There are a few papers reporting the rearing of the silkworm entirely on artificial diets, containing dried mulberry leaf powder at high concentrations such as 50% or higher than this. The present author has subsequently clarified several nutritive substances for the silkworm (ITO, 1961 a, b, c) and established physical conditions of diets required for better nutrition or feeding (ITO, HORIE, and TANAKA, 1961), by the use of artificial diets containing 10% leaf powder. On the basis of those findings, the rearing on artificial diets containing 10% leaf powder through all instars became possible (ITO, 1961 c). However, it has still been felt that further improvement is necessary possibly by reducing the amount of leaf powder until zero per cent or by replacing it with pure compounds.Recently an entire rearing on semi-synthetic diets, which did not include any leaf powder at all, was achieved. Though some improvement on such semi-synthetic diets is of course necessary, a short account about this will be made in the present paper.
The composition of semi-synthetic diets used for the present purpose is represented in Table 1. In formulating diets, previous results on nutritional requirements established already, not only qualitatively but also quantitatively, were taken into consideration. The methods of the preparation of diets and of rearing of larvae were similar to those previously described (ITO, 1961 a). Silkworm race was (J112×C110)×Daizo (the last one is multi-voltine race). The larvae were reared by means of Petri dish at 25°C throughout all instars.
The result of rearing is shown in Table 2. With diet A many larvae died by starvation in a few days after hatching and only 13 larvae survived after 7 days out of 40 newly hatched ones. Six larvae reached the fifth instar, two died during in this instar, and remaining four larvae made an extra molting to reach the 6th instar. Finally, one 6th instar larva started spinning after 40-day rearing and two larvae after 41-day rearing.
When diet B, the composition of which is somewhat different from that of diet A, was used, the larval development was recorded after 3-day rearing from hatching, considering a high mortality of newly hatched larvae caused by starvation. Larval development was much improved on diet B and one larva, not 6th but 5th instar, started spinning after 27-day rearing. The mortality by the end of the 4th instar was rather low, but some larvae died during the 5th instar.
Cocoons obtained were very white in color, since the diets did not contain any pigment precursors from mulberry leaves. However, the pigments contained in soybean casein and oil might color cocoons very faintly.
The result shown here is one of the instances of the rearing of the silkworm on semi-synthetic diets, and the rearing on other semi-synthetic diets of somewhat different composition has often been successful. The present diets do not contain any attractant so far reported, but some larvae grew well and made cocoons. The inclusion of attractant into semi-synthetic diets has recently been shown not to improve diet efficiency markedly (ITO and HORIE, 1962).
The present diets contained soybean oil, β-sitosterol, and ascorbic acid, all of which had been proved to be highly effective for silkworm nutrition (ITO, 1961 a, b, c), but at the same time it has been proved that all of them are more or less of phagostimulating action for the silkworm. ITo (1960) has previously emphasized the importance of “taste” in the mechanism of feeding reaction of the silkworm, and the present results confirm this obviously. Especially as for β-sitosterol and ascorbic acid, the present author considers them nutrients stimulating feeding simultaneously.

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In the rearing of the silkworm on artificial diets no aseptic method has hitherto been employed. It is, however, necessary to establish aseptic technique for further nutritional studies of this insect in detail. The present paper reports briefly the fact that silkworm larva grown aseptically made cocoon for the first time.
Composition of artificial diet employed is shown in Table 1, which contained 20% dried mulberry leaf powder. Other ingredients were added as to fulfil nutritional and physical requirements of the silkworm, qualitatively and quantitatively. 500ml Erlenmeyer's flask was used for rearing.Artificial diet, previously autoclaved at 100°C and sliced after cooling, was placed in the flask. Subsequently, the flask with cotton plug was autoclaved twice during successive two days, each for 30 minutes at 10 lb. pressure. Silkworm eggs on a paper were immersed in 0.1% HgCl₂ solution for 10 minutes, washed in sterile water, then placed carefully on diet-slices in the flask.
The larvae hatched in the flask, gathered on the diet, started feeding, and continued growth. Growth and development were much inferior to those in the case of non-sterile rearing (by the use of Petri dish). Out of several flasks used, only one larva started spinning cocoon 41 days after hatching (Figures 1 and 2). No other larva was obtained which reached larval maturity. The weight of cocoon layer of this cocoon was 0.106g.
The possibility whether a high temperature such as 115°C exerts deleterious effect on diet efficiency was subsequently tested, using artificial diets containing 8% leaf powder. In this experiment the rearing was carried out non-aseptically for two weeks. As shown in Table 2, it is concluded that no deleterious effect was brought even by such a high temperature as 115°C.
Growth and development in aseptic culture were far inferior to those in non-aseptic culture. The possible reasons for this were considered, and the participation of micro-organisms in the gut in the nutrition of the silkworm was suggested.

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中腸型4角形多角体 (T) ウィルスと6角形多角体 (H) ウィルス間の干渉が, そのウィルスの状態, 宿主の生理的状態あるいは接種する2種のウィルスの相対的な濃度の相違などによってその様相がどのように異なるかについて追究を行なった。
1. 5令起蚕を48時間絶食した場合における2種ウィルス間の干渉現象は, 絶食しなかった幼虫における干渉と差異が認められなかった。
2. 4令期にT浮遊液を接種した幼虫を5令起蚕で低温処理すると, 無処理区よりもT形成個体の発生が多く, その発病率は接種濃度が大なるほど高い。しかしH形成個体および核多角体病発生の傾向はT浮遊液の濃度が低いほど多く逆の関係がみられた。1令期接種5令起蚕低温処理区ではこのような関係はみられない。これは接種時期によって5令起蚕体内に保持されているいわゆる潜在状態にあるウィルスのstateに相違があるためではないかと考えられた。
3. 経口接種する2種のウィルス濃度が異なった場合の干渉について研究し, 両種ウィルス間の干渉はそれらの量的関係においてもそれぞれ異なった表現を示すことを明らかにした。さらに初に接種したウィルスの体内に保持されている状態は殆んど増殖しないいわゆる潜在状態であっても, challengeウィルスの増殖に干渉する場合があることを明らかにした。さらに上記の現象を利用して, 中腸型多角体病の発生を抑えることが可能であろうことを指摘した。

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1) 中腸型多角体病ウイルス (5%多角体浮遊液) は80℃, 10～15分あるいは60℃, 140～160分の処理によって不活化される。
2) 蚕に不活化ウイルスを前もって接種しておくことによって, challengeウイルスによる多角体病発生率を減少させることができることを明らかにした。
3) challengeウイルスの侵入あるいは増殖の抑制における不活化ウイルスの作用機構について考察を行なった。

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1. 家蚕幼虫の脂肪組織を用いてキサンチン脱水素酵素を抽出分離した。
2. 家蚕のキサンチン脱水素酵素の吸収スペクトルは360mμ および405～410mμ に吸収を有し, 405～410mμ の吸収はハイドロサルファイトによって還元される。また差スペクトルにおいてブラビンの特異的吸収 (450mμ) は認められず, フラビンがもし存在するにしてもその量は極めて微量であると考えられる。したがって牛乳等のキサンチン酸化酵素と異なることが判明した。
3. この脱水素酵素には鉄, モリブデンおよびFADが含まれており, その含量比は9: 1:1であり, ニワトリのキサンチン脱水素酵素と似ている。

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家蚕のキサンチン脱水素酵素の基質特異性および阻害剤の影響について検討した.
家蚕のキサンチン脱水素酵素はキサンチン, ヒポキサンチンおよびベンズアルデヒド, 3, 4- ディハイドロオキシベンズアルデヒド, フォルムアルデヒドを酸化することが判明し, 前3者は大略同レベルの酸化を受ける. その他アデニン, グアニン, キサントプテリンおよびAHPを酸化 (脱アミノ) し, とくにグアニン, キサントプテリンならびにAHPの酸化のレベルはキサンチンを基質にした場合より高い.
KCNおよびο-Iodobenzoic acidは家蚕のキサンチン脱水素酵素を阻害するが, ハイドロキシルアミン, アスコルビン酸, ρ-アミノフェノール, キニーネおよびα, α'- Dipyridyl, Antimycin Aによっては阻害を受けないことが明らかとなった.

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家蚕, サク蚕, クス蚕, シンジユ蚕およびヒマ蚕のそれぞれの後部絹糸腺からKIRBYのフェノール法によってRNAを調製し, 塩基組成を分析した。これらのうちで科または種が異なるものはフィブロインのアミノ酸組成が異なるが, RNAの塩基組成にも明らかに差異が認められた。これに対して亜種 (シンジュ蚕, ヒマ蚕) の間ではアミノ酸組成にもまた塩基組成にも差異が殆んど認められなかった。フィブロインのアミノ酸組成と同じく, 後部絹糸腺RNAの塩基組成もまた種特異性を示すようである。これらの絹糸虫類はフィブロインの生合成におけるアミノ酸配列決定機構の解明のために有力な手掛りを与えるであろう。

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本報告には赤渋病と桑品種の関係について記述した。37品種を供試して桑葉および桑条における侵入の難易ならびに病斑の拡大度を検討した結果, 桑葉と桑条とにおける侵入の難易は両者ほぼ平行関係を示し, 露国野桑・赤木・早生十文字・一の瀬・六の丞・柳田・紫早生・伊達市平・福島大葉・島の内・特畑・十島・小幡・鶴田の14品種は本病に対して極めて弱く, 改良一の瀬・剣持などはやや弱く, その他改良鼠返ほか20品種は抵抗性が大であることが判明した。しかし桑樹の生長休止期には罹病・抵抗性に関係なく総ての品種が罹病する。また潜伏期間および病斑形成期間も品種間に差があり, 潜伏期間の短かい品種では病斑形成期間が長く, 病斑も大で病勢も強いが, 潜伏期間の長いものはその反対である。本病の初期感染は桑葉では7葉位迄, 桑条では先端緑色部に限られ, 桑の系統間には差を認められない。病原菌の初期侵入過程の病理学的意義として三叉状体の形成を桑品種との関連において論じた。すなわち三叉状体の形成如何が, 罹病性の大小決定または拡大勢力に関係するものと考えられる。しかし本病の環境条件に対して感受性の大きいという特性からみて, 本菌に対する罹病性あるいは抵抗性は寄主体組織内の化学的あるいは生化学的要因の如何によるものと推量される。
終りにのぞみ懇切なるご校閲を賜わった農林省蚕糸試験場青木清博士, 福島県蚕業試験場会津支場長斎藤円蔵氏ならびに実験に協力賜わった福島県蚕業試験場原町支場太田輝夫研究員, 森昌洋氏に深謝の意を表する。

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The authors succeeded in feeding the silkworm, Bombyx mori L., on elm leaves (Ulmus pumila, LINN.) throughout the larval life from beginning to end, though the larval life was prolonged accompanied with high mortality. Cocoons of the elm-fed larvae were poorer in shape than those of mulberry-fed larvae.
It is said that the appearance of 3-molters in 4-molting strains is often induced in favorable nutritional conditions and, on the contrary, that of 5-molters in unfavorable conditions. But this rule does not apply to the present case, because many 3- and 5-molters appeared in the same lot of 4-molting silkworms fed on elm leaves.
Two female and five male moths emerged from the cocoons of 3-molters and one male moth from the cocoons of 4-molters. One of these two female moths laid only one fertilized egg being mated with a normal male which was fed on mulberry leaves, and the other no egg, both of them containing no other eggs in their ovaries. All of the six male moths emerged from cocoons of elm-fed larvae were fertile when mated with normal females.

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全ての絹織物に今やwash and wearを
生糸糸条の繊度測定用差動滑車型の感応要素の理論について
蚕繭の形状と繰糸能力および繭形の分析研究について

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