It is difficult to prepare a thin sliced observational sample of a starch-rich plant structure for optical microscopic observation because such plants have high density of starchy particles. To solve this problem, the commonly employed method for observing starch particles has often been to extract them from such starch-rich plants.
In this study, the writer employed a unique technique to prepare 5-micrometer-thick observational samples slicing the structures of various starch-rich food plants. In addition to this specific technique, a carefully-considered method of dyeing and a carefully-selected optical filter were employed to observe the structure of a certain food plant for optical microscopic observation.
Employing such unique techniques and methods, structures of starch particles in various food plants were observed using optical microscopes. In this study, 1,200 morphological samples of starch-rich food plants were observed and around 80 photographs of them were shown. In addition to introducing the photographs taken, morphological classification of the starch particles observed in the study was suggested considering the hilum position of a starch particle with a polarized cross of polarizing microscopic observation. The specific techniques and methods of preparing samples and observation employed in the study were also introduced.
The longest and shortest dimension of each individual starch particle observed in the study was measured. The result of the measurement in order of the longest dimension measured in micro-meters was shown as in following: lotus roots 93, potatoes 87, lily bulbs 54, azuki beans 48, broad beans 48, bananas 48, pinto beans 38, sweet potatoes 31, Chinese yams 29, bulbils 27, arrowhead bulbs 25, ginger roots 22, pumpkins 17, chestnuts 15, peas 14, rice 5, corns 5, soybeans 5, taros 2. This observational study of starch particles was also conducted in heated condition.
As an additional comment to the study, because the starch particles of taros are the smallest ones, observations of a starch particle were possible only when the structures were sliced into 2 micro-meters thick.

著者追加指定部分あり：
p2 右列14～15行目”使用するパラフィンの融点は58℃前後。”に下記の一文を追加。”53℃前後が適している場合もある。”