Types of hatching under various light conditions; 8L-8D, 12L-12D and 24L-24D, were investigated. The hatching mechanism was studied with the embryo in the silkworm egg at the body pigmentation stage. The hatching mode depended on the length of the scotophase inserted during the light phase after complete embryonic development. For the 12L-12D or 12D-12L regimen, the hatching could be divided into two fundamental types according to the positions of light and darkness during the embryonic developmental stage; one regimen produced a hatching curve with one peak and the other a curve with two peaks. The scotophase had to be continued for 6 hr to activate the effective response for hatching. Egg shell eating by hatching larva was induced by a switch-on after the completion of the effective response for hatching. Stimulation also might be necessary before the silkworm will leave the shell. The effect of light conditions on hatching is discussed.

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An analytical solution for bed-soil temperature was obtained from a theoretical analysis of the heat transfer system in a double-roofed greenhouse sprayed with well water between the roofing layers in which heat transfer characteristics were considered to be constant at night. Therefore, the bed-soil tempera-ture in the double-roofed greenhouse in which the evening bed-soil temperature distribution is known can be obtained from the temperatures of the im-mediate surroundings, the sky and the spray of water. The heat flux density in the bed soil then can be obtained from the solution. Temperatures for the aboveground part of the greenhouse at vari-ous points can be obtained by substituting the solu-tion for the bedsoil temperature for the solution obtained in a previous paper.
The solution for the bed-soil temperature is represented by the sum of the temperatures contributed by the initial bed-soil temperature distribution; the temperatures of the immediate surroundings, the sky and the spray of water. Temperatures contributed by each environmental factor are expressed by the product of their native contribution and weighting factors. The weighting factor for each environmental factorr was determined entirely by the heat transfer mechanism for the aboveground part of the green-house. Only one greenhouse heat transfer parameter existed for native contribution, that was a comprehensive time constant for soil surface temperature, T_so, defined by ρcK/g²_so, in which ρc is the specific heat of the bed soil in volume, K is the heat conductivity of the bed soil and g_so is the overall heat transfer coefficient for the bed-soil surface in Eq. (7) .
The temperature contributed by the initial bed-soil temperature is expressed by the total sum of the products of the initial bed-soil temperature distribution and weighting factors that were functions of depth and elapsed time. The greenhouse heat transfer parameters in these weighting factors were T_so and the equivalent soil thickness, l, that was defined by K/g_so.
T_so determines the time scale of the bed-soil temperature change. The larger the T_so, the slower the change in speed of the bed-soil surface temperature. Thus, the better the warmth-retaining property of the greenhouse. With a large l, the temperature contributed by the deep soil was relatively large for greenhouses with the same T_so values.

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Japanese Society of Environment Control in Biology has been promoted the studies on the bio-production during a decade particularly focused on the control system of environmental factors. Since (1979) our membership obtained the Special Scientific Research Foundation by Ministry of Education, Science and Culture on the title “A Comparative Agricultural Study of Biological Production in the Tropical and Temperate Regions, ” we arranged a group “Salon-Bioresource” for the coordination of bioresource study to provide against the great population increase. In this paper, Salon member proposed the contemporary problem and new idea particularly for the agricultural production in future.

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