16 



repeated daily during the hatching, the second sheet always being 

 renewed. 



The duration of the hatching varies from three to five days, the eggs 

 hatching about as follows: During the first da}'^, 5 per cent; during 

 the second, 33 per cent; during the third, 50 per cent; during the fourth, 

 5 per cent; during the fifth, 7 per cent. 



Twenty-five grams of eggs will give about 17 grams of worms. In 

 small rearings most cultivators raise only the worms that are hatched 

 on the second and third days, to avoid the necessitj'^ of forming too 

 many classes. The worms must be classed according to the date of 

 birth, and the insignficant number hatched on the first and last days 

 scarcely compensate for the trouble of rearing them. Different races 

 must also be reared separately. 



Where several in one neighborhood are engaged in silk culture it 

 greatly reduces the cost to have all the eggs hatched in one incubator. 

 The person best acquainted with silk culture can undertake the incu- 

 bation, and distribute the young worms on the second or third days to 

 those who are to rear them. This is the plan adopted among the Italian 

 peasantr}^, the wife of the supervising farmer hatching the eggs for 

 whole villages. 



THE REARING OF SILKWORMS. 



Before entering into the details of a rearing some general directions 

 must be given concerning the rearing room — the heating, ventilation, 

 and disinfection. 



GENERAL DIRECTIONS. 



The place chosen for a rearing should be relatively high, and not 

 exposed to malaria or bad odors, and mulberry trees should grow 

 around it. Any room that can be properly heated and ventilated will 

 answer the purpose. An open fireplace is the best means of heating, 

 but is expensive, as much of the heat is lost. Hot- water pipes, such 

 as are used to heat a greenhouse, are good for a building specially 

 built for silkworm rearing. Iron stoves should not be used, unless 

 placed in an adjoining room w'itli communicating pipes. Never emplo}'^ 

 charcoal as fuel. 



Ventilation. — The domesticated worm should be surrounded contin- 

 ually b}^ pure air. The amount of carbonic-acid gas given out by 

 the worms and their attendants is very considerable; besides this, a 

 quantity of deleterious gas is generated by the litter of the beds, and 

 the lights and fires consume a great deal of ox3^gen. Myriads of 

 spores and germs of organic life float in the air of the rearing room, 

 and their influence paral^'zes the vital energ}'^ of the skin and of the 

 organs of respiration, on whose normal functions the robustness of the 

 worm so much depends. Hence, it is evident that the quantitj'^ of 



