The water-supply for the occupants of our huge prehistoric “camps” has always been somewhat of a mystery, and it has been suggested that they were only temporary refuges... But the watering of men and animals on the scale indicated by the areas enclosed would be a formidable task even for a day, and other explanations must be sought. The late General Pitt-Rivers, for example, held that the water-level of the combes was higher then than now, and streams would have been plentiful on the slopes; but, feeling the inadequacy of this view, he also had recourse to the dew-pond theory... An exposed position innocent of springs was selected, and straw or some other non-conductor of heat spread over the hollowed surface. This was next covered with a thick layer of well puddled clay, which was closely strewn with stones. The pond would gradually fill, and provide a constant supply of pure water, due to condensation during the night of the warm, moist air from the ground on the surface of the cold clay... Some ponds of this kind, no doubt of very early and perhaps of Neolithic date, may still be seen in working order.

From Nature 27 April 1905.


In 1949 Burnet and Fenner postulated that antibody production against a particular antigen can be specifically suppressed by exposure to the same antigen during embryonic life... The decisive step which brought the principle of immunological tolerance from the sphere of Nature's eccentricity into the domain of an experimental method of possibly very wide applicability was the artificial production of a similar type of tolerance... The present investigations were carried out on birds by the method devised by Billingham, Brent and Medawar, and had a threefold purpose: (1) investigation of whether tolerance could be acquired to cells of foreign species; (2) if so, whether the tolerance would also extend to a virus from the donor animal to which the recipient was not normally susceptible; (3) whether a sexual cross between species which is not normally possible could be made so by means of acquired tolerance. Positive answers to the first two questions have been obtained; the answer to the third awaits the sexual maturation of the treated birds.

Morten Simonsen

From Nature 30 April 1955.