Nov. 1, 1864] THE TECHNOLOGIST. 



RESTORATION OF THE SILKWORM. 177 



varieties of the same species, and that in a state of domestication all 

 may, by the application of certain temperatures, be made to yield 

 several crops of silk annually. This, however, may fairly be denounced 

 as pure nonsense, the occurrence of the two crops arising solely out of 

 the fact of our having in autumn a recurrence of the spring temperature, 

 or what may be called a double season. Hence, since a particular 

 degree of temperature causes the egg to hatch, whenever the season 

 returns in which that temperature is produced, the young worm is of 

 course excluded from the egg. It is quite possible, then, and even pro- 

 bable, that these species may originally have done the same in their 

 native country, and the reason why they have ceased to be double- 

 brooded in Europe and other localities is to be attributed solely to the 

 uncongenial temperature, which is sometimes too high, at other times 

 too low ; and with respect to those species which are termed " monthly " 

 worms, if it were really the case that the number of crops is due to 

 cultivation in warm climates, it ought to follow that, when domesticated 

 in a cold climate, the frequent succession of silk crops should become 

 less frequent, and the worm give symptoms of reverting to its old habits. 

 Such, however, I have not found to be the case ; for although I have 

 succeeded in obtaining two broods from Bombyx mori of Cashmere and 

 B. textor of China, yet the small monthly China worm (B. sinensis, nob.) 

 has continued yielding crop after crop even to the middle of December, 

 when the eggs were again deposited in a temperature of 53° of Fahr. 

 Hence I adhere with good reason to the opinion that all are naturally 

 distinct species. Consequently, as all the other accounts, quoted by Mr. 

 Moore and other authorities, lead to the conclusion that one spring crop 

 only was produced by the worm originally cultivated in China, it will 

 be well to allow the animal species domesticated in Europe as B. mori 

 to retain that distinctive title, more especially when we consider that as 

 the people were forbidden to rear — not merely a second crop of silk, 

 but — " a second breed of worms" the stock, if double-brooded, would 

 speedily have been destroyed and lost by such interdiction. This, then, 

 would tend to prove that the worm under cultivation was an annual 

 only, and that the prohibition extended to other species. 



From the year before Christ 2640 until 550, or thereabouts, of the 

 Christian era, the domestication of the worm appears to have been ex- 

 clusively confined to China, severe punishments being inflicted upon 

 anyone who ventured to attempt its exportation into other countries, 

 when, at length, about the latter year, through the laudable zeal of 

 mission, try monks who had visited China and there learnt the mode of 

 cultivation, the eggs were secretly conveyed into Europe and presented 

 to the Emperor Justinian. 



Thus, for a period of more than 3,000 years, the so-called cultivation 



of the worm had remained exclusively in Chinese hands. What wonder, 



then, if the constitution of the insect had during that time been 



gradually undermined by a course of imperfect feeding, close and tainted 



vol. v. x 



