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1. The secretion of the adrenal cortex in several mammalian species has been studied by direct analysis of samples of adrenal venous blood, using paper chromatography. 2. All the species examined were found to secrete large amounts of 17-hydroxycorticosterone and/or corticosterone, and some a third compound, provisionally identified as 11-hydroxy- androst-4-ene-3:17-dione. 3. The ratio of 17-hydroxycorticosterone to corticosterone secreted, varied from < 0·05 in rats to > 20 in rhesus monkeys, but did not vary appreciably between members of any one species. 4. In any individual, changes in total secretion rate produced no change in the relative amounts of the different components of the secretion. 5. ACTH increased the secretion rate of all components of the secretion. 6. It is suggested that the species differences observed in adrenocortical secretion are genetically determined, and cannot at present be related to any known differences of adrenocortical function in these species. Observable physiological differences may, however, be discovered, and caution should be exercised in generalizing from the results of ACTH treatment in the rat and rabbit.

hypothesis that A. xylinum is a phylogenetic ancestor of A. 8uboxydan8 thus might imply only that A. xylinum has been able to undergo consecutive loss mutations of two non-essential enzyme systems. An opposing view, namely that evolution proceeded from a simple state to a more complex one, may be more attractive on philosophical grounds. In that case, the interesting possibility has to be considered that the ancestor of Acetobacter was equipped with a mutative potential so broad as to comprise within its range two enzyme systems (respectively for cellulose synthesis and acetate oxidation) which are facultative in Acetobacter but have elsewhere assumed cardinal roles in cellular survival. SUMMARY 1. A cell-free extractofAcetobacterxyltinumfailed to form cellulose from a range of tested substrates. 2. The extract (with added phenazine methochloride) oxidized glucose aerobically to gluconate. When this system was further supplemented with diphosphopyridine nucleotide, it oxidized gluconate to oxogluconate (largely 2-oxogluconate). 3. The extract with adenosine triphosphate oxidized glucose aerobically to carbon dioxide. The extract contained kinases (glucokinase and gluconokinase), phosphoglucomutase, a complete pentosecycle set of enzymes, and a set of enzymes by which triose phosphate could be converted into pyruvate. 4. A scheme of altemate pathways for glucose metabolism that can be operated in an A. xyltinum cell is proposed. The scheme shows a pentose cycle which has several ports of entry and exit. The latter lead from the pentose cycle into a citrate cycle. 5. Biochemical evolution in the genus Acetobacter is briefly discussed. Note added in proof.

Adrenal venous blood was collected from six anaesthetized sheep, of which two had been previously hypophysectomized. The blood was extracted and analysed for adrenocortical steroids by paper chromatography. In each case the predominant secretory product found in the extracts was 17\g=a\-hydroxycorticosterone. Small amounts of corticosterone and a substance tentatively identified as 11\g=b\-hydroxyandrost-4-ene-3,17-dione were also found in all the extracts. Only traces of other reducing steroids or \g=a\\g=b\-unsaturated ketosteroids were found: their irregular appearance makes it likely that they were artifacts. It seems unlikely that the secretion of the adrenal cortex in vivo is as complex as the mixture of products released by the perfused beef adrenals in the experiments of Hechter, Zaffaroni, Jacobsen, Levy, Jeanloz, Schenker & Pincus [1951].The reported actions of cortical steroids, or whole adrenal extracts, when injected into mammals or added to isolated tissues have become so numerous that it has become essential to find out by direct experiment what the adrenal cortex actually secretes into the blood in various conditions. In the absence of direct knowledge of the nature of the cortical secretion, various theories of adrenocortical function have been proposed from time to time [e.g. Sayers, 1950], but recent work has cast considerable doubt upon them. All such theories postulate that the adrenal cortex secretes one or more steroid substances at particular rates in various physiological conditions, and it is necessary to find out whether this is the case or not. This paper describes experiments on six sheep in which adrenal venous blood was collected and analysed by paper chromatography [Bush, 1953] in order to determine the rate and type of secretion in this species. METHODS Experimental techniqueFive adult ewes and one wether of 50-70 kg were used (two Suffolks, two crossbreds, one Hampshire, and one Romney Marsh). One ewe (no. 4) and one wether (no. 6) had been hypophysectomized 2 days and 11 months respectively before the experi¬ ments by a technique described elsewhere [Ferguson, 1953]. In the ewe serial sections of the pituitary fossa showed one fragment of coagulated pituitary tissue adhering to the walls of the fossa which had been cauterized with diathermy after removal of most of the pituitary gland. No viable tissue could be found in the sections.In serial sections of the pituitary fossa of the wether (no. 6) no pituitary tissue could be found. The depression of wool-growth observed in this animal was further evidence of complete hypophysectomy [Ferguson, 1951].

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