1. Intravenous injections of India ink into guinea pigs caused a decided drop in the complement titer which set in as early as 15 minutes after the injection, but did not reach its maximum for 3 hours. This drop was followed by a return to normal within the first 24 hours following the injection.
2. India ink mixed in vitro with guinea pig serum adsorbs the complement almost immediately to its full extent.
3. By means of reduction tests (methylene blue and nitroanthraquinone) it was shown that the respiration of the cells of the liver and spleen of guinea pigs was markedly impaired for the first 8 hours, following an intravenous injection of ink. Evidences of a return to normal functional vitality, however, became apparent by the end of the 1st day after the injection.