Sulla ibridazione fraTriturus helveticuse TV.vulgaris

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Abstract
A female of Triturus helveticus mated to males of T. vulgaris meridionnlis laid during two years (1955 and 1956) 301 eggs, 34 of which fertilized. These last ones developed normally and produced vigorous larvae, which grew up to sexual maturity. The phenotype of the Ft hybrids is intermediate between the parental species; the sex-ratio is normal. Spermatogenesis in hybrid males shows strong abnormalities, e. g.: failure of true first metaphase stages and great abundance of meta-anaphases; number of bivalents always lower than normal (12), some chromosomes remaining as univalents; chiasma-frequency of the bivalents very low. However, sperms can be produced, although in scarcer number as compared with the pure species. Fertility of the Ft hybrids seems reduced, but further researches are needed.