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Emergence from an aquatic environment to the land is one of the major evolutionary transitions within the arthropods. It is often considered that the first hexapods, and in particular the first springtails, were semi–aquatic and this assumption drives evolutionary models towards particular conclusions. To address the question of the ecological origin of the springtails, phylogenetic analyses by optimization alignment were performed on D1 and D2 regions of the 28S rDNA for 55 collembolan exemplars and eight outgroups. Relationships among the orders Symphypleona, Entomobryomorpha and Poduromorpha are inferred. More specifically, a robust hypothesis is provided for the subfamilial relationships within the order Poduromorpha. Contrary to previous statements, the semi–aquatic species Podura aquaticais not basal or ‘primitive’, but well nested in the Poduromorpha. The analyses performed for the 24 different weighting schemes yielded the same conclusion: semi–aquatic ecology is not ancestral for the springtails. It is a derived condition that evolved independently several times. The adaptation for semi-aquatic life is better interpreted as a step towards independence from land, rather than indication of an aquatic origin.

A total of 1026 patients over 65 years of age underwent abdominal surgery during the period from 22 September 1987 to 12 February 1992 at the Surgical Department of Aachen Technical University. The data of these patients were analysed with respect to pre-operative risk factors, pre-operative rest period, their history and mortality. The following most important pre-operative risk factors were considered: cardiovascular diseases (45.9%), hypertension (28.7%), pulmonary diseases (19.4%) and diabetes mellitus (16.6%). Patients without pre-operative risk factors showed the lowest mortality rates if the preoperative rest period was 1–2 days only, whereas patients with four or more risk factors showed the lowest mortality rates if the period of rest was 10–14 days. Mortality after emergency intervention (16.54%) was about three times as high as after elective surgery (5.54%). The anamnesis was 2–10 months for 30% of the patients whereas 8.2% of the patients reported a history of complaints of less than 24 h.