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A review of patients following a partial gastrectomy for benign peptic ulceration reveals very satisfactory symptomatic results. Minimal haematological and biochemical disturbances have been produced and all the patients with gastric ulcers were cured. The gastric resection has been limited to two-thirds in all the cases. One hundred and ninety patients were included in the review, and of these, 99 underwent detailed haematological and biochemical investigation. Ninety per cent of the patients were graded as Visick I or II. There was a low incidence of severe vomiting (1.5 per cent), diarrhoea (1.5 per cent) and dumping (1.9 per cent) Anaemia was manifest only in males (18 per cent). Iron deficiency was present in both sexes and increased in severity with time. The deficiency has been readily corrected with oral iron. There was no macrocytic anaemia, 10 per cent of patients having subnormal serum vitamin B12 levels. There was no folate deficiency. No biochemical abnormality was noted. Eight patients treated for duodenal ulcers developed recurrent ulcers but 6 of these followed Billroth I gastrectomy. Recurrence following a Poly a gastrectomy was 2 per cent. No gastric ulcer recurred. These findings justify treatment of both duodenal and gastric ulcers by partial gastrectomy. A modification of the Billroth I operation was used to overcome technical problems. Operation details are given and it is suggested that this operation is ideal for gastric ulcer.

The conditions for satisfactory fumigation with formaldehyde were investigated using suspensions of Staph. aureus and Ps. aeruginosa dried as drops on strips of polythene or after mixing with cotton dust. In laboratory experiments with controlled concentrations of formaldehyde and water vapour, satisfactory results were obtained at 86 % humidity, but at 32 % humidity the formaldehyde was virtually inactive.Measurements under field conditions showed that the permanganate method of vaporizing formaldehyde did not vaporize enough water to produce optimum conditions for sterilization, and that great care was necessary in the sealing of rooms. When sterilization was incomplete the surviving organisms were not uniformly distributed within the room.In the limited circumstances in which fumigation with formaldehyde is thought to be essential, the process should be controlled by estimating the formaldehyde and water vapour concentrations initially and after 3 hr.

The ability of a particle to remasn airborne, its ability to pass through filters, the site at which it may be deposited in the respiratory tract and the rate at which it will be removed from the air by sedimentation are all dependent on the size and density of the particle. In the course of a variety of investigations we have determined the size distribution of particles carrying various species of bacteria and fungi using the size-grading slit-sampler described by Lidwell (1959). A few of the results obtained have already been quoted in part, but the majority have not been published previously. The air sampler used separates the airborne particles into four size ranges, each of which is deposited on the surface of the agar medium contained in one of four 6 in. Petri dishes. This apparatus is constructed so that the air sample entering through a slit 7 mm. wide, impinges on to the surface of the first Petri dish at such a velocity that only the larger particles, i.e. those having an equivalent particle diametert greater than about 18,un are deposited. The air stream carrying the smaller particles is then ca.used to impinge in turn on to the surface of the three remaining Petri dishes, each time at an increased velocity and through a narrower slit, so that the minimum particle size for 50 °/0 deposition is about 10/6 for the second dish, 4,u for the third and less than l,u for the fourth and last. When the plates have been incubated the colonies found will be derived from organisms which entered the sampler carried on airborne particles corresponding approximately to the four size ranges, greater than 18ju, between 18 and lO,u, between 10 and 4ju and less than 4,sb. These size limits correspond to the value of equivalent particle diameter for 50 °/0 deposition so that there is, in fact, a considerable size overlap between the fractions. In spite of this however, reasonably good estimations of the particle size distribution within the sample and hence of the median equivalent particle diameter and of the dispersion, expressed either as an interquartile range or, if appropriate, as a standard deviation, caUn be made by plotting on probability paper the cumulative fraction oversize against the 50 °X0 collection limits, namely 18@2, 9@6 and 4 2,s6. As there are internal losses in the instrument it is necessary to correct the numbers of colonies counted in the later stages in order to arrive at a good estimate of the size distribution in the original sample. The numbers found on

Summary. Under field conditions wanted micro-organisms are often present in the air in small numbers and form a small proportion of the total flora. Selective techniques would be useful, but may be difficult to devise as airborne micro-organisms are easily damaged and passing air over organisms deposited on slit sampler plates may be traumatic. Selective media may be avoided by using indicator media or animal inoculation, or the organisms may be transferred to selective conditions after some growth has taken place. Five selective agents are discussed: specific nutrients, anaerobic incubation, temperature, antibiotics, and other added selective chemicals. A table of references for isolating individual organisms is given.

The measurement of the phase fluctuations caused by spontaneous emission in the oscillation of a He–Ne laser operating at 1.15 μ is reported. The frequency fluctuations in the signal resulting from heterodyning two independent modes in the laser were measured as f2(ν) =(9.6±2)×10−2 Hz2/Hz for 1.65×107 stored photons per mode and f2(ν) =(2.7±0.3)×10−1 Hz2/Hz for 6.2×106 stored photons per mode. These values are to be compared with the theoretical minima for these cases, which are calculated to be f2(ν) =5.1×10−2 Hz2/Hz and f2(ν) =1.4×10−1 Hz2/Hz, respectively.

Summary: Bacterial colonies grown on objects embedded in agar sometimes show a tendency to become confluent. Glass coverslips and polytetrafluorethylene (Teflon) discs were inoculated with Staphylococcus lactis and completely embedded in serum agar. If the surface of the agar were flooded with broth before the plates were incubated the colonies had a tendency to run together, but not if the plates were incubated after thorough drying. Drying also prevented confluence occurring when broth had been injected on to the surface of the embedded object. Drying the poured plate probably acts by removing fluid squeezed out at the interface.

SUMMARY Respiratory syncytial virus in 1 μl drops of tissue culture homogenate on polythene gave c. 10% survival on drying and c. 1% survival over 24 h, depending on the vehicle and humidity, but showed no significant loss in liquid suspension over 3 h, or if 100 ft3 of air were blown through the suspension. When drops were deposited on nutrient agar plates there was no significant loss over a period of 3 h, even if 10 ft3 of air were passed over the surface. However, only c. 10% of the virus deposited in this way could be recovered, though 90% of bacteria could be recovered by wiping the agar firmly in the presence of liquid. Air and surface samples were taken in 13 isolation cubicles in which there was an infant suffering from acute bronchiolitis without recovery of the virus, though virus had been isolated from the throats of 8 of the infants, 5 at the time of sampling. The total volume of air sampled was 226 ft3 with liquid impingers and 1146 ft3 on agar. Hartmannellid amoebae were isolated on 2 occasions, one from the air samples and one from surface samples, and an adenovirus type 10 was isolated from the swab of a chair.

A variety of surfaces was tested for self-disinfecting action againstStaph. aureusandEsch. coliat a humidity of 42%. Surfaces which had been treated with disinfectants sometimes reduced the survival when the organisms were applied subsequently in drops of broth, but the reduction was very small unless the surface was able to absorb appreciable amounts of disinfectant and the drop of inoculum spread. When the inoculum was applied dried in cotton dust, only surfaces which evolved formaldehyde showed any activity against the bacteria. These surfaces also reduced the survival of bacteria in liquid inocula.We would like to record our thanks to Dr O. M. Lidwell for much helpful advice.

Antisera were raised in rabbits to whole streptococci of group A grown in a semi-synthetic medium, containing tryptic digest of casein. Twelve of these sera were tested for their ability to react with a variety of human tissues by the immunofluorescence technique. One serum, raised against a type 6 glossy strain, contained no detectable antibodies to the sarcolemmal/subsarcolemmal region of the myocardium, but gave strong staining of fibroblasts, endothelial cells, smooth muscle and the pia-arachnoid. In addition there was staining of astrocytes, best demonstrated in sections of an astrocytoma, and of the stratum granulosum of the skin. This reaction was prevented by absorption with the homologous organism but not with Staph. aureus. In addition the titre of the serum against fibroblasts was not affected by the presence of 10 mg/ml tryptic digest of casein in the diluent. Antisera to two other strains of streptococci (type 6 matt and type 24) gave this staining reaction in addition to the sarcolemmal/subsarcolemmal staining reaction.

Isolation of' the amoebae Tissue culture method. Standard virus cultivation techniques were used. In outline, the method was to suck air into the liquid contained in a special modification of the slit sampler (Lidwell, 1966) and then to inoculate as much as possible of the liquid on to HeLa cells. The cells were maintained on Gey's solution with 5 per cent. rabbit serum, 0.25 per cent. lactalbumin hydrolysate, and with 100 units each of penicillin and streptomycin and 5 pg Fungizone per ml. The cells were incubated at 33"-37"C, mean c. 35°C. This technique was used because virus isolation was the original object of the work. This approach has the disadvantage of being laborious, of requiring the cell sheet to be washed after an initial short period of incubation to prevent bacteria and fungi breaking through the antibiotic cover, with the risk of losing amoebae, and of requiring the use of a fungistatic agent, that used being Fungizone, which is toxic to some amoebae (personal communication from Dr C. G. Cu 1 bertson). Agar plate method. This method is based on that used by Singh (1952) for cultivation of small free-living amoebae from the soil. Oxoid Ionagar no. 2 was dissolved in glassdistilled water to give 1.5 per cent. water agar, which was poured into 5+ in. (14 cm) diameter petri dishes. When set, the plates were dried in the hot room for about 1 hr. Klebsiella aerogenes (NCTC9667) was inoculated into a 100-ml bottle of Oxoid nutrient broth no. 2, and after overnight incubation at 37°C the bacteria were harvested by centrifugation and resuspended in about 20 ml sterile distilled water. Three millilitres of this suspension was spread on to each water agar plate and allowed to adsorb. The plates were then used for air sampling either by exposing them for 10 min. in a 20 cu. ft (570 litre) per min. slit sampler or by leaving them open to the air for various periods up to 7 hr (" settle plates "). Unless otherwise stated, exposure was by the slit-sampler technique. In some preliminary experiments, not reported here, the klebsiella suspension was killed by heating for 2 hr at 56°C before being spread on to the plates, but this treatment was discontinued as heat-killed bacteria will not support the growth of some amoebae. The plates were incubated at 30"

Polynoxylin and noxythiolin (Anaflex and Noxyflex) have been recommended for the treatment of certain bacterial infections. Both compounds were shown to release formaldehyde. Detailed studies with noxythiolin showed that it decomposed in solution to liberate most of its formaldehyde, and that solutions of formaldehyde of the appropriate strength gave zones of inhibition on seeded plates comparable in size with those given by noxythiolin. It is suggested that the effects observed with these compounds are caused by the formaldehyde released.