How the parts of a body work together

Look at the expectation: it asks for links between cells, tissues, organs and systems. Ask what each record uses to group the parts, and whether the groups are the ones you learn in class.

Pick two systems from your own notes. Ask what one hands to the other, and what happens to the organism if the hand-over stops.

Read the passage at the centre of the discovery. Ibn al-Nafis's account rests on two passages of his commentary, which West quotes in Meyerhof's translation ². On folio 46 recto Ibn al-Nafis writes that the blood, once refined in the right cavity, must pass to the left cavity, where the spirit is generated. But there is no passage between the two cavities, because "the substance of the heart is solid in this region and has neither a visible passage, as was thought by some persons, nor an invisible one which could have permitted the transmission of blood, as was alleged by Galen" ². On folio 65 he says that the blood enters the left ventricle from the lung, after it has been heated in the right ventricle and risen from it ².

The records give a purpose in two places. In the record of the discovery, West says Ibn al-Nafis did not set out to write a book of his own: his aim was to explain Ibn Sina's anatomy, and when he reached the heart he departed from Ibn Sina and from Galen before him ³. In the commentary, as the anatomy record reports, Ibn al-Nafis says that he did not perform dissection himself, for religious reasons and because compassion prevented him; for the forms of the inner organs he relied on what earlier writers described, especially Galen, and for their functions on observation ⁴. His frame was inherited: a correction concerning passage can coexist with inherited spirit terminology ⁵.

Did Servetus know Ibn al-Nafis's work? West's account sets out the evidence on each side. Servetus's words on the septum and the lungs resemble Ibn al-Nafis's, which might suggest he knew the earlier work. A 1940 study by Owsei Temkin pointed out inconsistencies between the two statements, and the 1547 Latin translation of the Commentary on Compound Drugs apparently said nothing about the pulmonary circulation. West writes that many historians believe Servetus did not know Ibn al-Nafis's work; if so, both deserve credit for the discovery of the pulmonary transit of blood, each in his own time ².

A short summary can make this sound like the modern account of circulation. The record is more careful. The discovery has three parts, and the third, small passages between the pulmonary artery and the pulmonary vein, is a prediction of what would be known centuries later as the pulmonary capillaries ². The record says rejecting the pores did not replace the entire framework with twenty-first-century physiology ⁵. The passage is not known to have reached the West before the twentieth century ², and the source does not say that the account spread in Islamic medicine after Ibn al-Nafis ⁶.

The surviving evidence is the manuscripts of the Commentary itself ². In the twentieth century the young Egyptian physician Muhyi al-Din al-Tatawi came across the manuscript in the Prussian State Library in Berlin, submitted his thesis in 1924 and never saw it published; Max Meyerhof learned of the discovery, wrote about it and translated the passages ². West, then, is read through Meyerhof's translation. A manuscript in the Wellcome Collection, WMS Or. 51, is described by its catalogue as containing the first description of the pulmonary circulation ⁷. The sources also differ on Ibn al-Nafis's birth year ³.

Servetus's words resemble Ibn al-Nafis's, which might suggest he knew the earlier work, but a 1940 study found inconsistencies and the 1547 Latin translation was of a different book. Does a resemblance between two statements count as evidence of transmission? What evidence of reading or contact would you require before saying one man took the idea from the other, and why?

• The pulmonary circulation: the three parts of the account, the folios, and the question of who knew whose work.
• Anatomy: how Ibn Sina's Canon grouped organs, and what Ibn al-Nafis says he relied on.
• Ibn al-Nafis: the shaykh of medicine in Egypt and his works.
• The Commentary on the Anatomy of the Canon: the book where the passage is found.