198 DOMESTICATED ANIMALS 



The mulberry silkworm can readily be bred in confine- 

 ment. The eggs are easily gathered and preserved, and are 

 so readily kept that they may be sent the world about. At 

 a given temperature they with infrequent failures hatch ; and 

 if sufficiently fed with the fresh leaves of the mulberry, will 

 in a short time attain to as perfect a development as though 

 they grew, not in close rooms, but in the open conditions 

 of the trees. When of adult size, the grubs proceed to spin 

 themselves in, forming a thick cocoon composed of threads 

 of a material which, though as soft as paste when emitted 

 from the body, hardens so as to form a strong and even 

 thread. If the insect be allowed to remain for a sufificient 

 time in the cradle which it has spun for its second birth, 

 the body within the chrysalis case will proceed in a manner 

 to dissolve ; and in the milky fluid thus produced, where only 

 faint traces of its former state remain, the beautiful image or 

 perfect form will arise. In the economic use of the creature, 

 however, except as far as a supply of eggs may be desired, 

 it is necessary to prevent the completion of its development ; 

 for in escaping from the chrysalis case, the butterfly cuts 

 many of the delicate threads, so that the silk is made unser- 

 viceable. It is necessary to wind it off before the insect 

 escapes. In this part of the work we notice the most perfect 

 adaptation of the creature to the needs of man. While the 

 silk threads from the cocoons of other species which might 

 prove of value cannot be easily reeled off, those of the silk- 

 worm, when placed in hot water, readily separate, and can 

 be crathered in a condition for spinning. Thus, while some 

 success has been attained by carding the cocoons of other 

 species, thereby making a fibre which has a certain utility, 

 the silkworm alone yields material fitted for delicate fabrics. 



