Our experiments comprised the third series in a study, still in progress, of the toxicology of rare elements.1 They were twenty-seven in number, and were performed on as many animals (frogs, mice, dogs). They were carried out before Baskerville's announcement of his discovery that thorium contains two new elements, named by him berzelium and carolinium. Publication of our results was deferred because of our desire and intention to complete the work with a study of the toxicological effects of these two new elements, which Professor Baskerville has generously agreed to furnish at a later stage in his investigations. The foregoing communication by Professor Sollmann has induced us, however, to present our results as they stand.In some of the early experiments (1900) it was found that thorium (nitrate) had a uniform precipitative effect on various connective tissue mucoids. In a study with Professor Loeb (1902), on the antitoxic influence of ions, thorium (nitrate) was used as a tetravalent element, and was ...