VARIOUS root diseases which cause serious loss in crops of cacao, coffee, limes, and arrowroot in the West Indies have been investigated by Mr. W. Nowell, whose conclusions are published in the West Indian Bulletin (vol. xvi., No. i). In all cases the roots are attacked by the mycelium of species of Rosellinia, a cosmopolitan genus of fungi which has long been known to include several parasitic species. In most cases the source of infection has proved to be either the forest stumps left to decay when the land was originally cleared, or, in the case of cacao, the stumps of shade trees, such as bread fruit and avocado pear. The fungus establishes itself on the dead stumps as a. saprophyte, and from these the mycelium spreads to the healthy roots of the crop. The general conditions which favour the spread of the parasites and the most suitable methods of isolating the infected area and controlling the disease are carefully discussed.