spective dates 1667, 1679, 1738, the two former in 8vo, the latter in 4to.
All his scientific pursuits, however, were suddenly interrupted in the course of this year by a severe attack of quartan ague, by which he was so much reduced, that he was obliged to refrain, for a time, from all mental and bodily exertion. When able to resume his labours, they were directed to a subject which had temporarily been superseded by other interests, but to which he always reverted with the ardour of a first affection, viz. the Anatomy of Insects. An impulse was given to his zeal by the interest which men of rank and science now began to manifest in his investigations; and many of them visited him to witness some of the arcana of nature revealed by his singular dexterity and penetration. Among the most eminent of his visitors, in regard to rank, was the Grand Duke of Tuscany, who had come to Holland, accompanied by Mr. Thevenot, partly with the design of examining whatever was most interesting in nature or art in that country. As this prince was a lover of natural history, Swammerdam was eager to gratify his curiosity, and made several dissections of insects in his presence; demonstrating, among other things, that the forms of the perfect Butterfly can be detected in the Caterpillar, and actually extricating all its parts, and rendering them distinctly recognisable,—an operation of sufficient delicacy to evince his consummate address, and the perfection of his instruments. So much struck was the Duke by his ingenuity, that he tried to prevail
