Major mechanisms in formation of spodic horizons

Current explanations of the formation of spodic horizons do not accomodate all features of the horizons in their natural state. In this paper, a more complete explanation of major mechanisms is proposed, using two principles of colloid chemistry: (1) organic substances may form hydrophylic colloids with surface charges, and (2) the hydrophylic character and negative surface charges determine the dispersibility of the colloids. The hydrophylic character is due to the presence of hydrophylic radicals as parts of the organic compounds in soils. The surface charges are the result of dissociation of -COOH and possibly phenol-OH radicals.The neutralization of the surface charge can in principle occur: (1) through electrostatic or physical adsorption and (2) through chemisorption. The first case is typical for monovalent alkali cations. The adsorbed cations are distributed in a double layer, which favours dispersion. Chemisorption occurs mostly with polyvalent cations. This process corresponds in reality to the formation of organo-metallic compounds. It results in a relatively complete disappearance of the double layer and in the formation of large immobile “polymerized” organo-metallic compounds. Because these compounds contain much hydrophylic water, they form a gel. Transition into the solid state is accompanied by the loss of most of the hydration water. The dehydration may be induced by a decrease in thickness of the double layer. At a certain stage of the dehydration process, Van der Waals bonds and protonic bridges can form and bring about a certain degree of hydrophoby.In soils, mobile organic substances are formed during breakdown of plant remains. If at the top of the mineral soil enough polyvalent cations, especially Al and Fe, are available, the mobile organic substances formed are immobilized immediately and no migration occurs. In case insufficient amounts of Al and/or Fe are available to completely immobilize the mobile compounds, these cations are complexed by the mobile compounds and transported downward. Immobilization may occur at some depth through supplementary fixation of cations, through dessication or on arrival at a level with different ionic concentration.In nature, spodic horizons range from loose, with many roots, to very cemented with few roots. These differences can be related to changes in microstructure. Loose spodic horizons have a predominance of polymorphic pellets and aggregates, whereas organans or monomorphic coatings prevail in cemented horizons. The former horizons have many features suggesting major biological influences during their formation, viz., high numbers of roots, thorough mixing of the organic units with clay and silt, the presence of pedotubules and relatively young mean residence times. The latter horizons have features consistent with organo-metallic compounds immobilized in a gel-state, viz., the coatings are strongly cracked, indicating the transition of a gel into a solid; they contain much Al or Al plus Fe but very little or no Si, and the mean residence time is considerably higher than in loose horizons.The two processes seem to operate simultaneously during the formation of spodic horizons and their relative intensities determine the composition of each spodic horizon at any moment in its evolution. As long as the biological activity predominates, the horizon remains loose; if the accumulation of mobile organo-metallic compounds starts to prevail, the horizon is gradually cemented and fossilized.     

Analysis of fat-soluble vitamins. XXIII. High performance liquid chromatographic assay for vitamin D in vitamin D3 and multivitamin preparations.

Vitamin D is determined in preparations containing other fat-soluble vitamins by high performance liquid chromatography (HPLC). The unsaponifiable residue is extracted and separated from interferences by reverse phase chromatography; the fraction corresponding to vitamin D3 is collected and quantitated using normal phase chromatography (amylalcohol-n-hexane as mobile phase) by measuring the vitamin D3 and pre-vitamin D3 peaks at 254 nm. Previtamin D3 content is calculated as vitamin D3 with a conversion factor (determined on the equipment used). Application of the method to vitamin AD3 mixtures in oils gives 98-102% recovery. The reproducibility, using an external standard, is 2-3%, calculated as the coefficient of variation; with an internal standard, the coefficient of variation is 1-1.5%. The method measures potential vitamin D3 content in preparations containing greater than or equal to 200 IU/g in the presence of all known vitamin D3 isomers, vitamin A, and vitamin E.     

Estimating the abundance and diversity of butterflies

Concern about the apparent decline in butterfly populations has led to projects designed to obtain quantitative information on their abundance and diversity. Three methods of sampling communities of butterflies are suggested, and the use of a diversity index, β, is recommended. This index gives an estimate of the probability that an individual sampled at random from a community will be different from the previous individual sampled. Change and stability in diversity can be used as a guide for conservation and management programmes.     

Ergänzungen zum Nachweisverfahren Des Y-Virus in der Kartoffelknolle

Zusammenfassung Der Nachweis des Kartoffel-Y-Virus im Gewebeanschnitt von Licht- und Dunkelkeimen stimmte überein und war im Vergleich zum Anschnitt des Kronenendes in den Herbst- und Wintermonaten sortenweise ungünstiger. In kéimenden Kartoffelknollen nach Winterlagerung und 3-w?chiger Vorkeimung bei 20 C hatten Verwundungen keinen Einflu? auf die Virus-aktivit?t; sie war in isolierten Kronenendestüken gegenüber ganzen Knollen erh?ht. Die Virusaktivit?t nahm in Kartoffelknollen w?hrend des Vegetationsablaufes mit fortschreitender Entwicklung bis zum Eintritt der Keimruhe st?ndig ab.

---

Summary In supplementary experiments for the identification of the Y virus in potato tubers (Nienhaus: 1960, 1961/62) the question arose as to which was the most reliabie test for virus Y,viz. rubbing the leaf of the A₆-test plant with the cut surface of a sprout or with the surface of a section cut from the rose end of the tuber. The inhibitory effect of expressed sap from sprouts produced in light or darkness on the development of local lesions in leaves of A₆ averaged 93% and 94%, when two volumes of sap were mixed with one volume of virus suspension. The sprouts of theAckersegen, Capella, Dt. Erstlinge andMaritta varieties were particulaly rich in inhibiting material (Table 1) No differences in the number of local lesions occurred when cut surfaces taken from different parts of infectious sprouts produced in light or darkness were tested (Table 2), but in six varieties tested the virus activity in autumn and winter was usually higher in the cut surface of the rose end than in that of the sprouts grown in light. It was very low in the rose end of tubers after unusually long storage (Table 3). When the tubers were wounded before a 3 week's storage at 20°C, after the end of the dormant period in spring no activation of the virus was found, but the activity was higher in isolated pieces of rose end than in whole tubers (Table 4). The virus activity decreased in growing tubers during the vegetation process and in prematurely harvested tubers during subsequent storage at 20°C. There is assumed to be an inactivating process with increasing ripening of the tubers; this process becomes retrograde again when the dormant period is broken during winter storage (Table 5).

---

Résumé Dans des essais complémentaires d'identification du virus Y dans le tubercule de la pomme de terre (Nienhaus; 1960, 1961/62), nous avons recherché lequel des deux tests permettrait de démontrer avec plus de certitude la présence du virus Y: la friction du limbe de la plante test A₆ avec la coupure d'un germe ou avec celle au sommet du tubercule. L'action inhibitrice des jus exprimés de germes développés à la lumière et dans l'obscurité sur l'apparition de lésions sur les feuilles de la plante test A₆ atteignait les moyennes respectivement de 93 et 94% en cas de mélange de deux tiers de jus de germes avec un tiers de suspension de virus. Les germes des variétésAckersegen, Capella, Dt. Erstlinge etMaritta étaient particulièrement riches en substance inhibitrice (Tableau 1). En frictionnant les feuilles avec des coupures à différentes régions des germes infectieux développés à la lumière et dans l'obscurité, il ne fut constaté aucune différence du nombre de lésions (Tableau 2). Cependant, chez 6 variétés étudiées, il fut observé qu'en automne et en hiver, l'activité du virus dans la coupure au sommet du tubercule souvent etait plus grande que dans celle du germe développé à la lumière. Mais l'activité dans la coupure au sommet du tubercule était extrémement basse si les tubercules avaient été conservés pendant un temps excessivement long (Tableau 3). Si les tubercules étaient blessés avant un stockage de trois semaines à 20°C, au printemps aprés la fin de la dormance, aucune activation du virus dans le tubercule n'était démontrée, mais l'activité dans des morceaux de sommet isolé, était plus grande que dans le reste du tubercule (Tableau 4). Dans le tubercule en développement, l'activité du virus diminuait pendant la phase terminale de la végétation: dans les tubercules récoltés trop t?t, il en était de même durant un stockage prolonge à 20°C. Il est supposé qu'à mesure que le tubercule m?rit, il se déroule un processus d'inactivation, lequel régresse à son tour après interruption de l'état de dormance pendant le stockage d'hiver (Tableau 5).