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Ultraviolet absorption studies of aqueous solutions of the tosylate, sulfate, perchlorate, and tetrafluoroborate salts of Ag+ show that three bands at 225,210, and 192 nm are attributable to isolated Ag+ ions. These bands are believed to emanate from the parity-forbidden (4d95s) 'D -(4d'O) 'S excitation of Ag+, subject to ligand field effects of the primary hydration sphere. These bands have essentially temperature-independent oscillator strengths, which suggests that the static ligand field does not have a center of inversion. A tetrahedral arrangement of four water molecules in the primary hydration sphere, proposed earlier as a result of ESR studies, is consistent with these temperature-independent optical data. These same Ag+ bands appear (red shifted) in methanol solutions, which is again consistent with ESR studies showing a primary solvation sphere of four molecules and suggests that these molecules are arranged tetrahedrally. The absence of these bands in acetonitrile solutions corroborates the Dewar-Chatt bonding mechanism proposed to explain the preferential solvation of Ag+ by acetonitrile over water. The oscillator strength of the 225-nm band increases dramatically and linearly as the mole percent of ethanol in water/ethanol solvent is increased. These observations suggest that solvation of Ag+ by ethanol has a local symmetry that is less than tetrahedral and that the "preferential solvation" effect observed at 13 mol 70 ethanol by ESR is attributable to a polycrystalline glass transition. IntroductionThe ultraviolet spectrum of aqueous Ag+ has received very little attention, although the structure of the primary hydration shell of Ag+ has been studied intensively. This paper presents and characterizes the ultraviolet absorption bands of aqueous Ag+ at wavelengths >185 nm. The multiplet structure and the temperature dependence of the oscillator strength are interpreted in terms of ligand field effects as they relate to the symmetry of the primary hydration shell. A comparative study of this ultraviolet Ag+

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Lobster agglutinins, which were shown in the preceding paper to be structurally heterogeneous, were analyzed to determine the chemical characteristics of their binding to erythrocytes. The analysis included agglutinin inhibition studies with simple saccharides, enzyme treatment of erythrocytes, studies of absorption of agglutinins, and microagglutinate preparations. One agglutinin (LAg-2) was shown to contain an A-acetylgalactosamine (GalNAc) site which bound to GalNAc residues on mouse, horse, and hamster erythrocytes. Another agglutinin (LAg-1) contained an V-acetylneuraminic acid (NANAc) site which bound to studied the chemistry and biology of the agglutinins of a representative invertebrate, the lobster, Homarus americanus, in order to more fully understand how invertebrates defend themselves against foreign pathogens. In the preceding paper (Hall and Rowlands, 1974) we described experiments which demonstrated structural heterogeneity of invertebrate agglutinins. Two agglutinins differing in molecular weight, electrophoretic mobility, antigenic properties, and erythrocyte binding specificity were purified from lobster hemolymph. This finding of heterogeneity in invertebrate agglutinins provides evidence for the hypothesis that invertebrate agglutinins function as recognition factors for a variety of foreign substances leading to their phagocytosis and detoxification. The agglutinins would, in this respect, be functionally analogous to vertebrate antibodies.The present communication describes experiments conducted to investigate the chemical structures involved in agglutinin-erythrocyte binding. From these experiments we could determine if differences between the two purified agglutinins included heterogeneity of erythrocyte binding specificity as well as the structural heterogeneity described previously (Hall and Rowlands, 1974). Binding specificity heterogeneity of agglutinins would be required to sustain the hypothesis that agglutinins function as recognition factors. Materials and MethodsAgglutinin Preparation. Lobster agglutinins (LAg-1 and LAg-2) were purified from native hemolymph by ammonium sulfate precipitation, pevikon block electrophoresis, and gel t From the