These insects (_Myrmecocystus_) live in Texas, and form colonies in which certain individuals play a very special part They exaggerate to an extreme point the power of preserving provisions in their crops. These materials are not assimilated; they do not form part of the animal's body, and although placed inside it cannot be compared to physiological reserves. It is especially curious that they are not to be utilised only by the animal itself, but also by the other members of the colony who are not able to form such stores. Among the _Myrmecocystus_ there are workers of two sorts; the first kind resemble other ants with some differences of detail, and build and hollow the earth nest which shelters the community. The second kind is quite different; the abdomen in these workers is enormously distended so as to constitute a voluminous sphere, which may become four or five times larger than the thorax and head together. (Fig. 12.) On this distended receptacle appear several darker plates; these are the remains of the chitinous parts of the primitive wings. In the fine season these ants go out in a band and collect a sweet liquor which forms pearly drops on certain galls of oak leaves. These drops, elaborated into honey, gradually fill the crop, distending it and pushing back neighbouring organs until it receives its globular form. When they have arrived at this obese condition, the heavy honey ants no longer leave the nest. They remain without movement, hanging by their legs to the roof or lying against the walls of a room. The workers who have remained slender come and go, attending to their usual occupations, and pass near the others without paying attention to them or going out of the way to lend assistance to their impotent sisters when one of them has rolled over on the ground and can no longer arise unaided. (Fig. 13.) They only cease to be indifferent when impelled by the selfish sentiment of hunger, and then it is to ask and not to give assistance. The fat ants in fact could not themselves consume all the honey that they have elaborated; the others in times of famine approach them, caress them with their antennae, and obtain by solicitation a drop of honey which the large ones disgorge from the crop. Here, then, is a colony in which the division of labour has reached a remarkable degree of polymorphism. Some of the members accomplish the work of engineers and masons, while the others fabricate for the community a store of honey. Instead of depositing these provisions in cells like bees, they preserve them in their own digestive tube. This custom has re-acted to such an extent on the form of their bodies that at first sight they seem to belong to a different species. [Illustration: FIG. 14.]