Abstract
The eggs develop regularly between 15[degree] and 32[degree] C. The time necessary to reach stage 20 at 20[degree] C is 134 hrs. This species has the highest range of temp. tolerance and the slowest development of any of the 5 spp. of Rana common in the n.-e. U. S. No difference in either rate of development or temp. tolerance was found in animals from different localities. The relation between the temp. coefficient (Q10 or b) of development and thermal adaptation is discussed. In frogs the value of b is greater in spp. adapted to high temps.