THE INFLUENCE OF CERTAIN MANUFACTURING PROCESSES ON THE STAPHYLOCOCCUS AUREUS CONTENT OF SPRAY-DRIED MILK

SUMMARY: Dried milk was prepared from milks inoculated with pure cultures of Staph. aureus , using a small pilot-type batch vacuum evaporator and spray drier. Vacuum evaporation reduced the numbers of Staph. aureus in most experiments but one strain was capable of multiplication at evaporating temperatures up to about 43°. Above 49° the organisms declined rapidly and at 56° they were eliminated. Residual staphylococci present in the warm concentrated milk feeding the drier increased in some experiments but declined markedly in others. Staphylococci added directly to warm concentrated milk always proliferated. A small proportion of staphylococci survived spray drying, even with high hot air temperatures. Different strains varied in their susceptibility to different stages of the whole process.     

Primary faunal succession in volcanic terrain: lava and cave studies on the Canary Islands

Invertebrate communities in volcanic habitats of different ages on the islands of La Palma and El Hierro were studied using standardized trapping and searching techniques. A variety of graphical and numerical approaches were used to analyse relationships among the sites. Young, barren lava flows constitute aeolian ecosystems with a fauna of generalized detritivores and predators, especially collembolans, earwigs, thysamirans and crickets. Surface samples have many individuals and low diversity; those from caves have smaller numbers but similar taxonomic composition.
Vegetated surface habitats have richer communities, with diverse herbivores and predators but largely without the pioneer 'lavicolous' species. Caves with high humidity and stable temperature contain mainly specialized troglobitic species, but if there are both dry and humid sections lavicoles may also be present. Divergence into distinct epigean and hypogean communities results from both abiotic and biotic processes, including erosion and plant succession. While these occur mainly on the surface they also affect caves, increasing humidity and providing insulation from variations in external environmental conditions; the process is considered as a form of 'maturation' of the caves. Various models of succession are considered, which might help to account for the disappearance of lavicoles from mature epigean and hypogean communities.     

THE ACTION OF METALDEHYDE ON THE SLUG AGRIOLIMAX RETICULATUS (MÜLLER)

Metaldehyde both as powder and in solution can act on slugs either by contact or as a 'stomach poison'. The characteristic effects of metaldehyde poisoning were immobilization broken by outbursts of unco-ordinated muscular activity and sliming which usually resulted in severe water loss. 24 hr. after treatment with moderate doses slugs were still abnormal and rarely fed within 30 hr. of treatment. It was not possible to determine the M.L.D. with the methods used, but 0·06 nig. solid metaldehyde taken orally could be lethal to slugs of 400–800 mg. body weight. Lethal effects were produced by contact of 1 hr. with concentrations equivalent to 0·0063 mg./cm.². Toxicity increased with rise in temperature and recovery from moderate doses was dependent on slugs being in a saturated or almost saturated atmosphere. No obvious gut lesions were found in slugs which had been dosed with or had eaten metaldehyde. Its action was not by depolymerization in the gut or body cavity. In the light of laboratory and small scale field trials it is suggested that broadcasting and spraying are the best methods of applying the material.