88 EXPLANATION OF THE PRESENT STATE OF 
of Tetramorium, and in some manner contrive to assas- 
sinate their queen. I have shown that a nest of ants 
may continue, even in captivity, for five years, without 
a queen. If, therefore, the female of Anergates could 
by violence or poison destroy the queen of the Tetra- 
moriums, we should in the following year have a com- 
munity composed of the two Anergates, their young, 
and workers of Tetramoriwm, in the manner described 
by Van Hagens and Forel. This would naturally not 
have suggested itself to them, because if the life of 
an aut had, as was formerly supposed, been confined 
to a single season, it would of course have been out of 
the question; but as we now know that the life of ants 
is so much more prolonged than had been supposed, it 
is at least not an impossibility. 
It is conceivable that the Tetramoriwms may have 
gradually become harder and stronger; the marauding 
expeditions would then be less fruitful and more dan- 
gerous, and might become less and less frequent. If, 
then, we suppose that the females found it possible 
to establish themselves in nests of Tetramorium, the 
present state of things would almost inevitably be, by 
degrees, established. Thus we may explain the re- 
inarkable condition of Strongylognathus, armed with 
weapons which it is too weak to use, and endowed with 
instincts which it cannot exercise. 
At any rate, these four genera offer us every grada- 
tion from lawless violence to contemptible parasitism. 
Formica sanguinea, which may be assumed to hare 
