INFLUENCE OF HEAT AND COLD. 59 



carefully wrapping them in paper, and keeping 

 them in his waistcoat-pocket, where they have all 

 the comfort and warmth of his body to bring them 

 forward. In countries where the silk-worm is 

 reared, women carry them in their bosom, and by 

 this means cause the young larva to come forth 

 from the egg in much less time than it would 

 naturally occupy. By removing a twig of a plant 

 upon which in the preceding autumn an insect 

 may have been found to have deposited its eggs, 

 into a warm room, an opportunity will be had of 

 putting this operation practically to the test. In 

 a short time it will be found that the eggs are all 

 hatched, and that a number of minute Iarva3 are 

 crawling actively about, while their brethren in 

 the snow-covered fields are yet safely asleep in the 

 shell. 



On the other hand, eggs which would otherwise 

 be hatched the same year are arrested by the ad- 

 vancing cold of the winter season, and are now 

 compelled to wait until the ensuing spring, before 

 their time of hatching arrives. Evidently, there- 

 fore, to the commencement of the life of an insect 

 the condition of the external temperature is an all- 

 important consideration. Before proceeding imme- 



