Regulation der Cilienmetachronie bei der “Fluchtreaktion” von Paramecium*

SYNOPSIS. Paramecia induced to perform high rates of avoiding reactions by mechanical stimulation and the action of Ba ions were instantaneously fixed with OsO₄. Quantitative evaluation of the preparations revealed, among other things, metachronal stages of the transition between the ciliary patterns of swimming backward and forward. In each of the transitory stages, metachronal waves of swimming forward were found at the anterior end and waves of swimming backward at the posterior end of the animal. This confirms the so-called Párducz-scheme of avoiding reaction for the case of homogeneous chemical stimulation as well as for mechanical stimulation.     

Defence and development in a gregarious leaf-mining beetle

Abstract.

• 1 The gregarious larvae of the chrysomelid beetle Microrhopala vittata mine the leaves of goldenrods (Solidago spp.). These mines serve both as food and as shelter for the larvae.
• 2 Life-table data and experiments indicated that mine initiation and moves to secondary mines represented especially vulnerable stages during larval development. Leaf mines effectively protected M.vittata against predators in the field.
• 3 Field experiments indicated that larvae hatching from larger clutches of eggs stood a greater chance of surviving to pupation, primarily because larvae hatching in groups proved more successful at initiating leaf mines. Once inside the leaf mine, however, larvae feeding in large groups attained lower adult masses, and were more likely to abandon the natal mine and did so earlier in development because large groups more rapidly destroyed a leaf.

     

Weight loss of the female during the first brood as a factor influencing second brood initiation in Great Tits Parus major and Blue Tits P. caeruleus

We tested the hypothesis that the weight lost by female Great and Blue Tits Parus major and P. caeruleus while raising their first brood influences their ability to start a second brood. The evening weight of female parents was recorded when the nestlings were 5 and 13 days old, in different years and habitats. Several predictions were tested: (1) both species lose weight while raising nestlings and Great Tit females which start a second brood lose less weight than females which do not; (2) differences in the average weight lost between years and areas correlate with differences in the proportion of second broods; (3) the relative weight loss in Blue Tits, which only rarely undertake second broods, is higher than in Great Tits in which second broods are more common. Other factors also are related to the probability of undertaking a second brood: more second broods are undertaken by more successful females, adult females and females that lay earlier.
The comparison of Great and Blue Tits suggests that the two species use different reproductive strategies.     

Nesting activity,breeding success and colony size for the Wedge-tailed Shearwater Puffinus pacificus on Heron Island

Abstract The Capricorn Group of islands in Australia's Great Barrier Reef Marine Park sustains one of the world's largest breeding populations of the Wedge-tailed Shearwater Puffinus pacificus. Heron Island, a 13.5 ha coral cay which supports tourist and research station leases as well as a national park, is the third largest nesting island in the group. Sample censuses of breeding burrows were conducted each year between 1985 and 1990 and a further survey was completed in 1993. These returned estimates of between 13 264±1387 and 16 337±1545 active burrows (Y±SE). Burrow densities within each of the habitats monitored showed no significant trends between years, although there were large differences in burrow density between habitats. There were roughly the same number of burrows in the developed (west) and national park (east) halves of the cay. A miniature video camera system (burrowscope), which allowed nesting chambers at the ends of burrows to be inspected, was used in 1989, 1990 and 1993. This demonstrated that around half the burrows were occupied by incubating birds. Variations were found in the distribution of incubating birds between habitats, although this did not remain constant between the years. In the 1993 season, breeding activity was traced from the burrow establishment to fledging stage. Fifty-one per cent of burrows were used for breeding (eggs laid), 77% of eggs hatched and 80% of chicks produced a fledgling. Overall breeding success for the island was estimated at 61%. In 1993 the area designated as Buildings was found to have significantly lower hatching success compared with natural habitats. Most mortality occurred at the egg stage; however, in the Fringe habitat, mortality was highest at the chick stage. Previous surveys have estimated the breeding population from burrow counts. It now appears that only about 30% of such burrows produce fledglings.     

SENSORY ANALYSIS IN MARKETING PRACTICE: COMPARISON AND INTEGRATION

Sensory analysis has traditionally played a prominent role in quality control for food products. More and more principles from sensory analysis are also applied in the area of food product development, bringing sensory analysis more closely into the domain of marketing. Unfortunately, in practice integration between sensory and marketing practices is far from optimal. Differences in basic orientations between sensory and marketing are a major source contributing to this defective cooperation.
Sensory analysis has traditionally been product oriented with an emphasis on internal validity of the test results. Implicitly or explicitly this approach emphasizes the relationships between sensory evaluation and characteristics of the product. Marketing, on the other hand, stresses the external validity of test results: the extent to which test results can be generalized to market behavior. Emphasis on external validity requires an approach to sensory analysis that is fundamentally different from current sensory practice in terms of type of respondents, type of stimuli, scaling procedures adopted and test circumstances.
Closer integration between the product and consumer oriented approach to sensory analysis may contribute to the success of product development in the food industry. The literature suggests several factors that may contribute to a more fruitful cooperation between the two approaches to sensory analysis. The company's senior management plays a central role in the achievement of this integration by providing an infrastructure (in terms of personnel, organizational structure and financial resources) that paves the way for closer cooperation.     

Sap Exudation via the Epidermis of Leaves

Reports of stomatal guttation in Gladiolus and of active waterexudation in Vidafaba could not be confirmed by an experimentaland anatomical investigation. Exudation of water from detachedpine needles is considered to be due to processes distinct fromthose causing guttation. Water soaking of leaves, or the flooding of leaf air spaces,and the wettability of cell walls under root pressure as distinctfrom their wettability by water externally applied are discussedin relation to the experimental results.