Among the properties of the red blood corpuscles, that have from time to time been investigated, the resistance of this type of cell to the destructive action of various lytic agents occupies a place of some importance. Very many substances have been studied from this point of view, and no useful purpose would be served by enumerating them here; but it should be noted in passing that, as regards the great majority of them, we have no evidence that they play any part in blood destruction as it occurs “in vivo” under either physiological or pathological conditions.

In former reports by us, considerable attention was devoted to a study of the number and nature of the cellular elements in milk.We found that cells, sometimes in enormous numbers, are present in all milk (cow, goat, ass, man), that considerable variations in number occur without apparent cause, and that the presence of the slighter forms of non-suppurative mastitis does not seem to influence definitely the number of these cells.

In recent years much work has been done on the bacterial content of milk, chiefly with a view to demonstrating the principal sources of contamination and at the same time collecting data to aid in the fixing of a bacterial standard for “clean” milk. On looking through the various publications one is particularly impressed by the lack of uniformity in the length of the period of incubation of gelatine and agar plates. Some observers adopt a period of only a few days while others prefer to incubate for 8–10 days before counting their plates. It does not yet seem to be generally recognised, in Britain at all events, that, if the highest figures possible are to be obtained, the incubation period must be longer than three days.

(1) From a horse injected with sheep's red cells three months prior to the first bleeding and in a condition of constant haemolytic titre 122 litres of blood were taken in a period of 11 months. The horse's condition remained good throughout and has markedly improved during the year.

(2) The net result was that the haemolytic titre during that time fell only to about 66% of its original value, the leucocytes to about 66%. haemoglobin scarcely at all, while the specific gravity of the blood and total protein have increased, the former by 10% the latter by 5%;.

(3) There was no relationship between the total number of leucocytes and the amount of antibody. The differential count showed an increase of 12% in the polymorphonuclear and a decrease of 12% in the mononuclear cells, these figures being not very far outside the experimental error. The eosinophile and mast cells showed no marked alteration in number, size or staining reactions.

The process of subjecting flour to the whitening action of dilute nitrous fumes has grown so extensively during the past ten or twelve years, that it is estimated that more than half of the enormous amount of flour utilised for making bread and for other purposes is now bleached or tinted by this method. Yet none of this bleached or artificially whitened flour is sold to the public as such specifically, or marked by any distinctive label, to show that it has passed through a chemical process.

The American method of standardizing tetanus antitoxin has been studied and two samples (Toxins 3 and 4 of this paper) have been examined.

It has been found that:

1. Toxin 3 remained stable for two years under conditions which were not absolutely ideal, as the tube containing the supply was repeatedly opened during that time and the air in this neighbourhood, especially in winter, is very moist.

Toxin 4 has so far remained stable for 12 months. This toxin has been distributed in small quantities in tubes which have been exhausted and sealed in the flame.

2. By itself each of these toxins has given results consistent within the error of experiment when used to establish the M.L.D. and also to test a serum. But when the same serum was evaluated by both toxins they gave differing values. This dffference in value appears to be due to

(a) Deterioration in Toxin 3 which raised the L + dose from 00006—000075.

(b) Excess of toxicity in Toxin 4.

Whether this is due to increased susceptibility of the race of animals used for the tests can at present be only a matter of surmise.

3. The American method shows clearly that tetanus antitoxin can be heated at 57°C. for one hour on each of three successive days without loss of antitoxin provided no antiseptic (e.g. phenol) be present. Should such a preservative have been added then the loss on heating amounts to about 12% and occurs during the first hour.

4. Tetanus antitoxin containing phenol appears to be more susceptible to heat than diphtheria antitoxin under the same conditions.

The general conclusion arrived at is that, provided control experiments are carried out from time to time (as in the case of standard diphtheria toxin), this method of standardizing tetanus antitoxin is—as claimed for it—simple, accurate and reliable.