Experimental Production of Tumor I N a White Rat

Ever since the establishment by Virchow of a n etiological theory of cancer due to irritation, cancer investigators have attempted to find a means of producing cancer experimentally by some form of irritation. The first successful results were reported by Yamagiwa and Itchikawa in 1915, using rabbits ,the ears of which were painted with coal-tar every second or third day. In 1918 Tsutsui published the fact that by painting the skin of the interscapular region of mice repeatedly with tar he had succeeded in producing hyperkeratosis, papillomatous growth, and carcinoma. From the report of these experiments, it appears that out of 67 mice surviving more than 100 days after painting with tar was commenced, cutaneous carcinoma developed in 16 animals, and sarcoma in one. Metastatic nodules were found in the lungs of two mice. Since then, Murray and Woglom, Block and Dreifuss, Roussy, Deelman, Fibiger and Bang, Caspari, Teutschlander, and Lipschutz have repeated this experiment with essentially the same results. An investigation, recently undertaken by H. Jordan in the pathological laboratory of Teutschlander in Heidelberg, demonstrated that with Gasworks' tar it is possible to produce almost 100 per cent. carcinoma in white laboratory mice which survive the painting for four months. He also found that the specific agent that produced the precancerous warts seems to be contained in the sediment of coal-tar distilled a t 400 degrees C. When this sediment is used for painting, results are obtained in one-half the time it takes for full tar. For painting, coal-tar was used.