414 THE PEOBABLE MODE OF RECOGNITION. 



many. At any rate none were being attacked nor had 

 any been killed. 



These observations, therefore, quite confirm those 

 previously made, and seem to show that if pupoe are 

 taken from a nest, kept till they become perfect in- 

 sects, and then replaced in the nest, they are recog- 

 nised as friends. 



When we consider the immense number of ants in 

 a nest, amounting in some cases to over 500,000, it is 

 a most remarkable fact that they all know one another. 

 If a stranger, even belonging to the same species, be 

 placed among them, she will be at once attacked and 

 driven out of the nest. Nay, more, I have already 

 shown that they remember their friends even after 

 more than a year's separation, and that it is not by any 

 sign or password, because even if rendered intoxicated, 

 so as to be utterly insensible, they are still recognised. 

 As regards the mode of recognition, Mr. McCook con- 

 siders that it is by scent, and states that if ants are 

 more or less soaked in water, they are no longer recog- 

 nised by their friends, but are attacked. He mentions 

 a case in which an ant fell accidentally into some 

 tv^ater : — 



' She remained in the liquid some moments, and 

 erept out of it. Immediately she was seized in a hos- 

 tile manner, first by one, then by another, then by a 

 third ; the two antennae and one leg were thus held, 

 A fourth one assaulted the middle thorax and petiole ; 

 the poor little bather was thus dragged helplessly to 

 and fro for a long time, and was evidently ordained to 

 death. Presently I took up the struggling heap. Two 

 of the assailants kept their hold ; one finally dropped, 

 the other I could not tear loose, and so put the pair 

 back upon the tree, leaving the doomed immersionist 

 to her hard fate.' 



His attention having been called to this, he noticed 

 several other cases, always with the same result. I 



