The Structure of Meiotic Chromosomes in the Grasshopper and Its Bearing on the Nature of "Chromomeres" and "Lamp-Brush Chromosomes"

"Chromomeres" do not exist as definite structures. What has been described as "chromomeres" are (a) misinterpretations of gyres of the chromonematic helix (leptotene, somatic prophase); (b) points of overlap of chromonemata (diplotene); (c) heterochromatic sections consisting of more tightly coiled regions of the chromonema. The fundamental unit of the chromosome is a microscopically uniform thread. The longitudinal differentiation of the chromosome is due to differential coiling of this chromonema. 2. "Lamp-brush chromosomes" are typical diplotene chromosomes, but with tremendously enlongated chromonemata. The side branches are the gyres of the major coils of the individual chromonemata, which have laterally separated from each other.