The sociogenesis of insect colonies

Studies on the social insects (ants, bees, wasps, and termites) have focused increasingly on sociogenesis, the process by which colony members undergo changes in caste, behavior, and physical location incident to colonial development. Caste is determined in individuals largely by environmental cues that trigger a sequence of progressive physiological restrictions. Individual determination, which is socially mediated, yields an age-size frequency distribution of the worker population that enhances survival and reproduction of the colony as a whole, typically at the expense of individuals. This "adaptive demography" varies in a predictable manner according to the species and size of the colony. The demography is richly augmented by behavioral pacemaking on the part of certain castes and programmed changes in the physical position of colony members according to age and size. Much of what has been observed in these three colony-level traits (adaptive demography, pacemaking, and positional effects) can be interpreted as the product of ritualization of dominance and other forms of selfish behavior that is still found in the more primitive insect societies. Some of the processes can also be usefully compared with morphogenesis at the levels of cells and tissues.     

Magnetochemistry of Ions in the 4A2 Electronic State

Each of the following ions with spin S = 3/2, octahedral chromium(III), five-coordinate iron(III), and tetrahedral cobalt(II), possesses a (4)A(2) ground state. The theory describing their paramagnetic properties is therefore the same, though some of the parameters change appreciably from ion to ion. This theory is described along with examples of experimental data. The implications of the paramagnetic properties for the magnetic ordering phenomena exhibited by complexes of these ions are also described.