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SummaryA statistical method for the detection of immunity by means of the rabbit skin test.This paper discusses the statistical basis of a technique that has already, without detailed explanation, been applied in a previous paper by Dr Winsser (1).5 plots, arranged in 5 rows (25 plots in all) laid across the skin of a rabbits back, are injected with infectious matter in amounts inc easing in geometric progression. To four of these rows sera prepared from four different test persons are added; and the immunity is judged by the resulting decline in skin reaction as compared with the row, mostly situated at the caudal end, which serves as control.Since at the lowest concentrations of infectious matter the skin reactions were altogether too weak to show any marked decline, these were ignored. The sum, y, for each serum of the reaction values at the remaining four concentrations is compared with the corresponding sum, yk, for the control, and for the difference (yk‐y), 5 % and 1 % levels of significance are determined.To determine these limits, variations in sensibility between animals and over the area of skin of each individual had to be taken into account. This was done by analysing the skin reactions of 5 animals infected without serum; the use of more animals being considered too costly. The results show significant differences between individual means, insignificant differences between individual regressions along the back, and a significant common regression. In calculating the 5% and 1% percent limits it was assumed that the residuals with respect to individual regression lines are normally distributed, which they clearly are not; and that the individual regressions are equal, which, despite the insignificance observed, is probably not correct. To atone for these deficiencies the limits imposed were more severe than those commonly adopted. Some of the criticisms that may be directed against this procedure are recognized and discussed.

Stream networks have recently been discovered to be major but poorly constrained natural greenhouse gas (GHG) sources. A fundamental problem is that several measurement approaches have been used without cross-comparisons. Flux chambers represent a potentially powerful methodological approach if robust and reliable ways to use chambers on running water can be defined. Here we compare the use of anchored and freely drifting chambers on various streams with different flow velocities. The study clearly shows that (1) anchored chambers enhance turbulence under the chambers and thus elevate fluxes, (2) drifting chambers have a very small impact on the water turbulence under the chamber and thus generate more reliable fluxes, (3) the bias of the anchored chambers greatly depends on chamber design and sampling conditions, and (4) there is a promising method to reduce the bias from anchored chambers by using a flexible plastic foil collar to seal the chambers to the water surface, rather than having rigid chamber walls penetrating into the water. Altogether, these results provide novel guidance on how to apply flux chambers in running water, which will have important consequences for measurements to constrain the global GHG balances. ; Funding Agencies|German Research Foundation [LO 1150/9-1]; Leibniz Association within the Joint Initiative for Research and Innovation (BMBF); Erasmus Mundus program of the European Union; Swiss National Science Foundation [PA00P2_142041]; IGB cross-cutting research domain "Aquatic Boundaries and Linkages"; German Academic Exchange Service (DAAD) (Sustainable water management Program (NAWAM)) [A/12/91768]