Chromosomes being long, vary considerably within different metaphase plates, in length and proportion of arms or segments. Therefore mean values of segmental lengths of 20 chromosomes of each type of each strain has been considered in preparing the idiogram. Occurrence of a large number of chromosomal biotypes of L. odoratus, each having distinct chromosome morphology, suggests an important role of structural alteration by deletion, translocation, etc., in the evolution of different strains. © 1975, Japan Mendel Society, International Society of Cytology. All rights reserved.