613cataract than the retinal lesion itself. This point is being more fully investigated.The cataract is not due to a disturbance in the blood supply to the eye; the vessels of the retina and choroid were found to be healthy at the time of onset of the lens changes; the iris and ciliary body were found to be normal. Nor is it likely that the cataract results from some general metabolic disturbance, since the two eyes of an animal are not always affected to the same extent. The animals appear to be healthy and their diet is adequate in all known dietary essentials.It is interesting to note that Jess (1925) described an hereditary and congenital cataract occurring in a colony of white rats. Ihirty-four per cent. of the 300 eyes examined by him were affected. The cataract consisted of granular opacities in the anterior cortex; the number, size and density of these opacities varied greatly, often appearing as a thick " bee-swarm " in an otherwise clear lens. From this description it appears that Jess's cataract is different from the one described here. REFERENCES BOURNE, M. C., and GRUNEBERG, H.-To be published.

INTEREST in the metabolism of aromatic hydrocarbons has been stimulated by the recent work on the carcinogenic properties of certain members of this group of substances. But the problem of the metabolism of naphthalene is of especial interest because of the property which this substance possesses of being able to produce, when administered to rabbits in repeated doses, an opacity of the crystalline lens of the eye which, histologically, closely resembles human senile cataract [Bouchard and Charrin, 1886;Adams, 1930].The work reported in the present paper forms part of a series of investigations directed towards the discovery of the mechanism by which naphthalene acts upon the organism so as to induce degenerative changes in the lens-proteins. At present nothing is known of this mechanism; it is still uncertain whether naphthalene or some derivative of it formed in the body acts directly on the lens, or whether the cataract is a secondary phenomenon resulting from some metabolic disturbance or toxic action upon a tissue remote from the eye. An essential step in the solution of this problem appeared to be to obtain some knowledge of the fate of ingested naphthalene. Therefore an attempt to identify the excretory products of naphthalene in the urine of rabbits has been made.It is the purpose of the present paper to' describe the isolation and identification of one metabolic product of naphthalene, viz. 1-o-naphthylmercapturic acid; and to present evidence for the existence of a second metabolite, which has not been isolated, but which gives rise to naphthalene on acidification. EXPERIMENTAL.Buck rabbits weighing between 2 and 3 kg. and feeding on oats and cabbage were used exclusively. Naphthalene was dissolved in warm liquid paraffin and administered by means of a stomach tube. Doses of 1 or 2 g. were given to each rabbit and repeated at intervals of 2 or 3 days. The rabbits were kept in individual metabolism cages of suitable size, and the urine was collected separate from the faeces.Colour tests for naphthols and glycuronic acid. Certain authors [Igersheimer and Ruben, 1910; Edelfsen, 1905], on the basis of colour reactions applied to the urine excreted by dogs after naphthalene feeding, concluded that naphthalene was oxidised to naphthol in the body and was excreted in the urine as ocor /3-naphthylglycuronate. Lesnick [1888] isolated a small amount of chemically pure oc-naphthylglycuronate from dog's urine after the feeding of 12 g. of naphthalene. Penzoldt [1886] was unable to 1 Bayliss-Starling Memorial Scholar.

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DAY et al. [1931] in America first reported that they had obtained cataract in albino rats by feeding a diet deficient in vitamin B2. The ration used was that of Sherman and Spohn [1923] which has been widely employed in work with this vitamin. Cataracts were produced in 92 % of rats after an average period of 72 days.The work was developed by Langston et al. [1933] and by Langston and Day [1933] who observed an equally high incidence of cataract in mice and in young wild gray rats deprived of vitamin B2. By feeding diets deficient in vitamin B2 Day, Langston and Cosgrove [1934] obtained cataract in rats and chickens and Day [1934] reported cataract in rats, mice, chickens and monkeys. The importance of cataract as a symptom of vitamin B2 deficiency was stressed by these authors.Day and Langston [1934] published further evidence that in nearly all the cases examined rats receiving a diet free from vitamin B2 developed cataract. They found that the appearance of cataract was delayed where small but insufficient amounts of vitamin B2 were given; and the delayed appearance of cataract was correlated with the growth-rate data. It was concluded that cataract was probably a better criterion of vitamin B2 deficiency than was dermatitis.These observations are of great interest since they are related to the problem of the aetiology of cataract as well as to that of vitamin deficiency. It is important that it should be established beyond doubt whether or not degenerative changes in the eye-lens can be produced by the omission of a specific substance, such as a vitamin, from the diet. It is equally important from the point of view of vitamin studies to know if cataract, which can readily be observed, is in fact a consistent symptom of a vitamin deficiency. In addition a technique for producing cataract regularly in a laboratory animal by dietary control would prove most useful in further studies in the aetiology of cataract. For these reasons it was considered advisable to attempt to repeat the work of Day and his colleagues. Experiments were therefore undertaken in which diets deficient in vitamin B2, including the Sherman and Spohn [1923] diet as used by the American workers, were fed to rats and the eyes examined with an ophthalmoscope at weekly intervals. The results of these experiments form the subject of the present communication.EXPERIMENTAL. Thirty-six young black and white rats of about 70 g. weight were obtained from a commercial source and kept in single cages with wire screen bottoms. The Sherman-Spohn [1923] diet was fed. This consists of alcohol-extracted caseinogen ( 1865 )

IN an earlier paper [Herbert and Groen, 1929] it was shown that the discrepancies between the results of blood-sugar methods were due to non-glucose reducing substances present mainly in corpuscles. It appeared that ferric hydroxide filtrates and zinc hydroxide filtrates contained little or none of the non-glucose material, and that therefore the original MacLean method and the original Hagedorn-Jensen method gave figures close to the true sugar value. The non-sugar material was shown to be present in tungstic acid filtrates, and to have a marked effect on all the analytical methods applied to tungstic acid filtrates except that of Benedict [1928]; the Hagedorn-Jensen method, applied to tungstic acid filtrates, was affected most of all. It was suggested that the principal non-glucose substance responsible was glutathione.In the present investigation the effect of pure reduced glutathione on bloodsugar methods has been studied. The work falls into two sections; (1) a study of the effect of glutathione on the analytical methods, when no treatment corresponding to protein precipitation is used, and (2) a study of the behaviour of glutathione in various methods of protein precipitation, using mixtures of plasma and glutathione.Two different samples of glutathione were employed, both of which were received from Sir Frederick Hopkins's laboratories. The first, received in December 1928, was a deliquescent substance, the solutions of which had a smell resembling that of mint. The second sample was received in July 1929, and consisted of the pure tripeptide of glycine, glutamic acid, and cysteine, prepared by Hopkins's new method [1929].The following blood-sugar methods have been used.(1) The Folin-Wu method [1920].(2) The Shaffer-Hartmann method as modified by Somogyi [1926].(3) The Hagedorn-Jensen method [1923].(4) The Benedict method [1928].