PREPAEING COCOONS FOR MARKET. 27 



spoiled. They ai'e then spread out in 4-inch layers, on clean shelves, 

 in an aii-y, dry room, not exposed to sunlight, and very carefully 

 guarded from rats, mice, and insects. The defective and discolored 

 ones are put in a separate room. 



The thread of a cocoon is continuous with that of the web, and 

 diminishes in diameter within. Its length varies from 1,200 yards to 

 1,000 yards, and its value accordingly. Different races, sexes, and 

 conditions of rearing often produce notal)le ditferences in weight of 

 cocoons. Thus the weight may vary 

 from 155 to 820 cocoons to the pound 

 (340 to TOO to the kilogram). 



Often two or more worms are in- 

 closed in the same cocoon. Cocoons 

 formed from such collaboration are 

 larger than single ones, irregular in 

 form, and cottony in texture. They 

 can not be unreeled, and consequently 

 are far less valuable than single ones. F'«- n.-Device for removing floss from 



_^, . (• Ml • cocoons. (Redrawn from Nenei.) 



ihe proportion or silk in a cocoon 

 varies according to the race and the regime to which the worm has 

 been subjected. The average normal cocoon at the time it is sold is 

 thus composed: 



Per cent. 



Water 68. 2 



Silk 14. 3 



Web and veil 7 



Chrysalis , 16. 8 



If the cocoons are not sold as soon as gathered, the chrysalides 

 should be killed without delay unless they are to be reserved for 

 reproduction. Otherwise the moths may pierce the cocoons, thus 

 rendering them unfit to be reeled. 



The chrysalides are usually killed either by heat or suffocation. 

 The means most commonly employed are (1) the heat of the sun; (2) 

 hot dry air in a stove; (3) hot humid air in a stove; (4) steam; (5) oil 

 of turpentine; (6) carbon bisulphid or some other gas. Probably the 

 best of these means are steam at a temperature not above 212° F. 

 applied without pressure, or hot damp air at a temperature of 196° F. 



The killing of the chiysalides is an important operation and one 

 requiring care and judgment. If some are left alive, the moths will 

 issue, thus rendering the cocoons of little value. On the other hand, 

 if the operation is continued too long, the silk may be injured. The 

 best methods are those in which the heat is carefuU}^ controlled and 

 excessive dryness is avoided. 



The following is a very simple and easy way to destroy the chrysa- 

 lides by the use of steam: 



Place a cauldron of water on a stove. When boiling begins set over the cauldron 

 a white liollow wooden cylinder, about 3 feet high and 2 feet in diameter, with 



