In a comprehensive survey of his earlier studies he wrote: "When a larger number of pollen mother cells are investigated and when the most frequent number of bivalents is found, we can estimate then with great certainty the degree of the chromosome homology, which gives some criteria concerning the relationship between the parental species" (Kostoff, 1943: 739).
However, as stated above, chromosomes have only few morphological hallmarks, and the only features that can routinely be assessed at metaphase I of meiosis are the different chromosomal configurations (univalents, bivalents, trivalents, etc.
the reciprocal exchange of parts of the chromatids of the homologous chromosomes - can take place, and it ensures that bivalents are formed from the homologous parental chromosomes and are held together by chiasmata until first meiotic division.
Although the number of association sites and their distribution on each chromosome is unknown (it is likely that there is more than one on each chromosome arm), their possible role in chromosome pairing raises a number of interesting questions: how many of the association sites must match before normal bivalents are formed in a species-hybrid?
globosus showed that the autosomal bivalents and the univalent X chromosome exhibited a regular behavior similar to those described by Suzuki (1954), Bole-Gowda (1958), Cokendolpher (1989), Tugmon et al.
2006), and with autosomes of some entelegyne species, such as two autosomal bivalents of Allocosa georgicola (Walckenaer 1837) (as Lycosa georgicola) (Lycosidae, Entelegynae), with 2n = 28 = 26 + [X.