104 



it, thus justifying Taschenberg's remark, in his Wirbellose Thi^re : 

 *'The most useful of all insects, like the loveliest songsters among 

 birds, is clothed in the soberest garments." 



The larva (or "worm " par excellence) is a stout thick-bodied grub, 

 of nearly the same tint as the moth, with a small head and naked 

 body, of which the first segment is much swollen, and the last but 

 one bears an upright horn. The worm feeds by preference on the 

 mulberry — not the common sort with the luscious fruit, known to 

 botanists as Morus nigra, but another species, Morus alba, of which 

 the fruit is worthless as food. The insect can also support itself on 

 lettuce, and some other juicy plants ; but the silk is said in such 

 case to be much inferior. 



The Cocoon enclosing the chrysalis is egg-shaped, and is composed 

 of the much-coveted silk, varying in colour from pure white to golden 

 yellow ; occasionally it assumes an apple green tint. Leunis, the 

 learned author of the Synopsis der Thierreich, tells us, that blue 

 cocoons can be obtained by sprinkling the food with indigo ; and 

 that a pink hue is communicated, if the powdered leaves of a South 

 American plant, Bignonia chica, are employed. 



The threads issue from two glands situated near the mouth, 

 aggluminated together and covered with a glossy varnish — each 

 thread measuring about the 2,000th of an inch in diameter. 



A cocoon contains from 700 to 1, 100 feet of thread ; and it takes 

 some 2,000 of these indefatigable spmners to procure one lb. weight 

 of the raw material. 



The outer covering of the cocoon is made up of loose broken fibres, 

 well-known as Floss or Bourre, which is carded and spun like 

 cotton. 



Besides the Floss, three forms of raw silk are recognised in 

 commerce. 



1. Singles : Formed of a single thread to give it firmness. 



2. Train : Formed of two or more threads slightly twisted together. 

 It is generally used for the shoot or weft. 



3. Organzine, which is, in fact, Thrown Silk, is made up of several 

 threads twisted firmly together m a direction contrary to that of 

 the individual threads. It serves for the warp of the best stufis. 



I may mention, in passing, that the Throwing machine has been 

 so much improved of late years that the extraordinary speed of 5000 

 revolutions per minute is given to the spindles. 



Silk-worms, owing no doubt to their purely artificial condition, 

 are subject to various diseases, many of which are as destructive to 

 them, as are cholera or yellow fever to their owners. Among them 

 are conspicuous muscardine, pebrine, jaunisse, and others much 

 dreaded by the silk-farmers of Italy and France. The devastation 

 caused by these epidemics has interfered seriously with the 

 supply of silk ; as the infected "grains" or eggs have been trans- 

 ported from one country to another, and have spread disease far 

 and wide. Even China, the cradle of silk culture, has not been 

 spared. It is principally from Japan, that growers are now supplied 

 with grain, as that country has hitherto escaped the plagues that 

 have devastated other lands. At the same time, this immunity 

 ■will be of short duration, if, as reported, the Japanese, with 

 short-sighted policy, are actually importing infected eggs for 

 the purpose of adulterating healthy ova for the foreign market. 



