Letter, from Antoni van Leeuwenhoek to John Somers, dated at Delft Signed autograph Observations of the sperm of young cocks; life span of these spermatozoa to fertilise a hen's egg No original figures attached Read to the Royal Society on 7 January 1702 English translation see EL/L3/39 Covering letter EL/L3/37 Transcribed in JBO/10/236 Transcribed and translated in 'Alle de brieven van Antoni van Leeuwenhoek', edited, illustrated and annotated by Committee of Dutch Scientists, vol 14, p 35 English translation printed in 'Philosophical Transactions', vol 23, no 279, p 1137 6 December 1701