944 resultados para White, John, 1685-1755.


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v. 1

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v. 2

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v.2 (1886)

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v.1 (1886)

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ABSTRACT In forest ecosystems, numerous species of insectivorous birds use certain tree species as feeding and nesting substrates. Between 2009 and 2010, the use of different floristic components as feeding substrate by the Pygarrhichas albogularis King, 1831 was evaluated in a southern Chilean secondary native forest. From a total of 13 trees and bush species, six tree species were used by P. albogularis as a feeding substrate. Tree use was limited to intermediate heights (11-20 m) and, mainly, to the trunk (40% of observations) and secondary branches (26%). Pygarrhichas albogularis showed a disproportionated use of N. dombeyi and an important use of trees with a greater age structure (DBH 81-100 cm). Nothofagus dombeyi presented a significantly greater tree bark crevice depth than E. cordifolia. In turn, covariance between crevice depth and invertebrate supply in tree bark was positive and significant. We consider bark depth and invertebrate supply to be the proximate causes explaining P. albogularis disproportionated use of Nothofagus dombeyi.

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The classification of salmonellae in accordance with the Kauffmann-White schema accepted by the presents various inconveniences and difficulties to application. Among these is the necessity of preparing, dosing and preserving a considerable number of specific sera whose validity as is well known, is limited. The criterion of Kauffmann’s classification is exclusively, for it abandoned cultural tests, leaving therefore only a unilateral criterion. By following it one might include Chromobacterium typhi-flavum in the Salmonella genus as well as other bacteria which differ completely from the Salmonella, as long as they are antigenically related. On the other hand, the chart approximates or separates in the different groups of antigen O species or types of salmonellae which are biologically close or almost indistinguishable. The chart has given rise to an excessive number of species and lypes of salmonellae which from 44 in the chart approved by the in 1934 rose ro 60 in Bergey’s Manual and everything leads one to believe that the end is not yet for every day new lypes or species are found. And perforce this must be so for new antigenic factors have been found which give rise to new structural combinations. Applying the formula of combinations (formule) to the factors already known, there are probable possibilities of having 260 different antigenic combinations in group A, or 3260 lypes or species if all the flagellate antigens of the other groups should be found, in it combined 2 and 2. Futher applying the formula of combinations to the other groups there would be possibility of so many combinations that the number of salmonellae would exceed the number of known bacterian species or perhaps the number of those existing on earth. Undoubledly Kauffmann-White’s chart is an improvement, but the bacterian analysis made with it was exaggerated and exceeded the limit of the present possibilities of the realities of life. It revealed interesting aspects of the somatic complexity of bacteria but seems untenable because of its use in pratical sense.