Cytogenetic is a science of correlations, of the presence and transmission of a predictable trait with the presence of a physical entity. It is but a matter of degree whether the physical unit is a cloned ontogeny related to a particular malignancy, a single extra chromosome responsible for Down’s syndrome or altered fruit morphology in the Jimsonweed, or elimination of male chromosomes determining maternal inheritance in the fungus gnat Sciara. All are comfortably embraced under the aegis of cytogenetics. However, the breadth of cytogenetics, the diversity of its test organisms and the vigor of its cutting edge sometimes promote easy fragmentation, sequestering one or another portion as a new discipline. As a science, cytogenetics followed a typical path as it gained identity. The early papers were descriptive, their correlations couched in tentative terms and their conclusions cautious. Only later would cytogenetic presentations become more quantitative and more critically analytical. Scientists have been urged to be audacious in speculations but only when meticulous in observation and experiment. Meticulous, to be sure, but audacious hardly seems characteristic of cytogeneticists of my own and earlier generations.
