370 MISCELLANEA. [1874. 



carrying cocoons from a nest which was the largest I ever saw 

 and which was well known to all the country people near, 

 and an old man, apparently about eighty years of age, told 

 me that he had known it ever since he was a boy. The ants 

 carrying the cocoons did not appear to be emigrating; fol- 

 lowing the line, I saw many ascending a tall fir tree still car- 

 rying their cocoons. But when I looked closely I found that 

 all the cocoons were empty cases. This astonished me, and 

 next day I got a man to observe with me, and we again saw 

 ants bringing empty cocoons out of the nest; each of us fixed 

 on one ant and slowly followed it, and repeated the observa- 

 tion on many others. We thus found that some ants soon 

 dropped their empty cocoons ; others carried them for many 

 yards, as much as thirty paces, and others carried them high 

 up the fir tree out of sight. Now here I think we have one 

 instinct in contest with another and mistaken one. The first 

 instinct being to carry the empty cocoons out of the nest, and 

 it would have been sufficient to have laid them on the heap 

 of rubbish, as the first breath of wind would have blown them 

 away. And then came in the contest with the other very 

 powerful instinct of preserving and carrying their cocoons as 

 long as possible ; and this they could not help doing although 

 the cocoons were empty. According as the one or other 

 instinct was the stronger in each individual ant, so did it 

 carry the empty cocoon to a greater or less distance. If this 

 little observation should ever prove of any use to you, you 

 are quite at liberty to use it. Again thanking you cordially 

 for the great pleasure which your work has given me, I re- 

 main with much respect. 



Yours sincerely, 



Ch. Darwin. 



P.S. — If you read English easily I should like to send 

 you Mr. Belt's book, as I think you would like it as much as 

 did Fritz Muller. 



