Blue light-induced absorbance changes were measured from differentially centrifuged membrane fractions from dark-grown coleoptiles of Zea mays L., and mycelia from an albino mutant of Neurospora crassa Actinic irradiation caused changes in absorbance consistent with a flavinmediated reduction of a b-type cytochrome. Both corn and Neurospora showed similar light-minus-dark difference spectra, dose response curves, and kinetics of dark recovery after irradiation. The photoreducible cytochrome system from Neurospora showed the same distribution as the activity of a sodium-stimulated adenosine triphosphatase, thought to be a plasma membrane marker, in differential centrifugation experiments. The fraction showing the absorbance change did not co-sediment with the mitochondria, nor with the endoplasmic reticulum. Comparison of absorption spectra of fully oxidized, partially reduced, and fully reduced preparations showed that approximately a 30% reduction of the cytochromes involved with the process was needed to obtain the lightinduced absorbance changes.There is currently a substantial body of literature concerning the effects of blue light on biological processes in higher plants and fungi. Only recently has any real progress been made toward the identification of the blue light photoreceptor associated with these effects (see ref. 6). Poff and Butler (16) ation in that report was the separation of soluble from pelletable components. Mufioz and Butler (15) did report light-inducible Cyt reduction in soluble extracts of Neurospora, but they studied supernatant rather than pelletable activity, observed reduction both of Cyt b and c, and had to add FMN or FAD in order to observe the reaction. It seems likely that they were studying the same phenomenon as Schmidt and Butler (20) who found photoreduction of Cyt c in the presence of added flavins in a model system. Widell and Bjorn (24) have reported light-induced A changes in another higher plant system, intact wheat coleoptiles, but the responses measured were not the same as those monitored by Briggs (5) or Munioz and Butler (15).The purposes of the study reported here were: (a) to isolate and characterize partially purified membrane fractions of Neurospora with a photoreduction system similar to that found in intact mycelia by Munoz and Butler; (b) to study further the blue light-induced A changes found in corn membrane fractions and compare them to similar changes found in Neurospora; and (c) to determine qualitatively the redox state necessary for observation of these changes. A preliminary account of these studies has appeared elsewhere (3, 7). To prepare the mycelia, approximately 70-ml liquid suspensions were made of the 7-day-old agar cultures, and added to a 2,000-ml Erlenmeyer flask, filled with 1,000 ml of liquid medium (the same as solid medium except dextrose instead of sucrose, and no agar). The cultures were grown aerobically in the dark at 30 C for 24 hr at 250 rpm in an incubating rotary shaker (New Brunswick Scientific,. MATERIALS AND METHODSA...

The photosynthetic rates of intact sporophytes or gametophytes of the fern Todea barbara grown in sterile culture were measured using an infrared gas analyzer. We have overcome some of the attendant difficulties of comparing sporophyte and gametophyte photosynthesis by using cultured sporophytes and gametophytes in sterile tube culture where conditions can be controlled and the two life cycle stages compared under identical conditions. The entire plant is used in both gametophyte and sporophyte gas exchange measurements, thereby making the comparison of the two more physiologically meaningful in the sense that the root system and stem are included as an integral part of the sporophyte plant being measured. MATERIALS AND METHODSCultures of Todea barbara L., originally obtained from R. H. Wetmore, were grown on a medium (7) consisting of 6.25 mm NH4NO3, 1.47 mm KH2PO4, 0.81 mM MgSO4, and 0.51 mm CaCl2, supplemented with 0.033 mm ferric citrate, 1 ml/l trace element solution (8), and 0.8% (w/v) agar (pH 5.5). Sporophytes and gametophytes were separated from mixed cultures, grown for several weeks, and transferred to slightly slanted tubes of fresh medium where they were allowed to grow for at least 2 weeks before measurements were taken. Gametophytes in sterile culture are similar in size and morphology to those in nature. Cultured sporophytes are much smaller than naturally occurring plants and their leaves tend to be juvenile in form. However, they have roots, stems, and leaves in roughly the same proportion as naturally occurring sporophytes. Sporophyte tubes contained one complete plant with roots and six to eight leaves, the largest leaf being 3-4 cm in length. Gametophyte tubes contained several gametophytes which covered the surface of the agar. Cultures were maintained at 22 C and a combination of cool-white fluorescent and incandescent lamps at an intensity of 160 ,uE m-2 s-' was used for illumination on a 12-h on, 12-h off cycle. Cultures were grown in 25-mm tubes in which the agar surface was slanted so that they could be illuminated at the same angle during growth and during the measurement of photosynthesis.Photosynthetic rates were determined by measuring the change in CO2 concentration in a tank air mixture (0.033% CO2, 21% 02,

FREEBERG, JOHN A. (Lehigh U., Bethlehem, Pa.) Lycopodium prothalli and their endophytic fungi as studied in vitro. Arner. Jour. Bot. 49(5): 530-535. Illus. 1962.-A fungus isolated from a prothallus of Lycopodiurn obscururn is described. This fungus was found to invade prothulli of L. cornplanaturn, L. selago and L. cernuum, The association of the fungus with L. conrplanalum in vitro is such that the form of the prothallus as well as the general area of fungus invasion approaches that of prothalli in nature. Prothalli grown with the fungus on a starch medium wen' found to gain in weight more rapidly than prothalli grown alone. This suggests that the presumed symbiotic relationship in nature can be duplicated in vitro under certain conditions.

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Roots of the Osmundaceae differ from most ferns in having more than one apical cell. The size of the apical initial group, which includes cells that are considered to be apical cells, varies directly with root diameter in Osmunda regalis L. Mitotic indices were 6.63% for apical cells, 7.45% for the entire apical group, 6.25% for distal derivatives, and 7.15% for developing cortical cells. Cytophotometric measurements of Fuelgen‐stained nuclei indicated no endopolyploidy in the populations of cells studied. These findings demonstrate that there is no quiescent center in the roots of O. regalis.