Sir John Lubbock's use of the terms Palaeolithic ("Old Stone Age") and Neolithic ("New Stone Age") were immediately popular. They were applied, however, in two different senses: geologic and anthropologic. In 1867–68 Ernst Haeckel in 20 public lectures in Jena, entitled "General Morphology", to be published in 1870, referred to the Archaeolithic, the Palaeolithic, the Mesolithic and the Caenolithic as periods in geologic history. He could only have got these terms from Hodder Westropp, who took Palaeolithic from Lubbock, invented Mesolithic ("Middle Stone Age") and Caenolithic instead of Lubbock's Neolithic. None of these terms appear anywhere, including the writings of Haeckel, before 1865. Haeckel's use was innovative.