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The forest annual, Amphicarpaea bracteata L. can reproduce via aerial chasmogamous, aerial cleistogamous, and subterranean cleistogamous flowers. Both plant size and light intensity influenced the utilization of the three modes of reproduction. chasmogamous and aerial cleistogamous flower number and the ratio of chasmogamous flowers to the total number of aerial flowers increased with plant size. The latter demonstrated a shift to xenogamy and outbreeding in larger plants. Light intensity indirectly influenced reproductive modes through its infuence on plant size. Seed set by both types of aerial flowers was low and unrelated to plant size. Subterranean seed number and the total dry weight of subterranean seeds per plant increased with size. The subterranean seeds of Amphicarpaea bracteata are thirty-four times larger than the aerial seeds (fresh weight). Under field conditions, subterranean seeds had greater germination after one year than acrial seeds. The plants arising from subterranean seeds were significantly larger and more fecund than those from aerial seeds. Seeds produced by aerial cleistogamous, hand selfpollinated chasmogamous, and naturally pollinated chasmogamous flowers had equivalent germination rates and produced plants of equal size and fecundity. This suggests that the outbred progeny from chasmogamous flowers have no advantage over the inbred progeny from aerial cleistogamous flowers.

We investigated changes in the reproduction of Pastinaea sativa which result in compensatory reproduction when herbivore feeding destroys the first infloresence produced. Late developing infloresences of damaged plants produce more flowers and a greater proportion of hermaphroditic flowers than late developing infloresences of control plants. In damaged plants the proportion of hermaphroditic flowers producing seeds in late developing infloresences also increases. These effects are due to the mechanical damage resulting from larval feeding. The herbivore acts as a mediator in a number of important plant processes affecting fecundity, including expression of sex.

Im Jahre 1964 wurden im Grenzbereich von Österreich und der Tschechoslowakei magnetische Messungen durchgeführt. Zweck dieser Messungen war es, die Bezugsniveaus der beiden Landesaufnahmen anzugleichen und einheitliche geomagnetische Karten für diesen Teil Mitteleuropas zu erstellen. In einem weiteren Schritt wurde durch die “Methode der Isobänder” der ausgeglichene Verlauf vonD, H undZ bestimmt. Für die Vertikalkomponente wurde das Normalfeld hergeleitet, damit in der Folge regionale magnetische Anomalien gefunden werden könnten. Als besonders interessant kann die sogenannte “Mährische Anomalie” mit einer Streichlänge von über 100 km bezeichnet werden.

The effect of seed mass on emergence, survival, and recruitment to flowering in Pastinaca sativa, a species that produces progressively smaller seeds on the primary, secondary, and tertiary umbels, was analyzed in two field experiments begun in 1982 and 1983. In both experiments, overall emergence was positively related to seed mass, but the effects of seed mass on emergence in fall cohorts was relatively unimportant. Initial seed mass was positively related to overwintering survival in one experiment but not the other, possibly due to differences in winter conditions. Survival to flowering was positively related to seed mass in the 1982 experiment but negatively related to seed mass in the 1983 experiment. This difference is due to greater survival of seedlings from small seeds during short‐term droughts, a previously unrecognized advantage of small seeds. Because of differences in survival in the two experiments, recruitment (number of flowering plants/number of seeds sown) was positively related to seed mass in the 1982 experiment but not in the 1983 experiment. The effects of timing of emergence on survival generally disappeared within 12 months. Our results suggest that the relationship between initial seed mass and recruitment in Pastinacarepresents a distribution of outcomes, variable from year to year. However, because short‐term droughts in Iowa are common, we hypothesize that in most years, seed mass has little impact on recruitment. Furthermore, small scale heterogeneity may often overwhelm any potential effects of seed mass and timing of emergence on recruitment.

The dispersal of the chasmogamous, aerial cleistogamous, and subterranean cleistogamous seeds of Amphicarpaea bracteatawas examined. The chasmogamous and aerial cleistogamous seeds are ballistically dispersed. Chasmogamous seeds were dispersed farther than the aerial cleistogamous seeds due to the height advantage of the chasmogamous pods. There was no difference in the firing angle or the initial velocity of the seeds discharged from the two aerial pod types. The subterranean cleistogamous seeds are “dispersed” the shortest distance by the elongation of runners. Differential dispersal of the three types of seeds may be a factor involved in the evolution of cleistogamy in A. bracteata.

Nach einer knappen Einführung in die Magnitudenberechnung wird über die Ableitung der Stationsgleichungen für Wien (12) und Graz (13) berichtet. Den Berechnungen lagen 158, bzw. 121 Erdbeben normaler Herdtiefe und von der „Größe”M≧7,0 zugrunde. Für beide Stationskonstanten wurde der gleiche WertC=+0,15 gefunden. Die Tabelle 2 enthält 94 von beiden Stationen registrierte Erdbeben mit Angabe der UnterschiededM (=D) von Wien und Graz gegenüber denM-Werten von Pasadena.

Um die Seismizität in einem Landstrich, der selbst seismisch inaktiv, jedoch ringsum von Erdbebenzentren umgeben ist, anschaulich darstellen zu können, wurde ein Verfahren ausprobiert, das seit langem in der Klimatologie bei der Auswertung und Darstellung des Windes üblich ist. Auf solche Art wurde ein Bild der Erdbebenwirksamkeit in dem steirischen Landbezirk Voitsberg (Österreich) entworfen.