19. (1) No person shall publish or cause to be published, an advertisement (not being a label referred to in section 18) which falsely describes any article of food or is otherwise calculated to mislead the public as to its nature, substance or quality. (2) In any prosecution under this section, it shall be a defence for the accused to prove either- (a) that he did not know, and could not with reasonable diligence have ascertained that the advertisement was of such a character as aforesaid; or (b) that, being a person whose business it is to publish or arrange for the publication of advertisements, he received the advertisement for publication in the ordinary course of business. (3) In any prosecution under this section against the manufacturer or the seller, the Court shall, until the contrary is proved, presume that such advertisement was published or caused to be published by such manufacturer or seller as the case may be.