KEISAR, Mauritius van, Dutch physician, born in Essequibo, Guiana, in 1663; died in Demerara in 1725. He was graduated at the University of Leyden, and was for some time a military surgeon; but his father having died in 169;5 and left him a large estate in Guiana, the son tendered his resignation, and, returning to America, settled in Demerara, where he divided his time between the exercise of his profession and agricultural schemes. He made experiments on his own estate, and urged the adoption of artificial guano. The country greatly benefited by his exertions and his experiments, as he established at his own expense a model farm in which a practical agricultural education was given free to those who were willing to learn. Keisar published many books, some of which are yet standard works. These include "Expose des moyens de mettre en valeur et d'administrer la Guiane" (Amsterdam, 1709); "Notions sur la culture des basses terres dans la Guiane Hollan-daise" (Leyden, 1706); "Land und Leute yon Guiana" (Demerara, 1719)" " Traite du cafe" (Amsterdam, 1720); "Traite du tabac" (1721): "System der Nedaln" (Leipsic and Amsterdam, 1721); and "Grundlage der Pathologic und Thera-pie des Mensehen" (1723).