Bacteriological diagnosis of the Enterica is only established with certainty on recovery of the infecting organism by recognised laboratory methods. In default, recourse must be made to a serological investigation into the agglutinating power of the patient's serum, when, theoretically, little difficulty ought to be experienced. In enterica suspects, unvaccinated or uninfluenced by previous enterica disease, demonstration of agglutinins reacting with the Bact. typhosum, paratyphosum A, B, or C in relatively high dilutions of their sera should be considered adequate evidence. In the vaccinated, elevation of agglutination titre—as determined by repeated examinations during the course of the disease—has been generally accepted as criterion for existence and type of infection. The principle of ascending dilutions, on which such “quantitative serum analysis” is based, is explained by the fact that in an infection with one organism a specific agglutinin is formed for that particular organism and group agglutinin is for other organisms closely related biologically; the specificity, therefore, of the agglutination reaction must be wholly dependent on the basis of dilution, the specific agglutinin being present in greatest quantity and operative in a range much exceeding that of the secondary group agglutinins. Reasonable as this view may seem in principle, it is far from easy of application in practice. Lack of accurate information as to the day of disease on which serum was taken, unreliable case histories in regard to vaccination or previous enterica infections, and inability of private practitioners to induce patients to submit to repeated blood collection constituted here primary difficulties.

In the course of a paper by the present writers (this Journal, xxv, 336–53) an attempt was made to assess the relative importance of selective mortality on the one hand and sub-lethal infection on the other in increasing herd resistance to subsequent exposure to infection. The subject was further considered by one of us (E.M.N.) in a later report (this Journal, xxvi, 19–27).

Dans trois courtes notes, j'ai décrit précédemment des variations très particulières que présentent certaines souches de bacilles fluorescents, et j'ai montré comment on peut arriver à les reproduire in vitro dans des conditions déterminées. Je compte reprendre ici cet exposé des faits et des considérations théoriques qui en découlent.

If a medium containing either 1 per cent. ammonium succinate or 1 per cent. ammonium fumarate together with certain inorganic salts be inoculated with B. pyocyaneus and incubated aerobically at 37° C. a vigorous growth of the organism will ensue, the rates of growth in both cases not being markedly different from each other. If the growth be allowed to proceed for a fortnight, analysis of the media shows that essentially similar products (mixtures of the lower fatty acids) have been produced in both cases. If the growth be allowed to proceed for not longer than three days, analysis shows that in the succinate medium over 80 per cent. of the succinic acid has not been utilised, whilst in the other medium the entire fumaric acid has disappeared, giving rise in its stead to pyruvic acid which is further utilised as growth proceeds(1). Quantitative data support the view that the breakdown of succinic acid occurs through the intermediate production of fumaric acid, the rate of fermentation of fumaric acid being greater than that of succinic acid, so that fumaric acid is not detected among the products of fermentation of succinic acid. If this view is true, it should be possible to show that B. pyocyaneus has the power of oxidising succinic acid to fumaric acid. It is clear that the proliferating organism cannot be used to demonstrate this experimentally, for the fumaric acid is utilised as quickly as it is formed. Hence it is necessary to use the organism in such a condition that proliferation is completely (or almost completely) eliminated. Under such circumstances the fumaric acid will accumulate and its detection will be made possible.

In the early records of mortality there was much confusion between scarlet fever and diphtheria. According to Hirsch, after scarlet fever had been clearly differentiated from measles about the middle of the eighteenth century a new error was introduced into the doctrine of scarlet fever. Emphasis was placed on the inflammatory process in the throat which frequently occurs in scarlet fever, and this led to its being confused with diphtheria.

1. The influence of temperature on the germicidal power of selected disinfectants has been studied, and it has been found that germicides may be classified broadly into three main groups, viz.

Germicidal power (a) unaffected by rise in temperature: chiefly chemical substances, possessing reducing properties;

(b) approximately doubled by rise in temperature from 20 to 37°C.—phenol, alcohol;

(c) increased as much as 10 or 20-fold by the same temperature rise: oxidising agents.

2. The effect of temperature on bactericidal action is different for B. coli and B. fluorescens, thus causing very complex changes in selective action, which are discussed in this paper.

3. The temperature coefficient for the process of protein-precipitation by phenol is 2·2 per 10°C. rise in temperature, and thus similar in magnitude to the coefficient for disinfection by phenol. This supports the view that the germicidal action of phenol is associated with its denaturating effect on the cell-proteins.

4. Previous experimental work had suggested that the bactericidal action of the quinones was due to their chemical reactivity with the simple cell-constituents, e.g. the amino-acids, rather than with the complex colloids. The temperature coefficient of the reaction between benzoquinone and glycine is, however, the normal one, viz. 2 for 10° C. rise, for chemical action, although the germicidal action of the quinones may be actually 20 times more effective at 37° than at 20° C. The presence of certain inorganic cell-constituents accelerates the velocity of reaction between quinone and glycine, but does not increase the temperature coefficient.

5. The bactericidal power of picric acid and potassium permanganate, as well as the quinones, is greatly increased by rise in temperature: and there would appear to be some other factor common to all these disinfectants associated with their high temperature coefficient.

1. When a solution of commercial peptone is substituted for antigen in a complement-fixation test with the unheated normal serum of certain species (man, ox, sheep, horse, rabbit, white rat), a definite fixation reaction occurs both at 37° C. and at 0° C. In the ox, sheep, horse and rabbit this property of serum is partially stable at 55° C., but normal human serum and the serum of the white rat are inactive after heating at this temperature. The property is resident mainly in the carbonic-acid-insoluble globulins of the serum.

2. The same results are obtained when ethyl alcohol diluted with several volumes of normal saline solution is substituted for antigen in a complement-fixation test with normal serum.

3. Analysis of these reactions shows a close correspondence with complement-fixation by the sera of normal animals plus the Wassermann “antigen”—the Wassermann reaction of normal animals.

4. Marked complement-fixation effects are also obtained with heated normal serum of the rabbit, ox, sheep, horse plus cholesterol suspension, and particularly cholesterolised-peptone, these effects occurring in parallel with those produced by serum plus alcohol-saline, peptone solutions and the Wassermann “antigen.” The heated normal serum of the pig, white rat and guinea-pig do not exhibit these reactions, and the same applies to heated normal human serum. Unheated pig serum fails to react. Such results also elicit a close relationship between these non-specific reactions and the Wassermann reactions of normal animals.

5. The reacting property is absent from the serum (heated and unheated) of young rabbits during the first 2 to 3 weeks of life, but appears soon after this (e.g. by the 37th day) and is progressive in development. Its development in early life runs parallel to that of the natural haemolytic property of the serum for sheep's blood (due to a natural antibody-like substance). The two properties are, however, independent as illustrated by absorption tests.

6. Besides the agents referred to above as capable of fixing complement along with normal sera, other substances possess a similar property, e.g. certain alcohols, sodium oleate, tissue proteins, certain amino-acids and sodium nucleate. Commercial peptone purified by precipitation with alcohol is equally active with the original material. Cholesterolisation of these agents may yield a product whose activity is greater than that due to summation of effects.

7. Wassermann-positive and -negative human sera have been tested in the complement-fixation reaction with certain of these “pseudo-antigens,” viz. alcohol-saline, peptone, cholesterol, and cholesterolised-peptone, but a uniform parallelism has not been demonstrated between the reactions with these agents and the Wassermann effect. Some Wassermann-positive sera react also with alcohol-saline, peptone, cholesterol and cholesterolised-peptone, while sera from selected normal persons are quite inactive. A considerable proportion of Wassermann-positive sera yields definite complement-fixation with cholesterol and cholesterolised-peptone; a small proportion of Wassermann-negative sera reacts with these agents.

8. The thermolability of the serum principles acting with various “pseudoantigens” has been studied by testing unheated serum and serum heated at temperatures ranging from 46° to 60° C. Two types of thermolability curve have been demonstrated with different specimens of rabbit serum: (1) a more or less progressive weakening of the various reactions with inactivation at 60° C.; (2) inactivation of the effects with Wassermann “antigen,” alcoholsaline and cholesterol at 50–52° C., activation of the effects with the Wassermann “antigen” and cholesterol at 54–56°C. and inactivation again above 60° C.; in this case the curves for peptone and cholesterolised-peptone do not show such double inactivation. Unheated normal human serum yields reactions with the various agents (including the Wassermann “antigen”) but inactivation occurs at 50° to 54° C. whereas certain syphilitic sera yield thermolability curves somewhat similar to type (1) of rabbit serum, with inactivation at 60° C. or over.

The results of this investigation show that tuberculosis in captive wild mammals may be caused by any one of the three types of tubercle bacilli—human, bovine or avian.

In the Primates, which under experimental conditions are susceptible in an equal degree to bovine and human tubercle bacilli, natural tuberculosis may result from infection with either type. The human tubercle bacillus is however found more frequently than the bovine bacillus. Taking the condition of the regionary lymphatic glands of the body as an indication of the probable portal of entry of the infecting bacilli, e.g. greater enlargement and more advanced caseation of the thoracic than of the abdominal lymphatic glands as denoting respiratory infection, it would appear that the monkey may become infected with bovine tubercle bacilli, as well as with human tubercle bacilli, not only through the alimentary tract but also by inhalation.

Cultures of acid-fast bacilli were obtained from four caymans, one frog and one snake, which died in the Zoological Society's Gardens.

The strains from the four caymans were identical and indistinguishable from Aronson's Mycobacterium marinum.

The snake strain closely resembled the fish tubercle bacillus of Bataillon, Dubard and Terre.

The frog strain could not be identified with any of the cold-blooded strains of tubercle bacilli mentioned above.