No. 415.] NESTS OF AMERICAN ANTS. 525 
for the sap of the plants. For this reason the files bifurcated 
towards their ends, each species going to its own destination. 
I finally discovered in the trunk of a mango a large termite nest 
which had been appropriated by the two species of ant under 
discussion, and served them as a common dwelling in a manner 
hitherto unknown. The time was decidedly propitious, as each 
species had its winged sexes and its pupz in the nest. The 
nest was inhabited as it had been left by the termites without 
additions or alterations. In no portion of the nest was there a 
blending of the two species of ants. Some of its corners were 
still tenanted by the termites. But the chambers and galleries 
throughout nearly their whole extent were occupied either by the 
Cremastogaster with their females, males, and pupæ, or by the 
Dolichoderus with the corresponding sexes and developmental 
stages. Each species had its own household, in contradis- 
tinction to the mixed formicaries of our Polyergus and Formica, 
which have but a single household in common. But all the 
chambers and galleries inhabited by one of the two species 
communicated freely with the cells tenanted by the other, and, 
as if intentionally, the apartments of one were interlaced with 
those of the other. Instead of one species taking possession 
of one-half of the nest, and the other of the remainder, they 
interdigitated throughout, so that there was not a piece of the 
nest as large as an egg which did not contain both species. 
The whole nest was about four or five decimeters in diameter. 
Thus the case is altogether different from that of the double 
or compound mests in Europe, where two or several inimical 
species may have their galleries interlacing to some extent 
but not inosculating. In this case we are concerned with an 
amicable association for lodging and for the files, which go fora- 
ging together, but without actually blending, so that the two 
species lead an independent life side by side. Hence the term 
“parabiosis’ which I have thought best to-apply to this kind of 
association. It should be remarked, however, that the parabiotic 
association of these two species is not constant, though very fre- 
quent. I have also found the nest of each species by itself." ! 
! In conclusion Forel calls attention to the fact that some birds exhibit a sim- 
ilar parabiosis, €g., the joint flocks of Corvus cornix and C. corone in Europe. 
