COMPARATIVE STUDIES ON RESPIRATION : IX. THE EFFECTS OF ANTAGONISTIC SALTS ON THE RESPIRATION OF ASPERGILLUS NIGER.

1. In the presence of 0.05 per cent dextrose the respiration of Aspergillus niger is increased by NaCl in concentrations of 0.25 to 0.5M, and by 0.5M CaCl₂. 2. Stronger concentrations, as 2M NaCl and 1.25M CaCl₂, decrease the respiration. The decrease in the higher concentrations is probably an osmotic effect of these salts. 3. A mixture of 19 cc. of NaCl and 1 cc. of CaCl₂ (both 0.5M) showed antagonism, in that the respiration was normal, although each salt alone caused an increase. 4. Spores of Aspergillus niger did not germinate on 0.5M NaCl (plus 0.05 per cent dextrose) while they did on 0.5M CaCl₂ (plus 0.05 per cent dextrose) and on various mixtures of the two. This shows that a substance may have different effects on respiration from those which it has upon growth.     

Detection of Polyhedra from Insect Virus Diseases on Filter Membranes

Polyhedra filtered directly from the air or from aqueous suspensions by means of Millipore filter membranes, are stained on the membranes as follows: To a microscope slide mount consisting of a small piece of membrane filter on which the polyhedra are retained, are added 1 drop of a 1:4 dilution of saturated aqueous picric acid and 1 drop of staining solution: 0.1 gm of naphthol blue-black, C.I. 246 (Hartman-Leddon Co.) dissolved in a mixture of 98% methanol, 5; distilled water, 4 and glacial acetic acid, 1—parts by volume (Grosset et al. Proc. Soc. Exp. Biol. Med., 97, 72-7, 1958). The slide is placed on a hot plate at 600° C (dull red heat) until evaporation takes place and the filter membrane turns blue. Before the membrane begins to burn, the slide is removed and allowed to cool. For stain-sensitive polyhedra the above procedure is adequate. However, for stain-resistant polyhedra it is sometimes necessary to heat the mount with the picric acid alone, followed by the stain and a second heating. For highly resistant polyhedra it can be necessary to heat the untreated mount, follow with a second heating with double strength picric acid; and follow this with a third heating with stain. Revealing the polyhedra, stained dark lilac-blue or green blue, for bright-field illumination, is effected by clearing the membrane with media such as Euparal, aniline, linseed oil or clove oil. This method is suitable for the detection and observation of polyhedra dispersed in nature. Groups of different size can be separated by graduated pore-size filtration during concentration and purification. Enumeration and morphological studies are thereby facilitated.     

Studies on Foliar Penetration: IX. PATTERNS OF PENETRATION OF 2,4-DICHLOROPHENOXYACETIC ACID INTO THE LEAVES OF DIFFERENT SPECIES

The comparative patterns of penetration of 2,4-dichlorophenoxyaceticacid (2,4-D) into the leaves of Phaseolus vulgaris, Zea mays,Pisum sativum, Beta wlgaris, Helianthus annuus and Gossypiumhirsuium have been examined. Save for Zea and Gossypium where there is little change withthe stage of leaf development the rates of penetration intoboth surfaces decrease as the leaf matures. The relative ratesare dependent on the species and the age of the leaf but thereare differences between the surfaces. In Phaseolus the characteristicsof primary leaves differ from those of trifoliate leaves sinceonly in immature trifoliate leaves is penetration into the adaxialsurface greater. In darkness the rates of penetration over 24 h remain constantor fall but slightly for all species. Light consistently promotespenetration but with Beta there is a lag before entry is acceleratedinto the abaxial surface as has previously been reported foryoung primary leaves of Phaseolus. For the remaining speciesthe courses of penetration in both light and darkness into bothsurfaces follow similar patterns. As the light intensity isincreased entry is enhanced but the limit of response variesbetween species, between surfaces within species, and in trifoliateleaves of Phaseolus with age. For the six species the order of the relative rates of entryis closely similar whether comparisons are made in light ordarkness or between abaxial and adaxial surfaces: viz. Zea >Helianthus > Phaseolus (primary) > Phaseolus (trifoliate)> Pisum = Beta = Gossypium. The observed specific differencesare discussed in relation to variations in leaf structure, theproperties and thickness of the cuticle and the physiologicaland metabolic processes which influence transport within theepidermal tissues after it has passed through the cuticle bydiffusion.     

THE KINETICS OF PENETRATION : IX. MODELS OF MATURE CELLS

To imitate cells which have ceased to grow we have made models in which artificial sap is separated from the external solution by a non-aqueous layer (representing the protoplasm). A stream of CO₂ is bubbled through the artificial sap to imitate its production by the living cell. Potassium passes from the external solution through the non-aqueous layer into the artificial sap and there reacts with CO₂ to form KHCO₃: its rate of entrance depends on the supply of CO₂. Hence the increase of volume depends on the supply of CO₂ (as is probably true of the living cell). By regulating the supply of CO₂ and the osmotic pressure we are able to keep the volume and composition of the artificial sap approximately constant while maintaining a higher concentration of potassium than in the external solution. In these respects the model resembles certain mature cells which have ceased to grow.     

鸟类核型研究Ⅸ，画眉亚科17种

本文报道了雀形目（翁＋鸟）科画眉亚科17种类核型,臂间倒位和小染色体缺失在该亚科进化中起重要作用。在核型比较基础上结合古地理以及生态资料对该类群的起源和进化作了初步探讨。     

Growth Inhibition Studies: I. MEASUREMENT OF THE EFFECTS OF INHIBITORS ON THE GROWTH RATE OF FLAX SEEDLINGS

A method for measuring the rate of growth of small seedlingsunder special conditions suitable for inhibition and reversalstudies is described, and its use is illustrated in studiesof the inhibitory action of a variety of chemical substances. The limitations imposed, in such studies, by the osmotic pressureof the test solutions have been examined in the case of flaxseedlings.     

Further Studies on a Tomato Black Ring Virus Isolate from Artichoke

An isolate of tomato black ring virus from artichoke (TBRV-A) was compared biologically, physico-chemically and serologically with three strains of the virus, i.e. TBRV-potato bouquet (TBRV-BU), TBRV-beet ringspot (TBRV-W), and TBRV-celery yellow vein (TBRV-Ce). Cytopathic effects of TBRV-A infection in C. quinoa and its relationships with two strains of artichoke Italian latent virus (AILV-S and AILV-G) were also investigated. Physical properties in vitro, sedimentation coefficients and molecular weight of protein subunits and nucleic acid species of TBRV-A were very similar to those known for TBRV. In serological tests, TBRV-A appeared more closely related to TBRV-W (SDI = 1) than to TBRV-Ce and TBRV-BU (SDI = 2–3). Finally, TBRV-A was very, distantly related to AILV-S and AILV-G (SDI = 11–12).     

STUDIES ON THE FORMATION AND SPROUTING OF AERIAL TUBERS IN BEGONIA EVANSIANA ANDR. IX. EFFECTS OF TEMPERATURE ON TUBER INITIATION

The effects of temperature on the aerial tuber initiation ofBegonia evansiana Andr. in response to short-day condition wereinvestigated. Tuberization was inhibited by relatively low and high temperaturesduring the dark periods. The optimal nycto-temperature was 23°and hardly changed by not only photo-temperature but also daylength.There were two temperature-sensitive phases in the dark period;one came at its beginning, and the other later one came at varioustimes depending on the length of the light period. Low temperatureswere effective at both of these sensitive phases, but high temperatureshad an influence only at the later one. Photo-temperatures exerted little influence on tuberizationunder the sub-optimal daylength, but the lower temperatureswere promotive under longer daylengths. (Received August 2, 1963; )