“…It is worthwhile to reiterate that the frequency of PP in 1957 stood in these populations at a level which was apparently lower than in the Sierra Nevada populations, despite the fact that it was in the Coast Ranges that three out of the four PP chromosomes recorded in California before 1946 were found. in southern California, and studied by Dobzhansky (summary in Dobzhansky, 1947), and thereafter by Epling and his collaborators (summary in Epling and Lower, 1957 (Dobzhansky and Queal, 1938), but the frequency of PP stood at 6.3 per cent in 1955, while CH changed from 19.1 to 9.4 per cent (Epling and Lower, 1957). Nor were PP chromosomes found in 1937 on other mountain ranges in southern Nevada and in the adjacent Death Valley of California (Dobzhansky and Queal, 1938 of PP were lower, and the frequencies of AR were higher, in early spring (March and April) than in late spring (May) or in autumn (see Table 11, p. 113, Dobzhansky, 1944 In 1953, PP was still the predominant gene arrangement at Austin, Texas, although its frequency has dwindled appreciably since [1939][1940].…”