242 Rev. J. Macgarvie on the Brown Hornet 



the united energies of a score of naturalists for many years. Its 

 treasures are inexhaustible, and are almost entirely unknown. 



When, upon this subject, allow me to allude to a circumstance 

 connected with the beautiful Atropus Belladonna. This butter- 

 fly, in the state of a grub, as it is here called, forms a pyra- 

 midal and sometimes a circular nest of small twigs, which it may 

 be seen occasionally dragging up a tree, by short and easy 

 stages. This is the case with the same insect when very small ; 

 but in both stages, it may be seen moving about its head before 

 it commences its journey, and stopping at regular intervals as if 

 to reconnoitre. One unacquainted with its natural history, might 

 suppose it was apprehensive of danger. But the fact is, that 

 when it moves its head from side to side, it is spinning for itself 

 a thread, which it fixes to the tree, and, when it is strong enough, 

 it stretches out its fore claws, seizes hold of the thread, and 

 raises itself upward, on the principle of the common rope-ladder. 

 When you examine its path attentively, you see these steps 

 placed at the most regular distances, as regular as if made by 

 the hand of art, and intertwined in such a way, that if one 

 should break, the next will keep the animal up This is cer- 

 tainly instinct in one sense, but is common mechanics in another. 

 For the animal seizes hold of the thread by the second pair of 

 feet, stretches his head upwards, and makes the distance between 

 the two steps of the ladder precisely that of the distance between 

 his mouth and his second pair of arms, which is exactly one-fifth 

 of an inch in a common sized animal. We have watched him 

 ascending a smooth surface by this means, when it would have 

 been thought impossible to raise a large circular cylindrical nest 

 with so much dispatch on such a surface. Such paths you 

 have probably yourself seen long ago. 



Ascribing effects to instinct, therefore, is a great source of 

 error in natural history, and should not be resorted to, except in 

 those cases in which no rational account can be given of the effect 

 ^e contemplate ; for if men were to stop short at second causes, 

 every effect in nature might be denominated instinctive. The 

 best possible means have been always adopted to produce the 

 best possible ends. It is the business of philosophy to discover 

 the latter, and trace them by that means to the grand intelli- 

 gent source whence they originated. I am, &c. 



