JOHN SWAMMERDAM. 127 



tions was prejudicial to his health, and he was seized 

 with a quartan ague, which reduced him to a state 

 of extreme debility. On recovering from this dis- 

 ease, he remitted his professional studies for two 

 years; resuming the investigation of insects, the 

 structure of which he unfolded with astonishing 

 precision and success. 



It happened about this time that the Grand Duke 

 of Tuscany visited Amsterdam. Accompanied by 

 Thevenot, he examined the collections made by 

 Swammerdam and his father, and was so struck 

 by the wonderful dissections of insects that he of- 

 fered 12,000 florins for the museum, on condition 

 that its proprietor should accompany it to Florence, 

 and take up his residence in the palace. But the 

 young naturalist had been so much accustomed to 

 roam about at will, that he could not relinquish 

 his liberty, and therefore refused the offer. 



In 1669, he published his General History of In- 

 sects, which he dedicated to the senate of Amster- 

 dam. The expense which he incurred in procuring 

 specimens from all quarters, while no emoluments 

 resulted from his labours, so displeased his father, that 

 he earnestly urged him to relinquish his unprofit- 

 able pursuits, and engage in the practice of medicine. 

 At length, finding him unwilling to follow his ad- 

 vice, he was obliged to threaten a total intermission 

 of supplies ; though by this time the ardent student 

 had fallen into such a state of debility that he was 

 totally unfit to undergo the fatigues of practice. He 

 was, however, sensible of the propriety of the counsel 

 which was administered to him, and retired to the 

 country to recruit his strength ; but he had scarcely 

 arrived when he recommenced his studies, being 



