Triphosphatase of Cerebral Microsomes by Surface-Active Agents, especially Polyoxyethylene Ethers: Actions of Phospholipases and a Neuraminidase

sisting of a short length of 8 mm. diam. Visking tubing knotted to form a bag, the open end being secured to a piece of glass tubing by a close-fitting rubber stopper fitted to a test tube with a side arm. The bag, after being washed with distilled water, was equilibrated with a drop of the sample solution; this drop was discarded before evacuating the tube and introducing the rest of the sample. Approx. 0x2 ml. of the ifitrate was collected and diluted for the determination of the ultrafilterable magnesium. It was found necessary to perform the ultrafiltration with the undiluted sample since dilution affects the distribution between the residue and the filtrate. By equilibrating the membrane with the sample to be filtered the capacity ofthe membrane to adsorb Mg2+ ions is decreased.