To study the functions of an organ under well-controlled conditions frequently necessitates its removal from the body in order to avoid influences reaching it from other tissues, which it may not be easy to control. It is difficult, however, to maintain the isolated organ in a condition even approximating the normal. One of the greatest advances was made by Knowlton and Starling in 1912, with the introduction of the ‘heart-lung preparation’. This consists of the lungs artificially ventilated and heart of an animal, and pumps oxygenated defibrinated blood round an artificial circuit, which may include one or more different organs: the latter are thus perfused with blood under conditions approximating the normal. The preparation, however, only lasts for a few hours. It is reported in The Times of June 22 that Dr. Alexis Carrel and Colonel C. A. Lindbergh, the well-known American airman, have devised, at the Rockefeller Institute for Medical Research, New York, an apparatus by means of which isolated organs can be kept alive, even growing, for prolonged periods.