The Leeuwenhoek Lecture, 1966 - Obligate parasitism in fungi

Abstract

It might, at first sight, seem inappropriate for a botanist to give the Leeuwenhoek Lecture. But Leeuwenhoek was a man whose activities were not to be confined by arbitrary academic frontiers, and even the most casual perusal of his letters to the Royal Society discloses a good deal of botanical interest. He made several studies of vascular anatomy, in leaves and woody stems (Leeuwenhoek 1676, 1683) in the course of which he developed a speculative theory of translocation of solutes in plants and gave what is undoubtedly the first account of the formation of tyloses, structures of great contemporary interest to plant pathologists. He made what is probably the first mention of the alga Spirogyra (Leeuwenhoek 1674) and of rust uredospores (Collected Letters, II, 381-395). He also made some interesting observations on duckweeds. He described and illustrated one collection so clearly (Leeuwenhoek 1703) that it can readily be identified as Lemna polyrrhiza L. He was not unaware of the peculiar morphology of the Lemna frond, including the production of new fronds in pockets at the base of older fronds; these embryonic fronds he spoke of as ‘seeds’. With his usual antipathy to any ideas savouring of spontaneous generation he took the opportunity to castigate those ‘common people’ who say ‘that that Green Stuff or Weeds which are observed to drive upon the water spring out of the Ground from under the water’. ‘I could by no means admit of this Assertion, for as often as I have observed the said Green Weeds, I have always found that they are produced from the Seeds of the same kind, as all other Trees and Plants. . . . This being so, those who assert that these Green Weeds spring from under the Earth, ought to be asham’d of their prejudices, seeing as they do proceed from a Seminal Matter as well as other Plants.’