[buller] presidential ADDRESS 7 



of Yeast cells/ Volvox, Haematococcus, Polytoma, and other unicel- 

 lular forms of life. He also gave the first description of spermatozoa 

 which had been demonstrated to him by a physician named Hamm. 

 In 1683, in a letter to the Royal Society, he announced the discovery 

 of Bacteria which he had found when examining the white fur taken 

 from his own teeth.^ His microscopes were simply double-convex 

 lenses which gave various degrees of magnification. The high powers, 

 owing to loss of light, could only be successfully employed when the 

 object was transparent and directly illuminated by the sun. Medium 

 powers gave the best results. Since microscopes had become good 

 enough to detect even the smallest kinds of living organisms, it was 

 not the fault of instruments that the spores of Hymenomycetes, such 

 as the Mushroom, and of fungi generally, remained unknown at this 

 time. 



Tournefort, in 1707, in his admirable account of the culture of 

 Mushrooms in artificial beds, definitely ascribed the origin of these 

 fungi to seeds. It is true that he failed to understand the function 

 of the lamellœ which he called the leaves of the fungus, and was also 

 compelled to confess that Mushrooms "possess neither flowers nor 

 observable seeds"; but several times he intimated his belief in micro- 

 scopic reproductive bodies. In one place, after describing the my- 

 celium which he pointed out gives rise to young Mushrooms, he says: 

 "According to appearances these white threads are nothing but 

 developed seeds or germs of Mushrooms and all these germs may be 

 enclosed in so small a space that one can only perceive them, however 

 much care one may take, after they have grown out into little hairs." 



Another Frenchman whose name is not recorded, showed in a 

 report to the French Academy upon Tournefort's memoir on 

 Mushrooms, that he had perfectly correct ideas about the invisible 

 reproductive bodies of fungi, although, like Tournefort, he evidently 

 considered that they had not yet been observed.^ His scientific 

 imagination which had been excited by the discovery with the 

 microscope of the spores of Ferns a few years before, enabled 

 him to see the vast hosts of fungus spores which we now know 

 are scattered in the most wonderful profusion everywhere in 



1 Leeuwenhoek, Arcana Naturae détecta (1680), Vol. II, pp. 1-14. He discover- 

 ed that the Yeast cells give off bubbles of gas in fermenting wort. Cited from Miall 

 pp. 219-220. 



2 Leeuwenhoek, Phil. Trans. Roy. Soc, No. 159 (1684); also Arcana Naturae' 

 détecta (1683). Cited from Miall, p. 220. Cf. Hoole's Translation, p. 118. 



^ Tournefort, Observations sur la naissance et sur la culture des Champignons, 

 Mém. Acad. Sci. de Paris, 1707, p. 61. 



* An anonymous Frenchman, Sur les Champignons, Histoire de l'Acad. Roy des 

 Sci., 1707, pp. 46-49. The writers of the Histoire all wrote anonymously. 



