Mendelian and Non-Mendelian Factors Affecting the Cytochrome System in Neurospora Crassa.

hexane was shaken with 2 ml. of boron trifluoride etherate, BF3 + (C2H6)20 (b.-p. 124-126°), at room temperature. The dark blue complex was decomposed by the addition of 100-200 ml. of 95% methanol, then transferred with water into hexane. The hypophase was discarded and the epiphase washed, dried, adsorbed on a suitable lime-celite column (2:1) and developed with hexane. The respective zones were eluted with acetone and transferred into hexane. The cis members of the stereoisomeric ,8-carotene set were identified as such by catalyzing with iodine and showing that the resulting all-trans pigment did not separate in the mixed chromatogram test from ,B-carotene ex carrots. Pertinent spectroscopic observations were also made. The hexane solutions of pigment zones I and II were completely evaporated in a dry nitrogen stream; the light orange colored powdery residues were dissolved in the minimum amount of benzene and crystallized at 50° in a centrifuge tube by cautious addition of methanol (50°). The samples were recrystallized in the same manner. The curves given in the figures were taken in the Beckman instrument. The maxima, as observed visually in the Zeiss Evaluating Grating Spectroscope (LoeweSchumm) and compared with corresponding data for d-carotene, were located as follows: Pigment I: 448, 422 m,u (in hexane); Pigment II: 468, 441 m,u; ,B-Carotene: 484, 454 m,u. Summary.-(,-Carotene when treated with boron trifluoride etherate for one minute yields mainly some of its cis forms; however, upon longer treatment several new pigments with shorter chromophores appear, two of which have been crystallized. * Contribution No. 1806. 1 Lewis, G. N., and Seaborg, G. T., J. Am. Chem. Soc., 61 1886 (1939). 2 Strain, H. H., Ibid., 63, 3448 (1941).