A classification of skin diseases upon the basis of their clinical appearance. Until the time of Willan, von Plenck’s book was the greatest authority on dermatology. He mentioned 115 different skin diseases, all that were known at that time, and divided them into 14 classes.

Plenck provided the first classification of poisons based on origin: 1. Animal poisons. 2. Vegetable poisons. 3. Mineral poisons. 4. Poisonous vapors, gases, and dust. Plenck also issued this work in German from the same publisher during the same year as Toxikologie oder Lehre von den Giften und Gegengiften. Digital facsimile of the Latin edition from Biodiversity Heritage Library at this link.