legislative presumption

That a legislative presumption of one fact from evidence of another may not constitute a denial of due process of law or a denial of the equal protection of the law it is only essential that there shall be some rational connection between the fact provided and the ultimate fact presumed, and that the inference of one fact from proof of another shall not be so unreasonable as to be a purely arbitrary mandate. So, also, it must not, under a guise of regulating the presentation of evidence, operate to preclude the party from the right to present his defense to the main fact thus presumed