Qualitative differences between chromosomes

Physical Basis of Heredity 4. The Chromosome Theory of Inheritance
Association of paternal and maternal chromosomes at meiosis
Qualitative differences between chromosomes
Formulation of chromosome theory
Sex chromosomes and chromosome theory
The observations of T.H. Montgomery's (1901) and those of W.S. Sutton (1902) attained significance when T. Boveri (1902) demonstrated in sea urchin, that different chromosomes of a set possess different qualities. He also showed, that presence of a complete set of chromosomes was important for survival. This observation derives support now from the fact that a hypodiploid (chromosome number < 2n) does not survive while a haploid individual may survive. It is also proved by the fact that trisomics involving different chromosomes differed morphologically as in case of Datura and many other plant species and also in Humans (consult Numerical Changes in Chromosomes and Human Genetics).