Bryozoan frontal shields: studies on umbonulomorphs and impacts on classification

Umbonuloid frontal shields arc described in the type species of Lepraliella, Drepanophora, Frurionella, Tessaradoma, Hincksipora, Stephanopora , and Pseudolepralia. Consequences to classification include the following: the family group names Lepralielloidea and Lepralicllidae have subjective priority over Umbonuloidea and Celleporariidae, respectively; Cylindroporeh is excluded from the Tessaradomidae and included in the Gigantoporidae; Tessarudoma bifax Cheetham is included in Srnithsonius (Bifaxariidae); Hincksiporidae is confirmed as a family of Lepralielloidea; Stephanoporu , with newly discovered dimorphic orifices, comprises two species which are the basis for a new exechonellid subfamily Stephanoporinae; and a new umbonulomorph superfamily, Pseudolepralioidea, is established for Pseudolepraliu (Pseudolepraliidae). Kladapheles gen.n., is established for an erect branching species of Lepraliellidae from New Zealand.     

Analysis of growth during phototropic curvature of cress hypocotyls

Abstract. Growth rates throughout an organ curving phototropically under continuous, unilateral while light were monitored by lime-lapse photography of cress hypocotyls marked into 1 mm sections by two rows of ion-exchange beads. Curvature resulted from an integrated sequence of changes in growth rate on each side of the organ, but the actual patterns of change and, therefore rales of curvature, differed within even this one species, depending upon the immediate pretreatment of the seedlings. Transference of seedlings from darkness to unilateral irradiation gave immediate growth inhibition on both sides of the organ. Curvature resulted from differential recovery of growth rate, being seen first on the shaded side, most prominently in the apical regions; only 2h after initial exposure to light did growth recover on the lit (lower) side. On the other hand, transfer of seedlings from omnilateral to unilateral irradiation of the same intensity resulted in simultaneous growth inhibition on the irradiated side and stimulated growth on the shaded side: this growth stimulation of the shaded side was greater than occurred in totally darkened control plants.     

The flow of food in colonies of the fire ant, Solenopsis invicta: a multifactorial study

ABSTRACT. A study was conducted to determine the interaction of several factors in the trophallactic distribution of food in colonies of Solenopsis invicta Buren. Radioactive iodine (¹²⁵I) was used to quantify both the ingestion of test foods by foragers and the distribution of this food to nestmates. A multifactorial design tested the simultaneous effects of: (1) food-type (sugar water, casein hydrolysate, or oil), (2) temperature during foraging and food-sharing (25, 30 or 35°C), and (3) starvation period (colonies deprived for 0, 3, 7 or 14 days). The amount of food consumed by foragers was influenced by the interaction of food-type and starvation. Foragers from severely starved colonies ingested more aqueous foods than did those from slightly starved colonies, but oil was always taken in smaller quantities and its ingestion was least affected by starvation. Ingestion was generally lowest at 35°C, probably because of mutual interference of workers while feeding. Within the colony, food sharing varied with food type and increased with starvation. The sugar solution was utilized primarily by workers. Amino acids were shared throughout the colony, but were directed preferentially to the growing larvae. Soy oil was equally shared among workers and larvae and reached more colony members per initial unit volume than did the other foods. The test factors also interacted in their influence on trophallaxis. Starvation stimulated the dispersal of labelled foods, but at different intensities for different foods. The probability of the queen's receiving food increased when the labelled food was widely exchanged among her nestmates. Casein hydrolysate reached the queen in more cases than did the other tested foods.     

Regional growth patterns in the hypocotyls of etiolated and green cress seedlings in light and darkness

Abstract. A system is described whereby seedling development can be analysed in terms of growth rates of specific 1 mm regions of the hypocotyl. The technique involves time-lapse photography of marked hypocotyls in a specially designed chamber which accommodates seedlings in various orientations with respect to gravity, and under irradiation regimes differing in light quality, quantity and direction. The results of a preliminary study of the upward growth of etiolated or green cress seedlings in darkness or overhead while light are reported. Highest growth rates in etiolated seedlings were observed in zones in the upper one-third of ihe hypocotyl. In green seedlings, growth was more prominent within the subapical zones. Light further restricted growth of the median and basal zones in both types of seedling. However, in their immediate responses to the onset of irradiation, green and etiolated seedlings differed markedly. In etiolated seedlings, recovery of growth at the apex was accompanied by the development of inhibition in the median-basal regions; green seedlings showed a transient inhibition of growth in the apical zone together with a strong immediate inhibition in the median-basal regions.     

The Role of Dissolved Organic Material in the Nutrition of Pelagic Larvae: Amino Acid Uptake by Bivalve Veligers

SYNOPSIS. Studies on the role of dissolved organic materialin the nutrition of marine invertebrates have largely been confinedto adults. However larval forms, with a higher surface areato volume ratio, have a greater weight specific capacity forabsorbing dissolved organic material than adults. Autoradiographic,biochemical, and kinetic experiments with bivalve larvae allindicate that amino acid uptake and translocation mechanismscan operate efficiently at naturally occurring substrate concentrations.The mechanisms operate throughout the life-span of the animal,from fertilized egg to adult. Experimental evidence is presentedto show that the kinetics of uptake by larvae allow them tocompete with bacteria for dissolved organic material in seawater. In larvae, supplementary sources of energy may be moreimportant than in adults since larvae are provided with minimalfood reserves by the parent and must pass through periods whenpaniculate feeding cannot occur.