5℃または-5℃の低温塩酸による蚕卵の人工孵化について

In the routine method of artificial hatching of silkworm eggs, eggs 20 hours after laying are immersed in hydrochloric acid (specific gravity is 1.075) for about 5 minutes at 46°C.<br>In this paper two experiments on the artificial hatching by using hydrochloric acid at low temperature (-5°C or 5°C) are reported.<br>In the first experiment, eggs of Nichi 122, Nichi 124, Shi 122 and Shi 124 (all of them laid in July) were used as materials, and in the second experiment, eggs of (Nichi 122×Nichi 124)×(Shi 115×Shi 124).<br>Artificial hatching treatment was applied to the eggs 18 hours after laying, and after the treatment, the eggs were incubated at 25°C. The results obtained were as follows.<br>1. First experiment. By immersing the eggs in the hydrochloric acid (specific gravity, 1.100) for 12 hours at 5°C, more than 90% of them hatched. But when the time of immersing was so long as 24 or 36 hours, the percentage of hatching decreased, and in the case of 36 hours, the percentage of hatching was so low as 60-71%.<br>2. Second experiment. Eggs were immersed in the hydrochloric acid (specific gravity, 1.100 or 1.130) at -5°C or 5°C, and good results were obtained in the following cases. In the case of specific gravity of hydrochloric acid being 1.100, the time of immersing being 75 hours, and the temperature being -5°C, the percentage of hatching was 90.3%; in the case of the same specific gravity, but a time of immersing of 15 hours and a temperature of 5°C, the percentage of hatching was 93.4%; in the case of specific gravity being 1.130, a time of immersing of 4-10 hours, and a temperature of -5°C, the percentage of hatching was between 94.4% and 96.4%; in the case of the same specific gravity, and an immersion period of 3-4 hours, and a temperature of 5°C, the percentage of hatching was between 96.0 and 97.5%.