that could be achieved with simple non perfusion methods of hypothermic kidney storage. He based his technique on the observation by Keller that the loss of electrolytes from a kidney during storage could be prevented by the use of a storage fluid containing cations in quantities approaching those normally present in cells. In Collins' model, the dogs were well hydrated prior to nephrectomy, and were also given mannitol to induce a diuresis. Phenoxybenzamine, a vasodilator and lysozomal enzyme stabiliser, was injected into the renal artery before nephrectomy. The kidneys were immersed in saline immediately after removal, and perfused through the renal artery with 100-150 mL of a cold electrolyte solution from a height of 100 cm. The kidneys remained in iced saline for the rest of the storage period. The solution used for these successful cold perfusions imitated the electrolyte composition of intracellular fluids by containing large amounts of potassium and magnesium. The solution also contained glucose, heparin, procaine and phenoxybenzamine. The solution's pH was 7.0 at 25 °C. Collins was able to achieve successful 24-hour storage of 6 kidneys, and 30 hour storage of 3 kidneys, with the kidneys functioning immediately after reimplantation, despite immediate contralateral nephrectomies. Collins emphasised the poor results obtained with a Ringer's solution flush, in finding similar results with this management when compared with kidneys treated by surface cooling alone. Liu reported that Collins' solution could give successful 48-hour storage when the solution was modified by the inclusion of amino acids and vitamins. However, Liu performed no control experiments to show that these modifications were crucial. Difficulty was found by other workers in repeating Belzer's successful 72-hour perfusion storage experiments. Woods was able to achieve successful 48-hour storage of 3 out of 6 kidneys when he used the Belzer additives with cryoprecipitated plasma as the perfusate in a hypothermic perfusion system, but he was unable to extend the storage time to 72 hours as Belzer had done. However, Woods later achieved successful 3 and 7 days storage of dog kidneys. Woods had modified Belzer's perfusate by the addition of 250 mg of methyl prednisolone, increased the magnesium sulphate content to 16.2 mEq and the insulin to 320 units. Six of 6 kidneys produced life sustaining function when they were reimplanted after 72 hours storage despite immediate contralateral nephrectomies; 1 of 2 kidneys produced life sustaining function after 96 hours storage, 1 of 2 after 120