MIGRATORY INSTINCT. 



thrown out, of sufficient length to be carried by 

 the slightest breath of air to the edge of the basin, 

 to which it seems to adhere in consequence of 

 some glutinous substance at the end of the thread. 

 By means of this thread the spider makes its 

 escape. 



But to return to the migratory instinct of in- 

 sects. From what has been said, it is evident 

 that they are impelled by an Almighty Providence 

 to change their quarters, probably when their 

 numbers have increased to too great a degree. 

 This certainly is not the case with all migratory 

 animals. The Swallow, for instance, delights in 

 sunny regions, and quits us when autumnal chills 

 arise, but only for a season. When flowers, and 

 sportive insects, and soft gales assure us that 

 winter is over, we are again gladdened with the 

 sight of this graceful and twittering bird, who is 

 justly called, the herald of the Spring. 



