[The concept of Julius Cohnheim on tumor formation and metastasis from the viewpoint of new research results].

Study of Cohnheim's work reveals the substantial contribution which he made to the understanding of neoplastic disease. He was the first to make a clear distinction between true neoplasma and lesions resembling it. He distinguished between epithelial and mesenchymal tumors. His theory of the proliferation of developmental tissue rests contributed to the understanding of tumor etiology and pathogenesis. In contrast to the majority of his contemporaries he correctly interpreted the process of metastasis. His greatest error was his rejection of the theory of irritation promulgated by his teacher Virchow.