The bacteria which maybe included together as the Gaertner Group are of considerable importance, comprising as they do most of the bacteria found in outbreaks of food poisoning and in paratyphoid fever, while they are etiologically concerned with a number of diseases in animals both domesticated and wild.

In all countries which make statistical returns, attention has been directed to the large proportion of children failing to complete one year of life. Even the most highly civilised races lose in this way more than ten per cent, of their potential citizens as will appear from the data contained in the following table (Deutsche Sterbetafeln, 1910).

The document, of which a translation follows, was discovered by me in the National Library at Madrid (Coll. Salazar, Vol. MSS. 3207).

1. A method is described of rapidly evaporating to dryness bacterial emulsions contained in tarred flasks and from the increase of weight determining the strength of the emulsion.

The same apparatus can be used for a variety of purposes, e.g. drying serum, estimating solids in water, milk etc.

2. A very rapid method of drying bacteria smeared on a tarred piece of platinum foil, and from the dried residue preparing a vaccine is described.

3. A correlation between the number and weight of bacteria in vaccines made from agar cultures of the B. typhosus, B. coli, B. pyocyaneus, Meningococcus (Weichselbaum), Pseudo-Gonococcus, Micrococcus melitensis, B. pneumoniae Friedlander, Staphylococcus aureus and Streptococcus has been established.

4. The advantages of the gravimetric method are:

(a) That with a sensitive balance constant results are obtained.

(b) It is more rapid, and involves no strain ou the eyes.

(c) It can be applied to cultures of all bacteria growing on solid media, whether these form uniform emulsions or not, e.g. vaccines of Streptococci, Micrococcus catarrhalis, Diphtheroid organisms, B. tuberculosis, Streptothrices can be accurately standardised. Even small clumps in the vaccine considerably vitiate the results in Wright's method. The chief precaution to take in the gravimetric method is to remove the growth carefully, without breaking the surface of the medium and avoiding the condensation water.

(d) It brings into line the dosage of bacterio-proteins with that of other medical remedies.

Since the publication of my paper “A Medium for Bacillus diphtheriae” (This Journal, Vol. XI. p. 271), I have had further experience of the medium and have tried various modifications.

1. A male guinea-pig which has received a single injection of a mixture of diphtheria toxin-antitoxin causing severe constitutional disturbance, may beget offspring of slightly lower resistance than normal to diphtheria toxin

2. This effect is generally restricted to young born within twelve months after the injection of the father, being rarely noticed in the young of later litters.

3. An increased susceptibility to diphtheria toxin is likewise observed in the offspring of male or female guinea-pigs which have received a large dose of horse serum. The greater susceptibility to diphtheria toxin of the young of male guinea-pigs which have been treated with toxin-antitoxin may therefore be non-specific in character.

4. The injection of diphtheria toxin-antitoxin mixtures into guinea-pigs whether male or female reduces their rate of breeding and lowers the vitality of their young.

5. These effects are most pronounced when the toxin-antitoxin mixture produces severe constitutional disturbance or contains excess of horse serum

Following the subcutaneous injection of typhoid vaccine into rabbits the average antibody response was estimated from day to day, and found to vary for agglutination, bactericidal action, phagocytosis (including tropins), “precipitation” and probably for complement-fixation according to the dose of vaccine.

As estimated by the maximal value reached by the serum the response increases with increasing dose in nearly all cases. This increase becomes relatively less and less as the dose increases, and its progress suggests that with a sufficiently large dose a limiting-value might be reached, which if not actually a true limit would be practically one.

The observed relationship between dose and effect is such as to suggest that the combination of antigen and reacting-cell takes place in accordance with the rules governing adsorption processes; but this does not hold for the response in bactericidal power.

With increasing vaccine-dose the date at which the maximal value is reached gets later for the various antibodies, with again exception of the bactericidal power.

The precipitation observed differs from the usual precipitation reaction and is perhaps really an agglutination-phenomenon.

Phagocytosis was observed in three ways, and the bearing of the results on the mechanism of the action of the antibody concerned is considered; and the relationship between the bactericidal and other antibodies is also discussed.