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The effects of cordycepin (3'-deoxyadenosine), an RNA synthesis inhibitor, on auxin-induced elongation in Avena coleoptile segments were studied with a position-sensing transducer. Cordycepin rapidly inhibited auxin-stimulated growth in the coleoptile segments whether added before, at the same time as, or after, the 2 mum auxin treatment. Midcourse additions of 100, 50, and 25 mug/ml cordycepin inhibited auxin-promoted elongation in an average of 18, 22, and 35 minutes, respectively. Additions of cordycepin before or at the same time as the auxin treatment partially inhibited the magnitude of the subsequent auxin-promoted growth but did not appreciably alter the latent period of the auxin response. It was concluded that if cordycepin is inhibiting the synthesis of RNA required for growth, the decay time for this RNA may be considerably shorter than that suggested in the literature from actinomycin D experiments. Preliminary kinetic evidence indicated that cordycepin does not inhibit auxin-induced elongation by acting as a respiratory inhibitor. Studies in mung bean shoot mitochondria demonstrated that cordycepin has no effect on respiration, respiratory control, or ADP/oxygen ratios.

Agonistic postures of red jungle fowl hens were studied during initial pair encounters using time and motion analysis of motion picture films. Postures of each hen were quantitatively determined by measuring the angles of the trunk, neck and tail to the horizontal. The neck angle showed highly significant differences (P

Two investigations were conducted (i) to determine a reliable procedure for obtaining loudness discomfort levels (LDL) and (ii) to observe the effects of frequency on the LDL. Three psychophysical methods were compared in the measurement of the LDL—a programmed method of constant stimuli, the method of adjustment, and a tracking method. The method of constants provided the most reliable judgments over six trials for a 1000‐Hz stimulus. The LDL was then measured utilizing the method of constants for pure tones at octave frequencies from 125 to 4000 Hz, and for a wide and narrow band of noise. The LDLs (in dB SPL) were highest at low frequencies (through 500 Hz) and relatively constant for 1000, 2000, 4000 Hz, and the wide‐band noise. The relatively high LDLs in the low frequencies are explained on the basis of difference in the intensity level for low frequencies measured in a conventional 6 cm3 coupler and that observed in the ear canal when a supra‐aural earphone is fitted on the head. When a correction is made for this difference the LDL results across frequency compared closely with results from loudness‐contour studies.

A series of potassium salts of organic anions were examined for their effect on the volume change of bean shoot mitochondria as measured by spectrophotometric light scatterings. A passive osmotic swelling (substrate independent) as well as an active osmotic swelling (substrate dependent) was shown with a series of organic anions. Both oxidizable substrates and non-oxidizable substrates induce swelling. The monocarboxylic acids including acetate, β-OH-butyrate, propionate, and pyruvate induce active swelling which is partially inhibited by the presence of an ATP generating system or the uncoupler 2,4-dinitrophenol (DNP). Dicarboxylic acids produce less extensive rates and amounts of active swelling. Moreover, the swelling induced by dicarboxylic acids is inhibited less completely by an ATP generating system or by DNP. Metabolizable substrates including citrate, pyruvate, glutarate, and α-oxo-glutarate induced swelling despite their poor rates or lack of oxidation. It was concluded that with these anions, penetration across the inner membrane as measured by osmotic swelling of isolated mitochondria is not the rate limiting step in their metabolism.

Monaural masked thresholds for clicks were established on three listeners. Masking functions across selected Δt's (the time disparities between the masker and click) were determined for four masking conditions in which the 70 dB SPL masker was a 500‐msec burst of random noise. These four conditions were (1) simultaneous masking, (2) forward masking (FM) at Δt's from 1 to 250 msec, (3) backward masking (BM) at Δt's from −1 to −250 msec, and (4) forward‐backward masking at selected Δt's between two 500‐msec noise bursts. In this last instance, the interval between bursts was varied to achieve seven interburst intervals (IBIs) ranging from 25 to 500 msec. Simultaneous masking was 3–5 dB less at the boundaries of the noise burst than it was in the middle of the noise burst. The functions for FM and for BM were not inversely symmetrical with one another, although both showed less threshold shift (TS) the further displaced in time the click was from the masker. The masking that appeared when the click was presented between two noise bursts was greater immediately adjacent to a noise burst than near the center of the IBI. During the longer IBIs (500–300 msec), the configuration of masking was equivalent to that of FM followed by BM, with slight excess appearing only in the interval 20–40 msec before the second noise burst. The configurations of FM and BM were preserved during the shorter IBIs (200–50 msec), but the TSs were greater than either type would have produced if operating alone. These TSs became larger as the IBI was shortened, so that the brief IBIs were permeated with large amounts of masking even in the middle of the IBI. This cumulation of masking was so great when the IBI was reduced to 25 msec that the masking function lost the configuration characterizing the longer IBIs. The TSs during shorter IBIs exceeded the sum of the residual effective powers of FM and BM.

A series of experiments was performed to study the upward-spread-of-masking phenomena as it pertains to pure-tone and speech stimuli. In the initial two experiments, three maskers were employed over a 40–60-dB intensity range. They included a wide band (50–5500 Hz), a speech spectrum (50–1000 Hz), and a narrow-band (50–950 Hz) noise. All filter slopes were 48 dB/octave, except for the upper slope of the speech-spectrum noise that was 6 dB/octave. In the first experiment, pure-tone thresholds obtained by a tracking procedure revealed no spread of masking when the wide-band and speech-spectrum maskers were used. Substantial spread-of-masking effects, characterized by nonlinear threshold increments outside the spectrum of the masker, were observed with the narrow-band masker. The second experiment included three types of speech stimuli (PBs, spondees, and synthetic sentences) under the same mask conditions used with the pure tones. Threshold shifts observed for the wide- and speech-spectrum maskers were linear with the masking intensity level. However, increased shifts, attributable to spread of masking, were observed with the narrow band and progressed nonlinearly as a function of the masking level. Finally, two additional experiments, performed with two different narrow-band maskers and spondee words, provided insightful information regarding the effects of the spread of masking on speech stimuli.

This experiment investigated Inglis' hypothesis that dichotic verbal material presented to the right ear is produced correctly more often than the stimuli presented to the left ear because individuals respond initially to the material at the right ear and thus are subject to greater trace decay on that presented to the left ear. Two types of dichotic materials (digits and nonsense syllables) were used. The digits and nonsense syllables were presented in quiet and also in a background of white noise. Different groups of 24 young adult subjects were used in four basic experiments. The subjects in each experiment were tested under the following conditions: (1) no bias; (2) right bias (instructed to respond to right ear presentations initially), and (3) left bias (instructed to respond to left ear presentations initially). Results of the no bias conditions suggest a tendency for more correct responses from right ear than from left ear presentations (even though order of response was divided almost equally between the ears). However the superiority is only a modest statistical one. When instructional bias was imposed, the results always favored the ear of the instructed bias.

Monaural intelligibility functions for spondaic and monosyllabic words and identification functions for synthetic sentences were obtained for 14 experimental conditions of masking by random noise. The noise was presented continuously and interrupted or modulated (−14‐dB interburst ratio) at rates of 1, 10, and 100 interruptions per second. The intensity levels of the maskers were 50 and 90 dB SPL. Results demonstrated that (1) masking effectiveness decreased for spondees and sentences as the interruption rate decreased; (2) the greatest release from masking for monosyllabic words was found during the 10‐ips condition at favorable S/N ratios; however, at the more unfavorable S/N ratios, greater release from masking was observed during the 1‐ips condition; (3) greater release from masking occurred for interrupted than for comparable modulated noise conditions. The possible effects of the interaction between the type of speech material and forward and backward masking during the silent interval between noise bursts is discussed.

The relationships between earphone and sound-field speech audiometry have been poorly defined, primarily as a result of the uncertainties of performing sound-field speech testing with precision and validity. This article provides guidelines for specifying the intensity level of spondee words at threshold for loudspeakers at azimuth positions of 0° and 45° from the listener’s head. A technique for calibrating the speech stimulus through loudspeakers is suggested. Other related problems, such as the threshold differences between MAP and MAF, and differences in the physical characteristics of loudspeakers and audiometric test rooms are discussed.

A series of five experiments was conducted to investigate the effects of spatial separation of speakers on the intelligibility of spondaic and PB words in noise and the identification of synthetic sentences in noise and competing message. Conditions in which the spatial location of the speakers produced interaural time differences ranked highest in intelligibility. The rank order of other conditions was dependent on the S/N ratio at the monaural near ear. Separations of only 10° between the speech and noise sources resulted in measurable changes in intelligibility. The binaural intelligibility scores were enhanced substantially over the monaural near ear results during conditions where an interaural time difference was present. This result was observed more effectively when spondaic words or sentences were used rather than PB words. The implications of this result were related to the interaural time difference and the frequency range of the critical information in the primary message. Although the initial experiments were facilitated by recording through an artificial head, almost identical results were obtained in the final experiment when subjects were tested in the sound field.

The ultrastructure of the lichen Physcia aipolia was studied in the desiccated and hydrated states. No significant structural variation between these 2 states was noted for the fungus. The fungus contains unusual ellipsoidal structures heretofore unobserved. Their possible role in the formation of membrane is discussed. The plasmalemma of the fungus is convoluted while that of the alga is smooth. The convoluted projections have a "double-unit membrane" structure similar to fingerlike projections of the ellipsoidal bodies. With Os O4 fixation crystals are pre-served, enclosed in unit membrane sacs which extend to the convoluted surface. The pyrenoid of the associated alga does not produce starch in the desiccated condition, and electron-dense granules are present in the matrix associated with chloroplast lamellae which enter this area. In the hydrated condition, the alga contains abundant starch in the pyrenoid region, and the electron-dense granules are displaced to the preriphery of the pyrenoid starch. Mitochondria, endo-plasmic reticulum, and ribosomes are not clearly defined in the desiccated state while they are more so in the hydrated condition. Golgi bodies were not observed in the either lichen component. Finally, no fine structural basis for indicating an exchanged of materials between the alga and fungus was observed except, possibly, the convoluted plasmalemma of the fungus and the smooth plasmalemma of the alga.

The effects of a series of univalent cation salts on certain properties of pyruvate kinase, including sedimentation behavior, perturbation of tryptophan residues, and stability of the enzyme, have been investigated. Ultraviolet difference spectra of pyruvate kinase in 0.1 m solutions of activator univalent cation chlorides (K+, NH4+, or Na+) in comparison with enzyme in 0.1 m nonactivator univalent cation chlorides (Li+, or trimethylammonium ion, or tris(hydroxymethyl)aminomethane cation) were determined. Tryptophanyl difference spectra with absorbance peaks at 286 mµ and 295 mµ were obtained under these conditions only when the nonactivator cation Tris+ was included in the experiment. Difference spectra of pyruvate kinase in 0.1 m KCl versus enzyme in 0.1 m LiCl with or without various substrates and Mg++ in the reaction showed no absorbance differences characteristic of the perturbation of tryptophan residues. In contrast, different comparisons of univalent cation chlorides at concentrations of 0.5 to 0.86 m showed capacities to perturb tryptophan residues of pyruvate kinase that were inversely correlated with the known capacities of univalent cations to activate the enzyme. A study of the stability of pyruvate kinase in a series of univalent cation salt solutions showed a positive correlation between the capacities of cations to protect against inactivation and known capacities to activate. In addition to the effect of univalent cations, different anion species influenced the extent of perturbation of tryptophan residues and the stability of the enzyme. The perturbation of the tryptophan residues in the presence of Tris+ (cation) was inhibited by the addition of multivalent anions, phosphate, arsenate, and sulfate. Also, the enzyme consistently showed greater stability in buffer solutions containing the multivalent anions phosphate, arsenate, or sulfate than in buffer solutions in which the predominant anions were acetate, chloride, or nitrate. The sedimentation behavior of pyruvate kinase in the ultracentrifuge was not greatly affected by type of univalent cation salt in the environment, with the exception that the s020,w value was lower in a solution of Tris-Cl than in other salts.

The changes in masking for spondee words that result from varying both the level and the interruption rate of a white‐noise masker were studied with 14 normal hearing subjects and 14 subjects with sensorineural hearing loss diagnosed as resulting from cochlear otosclerosis. The masker was a white noise and was presented monaurally at either 90 dB sound‐pressure level (SPL) or 30 dB sensation level (SL). It was either continuous or was pulsed at rates of 1, 10, or 100/sec with 50% duty cycle. During the burst‐off half of each cycle, the noise was either dropped 14 dB in level or was fully interrupted. The masked speech reception threshold (SRT) was not improved re the masked SRT in continuous noise when the 30 dB SL masker was pulsed 100 times/sec. Reduction in masking was observed under all other circumstances of cycling the noise. This reduction was more pronounced when the noise was completely interrupted rather than only modulated by 14 dB, when the masker was at its higher level (90 dB SPL as opposed ...

Venn, Grant. Man, Education, and Work. Washington, D.C.: American Council on Education, 1964. xiv + 184 pp. $1.50. Barlow, Melvin L., editor. Vocational Education. Sixty‐fourth Yearbook of the National Society for the Study of Education, Part I. Chicago: the Society. (Scheduled for publication, January 1965).

The procedure for establishing speech reception thresholds (SRTs) with spondee words as proposed by Tillman and Olsen is described, with a suggested modification of that protocol. These systemized techniques incorporate 2- and 5-dB intensity decrements with two and five words being presented at the respective intervals. Threshold derivations from these two procedures are discussed in terms of a long-standing statistical precedent, the Spearman-Kärber method. Our data from 100 ears tested validate the procedures. We conclude that these techniques are clinically practical and suggest that the procedures be considered for adoption as standardized clinical methods, if additional data support their validity and reliability.

Two studies have been conducted to measure the loudness discomfort levels (LDLs) for subjects with normal hearing. First, the LDL for a 1000‐Hz stimulus was measured utilizing the method of constant stimuli, the method of adjustment, and a tracking method. The method of constants provided the most reliable judgments among subjects over six trials. In the subsequent study, LDLs were measured utilizing the method of constants for pure tones at octave frequencies from 125 through 4000 Hz and for two bands of random noise. LDLs (in dB SPL) varied as a function of the stimulus employed. LDLs were highest at low frequencies (through 500 Hz) and relatively constant for 1000, 2000, and 4000 Hz and for the wide‐band noise.