808 THE AMERICAN NATURALIST. [Vor. XXXV. 
must also be admitted that the same appearance is presented 
by the whole complex of conditions in compound and mixed 
nests, but the demonstration is more cogent when it can be 
shown that we have relations as different as those of dominant 
species (Z. emersont) and slaves (L. acervorum) not only in 
the same genus but among closely allied forms. This fact also 
suggests that the instincts of the same species may be so general- 
ised as to enable it to function like man, either as a slave or 
master, according to the circumstances. 
Although these considerations may seem to lack precision 
they certainly show that we cannot dogmatize on the inade- 
quacy of natural selection from a study of a few highly special- 
ized ants like FÆ sanguinea and Polyergus rufescens. The 
complicated phylogeny of the mixed nests can only be estab- 
lished after a patient study of genera like Leptothorax and 
Tomognathus. Another even more neglected group of small 
ants which promises to throw some light on this subject 
comprises the species of Monomorium with the allied genus 
Xenomyrmex. At present so very little is known concerning 
the habits of these genera that it must suffice merely to call 
attention to them in this connection. 
It is necessary in conclusion to consider very briefly the psycho- 
logical problems suggested by the phenomena of social symbio- 
sis, since, as above stated, the cases of dulosis have led authors 
to postulate unusual mental powers in ants. The accounts of 
sane and critical workers like Forel have been distorted by the 
* popularizer," till one almost believes that the ante-bellum 
Southerner might have learned many things in the management 
of his slaves from a conscientious observance of Proverbs vi. 6. 
‘Wasmann in his numerous writings ('91, '97, '99, '99b, etc.) 
has undoubtedly done much, at least in Germany, towards the 
exposure of this pseudo-psychology and a more rational con- 
ception of ant behavior. His long familiarity with these ARE 
mals and their guests has given him a singularly lucid insight 
into their activities. My own more limited observations On 
our North American species lead me to agree with him so ud 
as the facts are concerned and many of the inferences which 
he has drawn from them. I am constrained to say, however, 
