1. Attention is called to the widespread dissatisfaction with the standard of reproducibility attained with the existing disinfectant tests.

2. It is suggested that this lack of reproducibility is inherent in any 100% mortality test.

3. The trend in all recent disinfectant developments appears to be towards greater specificity than was the case with the older products.

4. Where a comparison is being made to ascertain the true relative efficiency of two or more disinfectants, this possible specificity necessitates their examination under a wider range of conditions than has been catered for in the past.

5. A technique is suggested for use in those cases where a more limited examination will provide all the information that is required. It employs a simple culture medium, uses a measured quantity for the transfer from the medication tube, and makes use of a compensated photo-electric circuit to determine the amount of growth produced by the organisms which have survived the contact with the disinfectant.

I wish to acknowledge my grateful thanks to the directors of Messrs Cooper, McDougall and Robertson Ltd. for permission to publish this paper, and to my colleagues of the Cooper Technical Bureau for assistance in various directions.

1. A method is described for estimating the disinfecting power of chemical substances on small cylindrical blood-clots of standard dimensions (about 1·5 mm. in diameter) containing a measured number of bacteria (Staph. aureus). It is capable of giving guidance for the use of disinfectants under the described conditions.

2. No practicable disinfectant regularly sterilized heavily infected clots (400,000 cocci) in 5 min. at 17–20° C.

3. In 30 min. the following were the only substances that were uniformly successful with heavily infected clots: 2·5% iodine in aqueous KI solution; 50% Chloros, containing about 5% chlorine; 70% alcohol containing 0·1% acriflavine. (The first of the three was tested on a larger scale than the others, and its potency is therefore the more firmly established.)

4. Reduction of the number of cocci in the clot increased the range of effective disinfectant solutions. Thus with 4000 cocci per clot regular clot disinfection was achieved in 30 min. with the following additional solutions: ethyl alcohol 70 and 50%; Chloros 25%; phenol 2·5% and lysol 1·25%. A few tests indicated that Zephiran (and probably CTAB) at 1 or 2% concentration would also pass this less exacting test.

The numerical aspects of bacterial growth have hitherto been investigated chiefly in fluid media and the laws governing the development of bacterial populations in fluid cultures are known in some detail.

The change by which a strain of B. dysenteriae Flexner becomes resistant to sulphonamides is similar in character to the change in B. coli mutabile from white (non-lactose-fermenting) to red (lactosefermenting).

The highest proportion of variants are found in papillae, while no variants are found in the growing margin of colonies.

Reversion does not take place during growth on sulphonamide-free media.

The variation is a direct and heritable response to a chemical stimulus and in adaptation to this part of the environment.

The variation described by Reiner Müller of B. typhosus on rhamnose and of certain coliform bacteria on arabinose may also be of the same nature.

Strains of B. dysenteriae Flexner resistant to sulphanilamide or sulphaguanidine 1/10,000 are only partially resistant to sulphathiazole 1/100,000 and to sodium sulphapyridine 1/10,000.

Technique. The size of (uncrowded) colonies on a plate containing 1/10,000 sulphanilamide or sodium sulphacetamide is a useful criterion of resistance or non-resistance, but a resistant strain must be able to grow on 1/5000 Sa and will not grow on 1/5000 Ssac.

The best culture medium for these tests is Lab. Lemco bouillon with agar, but without peptone.

In concluding I wish to express my thanks for their help to Prof. H. R. Dean, Prof. C. H. Browning, Drs E. T. C. Spooner, A. MacDonald, J. E. McCartney and R. D. Stuart. The sulphonamides I received through the kindness of the British Pharmacopoeial Commission and of Messrs May and Baker.

Considerable errors arose when the plate count method was used to determine the number of bacteria on dehydrated vegetables. Bacteria probably occurred on the surface of the vegetables only.

Plate counts tended to be greater when suspensions were prepared at higher temperatures over the range 10–40° C. Counts often increased by 20% and sometimes by 50% in the short period allowed in the standard procedure (25 min.), probably owing to multiplication of bacteria. Changes in the volume of suspensions, caused by rehydration of vegetables, led to small errors for which allowance could be made. Larger variations in count arose from sampling errors through differences in the number of bacteria on individual strips and, to a lesser extent, through imperfect distribution of bacteria in suspensions. The relation of plate counts to the actual number of bacteria on the vegetables was uncertain.

However, the error in counting a single sample (— 65% to + 150%) was appreciably smaller than that in counting successive samples from the same factory (about fivefold) and this in turn was less than the variation between different factories (up to a thousandfold). The plate count could therefore be used with some confidence as a general guide to the state of factory hygiene.

The author is grateful for assistance given by Dr M. Stephenson, F.R.S., of the Biochemical Laboratory, Cambridge, and by Dr M. Ingram, Dr H. G. Wager and others of the Low Temperature Research Station, Cambridge.

1. A comparative study of alcoholized and phenolized T.A.B. vaccines has been made.

2. No difference could be detected in the immunological potency of the two vaccines.

3. The contentions of Felix and others that the reactions with alcoholized vaccine are less severe and ‘Vi’ response greater than with phenolized vaccine are confirmed.

4. The change over of large scale production in the Sudan from phenolized to alcoholized vaccine is not considered justifiable.

I wish to record my grateful thanks to Dr E. S. Horgan, Assistant Director Research, Sudan Medical Service, for the help and advice given in the carrying out of these experiments and preparation of this paper and also to Col. H. T. Findlay for his helpful criticism and permission to quote the conclusions of his preliminary experiments.

The titres of the complement-fixation test and the agglutination test run parallel in rabbit sera, but not in human sera. These facts are explained in connexion with the specificity of complement.

1. Treatment with enzymic hydrolysate of protein after blood depletion has a significant action in restoring serum protein content.

2. Blood depletion of hyperimmunized horses alters the serum globulin fraction much more markedly than the serum albumin fraction.

Our thanks are due to Dr R. N. Roy and Mr Diptish Chakraborty for useful help.

1. Two men and four women carried out digestibility experiments on English and Canadian wheats at 90 and 80% extractions. The flour was the only source of protein and contributed 77−93% of the total dietary calories.

2. At 90% extraction the digestibility of the diets in terms of calories was unaffected by the source of the flour and amounted to 93·3%. At 80% extraction the digestibility of the diet containing English wheat amounted to 95·6% and of those containing Manitoba wheat to 96·7%. The difference is attributed to mild intestinal upsets on the English flour.

3. The apparent digestibility of the protein depended upon the amount of N in the wheat and fell as the extraction rose. A quantitative analysis of the results indicates that the protein in wheat flour of 90 and 80% extraction is completely digested and absorbed, and that the N found in the faeces is entirely derived from the secretions of the gut.

The Medical Research Council paid for the expenses of this investigation. We are very much indebted to Drs T. Moran, C. R. Jones and other members of the Cereals Research Station, St Albans, without whose help this study would hardly have been possible. We have also very much appreciated the help we have received from the subjects, Miss M. Costain, Miss C. M. Walsham, Miss E. Wilkinson and Mr R. Tayler, and also from Flt.-Sergeant Childs, who kindly made the bomb calorimeter determinations.

The findings of clinical nutrition surveys of 3351 children aged 8–15 years and of 3326 adults, of both sexes, were analysed statistically to ascertain the relationship existing between nutritional grade (good, fair and poor) and the incidence of a variety of clinical signs (pityriasis, folliculosis, gingivitis, etc.) observed at the time of the medical examination but not taken into account in grading the subjects according to their state of nutrition.

The analysis showed negligible correlations between the clinical signs singly and collectively and the clinician's nutritional grade. Further, when we compared the incidence of each clinical sign and the nutritional state as a combination of all the clinical signs (i.e. the general nutritional factor), there was negligible agreement as shown by the low general factor saturation coefficients, thus suggesting that the presence of these signs is not a dependable expression of the general state of nutrition.

A special clinical survey of 1067 children was carried out to provide data which would throw light on the relationship between the criteria (posture, muscular development, etc.) which the clinician consciously takes into account but does not as a rule record in deciding the nutritional grade, and the nutritional grade itself. The grading criteria in the survey were separately assessed and recorded and so also were the usual clinical signs (pityriasis, gingivitis, etc.).

For the grading criteria there was a high degree of correlation between each one and the nutritional grade and also between each one and the combined pool of all the criteria. The clinical signs showed only negligible correlations with each other, with the nutritional grade or with any of the grading criteria.

It would seem, therefore, that nutritional assessment as at present understood is determined mainly by the value placed on the grading criteria (posture, muscular development, etc.), and to a negligible extent or not at all by the presence or absence of clinical signs (pityriasis, folliculosis, gingivitis, etc.).

1. A dry pelleted diet is described which, supplemented with fresh greenstuff, dried cabbage, or ascorbic acid, is highly satisfactory for the growth and maintenance of guinea-pigs.

2. No evidence could be found that the pelleted diet alone was deficient in any other factor than vitamin C required by guinea-pigs, fresh greens and dehydrated cabbage being effective because of their high content of this vitamin.

3. Vitamin C added to the diet as crystalline ascorbic acid or as present in dried lucerne meal is mostly destroyed by the pelleting process and is further reduced during storage.

4. The aim of evolving a dry pelleted stable diet completely adequate for guinea-pigs has not yet been realized.

It is a pleasure to acknowledge our indebtedness to Miss M. Olliver, Messrs Chivers & Sons Ltd., who carried out the ascorbic acid determinations and gave us much valuable advice.

Our thanks are also due to Roche Products, who gave us the ascorbic acid, to the Director of Messrs Chivers & Sons Ltd. for the generous gift of 1 cwt. of standard dehydrated cabbage, to the Dehydration Division of the Ministry of Food for supplying two samples of sub-standard dehydrated cabbage, and to Mr D. G. Short, senior technician in charge of the animals at the Institute, who prepared the small-scale diets.

The authors have determined the vitamin A content of the liver in persons who had succumbed to sudden death in Copenhagen in 1939 and 1943 and in Oslo in 1943–4. The values in Oslo after three years of war and severe rationing were higher than in Copenhagen, the population of which had a much milder rationing during the war. The values in Copenhagen for 1943 were somewhat lower than those for 1939. The most plausible explanation of these findings seems to be that the pre-war vitamin A reserve in Norway was high.

A complex disease picture prevalent in this country has been traced (Spira, 1928) to the protracted ingestion of drinking water derived from the tap, and of food prepared in aluminium cooking utensils. No indication could at that time be given of the exact irritant, beyond stating that a mineral or metal seemed to be involved. Further observation revealed a frequent association with paraesthesiae affecting the hands and fingers, especially those supplied by the dorsal cutaneous branch of the ulnar nerve. The feet were affected to a lesser extent. Since there is, in the present state of our knowledge, only one poison which affects the ulnar nerve, namely, fluorine, Spira (1933) concluded that it may be this halogen which was one of the aetiological factors concerned. It was the wide-spread occurrence of mottled teeth in this country (Spira, 1942a, b), known to be produced by a drinking water with a content of not less than 1 part of fluorine per million parts of water (1 p.p.m.), equivalent to gr. 1/120 of fluorine to a pint of water, ingested during the period of calcification of the teeth, which helped to establish the fact that it is indeed fluorine which is the causative agent producing signs and symptoms of a hitherto obscure origin.

1. The effect of either or both caloric and protein deficiency on the susceptibility of rats and mice to peroral infection with Salmonella typhi murium was studied.

2. Moderate restriction of food intake (80% of normal diet) for a period of 5 weeks was without influence on the infection susceptibility of rats, even when the diet fed was low in protein.

3. Long-term restriction of food intake (10 weeks) led to a marked lowering of the resistance of rats to the infection, there being a direct relation between the magnitude of the intake restriction and the extent of the resulting loss of resistance.

4. The infection resistance of rats was lowered more markedly by a given total restriction of food intake, when the latter was imposed in the form of a gradually reduced ration, than when it was imposed in a uniformly restricted ration. The effect so produced was independent of the protein content of the diet.

5. The effect of gradual food restriction was diminished by gradual supplementation of the diet with non-proteins and was augmented by gradual supplementation of the same diet with protein.

6. In mice kept on a restricted diet loss of resistance to S. typhi murium has been shown to be due to a deficiency of both calories and protein.