Malpighi, M

NAME: Malpighi, Marcello

ACHIEVEMENT(S): Discovered the capillaries.

NICKNAME/ALIAS: None

DATE/PLACE OF BIRTH: 10 March 1628, at Crevalcore, near Bologna, Papal

States [Italy]

DATE/PLACE/AGE AT DEATH: 29 November 1694, in Rome, Italy.  Aged 66

DISCIPLINE: Anatomist

FIELD: Biology

LANGUAGE: Italian

PARENTS: Marcantonio Malpighi and Maria Cremonini (both died 1649)

SIBLINGS: Seven younger siblings

SPOUSE: ? Massari

CHILDREN: None

EDUCATION: University of Bologna, 1646-53

MAJOR WORK: 'De pulmonibus', 1667

LIFE AND TIMES:  Malpighi graduated as doctor of medicine and philosophy in 1653, and two years later - during which time he continued his researches in anatomy and medicine - he became a lecturer in logic at the University of Bologna.

In 1656 Malpighi was invited by <a patron was> Ferdinand II* of Tuscany to the professorship of theoretical medicine at the University of Pisa. There, at the <member of> Accademia del Cimento*, one of the very first scientific societies, Malpighi formed a lifelong friendship with the mathematician and naturalist <a pal of> Borelli*, with whom he discovered the spiral character of heart muscles.

In 1659, owing to poor health and family responsibilities, Malpighi returned to Bologna, where he was appointed lecturer in practical medicine. In September 1660 he began his first and greatest series of experiments on the lungs, which were completed by the summer of 1661.

At that time virtually nothing was known of the structure of the lung.  Using a microscope and working mainly on the lungs of dogs, Malpighi showed by December 1660 that the lung consists solely of membranous vesicles filled with air. After March he used the lungs of frogs; having first injected water into the pulmonary artery of a frog's lung, and watching it exit from the pulmonary vein, Malpighi then examined the lung (the water having made it more transparent) under a microscope and saw the network of capillaries and capillary action, a phenomenon he then  observed in thefrog's distended bladder. 

So, he had identified and described for the first time the pulmonary and capillary network connecting small arteries with small veins. Malpighi's discovery that blood passed through the capillaries therefore proved <proved theory of> Harvey's* theory of the circulation of the blood.  His discoveries were described in two letters to Borelli in Pisa, who published them as 'De pulmonibus' in 1661.

Malpighi's views evoked increasing controversy and dissent, and feeling restricted by the hostile environment of Bologna, in November 1662 he accepted a professorship in medicine at the University of Messina in Sicily. 

During his four years at the University of Messina, Malpighi carried on his microscopic studies using marine animals from the Strait of Messina while teaching and practicing medicine. He published the results in a series of treatises in 1665-66,  devoted mainly to neurology, adenology, and hematology.

In a small tract, 'De omento' (1665) Malpighi described how he had seen red globules of fat in blood vessels (corpuscles) and attributed the colour of blood to them.  In two more tracts of 1665, 'De lingua' and 'De externo tactus organo', he first described the papillae of the tongue, the rete mucosum (the Malpighian - reticular, or mucous - layer of the skin, between the true skin and the scarf skin), and the dermal papillae, which he recognized as the organs of touch, or taste buds.

He also speculated that these papillae could be reached through pores in the epithelium and stimulated by "sapid" particles dissolved in the saliva, the significance of which had been recognized a few years earlier by the Danish physician <work related to> Stensen*.

Then, in a fourth tract from 1665, 'De cerebro', Malpighi described the minute structure of the brain, showing that the white matter of the nervous system consists of bundles of fibres, arranged in tracts connecting the brain with the spinal cord, and he noted the grey nuclei in the white matter of the brain.

In January 1667 he decided to return to Bologna, where he remained for the next 25 years. Here he taught - his pupils including the anatomist <taught>  Valsalva*, who would in turn instruct <influenced> Morgagni* - and continued his medical practice, while during the late 1660s he studied the microscopic subdivisions of specific living organs, such as the liver, brain, spleen, and kidneys, and of bone and the deeper layers of the skin that now bear his name. His 'De viscerum structura', published soon after his return to Bologna in 1666, contained his work on histology.

In this work, Malpighi showed that the liver is structurally a secreting gland, and must therefore have a duct, the bile-duct, and correctly concluded that bile is not secreted (as had been previously thought) by the gall-bladder. He also showed that the tubules in the kidney opened into the apices of the pyramids, and found that each tubule began in the cortex in association with a sphere of blood-vessels.

This is now known as the Malpighian tuft, while the terminal association - the glomerules - is known as the Malpighian body.

Meanwhile, in the spleen he first described the Malpighian corpuscles, and showed that

it is a contractile vascular organ, and not a gland. As a result of this work he concluded that most living materials are glandular in organization, that even the largest organs are composed of minute glands, and that these glands exist solely for the separation or for

the mixture of juices.

Meanwhile, Malpighi's work at Messina had attracted the attention of the secretary of the Royal Society in London, <corresponded with> Oldenburg*, who in 1668 invited Malpighi to correspond directly with the Society. The following year he was named the first Italian honorary member.

In 1669 Malpighi published his memoir on the silkworm moth, 'De bombyce', the first full account of the structure of an insect. In this work, he carefully observed the construction of the three stages - larva, chrysalis, and moth - by which the silkworm is formed, and gave the first descriptions of the spiracles and tracheae, or air-tubes, the

multi-chambered heart, the nerve cord with its ganglia, and the silk glands. He also accurately described the organs of generation, and noted the movements of the last three segments in the larva, but could not decide whether they were respiratory.

Malpighi, now internationally famous, followed with two pioneering studies in the field of embryology, ''On the formation of the chick in the egg', 1672, and 'On the incubated egg', (1675). 

In 1675 Malpighi published the first part of his 'Anatome plantarum' (the second part appearing in 1679), an extensive comparative study of the microscopic anatomy of several different plants in which he saw an analogy between plant and animal organization.

In this work, which won him great acclaim in England as (along with <parallel work with> Grew*) the founder of the microscopic study of plant anatomy, Malpighi discovered and illustrated the annular rings of the dicotyledonous stem and the scattered bundles of the monocotyledons. He discovered also that the material required for growth is formed from the sap by the leaves, although he did not describe the movement of the sap as comparable to the circulation of the blood, as is often supposed. He discovered stomata in leaves, although he had no idea of their function, dealt comprehensively with the structure of the flower, and described the development of the plant-embryo.

During the 1680s his work on capillary circulation was extended in 1684 by <work extended by> Leeuwenhoek*, who rediscovered blood corpuscles and capillaries, and gave the accurate description of blood corpuscles, noting that those of birds, fishes and frogs are oval, while those of man and other mammals are disc-shaped.

ASSESSMENT: He gave the first clear description of minute circulation of the blood and the capillary connection between arteries and veins, and may also be regarded as the first histologist.

EXTRA CONNECTIONS:  EH Weber*?

ONELINER: Marcello Malpighi, who discovered the capillaries

BIBLIOGRAPHY:

EB, DSB

Adelmann, Howard B., Marcello Malpighi and the Evolution of  Embryology, 5 vols., Ithaca, New York: Cornell University Press,  1966