“ec 
182 LEEUWENHOEK AND HIS “ LITTLE ANIMALS” 
Hooke, who succeeded Oldenburg in 1677 as Secretary, 
himself repeated the experiments with pepper-water and other 
infusions. In 1678 he published’ some account of his obser- 
vations, which confirmed Leeuwenhoek’s findings: and his 
experiments were also briefly communicated to Leeuwenhoek 
by letter at the end of 1677. Hooke’s published description 
records that he succeeded in seeing the animalcules—-or some 
like them—described by Leeuwenhoek: “some of these,” he 
says, “so exceeding small, that millions of millions might be 
contained in one drop of water.”* A draft of Hooke’s unpub- 
lished letter is still in possession of the Royal Society; and as 
it contains several points of interest J will now give it. He 
wrote °: 
The papers you directed to the Lord Brouncker* were 
read at a full meeting of the Royall Society and very 
kindly accepted by the Members thereof and they have 
orderd me to returne you both their thanks for soe freely 
communicating your observations, and also an account 
of what hath been here done in order to verify your 
observation concerning the small animalls you have first 
discovered in Pepper-water. 
Having steeped then in Raine water pepper wheat 
most modern Fellows—that Bacon, whose writings had so profound an 
influence upon the Society at its inception, had emphasized the need of 
inquiry into the various substances which produce animalcules by putre- 
faction. Cf. Nov. Org., Lib. II, cap.50: “Etiam materiae diversae putre- 
factionum, unde animalcula generantur, notandae sunt.” 
* See Lectures and Collections made by Robert Hooke (1678). Part II, 
Microscopium. Also reprinted in Lectiones Cutlerianae (1679). 
* Ibid., p.83. Hooke evidently refers to bacteria—not protozoa. 
* MS. letter (unpublished)—R. Hooke to Leeuwenhoek, Dec. 1 [?— date 
partly obliterated], 1677. Roy.Soc.MSS. The original is in English, and 
I give it exactly as written—only omitting a part at the end which has no 
bearing upon the subject under consideration. I have merely expanded 
words which are contracted in the original—for the reader's convenience, 
and for typographical reasons. The letter is in Hooke’s own hand, and is 
signed “ your very great admirer and honorer R.H.” 
* William, second Viscount Brouncker (1620 ?—1684)—an Irish peer. 
He was M.D. (Oxford) and a mathematician, and an original Fellow and 
first President of the Royal Society on its re-foundation in 1662-3. 
