Following the previous investigation concerning the change by thawing in L-ascorbic acid content of frozen string beans, studies on histological changes are reported in the present paper.
1) Among four methods of thawing, i. e., thawing in a refrigerator, at room temperature, in microwave oven, and in running water, the least histological damage was observed in the material teawed in refrigerator. There was no appreciable difference in the extent of damage among other three methods.
2) The tissues being susceptible to the damage by thawing are endocarp, outer layer of exocarp and parenchyma around vascular bundle.
3) After thawing the residual L-ascorbic acid was found in spermoderm, and outer part of cotyledon. The result that the damage was slight in the materials thawed in refrigerator coincides with larger amount of residual L-ascorbic acid as shown in the previous chemical study.