The Royal Society published Leeuwenhoek's letter of October 9, 1676, reporting microbes in infusions

March 25, 1677

A long extract from the letter written on October 9, 1676, reporting observations of microbes in spice infusions, was published in Philosophical Transactions, vol. 12, no. 133. Oldenburg translated it himself, but included less than half of the original. In retrospect, we see this as Leeuwenhoek's most important publication because it introduced the microscopic world.

Volume 12 number 135 is dated January 1, 1677. The other nine numbers, 133, 134, 136-142, are dated March 25. It is doubtful that that were all issued at once. Also, the first number of volume 13 was not published until January 1683, six years later. If indeed it was published in March, then it was published around the time Grew was failing to reproduce Leeuwenhoek's findings of microbes in infusions and six months before Hooke succeeded.