. The culture of the mulberry silkworm. Silkworms. HATCHING SILKWORM EGGS. If) 0 r 1 ^ 1 ^ ts> From the fourth day on, gradually increase the temperature two degrees in twenty-four hours until 7:j> F. is reached, when, at this uniform temperature, hatchings will occur in ten days on an average. This period, however, varies from eight to fifteen day-, according to race, the cold supported during the winter, the first grade of heat, and the highest during the incubation, and the number of days taken to pass through these two grades of heat; and also according to the humidity. To obtain a g
. The culture of the mulberry silkworm. Silkworms. HATCHING SILKWORM EGGS. If) 0 r 1 ^ 1 ^ ts> From the fourth day on, gradually increase the temperature two degrees in twenty-four hours until 7:j> F. is reached, when, at this uniform temperature, hatchings will occur in ten days on an average. This period, however, varies from eight to fifteen day-, according to race, the cold supported during the winter, the first grade of heat, and the highest during the incubation, and the number of days taken to pass through these two grades of heat; and also according to the humidity. To obtain a good and complete hatching, a slight humidity is necessary, especially during the last four or five days. To secure this keep an open vessel of water near the fire, or sprinkle the floor with water occasionally. The temperature may be raised during the hatching to75° F., but sudden changes of heat must be avoided, and, unless the newborn worms can be kept in the same temperature, it is dangerous to have the maximum temperature of the incubator so high. It is better for the period of incubation to be protracted than suddenly short- ened. Holding the egg^ at a certain tem- perature, or slowly lowering the temper- ature a little does no harm. When the season is not propitious, the hatching may in this way be retarded. An incubating room is preferable, be- cause it also serves for the first two stages of the worms, but in small rearings an incubator is more economical, both with regard to service and to fuel. For a large quantity of eggs (5 to 1 ounces) a small incubator, which is very much used in chemical laboratories to dry substances, is recommended. Any ordinary tinsmith can make it. It consists o( a double case, cubical in form, with a zinc bottom. The space between the outer and inner walls is filled with water. The front face4 of the cube is furnished with a glass, so that the temperature within, indicated by the thermometer hanging on tin1 glass, may he seen with- out the
Size: 1591px × 1571px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectsilkworms, bookyear19
