(1696) I got no other answer but that when the Wheat , as it stands on the Stalk , is Ripe or nearly ripe , and the Wheat grains then , instead of a white floury substance , Combating the disease .contain only a black substance , we call that smutted Wheat , and that , in order to prevent this , before the Wheat is Sown they wash it in a big wooden tank in water and add thereto a substance which one farmer sells to the other as a secret ; others For L .' s ideas about sap transport in plants , see Baas , ‘ Leeuwenhoek ' s contributions to wood anatomy and sap transport ’ .