature. Distancing himself from Descartes's extreme views on the mechanization of the body and the thorough identification of natural productivity with mechanical agency, Malpighi did not rule out the animate and sentient character of the body, and he emphasized the unattainability of perfection in the natural mechanics of living beings. Being both a theoretical anatomist and a physician—his Consultationes Medicinales (Medical consultations; Padua, 1713; Venice, 1747) are evidence of his clinical expertise—Malpighi represents the intriguing case of an early modern practitioner confronted with the need to harmonize theory (a new image of the body) and practice (the continuing success of traditional therapy) in the context of the new medical discourse.

Bibliography

Primary Sources

Malpighi, Marcello. The Correspondence of Marcello Malpighi. Edited by Howard Bernhardt Adelmann. Ithaca, N.Y., 1975.

——. Opera Omnia. London, 1686. Rept. New York, 1975.

——. Opera Posthuma. London, 1697, Amsterdam, 1698.

Secondary Sources

Adelmann, Howard Bernhardt. Marcello Malpighi and the Evolution of Embryology. Ithaca, N.Y., 1966.

Bertoloni Meli, Domenico, ed. Marcello Malpighi: Anatomist and Physician. Florence, 1997.

—GUIDO GIGLIONI

Marcello Malpighi.

Marcello Malpighi (March 10, 1628 - September 30, 1694) was an Italian doctor, who gave his name to several physiological features.

Contents 1 Early years 2 Academic career 3 Research 4 Years in Rome 5 Memories of Malpighi in Bologna 6 Some of Malpighi's important works 7 References 8 External links

Early years

Malpighi was born in Crevalcore near Bologna in Italy, raised on the farm his parents owned and entered the University of Bologna at the age of 17. Malpighi began to study. When his father, mother and paternal grandmother died, he had to abandon his studies for more than two years to settle family affairs. He returned to university after two years, and became a doctor of medicine in 1653. The next year he married Francesca Massari, younger sister of his anatomy professor. She died a year later.

Academic career

In 1656 Malpighi received a chair of medical practice in the university, three years after he had applied for it, and later the same year University of Pisa created a chair of theoretical medicine for him. He stayed in Pisa for three years and then returned to Bologna. In 1661 he was called to University of Messina where he stayed for four years.

Most of Malpighi's research results were published as articles in the journal of the Royal Society of England. His first article appeared there in 1661 and was about anatomy of a lung of a frog during which he had discovered capillaries. In 1667 Henry Oldenburg invited Malpighi to correspond with the Royal Society regularly and he became a fellow the next year, the first such recognition given to an Italian.

Research

Malpighi used the microscope for studies on skin, kidney, and for the first interspecies comparison of the liver. He greatly extended the science of embryology. The use of microscopes enabled him to describe the development of the chick in its egg, and discovered that insects (particularly, the silk worm) do not use lungs to breathe, but small holes in their skin called tracheae. Later he falsely concluded that plants had similar tubules. However, he observed that when a ringlike portion of bark was removed on a trunk a swelling of the tissues would occur above the ring. He correctly interpreted this as growth stimulated by food coming down from the leaves, and being blocked above the ring. He was the first to see capillaries and discovered the link between arteries and veins that had eluded William Harvey.

Malpighi is regarded as the founder of microscopic anatomy and the first histologist. Many microscopic anatomical structures are named after him, including a skin layer (Malpighi layer) and two different Malpighian corpuscles in the kidneys and the spleen, as well as the Malpighian tubules in the excretory system of insects.

He also studied chick embryo development with detailed drawings and discovered taste buds of human tongue. Some of his studies he made by vivisection. He also studied the anatomy of a brain and concluded that this organ is a gland. In terms of modern endocrinology this deduction is correct because neurotransmitter substances represent paracrine hormones, and the hypothalamus of the brain has long been recognized for its hormone-secreting capacity. He was also among the first to study human fingerprints.^[1]

His treatise 'De polypo cordis' (1666) was important towards understanding how blood clots and its composition. He may have been the first person to see red blood cells under a microscope. He described how the form of a blood clot differed in the right vs. the left sides of the heart.

In addition to his anatomical studies, he was one of the rare contemporary scholars who studied plants; he published his findings in a book Anatomia Plantarum in 1671. It was the most exhaustive study of botany at the time. The Royal Society published it the next year. The great Swedish botanist Linnaeus named the genus Malpighia in honor of Malpighi's work on plants; Malpighia is the type genus for the Malpighiaceae, a family of tropical and subtropical flowering plants.

After the dissection of a black male, Malpighi made some ground-breaking headway into the discovery of the origin of black skin. Malpighi found that the black pigment was caused by a layer of mucus just beneath the skin^[2]

Years in Rome

In 1691 Pope Innocent XII invited him to Rome as Papal physician. He taught medicine in the Papal Medical School and wrote a long treatise about his studies which he donated to the Royal Society of London.

Marcello Malpighi died of apoplexy in Rome on September 30, 1694. The Royal Society published his studies in 1696.

Memories of Malpighi in Bologna

Malpighi's tomb in Bologna

The body of Malpighi is buried in the church of the Santi Gregorio e Siro, in Bologna, where nowadays can be seen a marble monument to the scientist with an inscription in Latin remembering - among other things - his "SUMMUM INGENIUM / INTEGERRIMAM VITAM / FORTEM STRENUAMQUE MENTEM / AUDACEM SALUTARIS ARTIS AMOREM" (great genius, honest life, strong and tough mind, daring love for the medical art).

Some of Malpighi's important works

• De viscerum structura exercitati
• De pulmonis epistolee

References

1. ^ Marcello Malpighi, De Externo Tactus Organo Anatomica Observatio (Naples, Italy: Aegidium Longum, 1685).
2. ^ The Physiology of the Pigmentary System

• Adelmann, Howard (1966) Marcello Malpighi and the Evolution of Embryology 5 vol., Cornell University Press, Ithaca, N.Y. OCLC 306783

External links

Wikimedia Commons has media related to: Marcello Malpighi

• Biography of Marcello Malpighi in the Encyclopaedia Britannica
• Some places and memories related to Marcello Malpighi
•  "Marcello Malpighi". Catholic Encyclopedia. New York: Robert Appleton Company. 1913. http://en.wikisource.org/wiki/Catholic_Encyclopedia_(1913)/Marcello_Malpighi. 

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