To his contemporaries he was best known as a botanist, though his botanical MSS. were not published till long after his death (at Nuremberg, 1751-1771, 2 vols, folio), he himself issuing only the _Enchiridion historiae plantarum_ (1541) and the _Catalogus plantarum_ (1542) in four tongues. In 1545 he published his remarkable _Bibliotheca universalis_ (ed. by J. Simler, 1574), a catalogue (in Latin, Greek and Hebrew) of all writers who had ever lived, with the titles of their works, &c. A second part, under the title of _Pandeclarium sive partitionum universalium Conradi Gesneri Ligurini libri xxi._, appeared in 1548; only nineteen books being then concluded. The 21st book, a theological encyclopaedia, was published in 1549, but the 20th, intended to include his medical work, was never finished. His great zoological work, _Historia animalium_, appeared in 4 vols. (quadrupeds, birds, fishes) folio, 1551-1558, at Zürich, a fifth (snakes) being issued in 1587 (there is a German translation, entitled _Thierbuch_, of the first 4 vols., Zürich, 1563): this work is the starting-point of modern zoology. Not content with such vast works, Gesner put forth in 1555 his book entitled _Mithridates de differentiis linguis_, an account of about 130 known languages, with the Lord's Prayer in 22 tongues, while in 1556 appeared his edition of the works of Aelian. To non-scientific readers, Gesner will be best known for his love of mountains (below the snow-line) and for his many excursions among them, undertaken partly as a botanist, but also for the sake of mere exercise and enjoyment of the beauties of nature. In 1541 he prefixed to a singular little work of his (_Libellus de lacte et operibus lactariis_) a letter addressed to his friend, J. Vogel, of Glarus, as to the wonders to be found among the mountains, declaring his love for them, and his firm resolve to climb at least one mountain every year, not only to collect flowers, but in order to exercise his body. In 1555 Gesner issued his narrative (_Descriptio Montis Fracti sive Montis Pilati_) of his excursion to the Gnepfstein (6299 ft.), the lowest point in the Pilatus chain, and therein explains at length how each of the senses of man is refreshed in the course of a mountain excursion. Lives by J. Hanhart (Winterthur, 1824) and J. Simler (Zürich, 1566); see also Lebert's _Gesner als Arzt_ (Zürich, 1854). A part of his unpublished writing, edited by Prof. Schmiedel, was published at Nuremberg in 1753.