Temperature dependence of cleavage rates in carp, pike, and whitefish.

The time taken by the first four cleavage divisions has been determined for the carp, pike, and whitefish (Coregonus peled) at various temperatures; a quantity tau-0 was calculated, and plotted against temperature. From the curves plotted for all species investigated, it was found that in the salmon but not in the more thermophile species the rate of division within the spawning temperature range could be described by a constant Q 10 which had a value exceeding 2 or 3. Criteria for determing the lower temperature limit of the range for optimum development of teleosts are discussed.