17 



vitiated air which should be expelled from the room requires the 

 introduction of a large quantity of fresh air. For this, a double 

 system of ventilation is necessary, which may be obtained by double 

 openings in the windows, to allow the heated bad air to pass out 

 above and the cool fresh air to come in below. To renew the air in 

 every part of the room, and to avoid a single and often violent cur- 

 rent, there should be more than one window. An open fireplace is 

 the best means of ventilation. When the difference between the 

 external and internal air is slight, or there is no difference at all, arti- 

 ficial means must be used to create a current. Light and frequent 

 fires, or a burning lamp in the fireplace, or a revolving fan, may be 

 used to prevent stagnation of the air. 



Disinfection. — Eight or ten da3^s before introducing the worms into 

 their quarters all the shelves and implements should be washed in a 

 solution of chloride of lime (11 pounds of chloride of lime to 88 quarts 

 of water), or in a solution of sulphate of copper (1 to 100 by weight). 



When everything is in order — tools, perforated paper, material for 

 the worms to spin their cocoons on, etc. , each in its own room — close 

 the doors and windows as tightly as possible and fumigate the rooms 

 with sulphur (11 pounds of sulphur to every 100 cubic yards of space). 

 To fumigate properly, powder the sulphur and place it in an earthen 

 or metallic vessel over a slow fire. The sulphur will gradually melt 

 and take tire. Place it immediatel}^ in the rearing room and leave it, 

 with the doors and windows completely shut, for twenty-four hours. 



Nets should not be exposed to sulphur fumes, for this would soon 

 rot them, but should be washed in a solution of sulphate of copper, and 

 immediately afterwards in plain water. 



Twent3^-four hours after the fumigation the floors should be washed 

 with a solution of chloride of lime or sulphate of copper, and the walls 

 should be whitewashed with lime. 



When dead worms are seen on the shelves, change the beds and create 

 in the rearing room sulphurous gas by burning a pound of sulphur 

 during six hours, or make a strong wood smoke, which is a good disin- 

 fectant and will not harm the worms. 



Precaution having been taken to destroy germs of disease in the 

 rearing room, the new-born worms may now be safely installed there. 



Space Required. — The worms from 1 ounce of eggs should cover at 

 birth 1 square yard. Doubling this space on the fourth day, they 

 would require 2 square yards, and at their change of beds after molt- 

 ing, 1 square yards. By the spacing of the third day of the second 

 age, and the doubling of beds preceding the second molt, they will 

 need for the second age 8 square yards. For the third age 16 square 

 yards will be required; for the fourth age 32 square yards; and for 

 the fifth age 60 square yards. The more space that is accorded to the 

 20838—03 2 



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