Abstract
Interest in and knowledge of the silicon content of animal and vegetable tissues, has existed ever since 1857, when Witting, (1) a German research worker, reported 0.5> silicon dioxide in the ash of a sample of human blood. Ho really thorough work, however was done on the subject until the beginning of the twentieth century. In 1901 Schulz (2) extended the work considerably and determined the content on a variety of animal and vegetable tissues, and collected all the previous data on the subject. In 1917 (3) and in 1918 (4) Gonnerman continued the work of Schulz.