The enzymatic and/or non-enzymatic methylation / hydroxymethylation of main trace elements renders a special, indispensable bridge between biological (organic) and inorganic world. These modified trace elements are potential formaldehyde (HCHO) generators and HCHO formed from them can participate in different characteristic interactions. On the basis of up-to-date biochemical results with HCHO it is supposed that trace elements as HCHO carriers transport HCHO molecules in dose-dependent level to different points of a given biological unit. On the basis of experiences with the time- and dose-dependent double immune response of plants to pathogens, a logical step was to extend it to the total Avogadro number range (in vivo conditions) in the case of trace elements as potential inducers as well. These new findings support that HCHO and its reaction products (mainly O3) as drastic molecules are responsible for the immunostimulating activity of trace elements as inducers. It is especially important that there are always four bioequivalent immunostimulating activity ranges in plants for the pretreatment with different doses of trace elements similar to organic compounds. It has to be noted that the trace elements as inducers actually don’t participate directly in the induction of the immunostimulating effect similar to organic inducers