Cell biology is moving at breakneck speed, and many of the results from studies on insects have helped in understanding some of the central problems of biology. The time is therefore ripe to provide the scientific community with a series of up-to-date, well illustrated reviews of selected aspects of the sub­ microscopic cytology of insects. The topics we have included fall into four general groups: seven chapters deal with gametogenesis, four concern develop­ ing somatic cells, seventeen chapters describe specialized tissues and organs, and three chapters cover cells in pathological states. These accounts are illustrated with over 600 electron micrographs. The more than 1100 pages in the two volumes of Insect Ultrastructure combined labors of 49 dedicated contributors from II countries. represent the These authors have digested and critically summarized a very large body of information, and some measure of this effort can be gained from consulting the bibliographies that close each of the 31 chapters. These contain 2400 publica­ tions authored by 1500 different scientists. However, before we congratulate ourselves on the advanced state of our knowledge, it is worth remembering that representatives of less than 0.01 % of the known species of insects have been examined with the electron microscope.