Constantijn Huygens wrote Letter L-167 to Leeuwenhoek about root trees

Date: 
December 17, 1685

This letter is known only from its inclusion in Leeuwenhoek's Letter L-199 of 24 August 1688 (Collected Letters, vol. 7 p. 360) 

Document: 

I have never tired of praising your indefatigable assiduity in the investigation of mysteries to which only a few of our Forefathers gave any thought, and which will serve as a light and a spur to many of our descendants, to dig out ever more profound truths. To this end, You, Sir, are nowadays on a fine path, from which you should not lightly deviate; so great is the result of the first start of all things, as You are becoming increasingly aware.

I do not know whether you have ever had any knowledge of the planting of Trees the other way about, so that the roots grow in the air into branches. I refer to Lime Trees. Up to now my Gardeners have not succeeded in achieving this. But my spokesman is far too distinguished to allow me to doubt it. This was, a few years ago, the Elector of Brandenburgh, when he was here with his second Electress, both of whom quite seriously confirmed to me a multitude of experiments with such root-trees that they have in their domain, excelling in breadth beyond the usual plants. My Son Van Zeelhem, having been since then in those parts with His Highness, also declares himself a witness of this.

Your discourses on the plants of Trees and Herbs have reminded me again of this. You might let your thoughts go over it, and reflect how it might be made to correspond to what You may discover in the laws of Nature so widely known to You.