Phospholipids in the Peritrophic Membrane of the Silkworm, Bombyx mori L

The silkworm, Bombyx mori L., possesses a soft colloidal thin membrane, called "Peritrophic membrane", in the alimentary canal. Examination of the peritrophic membrane shows that it consists of a single uniform circumference throughout its length, and under the electron microscope, of a fibrous networ

Courses of Height Growth of Cryptomeria japonica Trees Planted on a Slope : Comparison among the near ridge, the mid-slope and the near bottom in the Tokyo University Forest in Chiba

東京大学千葉演習林において，スギ造林木の樹高生長経過と土壌の理化学性およびスギ針葉の養分濃度との関係を，斜面上部，中部，下部間で比較検討した。老齢林の樹高は，斜面上部から下部にむかうにしたがって高くなる傾向がみられたが，若齢林や幼齢造林地では，上部と下部との樹高差が著しい調査地と大差ない調査地とがみられた。樹幹解析によってえた老齢林2調査地の樹高生長経過は，中，下部では，両調査地ともそれぞれ対応する地位の樹高生長曲線と似ていた。一方，上部では，20～30年生頃までは樹高生長曲線とにた生長経過であるが，その後生長が頭打ちとなる調査地と初期生長はよくないが中～後期にかけてもあまり頭打ちにならない調査地とにわかれた。中～後期にかけて生長が頭打ちであった調査地の土層は薄く，あまり頭打ちのみられなかった調査地の土層は比較的厚かった。それぞれの調査地の初期生長経過のちがいは，それぞれの老齢林を皆伐した後に植栽されたスギ苗木の生長でもみられた。土壌の化学性は，中，下部では，調査地による差が小さかった。上部では，pH値等に違いがみられ，初期生長の良い調査地の土壌は，pH値が6以上と中性にちかく，生長の劣る調査地は，相対的に酸性度の強い土壌であった。土壌の化学性は，位置的に近く，母材の同じ調査地で似ていたことから，母材の違いが影響していると考えられる。幼齢造林地での葉分析の結果，斜面上部，中部，下部で，それぞれ樹高生長のよい調査区ほど，針葉の窒素濃度が高い傾向がみられた。窒素濃度が同程度の場合，中，下部に比べて，上部で生長が劣る傾向がみられた。調査地間での土壌の理化学性の差が小さい斜面中，下部では，樹高生長経過の調査地間での差が小さく，一方，上部では，調査地間で土壌の化学性や土層の厚さ等の差が大きく，それに対応して生育初期や中～後期の樹高生長経過の調査地間の差が大きかった。Differences in course of height growth of Cryptomeria japonica trees planted on a slope were compared among near ridge, mid-slope and near bottom. The study was made in 14 study areas in the Tokyo University Forest in Chiba and causes of the difference were discussed in relation to properties of soil and nutrients contents of needle. In study areas of older stands, the height of Cryptomeria tree increased from ridge to bottom along the slope, while of younger stands and younger plantations before canopy closing, this difference was various, apparent in some cases and not apparent in other cases. On mid-slope and near bottom in the two study areas of older stands, the courses of height growth observed by stem analysis paralleled with the curves in each corresponding site class of the yield table. Near ridge, the height growth followed the yield table until 20-30-yr-old and depressed thereafter in the one area where soil layer was thinner, and the growth was not excellent in early stage but the depression with age was not obvious in the other area where soil layer was thicker. The similar difference in height growth in early stage was seen in seedlings planted on the study areas after clear-cutting of older stands. Differences in chemical properties of soil among the study areas were found near ridge, but was not apparent on mid-slope and near bottom. The height growth was affected by pH of soil, the values higher than 6 resulted in excellent growth and lower values in poor one. The chemical properties of soil depended on bed rock. In each part along the slope, the height growth increased with nitrogen content of needle. In comparison of the same level of nitrogen content, the height growths on mid-slope and near bottom were higher than near ridge. The differences in height growth between on mid-slope and near bottom were smaller reflecting smaller differences in physical and chemical properties of soil among the study areas. But near ridge the course of height growth was various throughout the earlier, middle and later stages resulting from different soil properties among the study areas