176 THE MINUTE ANATOMISTS 



structure. On his return to Amsterdam Swammerdam 

 threw himself seriously into human anatomy, and 

 worked at the structure of the spinal cord. He also 

 practised various modes of injection, and became expert 

 in this difficult art. In 1667 he was made Doctor of 

 Medicine of Leyden, presenting as his dissertation a 

 treatise on Eespiration.^ 



In 1668 Cosmo, duke of Tuscany visited Amsterdam, 

 and was taken to see Swammerdam and the museum. 

 With delicate tools and a sure hand Swammerdam 

 repeated a favourite demonstration. Opening a cater- 

 pillar which was ready to pass into the pupal stage, he 

 showed the butterfly with its wings, legs and proboscis 

 packed up within the larval skin. The duke was 

 delighted, and bid 12,000 florins for the collection, on 

 condition that Swammerdam would accompany it to 

 Florence, and accept an appointment in his service. 

 Swammerdam was at this time vexed with worldly 

 cares, and the prospect of a secure post, with unlimited 

 leisure for study, must have had its charms, but he was 

 Dutch and Protestant, accustomed to think his own 

 thoughts, especially about matters of religion. Life at 

 court, and in the service of a Catholic prince, was 

 impossible for him, and he refused the duke's ofier. 

 Swammerdam's friend, the anatomist and physiologist 

 Stensen, became the duke's physician, and not very long 

 after underwent a sudden conversion. He was moved, 

 not only to embrace the Catholic faith, but to take 

 orders, and having been advanced to the dignity of a 

 bishop, was sent back to the Protestant countries of the 

 north as a missionary. The labours and privations of 



' This was at first a brief abstract of Swammerdam's results in scholastic 

 form ; it was enlarged in a second edition (1679), and reprinted with annota- 

 tions by Haller (1738). 



