Abstract
A vegetable named chinese yam is mainly eaten raw in Oriental countries. It contains numerous needle crystals of calcium oxalate as well as large amounts of certain viscous substances, both being the main cause of skin-itching. Furthermore, this needle crystal is not soluble in hot water, but is soluble in 0.5% hydrochloric acid solution. This acid concentration is the same as that of normal gastric juice. According to the standard tables of food composition in Japan, the chinese yam cantains much calcium. The present analyses show that two-thirds of the total calcium contents in this yam are in the form of needle crystal.
