42 
Psyche 
[June-Sept. 
following sites in which she observed the typical sumichrasti 
nesting in various Mexican localities: in the trunk of a 
tree, in the stem-cavities of Cecropia mexicana, under the 
leaf -bases of bananas, in the stems of the Melastomaceous 
plant Conostegia xalapensis, in the pseudobulbs of the 
orchid Schomburgkia tibicinis, and most frequently between 
the overlapping leaves of Bromeliads, namely, Aechmia 
mexicana and the following species of Tillandsia: Balbi- 
siana, dasylirii folia, pruinosa, streptophylla, Valenzuelana 
and viridifolia. Forel (1908) records the typical sumi- 
chrasti as having been taken by Biolley at San Jose, Costa 
Rica (1160 m.) in decayed wood. The very different habi- 
tat of the Atitlan colonies might account for the deeper pig- 
mentation of all three castes and, perhaps, for the aptery 
of the males and females. The physiological causes of aptery 
in insects, however, are apparently obscure and very diverse. 
To contend that the “genes for winged” have completely 
dropped out of the germ-cells of these ants would be merely, 
if a mixed metaphor may be permitted, to make a “Ruhe- 
kissen” out of a photograph of the problem. 
It is more probable that each of the Atitlan colonies is a 
mixture of two species, one of which, comprising the apter- 
ous males and females, is an undescribed workerless para- 
site, the other an undescribed subspecies of C. sumichrasti, 
represented only by the workers and functioning as the host. 
(1) In the field the depauperate appearance of the colo- 
nies and the peculiar males at once suggested this interpre- 
tation, because Crematogaster colonies containing young 
sexual individuals are, as a rule, very populous. Accord- 
ing to Dr. Skwarra’s observations, those of the typical sumi- 
chrasti even contain several mother queens, frequently as 
many as 16 to 20, and are probably of pleometrotic origin. 
She mentions one colony which comprised 81 dealated 
females and 962 workers, and another 164 dealated females 
and about 1200 workers. These are by no means unusually 
large colonies compared with those of many other species of 
Crematogaster. As shown in the following table, however, 
the combined populations of the two Atitlan colonies, includ- 
ing their brood, are very meager : 
