(1) The strongest part of the angling line made . from the silk gland of the domestic silkworm is that which corresponds to the middle part of the middle division of the silk gland, showing about 2.5 kg in strength and about 15 % in elongation. The part produced from the posterior part of the middle division shows the strength and elongation of 2.0 kg and about 14 % respectively. The tendrilled portion which is produced from the curved part of the middle division is very weak, its strength being less than 1 kg and about 6 % in elongation. (2) Since the coarse line have very rough surface, owing to the gland cell remains and sericin covering, it must be scoured for practical use. The scoured line consists of the fibroin only and is transparent. After polishing it is called the polished line which is more uniform in fineness and stronger in strength per denier. (3) In wet condition the line decreases the strength of 30 %, and increases elongation of 22 %, compared to those in dry condition. The rate of water absorption of the line is about 30 %. (4) Comparing with the line from the wild fish-line silkworm (Eriogyna pyretorum Westwood) (Saturniidae) and the chemical line (Amylan), the line from the domestic silkworm is excellent in dry condition but not always in wet condition; that is, the effect of submersion is more remarkable in the domestic silkworm line than in the ordinary natural fish-line. Although the chemical line shows very large elongation, it is the strongest in wet condition and it has many advantages for practical use.
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