CARBOHYDRATE METABOLISM OF SKIN 289 cluding citrate, a-oxoglutarate, succinate, fumarate and malate, only glucose, fructose, lactate and pyruvate produced maximal mitotic activity over 4 hr. in mouse-ear skin in vitro. The effects of glucose 1-phosphate are difficult to interpret without further experiments to determine the fate of the compound. Barron et al. (1948) and Griesemer & Gould (1954) found citrate to have no effect upon skin respiration. Barron et al. also failed to demonstrate i80citric dehydrogenase in skin and found no stimulation on the addition of a-oxoglutarate. On these grounds they suggested that the citric acid cycle in its classical form did not operate in skin. Our results, which show a sharp contrast between the obvious usage of succinate, fumarate, malate and oxaloacetate and the transient usage of citrate and nonutilization of a-oxoglutarate, are consistent with their findings, but the evidence is as yet insufficient to conclude that skin differs in its oxidative processes from the majority of other tissues. SUMMARY 1. The respiration and glucose utilization of skin of the guinea-pig ear in vitro are unaffected by the glucose concentration within the range 0005-0*02M. 2. The respiration and fructose utilization increase as the fructose concentration is increased. 3. In glucose-fructose mixtures the utilization of fructose is reduced, the glucose utilization is unaffected and the total hexose utilization thus increases. This is not reflected in an increased respiration rate. 4. Inthe absence ofserumthe glucoseutilizationis only about one-half of that occurring in the presence ofserum, and the respirationis only slightlyreduced; the sum of lactic acid produced and the calculated glucose oxidized equals the observed glucose utilized. 5. Glucose, fructose, lactate and pyruvate stimulate respiration and maintain a relatively high respiration rate for 24 hr. 6. Succinate, malate and acetate stimulate respiration but permit a gradual decline over 24 hr. 7. Oxaloacetate maintains respiration for 5 hr. only, subsequently becoming toxic; fumarate also stimulates respiration initially but its effect declines between 5 and 24 hr. 8. Citrate causes transitory stimulation in the first hour and o-oxoglutarate is without effect. 9. Glucose 1-phosphate causes initial depression, but at 24 hr. a slight increase over the control occurs. 10. These findings are discussed in relation to the carbohydrate metabolism of skin.

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The Roman fort of Carlisle was first discovered by the late Dorothy Charlesworth in 1973 at Annetwell Street. Excavation by her and after 1980 by the Carlisle Archaeological Unit located the southern defences of the primary fort and identified a sequence of Roman forts extending from AD. 72/3 down to the fourth century. In 1981–2 excavation at Castle Street produced a sequence of timber phases closely matching the fort stratigraphy, with military association in the finds assemblages, but lying outside the fort defences. The early phases were arguably part of a defended annexe or within a military vicus, though proof was lacking.

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Aldhouse-Green (as former and present keepers), and departmental colleagues for their support. Mr Boon and Mr Brewer have kindly read drafts of this report which benefits from their helpful comments. Many of the finds were drawn by Mrs A. Leaver, to whom also my thanks. Site plans etc. are drawn by the author.