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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. British Ecological Society is collaborating with JSTOR to digitize, preserve and extend access to Journal of Applied Ecology. SUMMARY(1) The dynamics of the seed bank of the tropical weed Mimosa pigra were investigated in two regions of northern Australia by monitoring changes in the seed populations beneath mature stands, by a seed burial experiment, and by measuring the seed output of populations.(2) Seed populations were generally very high compared to the range expected for secondary tropical vegetation. For example, in 1986 they varied from 8500 m-2 in one region to nearly 12 000 m-2 in another.(3) In the seed burial experiment, viability declined with time. The rate of loss declined with increasing depth of burial, and differed between the two regions, with exponential half-lives ranging from 99 weeks at 10 cm depth in a light clay to 9 weeks at 1 cm depth in a heavier black cracking clay. These seed loss rates were within the range reported in the literature.(4) The measured seed banks broadly agreed with the values predicted by a simple model based on the rates of seed loss found in the burial experiment.(5) Although the decline in viability of M. pigra seeds can be fairly rapid, it is argued that, because of the large soil seed population, rigorous control of seedlings would have to be maintained for some years after the eradication of mature plants.

CAM is commonly used by patients with cancer. CAMs, particularly antioxidants, are being taken which could negate the underlying free-radical tumorcidal effects of radiotherapy. Oncologists need to have greater awareness of this use and of its potential adverse consequences.

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Eggs of Aëdes do not necessarily hatch on becoming mature, even though conditions are known to be compatible with hatching. Even the eggs laid by a single female in a single batch and kept submerged in a single container may hatch in instalments over a very long period and, although on one occasion a high proportion of the eggs may hatch within a given period, on another, for no apparent reason, very few may hatch.The problem of erratic hatching has been studied here mainly in Aëdes africanus (Theo.) and A. aegypti (L.). It is considered that mature eggs enter a state of diapause, the depth of which varies with the passage of time, and that the manner of this variation with time itself varies from egg to egg. Different batches of eggs laid by females of the same species vary in the proportion of the different kinds of egg present.Variation in response of the eggs has been studied by the application of a suitable hatching-stimulus in equal daily doses. The stimulus used was sufficiently weak to allow variation in response to be manifested, but sufficiently strong to outweigh uncontrolled variables in the environment.