On this subject of Antipodean leaves some valuable researches have come to a happy conclusion, partly as the result of the Whipsnade experiment. Our zoologists have discovered exactly which trees and bushes native to England supply overseas animals with the vitamins necessary to their health. Hawthorn, for example—whose leaves are often eaten by our village school children—is agreeable, I believe, to the constitution of the wallaby (which enjoys also puppy biscuits). But it is in problems regarding the breeding of animals that Whipsnadc will make the most useful contri- butions. A certain number of creatures in captivity cease to he effectively fertile, often for reasons that are not a little obscure. Vitality is easily depressed, even in apparently vigorous and healthy bodies. Even if fertile eggs are laid or young born, the offspring may need some food or some conditions whose essential attributes it is not easy to discover. Happily there is already good reason to hope that the pleasant healthiness of the air of this incom- parable Down in Bedfordshire may supply the zest of freedom which tends to productivity. Incidentally, if some of the more precious animals, and birds, breed as well as is hoped, the fertility may prove a source of considerable gain to the establishment.