1. Two Ayrshire cows in mid-lactation were fed for over 40 days on production rations containing from 16 to 20 g. of added borax.

2. The daily excretion of borate during the experimental feeding period was 13–16 g. in the urine, 5–7 g. in the faeces, and 0·3–0·6 g. in the milk, compared with figures of 1·5, 1·0 and 0·1 g. for the control period. There was no detectable retention of borate in the body, and the levels of borate excretion rapidly returned to normal after cessation of the experimental feeding.

3. No adverse effects were observed as a result of the borate feeding. The live weights of the animals remained normal, and there was no diuretic effect. The milk yield was also well maintained. The borate content of the milk increased from the normal level of 0·7 to over 3·0 p.p.m.

4. Attention is drawn to the risk of using farmyard manure which has been made from the excreta of animals fed on boronated rations.

A group of species, comprising Bacillus subtilis and related organisms, may be differentiated from other members of the genus Bacillus by (a) morphology and (b) the production of acid and acetylmethylcarbinol from glucose. The group may be divided into three species:

(1) B. subtilis Cohn emend. Prazmowski, the synonyms of which include B. aterrimus, B. globigii, B. mesentericus, B. niger, B. panis, and B. vulgatus.

(2) B. pumilus Gottheil, which resembles strains of (1) that produce a smooth glossy growth. It differs in failing to secrete diastase and in other features, but its separation as a distinct species is still an open question. It is sometimes identified as B. mesentericus.

(3) B. licheniformis (Weigmann) Gibson, the synonyms of which include B. subtilis (as used by Ford), B. globigii and B. mesentericus ruber. This species may be differentiated from (1) and (2) by its cultural characters, slow proteolytic action, vigorous CO2 production and ability to grow anaerobically.

Data are given which show that the solids-not-fat content of the milk produced in a certain dairying area in the early months of 1942 and 1943 was unusually low, a high proportion of the individual herds yielding milk containing less than the presumptive standard of 8·5% solids-not-fat. The freezing-point depression of this milk was normal. The solids-not-fat content showed substantial improvement in May. It is suggested that the low level of solids-not-fat was due to a low plane of nutrition of the cow.

The results of a series of determinations of the freezing-point depressions of the milk of the individual cows of a Shorthorn herd over a period of 16 months are reported.

The relative constancy of the freezing-point was confirmed, all but two values deviating by less than 4·5% from the mean Δ values.

Significant seasonal trends were observed, especially during the spring when the supply of ample amounts of young grass may cause the production of milk with somewhat smaller freezing-point depressions.

Systematic trends in the differences between the Δ of morning and evening milk were found, the evening values being generally higher, except for the winter period, during which the cows were housed at night, when the morning Δ values became the higher. The differences appear to depend on the changes in the temperature of environment to which the cows are exposed. These observations provide an explanation for the discrepancies reported in the literature.

The results of freezing-point tests on some 4000 samples of milk as delivered by individual producers to creameries in England and Wales are analysed. Prior to the war about six out of every 100 samples were found to contain added water, but, as cases of heavy adulteration were comparatively rare, the total effect on the bulked milk supplies was small. After 2½ years of war the position had remained virtually unchanged.

In studies previously reported (1) it was found that milk of normal appearance from cows having a latent infection with Streptococcus agalactiae yielded less cheese than that from cows with normal udders. Milk from cows free from Str. agalactiae infection, yet classed as ‘abnormal’ on the basis of biochemical tests, behaved similarly. The lower yield appeared to result from the lower casein and solids-not-fat contents of these ‘mastitis’ milks. With a single exception, the quality of the cheese made from these milks was not inferior to that of cheese made from normal milks. These findings appeared to warrant the extension of the studies to ordinary cheese-factory milks.

The presence, in the cheese milk, of phage active against the organisms of the ‘singlestrain ’ culture in use as starter leads to its multiplication during the cheese-making process. The extent to which the presence of phage is made evident in the vat depends largely upon the amount of initial infection. A heavy infection permits sufficient multiplication of the phage to cause lysis of the organisms and consequent cessation of acid development before the manufacturing process is completed. A light infection may have no noticeable influence upon the performance of the starter in the vat. Intermediate amounts have an effect on the rate of acid development in the later stages of the process, but within certain limits there is little adverse influence on the quality of the cheese produced.

Several cheese made from milk after the starter had failed, or during outbreaks of ‘slowness’ at three different places, were found to contain bacteriophage, which it is now possible to isolate from cheese where the whey is no longer available. The concentration of phage in cheese was found to be fairly constant when tested periodically during one year. The significance of such persistence on phage dispersal, its reintroduction into the dairy, and carry-over from one season to the next is pointed out.

1. Bacteriological studies have been made of some 400 samples of dried milk products comprising roller-dried separated milk, roller-dried full-cream milk, roller-dried buttermilk, roller-dried whey and spray-dried whey. The samples were derived from a total of plants operating throughout Great Britain.

2. The mean values for the plate counts at 37 and 55°C. of the roller-dried products were all below 1000 per g· as against ½–2½ million at 37°C. and 10,000–30,000 at 55°C. for the spray-dried products. The spray-dried products also gave three times as many positive presumptive coliform tests at all dilutions as did the roller-dried products.

3. The roller-dried whey and the roller-dried buttermilk both gave more variable counts at 37°C. and higher counts at 55°C. than the roller-dried separated milk and the roller-dried full-cream milk. The spray-dried whey gave higher and more variable counts at both 37 and 55°. than the spray-dried milk.

4. Marked differences were observed in the plate counts of samples derived from different plants, some plants giving consistently low counts and others giving higher and more variable figures. Differences were also observed in the counts at different stages of handling.

5. Evidence was obtained which indicates that mould counts do not provide a reliable indication of recontamination subsequent to drying.

It is evident from the foregoing results that decreases in count may occur during the storage of milk and whey powders. The extent of this decrease varies, however, with the type of powder and even between different samples of the same type. Further, many samples may show little or no alteration in the numbers of viable organisms surviving storage even for considerable periods.

Nevertheless, it is obviously important that for grading purposes or in relation to plant control a time limit should be fixed within which the plate count of any milk or whey powder should be determined. No data are available to show how rapidly organisms may die out during storage periods of less than 3 months, but it is tentatively suggested that all powders should normally be examined within, say, 14 days of manufacture. Unless such a limit is fixed, those samples in which the count does fall appreciably would reflect too favourably on the conditions of manufacture.

1. Full-cream unsweetened condensed milk (evaporated milk) and full-cream sweetened condensed milk (condensed milk) were prepared simultaneously on several occasions each time from a common bulk of raw milk. Heat treatment in the preparation of evaporated milk is, of course, much more severe than with condensed milk.

(a) There was no loss of vitamin A, carotene or riboflavin in either of the processes.

(b) The mean loss of vitamin C as compared with the raw milk was 10% for condensed and 60% for evaporated milk.

(c) The vitamin B1 losses were 3·5 and 27% respectively.

(d) Tests on rats showed that the biological values and true digestibilities of the proteins of the raw, condensed and evaporated milks were respectively 85·6 and 94·2, 84·6 and 98·8, 84·1 and 93·7. The differences in biological value are without statistical significance but the digestibility of the condensed milk was significantly higher than that of the other two milks.