series of papers the following year). Learning of this, Heitz accused Painter of deliberately ignoring their original publication to claim priority of discovery. In 1935, Hermann J. Muller and A.A. Prokofyeva established that the individual band or part of a band corresponds with a gene in Drosophila. The same year, P.C. Koller hesitantly introduced the name "polytene" to describe the giant chromosome, writing: Occurrence Polytene chromosomes are present in secretory tissues of dipteran insects such as the Malpighian tubules of Sciara and also in protists, plants, mammals, or in cells from other insects. Some of the largest polytene chromosomes described thus far occur in larval salivary gland cells of the chironomid genus Axarus. In plants, they are found in only a few species, and are restricted to ovary and immature seed tissues such as in Phaseolus coccineus and P. vulgaris (Nagl, 1981), and the anther tapetum of Vigna unguiculata and of some Phaseolus species. Polytene chromosomes are also used to identify the species of chironomid larvae that are notoriously difficult to identify. Each morphologically distinct group of larvae consists of a number of morphologically identical (sibling) species that can only be identified by rearing adult males or by cytogenetic analysis of the polytene chromosomes of the larvae. Karyotypes are used to confirm the presence of specific species and to study genetic diversity in species with a wide range of genetic variation. References Further reading External links (87A&C Heat-shock puffs) (High resolution spreads) Phaseolus Polytene chromosomes (Plants) Chromosomes Insect genetics Drosophila melanogaster genetics