Absence of Seed Dormancy in a White Mutant Strain of Helianthus annuus L.

the nutrient deficiency. The apparent narrow temperature range of maximum growth found in the old cultures of Chlorella and Anacystis also seem to be caused by such secondary effects. We have therefore prepared table I from the earliest clear pattern that developed. It should represent the optimum conditions for cultivating these algae. In figure 4 the development of a Chlorella pyrenoidosa and of an Anabaena culture are also shown. Some difficulties in preparing a uniform inoculum of the Anabaena are evident in the figure but do not distort the conclusions appreciably. With Haematococcus some growth was evident over the temperature range of 12 to 330 C and light intensities from 50 to 1000 ft-c with greater growth toward the high temperature side. At the higher intensities the color was red and shaded to brownish green at intensities below about 200 ft-c. The optima were broad and not clearly shown in this experiment.