Cytological examination of Leeuwenhoek's first microbial specimens

Of the nine packets of specimens sent by van Leeuwenhoek to London in the seventeenth century, and which were recently rediscovered in their original condition, three contained dried aquatic microorganisms. The author has reconstituted portions of this material. Several recognizable organisms have been noted, including portions of this material. Several recognizable organisms have been noted, including water-fleas, chlorophyte and cyanophyte algae, desmids, diatoms and rotifers. These provide evidence for the formation of the 'heavenly paper', which was believed at the time to represent charred notepaper dropped from the skies, but which Leeuwenhoek rightly assumed to be dried algal felts. Photomicrographs reveal many cytological details in the material, and this has been correlated with Leeuwenhoek's descriptions, extracted from the original correspondence.