Development and structure of the pericarp of Lannea discolor (Sonder) Engl.(Anacardiaceae)

Development and structure of the pericarp of Lannea discolor (Sonder) Engl.(Anacardiaceae). The exocarp develops from the outer epidermis and subepidermal, parenchymatous cell layers of the ovary wall. A parenchymatous zone with secretory cavities more or less delimits the exocarp internally. The inner part of the parenchymatous mesocarp is tanniniferous. The parenchymatous transition zone between mesocarp and sclercnchymatous endocarp or sderocarp, contains vascular tissue. The inner endocarp and operculum develop from the inner epidermis and subepidermal parenchyma of the ovary wall, while the outer endocarp develops from the parenchymatous zone with procambium strandS. Comparing the pericarp of L.discolor with those of Sclerocarya birrea subsp. caffra and Rhus lancea , the close affinity with Sclerocarya birrea subsp. caffra is evident.     

Sugar Content and Metabolic Activities in Cold-Stored Fragmented Xylopodium of Ocimum nudicaule Benth. var. anisifolia Giul. (Labiatae)

Sugar content and hydrolytic activities were measured in fragmentsof xylopodia of Ocimum nudicaule Benth. stored for one weekat 5 °C and 5.28 °C. At 5 °C the soluble carbohydratecontent first decreased and at 5.28 °C it increased duringstorage and then declined drastically during cultivation afterplanting. Galactose, glucose and fructose levels also rose at5–28 °C whereas at 5 °C only glucose increased.These changes in sugar level were found to be correlated withchanges in the activity of certain hydrolytic enzymes: at 5–28°C there was a rapid rise in the activities of -galactosidaseand hemicellulase followed by an increase in the activity ofinvertase and ß-galactosidase. The rapid changes inenzymes and carbohydrate levels are discussed in terms of adaptationof the plant to tropical and subtropical environments. Key words: Carbohydrates, Carbohydrate hydrolases, Underground organ (xylopodium), Cold storage     

Pacemaker Properties of Completely Isolated Neurones in <Emphasis Type="Italic">Aplysia californica</Emphasis>

SINGLE-CELL pacemaker activity is interesting because of its function in temporal organization and information processing in the nervous system. Many invertebrate neurones are regularly and autonomously active^1,2. Although the pacemaker rhythm probably originates within the recorded neurone, it is not clear whether it originates in the axonal tree or in the cell soma. Alving³ approached this question by studying pacemaker activity in the soma of Aplysia nerve cells, after ligaturing the axonal stem with fine sutures. The study described here presents evidence that nerve cell somata which are completely dissociated from all surrounding tissue and with or without axons, are able to maintain regular autorhythmic activity for periods of more than 24 h. The method of complete isolation of cells represents some progress over Alving's method because it is easier to accomplish, has a larger yield of viable neurones and allows longer recording periods.     

UEBER EINE NEUE FOSSILE REPTILFORM VON PROVINZ HUPEH,CHINA

Das zur Untersuchung vorliegende Exemplar wurde von einer geologischen Expedition derProvinz Hupeh in Nanchang-Distrikt in 1956 gefunden und übergeliefert.Der Erhaltungszustand dieses Exemplares ist wie folgende:Gut erhaltende Teile sind dieOberfl(?)che des hinteren Teils des Sch(?)dels,Hals-und Rumpf-Wirbel und-Rippen.Die mitteleund vordere Teile des Sch(?)dels sind abgerieben.Der Unterkiefer ist nicht erhalten.Der vordere     

Eimeria carolinensis n. sp., a Coccidium from the White-Footed Mouse, Peromyscus leucopus (Rafinesque)

SYNOPSIS. Eimeria carolinensis n.sp. (Sporozoa) is described from oöcysts in the feces of the white-footed mouse, Peromyscus leucopus (Rafinesque) taken in the vicinity of Durham, North Carolina. The oöcysts are ellipsoidal to elongate ellipsoidal, 14–19.5 × 10–13 μ, mean of 17.6 × 11.3 μ. Micropyle absent. Oöcyst wall composed of 2 layers. A refractile granule present but no oöcyst residuum. Sporocysts ovoid almost filling the oöcyst. Small Stieda body present.     

Histological Aspects of Root Formation in Petioles of Detached Leaves of Pereskia grandifolia (Cactaceae): Natural Conditions and Effects of GA3 and Dark

Adventitious roots arise naturally on petioles of Pereskia grandifoliaHaw. held in light. At about the 12th day after the beginningof the experiment, the root primordia arise in a callus tissuedeveloped from the basal portion of the petiole. Associatedwith the development of the callus, noticeable structural changesoccur in the originating organ. Petioles maintained in darkalso form callus; however, they die in a few days. On the otherhand, petioles treated with GA,, maintained in light, developcallus and survive; but they do not give rise to roots. Someaspects are discussed, such as: the kind of origin observedfor the roots, and the possible physiological basis for theirformation, as wdl as for the inhibition of their appearance Pereskia grandifolia, adventitious root formation, gibberelljc acid, petiole structure, rooting