A study of the biological characters of 1636 cultures of coliform bacteria, isolated from milk and bovine faeces, shows that the coliform group consists of a large number of different types. These types are so closely interlinked in characters and in relations to environment as to justify their inclusion in one genus. Nevertheless, to facilitate the identification of types, the group may be subdivided into subgroups, the Voges-Proskauer, Koser, inositol and indole reactions being reliable and outstanding criteria for this purpose. These characters show almost perfect correlations with various other characters. Thus Voges-Proskauer-negative types have a low CO2 to H2 ratio and are methyl-red-positive; Voges-Proskauer-positive types have a high CO2 to H2 ratio, are methyl-red-negative and Koser-positive. Koser-negative types are not highly resistant to brilliant green, are non-capsulated, do not form thick mucoid colonies and are Voges-Proskauer-negative, inositol-negative and indole-positive. Koser-positive types are highly resistant to brilliant green, and with the exception of group 2 and certain members of group 3, are frequently encapsulated and form thick, mucoid colonies. Non-inositol-fermenters are as a rule motile and adonitol-negative. Inositol-fermenters are Koser-positive, adonitol-positive, sucrose-positive and raffinose-positive; are frequently encapsulated and form thick, mucoid colonies; and as a rule are non-motile. Indole-negative types are Koser-positive, while indole-positive types are generally Koser-positive or negative according to whether the inositol reactions are positive or negative.

In previous reports (Watson 1937 a, b) one of us has described a series of experiments in which various diets were tested in regard to their effect on the growth, fertility, survival and resistance of mice. It was found that, when part of the oatmeal in a particular diet was replaced by dried skimmed milk, the does were more fertile, and the young mice gained weight more rapidly and showed a lower mortality during the first 8 weeks of life. Mice bred and reared on the latter diet were found to show a significantly increased resistance to per os infection with living cultures of Bact. typhi-murium, and to the intraperitoneal injection of a toxic fraction derived from that organism. The results obtained in a few tests suggested that these mice were also more resistant to the intraperitoneal injection of living Bact. typhi-murium; but the differences observed were smaller, and of doubtful significance. In the present paper we record the effect of these two diets on the epidemic spread of mouse-typhoid.

1. The effect of heroin, morphine, Dilaudid, Dicodid and Eukodol upon the human alimentary tract are described from observations involving the use of the barium meal and X-ray methods.

2. The effects of Dilaudid closely resemble those of morphine. Dilaudid produces a condition of increased tone in the pyloric and ileo-colic sphincters resulting in delayed emptying of the stomach contents into the duodenum and a delayed passage of the intestinal contents into the caecum.

3. Dicodid has a much weaker action upon the pyloric and ileo-colic sphincters than either morphine, heroin, Dilaudid or Eukodol. It causes only a negligible delay in the passage of food up to the 3 hr. stage, it being normal at the 6 hr. stage owing to a hastening of the motility rate.

4. Eukodol has an action resembling that of morphine and is described.

5. All these drugs possess well-marked analgesic properties.

6. No gross rectal symptoms were observed in any of the subjects under observation.

1. The presumptive coliform test was carried out by each of three workers, at each of four dilutions, on seventeen sets of five tubes for each of seven samples of 18-hour-old afternoon milk, held overnight in the ice chest.

2. With the exception of three slightly anomalous results, the data are consistent with the hypothesis that the chance of a tube remaining sterile is constant for all tubes inoculated from the same sample of milk at any one dilution.

3. The assumption of a Poisson distribution of organisms in parallel tubes is accurate enough, with these data, to give a good idea of the order of magnitude of the number of bacteria per ml.

4. There is, however, a tendency, more marked in our data in autumn than in spring, for the estimated count to rise at the higher dilutions. This may plausibly be attributed to the breaking up of clumps.

1. Ten pleuropneumonia-like strains isolated from various sources have been selected and studied with a view to discovering reliable criteria for differentiation. Three of them were isolated from the symbiotic association known in the literature as Streptobacillus moniliformis, six from lung lesions of rats and one from a swollen submaxillary gland of a rat. For comparison with these, six other strains, viz. three pleuropneumonia, one agalactia and two of Shoetensack's strains from lungs of dogs stated by him to be suffering from distemper and named by him Asterococcus canis type I and A. canis type II have been included in the inquiry.

2. Classification of the sixteen strains has been achieved by a comparative study of type of growth on liquid and solid media, morphology, pathogenicity and serological affinities. Table VII displays these differences.

3. The serological examination was of special importance for the whole problem of classification. For this purpose an agglutination test was devised which clearly revealed that the sixteen strains belonged to seven different serological types. As the strains of the same antigenic structure showed similar growth types in liquid and solid media and similar morphological appearances, seven species of pleuropneumonia-like organisms were set up:

(a) The L1 organism represents the first species. Three of the strains of this type were separated from Streptobacillus moniliformis cultures. The fourth culture of the same type was found in the lung of a rat, thus proving that this organism may occur independently as well as in symbiotic association.

New evidence of the symbiotic nature of the Str. moniliformis (an association of a streptobacillus with an L1) was given by the agglutination test, in so far as all sera prepared by immunization with Str. moniliformis cultures agglutinated to a fairly high titre the four different L1 strains.

(b) The L3 organism represents the second distinct type species. The five strains belonging to it originate from lung lesions of rats, viz. four from tame laboratory rats and one from a wild rat. This demonstrates that tame and wild rats contain the same variety of pleuropneumonia-like organism in the associated lung lesion. It is believed that 138 pleuropneumonia-like cultures isolated from lung lesions of rats by the writer belong to the same L3 species though only five of them have been studied here in detail.

(c) The L4 organism only once isolated from the enlarged submaxillary gland of a rat also suffering from lung lesions was proved to be definitely different from the L1 and L3 organisms by serological and other tests and represents therefore a third new type species.

(d) Furthermore the organisms of pleuropneumonia, agalactia, Asterococcus canis I and A. canis II would appear to be independent species of the same family.

4. Experiments on pathogenicity which are still in progress show so far that the L3 organism is pathogenic for mice. The L1 organism would appear to be devoid of pathogenicity when tested by similar methods.

5. The capacity of pleuropneumonia-like strains for forming associations with bacteria has been tested experimentally, and in a few cases success has been achieved. These associations with B. tetani and B. tetanomorphus, unlike that of L1 and the streptobacillus in the Str. moniliformis combination, though stable, are not such as to preclude the isolation in pure culture of the two anaerobic bacilli.

6. It is likely that the group of pleuropneumonia-like organisms is widely spread in nature. Search for such strains and thorough investigation of their properties would seem to be of prime importance in view of the minute size of the units which can give rise to growth and the light that might be shed by their study on the biological nature of the filterable viruses.

1. Group variants devoid of type antigen, described in the previous section, provide material for ascertaining the various components of the antigen in the mannitol-fermenting dysentery bacilli.

2. Flexner Y, as defined by Andrewes and Inman, is not a valid type. The strains which are regarded as being of this type, such as Y Hiss and Russell and Y Lentz, are old strains which have lost their type antigen and possess only group antigen. The reason why many newly isolated strains are identified as Y is because the antiserums used for their recognition contain more group than type agglutinin.

3. The four Flexner types V, W, X, and Z, each possess a distinctive type antigen and share a complex group antigen. They do not, as suggested by Andrewes and Inman, possess minor quantities of each other's type antigen.

4. 103, P 119, and the 88-Newcastle-Manchester series have also distinctive type antigens, and share the same group antigen with V, W, X, and Z.

5. It is considered that the existing Flexner group should be extended to include all organisms which have a type-specific antigen and share this common group antigen. The three types in (4) should therefore be placed in the group and named accordingly.

6. Six types which have the biochemical reactions of the Flexner group, and which have individual type antigens but no Flexner group antigen, are provisionally placed in a separate loose group.

Before dealing with this question it may be appropriate to present graphically the mortality of general paresis in Copenhagen in the period of 1866–1935 (see Fig. 1).

1. An account is given of enteric fever in a Mental Hospital, and the discovery of a “precocious carrier” of the Bact. typhosum, a man who, 4½ months before he showed symptoms of the disease, was a “carrier” and probably the source of infection in a milk-borne outbreak.

2. Description of a strain of Bact. typhosum forming dwarf colonies which was isolated (a) from a river, (b) from a patient who had drunk the water, (c) from the sewage of a mental hospital discharged into the river 4½ miles higher up, and (d) from patients in the mental hospital.

3. Isolation of the Bact. typhosum from a well of an institution in which an outbreak of enteric fever had occurred.

4. Isolation of Bact. typhosum from a stream adjoining a well in a farmyard in Belfast at a time when the milk was the source of infection of over 100 cases of the disease.

5. Isolation of Bact. typhosum from a cesspool discharging into a stream near Bournemouth, and the suggestion that Mrs A. from whose premises milk was obtained, which was the infective vehicle in the Bournemouth-Poole epidemic, may have been a “precocious carrier”.

6. An account of methods employed in the bacteriological examination of water and sewage.