Ladies a n d g e n t 1 e m e n, I have the pleasure to welcome you here in Prague in the name of the Czechoslovak Academy of Sciences and to open the Fifth Inter national Colloquium on Soil Zoology. We are very glad that Czecho slovakia was chosen for this important meeting. It is clear to all of us that the soil plays and will play a de cisive part in providing food for the explosive increase of human pop ulation. For this reason we watch with great anxiety the negative influence of human activities on the environment accompanied also by the other destructive intervention into the soil...