The Leeuwenhoek Lecture, 1968 - The physiology of an algal nuisance

Abstract

In his letter of 7 September 1674, addressed to Mr Oldenburg, Leeuwenhoek wrote as follows: About two Leagues from this Town [Delft] there lyes an Inland-Sea, called Berkelse-Lake, whose bottom in many places is very moorish. This water is in Winter very clear, but about the beginning or in the midst of Summer it grows whitish, and there are then small green clouds permeating it, which the Country-men, dwelling near it, say is caused from the Dews then falling, and call it Honey-Dew . This water is abounding in Fish, which is very good and savoury. Passing lately over this Sea at a time, when it blew a fresh gale of wind, and observing the water as above described, I took up some of it in a Glass-vessel which having view’d the next day, I found moving in it several Earthy particles, and some green streaks, spirally ranged, after the manner of the Copper or Tin-worms, used by Distillers to cool their distilled waters; and the whole compass of each of these streaks was about the thickness of a man’s hair on his head.