The British Library Leyden Medical Dissertations Collection is a collection of medical dissertations

Thesis

A dissertation or thesis is a document submitted in support of candidature for an academic degree or professional qualification presenting the author's research and findings...

 submitted to Dutch universities at Amsterdam, Utrecht, Harlingen, and Leyden. It includes, in particular, a fine set of Leyden medical dissertations and disputations for the period 1593 to 1746. The collection is in 53 volumes, all bound in white vellum

Vellum

Vellum is mammal skin prepared for writing or printing on, to produce single pages, scrolls, codices or books. It is generally smooth and durable, although there are great variations depending on preparation, the quality of the skin and the type of animal used...

, with 20 to 75 documents in each volume. The collection was formed principally by Hans Sloane

Hans Sloane

Sir Hans Sloane, 1st Baronet, PRS was an Ulster-Scot physician and collector, notable for bequeathing his collection to the British nation which became the foundation of the British Museum...

.