HEMIPTERA. 127 
where plant-lice are gathered together in great numbers. Are 
ants simply friends of the plant-lice, as thought the ancients? Or 
have their visits some selfish object ? 
Linnzeus, Bonnet, and Pierre Huber thought that the ants did 
not pay these visits for nothing, and that they had some object 
in view. But what could they want of the plant-lice? It is to 
Pierre Huber we owe the solution of this mystery. This natu- 
ralist has made the most beautiful observations on the relations 
which exist between plant-lice and ants. They are detailed in 
a chapter of his admirable work, entitled ‘‘ Recherches sur les 
Meceurs des Fourmis Indigénes.”’ 
The plant-lice have, as we have said, at the extremity of their 
abdomen two small movable horns. ‘These are in communication 
with a little gland which produces a sugary liquid. When one 
carefully observes plant-lice attached to the stem of a plant, one 
sees a little syrup droplet oozing out of the extremity of these 
tubes. 
M. Morren, who has made some interesting observations on the 
anatomy and generation of the aphis, says that, having shut 
up females in wide-mouthed glass bottles, he saw the young, 
a little time after their birth, suck the sweet juice which exudes 
from the little tubes at the extremity of the mother’s abdomen. 
This secretion seems, then, destined for the nourishment of the 
young in the first moments of their existence, before they are able 
to nourish themselves on vegetable juices. ‘The saccharine fluid 
produced by the mother must be, then, a sort of milk intended for 
the nourishment of her young. ‘This being established, listen to 
what follows. In all places where plant-lice are assembled in great 
numbers it is easy to observe how excessively fond ants are of the 
sugary liquid destined for suckling the young. But how do the 
ants manage to get the plant-lice to allow themselves to be, as we 
may say, milked ? 
“Tt had been already noticed,” says this celebrated observer, 
“ that the ants waited for the moment at which the plant-lice caused 
to come out of their abdomen this precious manna, which they im- 
mediately seized. But I discovered that this was the least of their 
talents, and that they also knew how to manage to be served with 
this liquid at will. ‘This is their secret. A branch of a thistle 
