The breeding conditions of Lymnaea ollula, the vector snail of the common liver-fluke of cattle Fasciola hepatica, were examined. 1) As containers, Petri dishes of about 24 cm in diameter were applied, filled with water to a depth of 1.5-2.0 cm. Water was renewed twice a week. Water temperature was regulated at about 24℃. In these conditions the adequate number of the snails for rearing was 10 or so in a dish. 2) City water, allowed to stand for a few days, was adequately used for rearing. 3) It was unnecessary for the snails to aerate the water or to prepare a wet resting place above the water surface especially. 4) Soil was a better diet for the snails than Chlorella and fine rice powder supplied twice a week. So, it was assumed that the snails had little digestive ability and could not digest the latter diets enough to maintain their lives. The result suggests that such easily digestible diets as some materials in the soil are necessary for them. Furthemore a simple rearing technic of the snail was devised. City water was available for the rearing of the snails after being boiled for about 30 minutes in a kettle, as well as the water allowed to stand for a few days. In the present experiments the boiled water was used. The container was incubated at an adequate temperature for a day after being filled with the water 1 to 2 cm in depth and added with Meiji Maimeal, a weaning food manufactured by Meiji Nyugyo Co. Then the snails were introduced into it At every renewal of water were needed those preparations. As a light source, a daylight color fluorescent lamp was used at 60 cm distant from the container, but it was not needed especially for the rearing of the snails. The renewal of water and supplying of food were done twice a week at a water temperature of 26±1℃., but once or twice at lower temperature. The life span of the snail was about 10 weeks at 26±1℃., when it was reared in the boiled water with the weaning food.

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