GROWTH OF SILK-WORMS. 



67 



stance about 60,000 times its primitive weight. In 

 warmer climates silk-worms consume a rather less 

 quantity of leaves, because these are perhaps more 

 nutritive ; but in that case, the silk produced is not 

 so delicate and fine. The following- statements are 

 the result of experiments made by Count Dandolo : — 

 Progressive increase of silk-worms in weight. 



A hundred worms just hatched weigh about 



After the first moulting 



After the second moulting 



After the third moulting 



After the fourth moulting 



On attaining their greatest size and weight 



GRAINS. 



1 



15 



94 



400 

 4628 

 9500 



They have, therefore, in thirty days increased 9,500 

 times their primitive weight. 



Progressive increase of silk-worms in length. 



4 



6 

 12 



20 

 40 



A silk-worm just hatched measures about 



After the first moulting 



After the second moulting . 



After the third moulting 



After the fourth moulting 



After the fifth moulting it may reach 



The length of the silk-worm, therefore, increases 

 about forty times in twenty-eight days*. 



By recalling to memory the comparisons of the 

 eggs of insects with the seeds of plants, and of 

 caterpillars with buds, which ought to be taken (if 

 we may trust Swammerdam) literally rather than 

 poetically, we shall arrive at more distinct notions of 

 the manner in which the growth and changes of 

 larvae are accomplished. The buds of plants are 

 composed of successive leaves closely embosomed 

 within each other's foldings, the outer one being 

 generally hard and corneous, from the exposure of 

 its vessels to the colds of winter, while the inner 

 * Count Dandolo on Silk-worms, p. 326, Eng. Trans. 



