230 THE INSECT WORLD. 



&c. So, for a rearing-house for 300 grammes of eggs, the building 

 should be constructed in such a manner that its front and back look 

 east and west, to avoid any inequality in the heat derived from the 

 sun. It ought to consist of a ground-floor, a very lofty first-floor, and 

 of a rather low roof. The ground-floor comprises the chamber of 

 incubation, the store-room for leaves, and the air-chamber with the 

 grate intended for warmth and ventilation. The first-floor constitutes 

 the rearing-room properly so called. 



But let us leave these grand industrial establishments, to return to 

 our rearing -houses on a small scale, such as are found among the 

 peasants of the Cevennes. They generally receive the silkworms' 

 eggs before the end of the winter. In order to preserve them till the 

 hatching season, they are placed in thin layers, in a piece of folded 

 woollen stuff, which must be hung up in a cool, but not a damp place, 

 exposed to the north. As soon as the buds of the mulberry tree 

 begin to be partially open, they proceed to the incubation of the eggs. 

 They are spread out on sheets of paper, in very thin layers, placed on 

 a table in a room having a southern aspect, and left thus during three 

 or four days, taking care to prevent the rays of the sun from touching 

 them. It is necessary also, from lime to time, to open the windows. 

 After three or four days, the fire is lighted, taking care not to have 

 more heat than 13^ Centigrade round about the table which supports 

 the eggs, and which should be placed as far as possible from the fire. 

 Each day the room is warmed a little more, in such a way that the 

 temperature is raised 1° to 2° a day, until 25° Centigrade of heat 

 have been attained, at which temperature it is to be maintained when 

 the eggs have reached the last stage, and till the hatching is termi- 

 nated. On the first day few worms are hatched ; but the hatching of 

 the second day is very abundant, as also that of the third. Of these 

 newly-born worms two divisions are made, separated by an interval oi 

 twenty-four hours. The worms which are born afterwards are thrown 

 away, unless they are so abundant that they can be made a third 

 batch of, which is to be mixed up with the second at the period of 

 the moult. 



In the large rearing-houses there is a special chamber for the 

 incubation. Various simple, convenient, cheap apparatuses, whose 

 main object is to create a permanent warm and damp atmosphere, 

 whose degree of heat can be regulated at will, have been proposed. 

 M. Louis Leclerc, in his pamphlet entitled " Petite Magnanerie," has 

 given a description and drawing of a little box which is very useful 

 for facilitating the hatching of eggs. We refer those of our readers 

 who wish for farther information on the subject to that work. As 



