the inclusion of grass as part of crop rotation, may have a beneficial effect. Grassland has been shown to have a higher density of earthworms than arable land, probably because more organic matter is available for food in the former. Adding organic manure may improve populations, and the effect of healthy earthworm populations on crop yields is such that worms are being bred commercially for this purpose (2). Research is being carried out into a number of other uses for earthworms. Experiments are in progress to determine ways in which they can be most efficiently used for disposal of organic waste, either producing a useful fertilizer, or the worm crop itself being used as a source of protein. Worm meal has a high protein content (58-71 per cent on a dry-weight basis), competing well with meat or fish meal in experimental trials, and there is good reason to believe that it will become an important component in commercial feeds for intensive livestock industries and fish culture (8). The bait market is another major consumer of earthworms. For example, huge quantities (all introduced species) are exported from Canada to the U.S.A. each year for this purpose, the worms having been collected at night from golf courses and sports fields (30). Vermiculture is big business in several countries. The Japanese are currently the foremost earthworm producers with the U.S.A. second and the Philippines third (8). Farms in the U.S.A produce as many as 05 million worms per day (2). Lumbricids are cultured in the more northerly states of the U.S.A. and the peregrine African earthworm Eudrilus eugeniae (Eudrilidae), the African Night-crawler, is cultured in the southern states. The potential of worms as human food is also being investigated (some people, such as the Australian aborigines (28) and the Paris in New Zealand, have traditionally made use of earthworms in this way) but worms are unlikely to become important in this way for many years (8). By contrast the Palolo Worm has long been important in Samoa. The spawning period is awaited with great expectancy, and as the epitome rise to the ocean surface they are scooped up in armfuls. The epitome also provide food for fish, birds and other predators (1). Many annelids contain compounds of value to man. Earthworms could prove to be a source of new drugs and new species should be studied with this in mind. Folk medicine in several countries has prescribed earthworms for a variety of ailments including jaundice, smallpox, haemorrhoids and rheumatism. More recently earthworm extracts have been shown to have an antipyretic activity that could be made use of in medicine. Some earthworms have a bioluminescence reaction which is dependent on peroxide and can be used as a clinical test for this substance (26). However, as yet there is no substantial evidence to suggest that earthworms could make any significant contribution to human or animal medicine, although the supposed rheumatism curing properties may be worth investigating (8). The use of the leech in medicine is well known, and current work on the Medicinal Leech Hirudo medicinalis is discussed in the data sheet. Haementeria ghilianii from French Guiana, the largest leech in the world, may prove to be the most important species in research on account of its easily dissected and simple nervous system, the extracts that can be obtained from it which have potential medicinal applications, and its large eggs which permit embryological studies, unlike those of the Medicinal Leech. It is now bred in large numbers in Berkeley, California (17). The polychaete Lumbrineris brevicirra produces a toxin in its integument which has been used in the development of an insectide, effective against pests such ais Colorado Beetle, Mexican Bean Beetle and insect strains resistant to organophosphates and organochlorides. It is also reported to be essentially nontoxic to warm-blooded animals and decomposes fairly rapidly in biological tissues and the natural environment (29). Aquatic oligochaetes play a major role in the retrieval of organic matter from the sediments of lakes and rivers. Leeches and aquatic oligochaetes have been considered as potential indicators of pollution, but many species that are an obvious feature of polluted waters also occur in clean habitats and there appears 199