Cytogenetics / edited by Ronald L. Phillips, Charles R. Burnham.

Date:
[1977], ©1977
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Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Cytogenetics / edited by Ronald L. Phillips, Charles R. Burnham. Source: Wellcome Collection.

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    Historical Perspectives 7. Chromosome number was shown to be halved at meiosis (Henking 1890; Boveri 1893; Rückert 1892; and others). This was a prediction Weismann had made previously. Hence soon after the rediscovery of Mendel's contributions, Correns (1900) and Strasburger (1901) suggested a connection be¬ tween Mendelian segregation and the reduction division. Sutton (1903) and Boveri (1904) furnished more complete formulations of the chromosome mechanism of Mendelian inheritance, including the prediction of linkage. Wilson and his students in America and Boveri, Goldschmidt, and others in Europe added important information about chromo¬ somes (1902-1912). That the chromosomes in a species are qualita¬ tively different was shown in 1902 by Boveri in Ascaris and also by Sutton in Brachystola. S. Nawaschin (1912) first reported that satel¬ lited chromosomes were attached to the nucleolus in Galtonia can- dicans. He also reported heterozygosity for a difference in size of the satellite. Such heterozygosity was known up to then only for sex chromosomes. Carothers, 1913 and again in 1917 (Paper 38), re¬ ported heteromorphism for autosomal chromosome pairs in grass¬ hoppers in the wild. Stebbins (1950) states that Nawaschin and his school established firmly the fact that most species of plants and ani¬ mals possess a definite individuality in their somatic chromo¬ somes, which is evident in their size, shape, position of prima¬ ry constrictions or centromeres and in such additional features as secondary constrictions and satellites. In response to a report by Delaunay at a meeting of the Caucasian section of the Russian Botanical Society, S. Nawaschin (1921) stated that for many years in lectures to his students he had named the characteristic composition of the nucleus for a species its idio- gram. This appears to be the paper usually cited as the source of the term, e.g.. Sharp (1934). Idiograms representing the chromo¬ some complement have been useful in comparative cytogenetics. M. Nawaschin (1925), the son of S. Nawaschin, reported com¬ parative studies of the chromosomes of 11 species of Crepis and referred to S. Nawaschin's use of the term idiogram for the specif¬ ic picture of the chromosomes of a species but cited no refer¬ ence. Heitz (1926) also reported comparative studies of several spe¬ cies in three different families of monocots and used the term idio¬ gram without reference to any earlier use. Both Nawaschin and Heitz used schematic representations of chromosome sizes and shapes, with centromeres arranged in a line at the base of the V's, 2