De Graaf was an early investigator of the pancreatic secretion. He collected the pancreatic juice of dogs by means of artificial pancreatic fistulae, commenting on the small quantity of juice secreted and on its alkaline character. The French edition, Paris, 1666, contained a revised and enlarged text. Partial translation in J. F. Fulton, Selected readings in the history of physiology, 2nd ed., 1966, pp. 167-68. Full English translation from 2nd ed. (1671), London, 1676.

Exact and detailed account of the male reproductive system. This work and No. 1209 were translated into English and published as Suppl. 17 to J. Reprod. Fertil, 1972. Facsimile of originals, Nieuwkoop, De Graaf, 1965.

De Graaf demonstrated ovulation anatomically, pathologically and experimentally. In the above work he included the first account of the “Graafian follicle”. Translation of Chapter XII, dealing with the ovaries, by G. W. Corner in Essays in biology in honor of Herbert M. Evans, Berkeley, 1943. Complete English translation of this and No. 1210 by H.D. Jocelyn and B.P. Setchell, J. Reprod. Fertil., Suppl. 17, 1972.