THE SILK WORM. Oft 



rnent of Arts, &c. contain many experiments on sub- 

 stituted feed, which throw some lighten the subject, 

 one or two of them may bo both useful and interest- 

 ing. We copy them from Lardner's Cabinet Cyclo- 

 paedia : 



" A letter from Miss Rhodes relates, that in the 

 summer of 1785, she subsisted several thousand 

 Worms entirely on lettuce leaves during three weeks, 

 and that for the remaining short term of their lives 

 she afforded them thsir natural food. At the end of 

 a month from thsir first hatching, they began to spin, 

 and eleven ounces of silk were procured from four 

 thousand cocoons. After repeated trials, this lady 

 had become convinced that Silk Worms could not 

 safely be fed on lettuce leaves for a longer period than 

 three weeks ; as on persisting further in their use, 

 the greater part of the Worms died without forming 

 their cocoons. Some indeed, possessed sufficient 

 vigor to spin and to produce perfect and well-formed 

 balls, even when lettuce leaves had constituted their 

 only food. Reasoning from this fact, Miss Rhodes 

 was brought to suspect that the premature mortality 

 of her brood was not altogether occasioned by the un- 

 wholesome nature of the aliment on which they had 

 fed, but might be owing to some extraneous circum- 

 stance ; and further observation led her to the con- 

 clusion that it was the coldness of the lettuce leaves, 

 rather than any inherent property, which made them 

 detrimental. This lady having thence suggested that 

 if the Worms were kept in a higher temperature, they 

 might be successfully supported through their lives on 

 lettuce leaves, General Mordaunt caused a consider- 

 able number to be hatched and reared in hot houses. 

 These were fed entirely on lettuce leaves; they 



