Protein concentration in the arterial and venous renal blood serum of the rabbit

In normal rabbits, under Nembutal anesthesia, the total protein and albumin content of the arterial blood serum are significantly higher than the same fractions of the renal venous blood serum. This condition is reversed in the rabbits after removal of more than 15 ml. blood/kg.Renal innervation plays a role in the regulation of the protein concentration in the renal venous blood, after hemorrhage.No significant difference of protein fractions in the arterial and renal venous blood sera has been observed in a series of rabbits with experimental renal hypertension.Parallel estimations of color intensity of previously injected Evans Blue, and of the protein fractions (by electrophoretic and turbidimetric methods) in the arterial and renal venous blood specimens of normal rabbits corroborate the possibility of a renal mechanism of albumin storage.     

The Peltier Effect and its Use in the Measurement of Suction Pressure

1. A method is described by means of which the suction pressureof living material may be measured by observations on its equilibriumvapour pressure.
2. It employs a very fine thermocouple whosetip is cooled by meansof the Peltier effect, below the dew-point.It collects a minuteamount of dew, and can thus be used asan exceedingly fine ‘wet-bulb’thermometer. As suchit is convenient to use, quick in action,and causes very littledisturbance to the system under observation.
3. The thermocoupleis calibrated by means of salt solutions ofknown strength.The scale is fairly linear.
4. The method possesses the advantagesof giving the suction pressureby direct observation ratherthan by interpolation; of speedin the actual measurement; ofnot subjecting the tissue to immersion;and of permitting organslike leaves, otherwise difficult tohandle, to be easily dealtwith. It also opens possibilitiesoutside the range of the conventionalmethods.

     

Influence of visual targets and landmarks on honey bee foraging and waggle dancing

Animals use diverse sensory stimuli to navigate their environment and to recognize rewarding food sources.Honey bees use visual atributes of the targeted food source,such as its color,shape,size,direction and distance from the hive,and the landmarks around it to navigate during foraging.They transmit the location information of the food source to other bees if it is highly rewarding.To investigate the relative importance of these attributes,we trained bees to feeders in two different experiments.In the first experiment,we asked whether bees prefer to land on(a)a similar feeder at a different distance on the same heading or on(b)a visually distinct feeder located at the exact same location.We found that,within a short foraging range,bees relied heavily on the color and the shape of the food source and to a lesser extent on its distance from the hive.In the second experiment,we asked if moving the main landmark or the feeder(visual target)influenced recruitment dancing for the feeder.We found that foragers took longer to land and danced fewer circuits when the location of the food source,or a major landmark associated with it,changed.These results demonstrate that prominent visual atributes of food sources and landmarks are evidently more reliable than distance information and that foraging bees heavily utilize these visual cues at the later stages of their journey.