Continuous records of the temperature of potatoes stored in clamps were made in 1942–3 (one clamp) and in 1943–4 (three clamps). In the first year, the temperatures at various positions in the clamp coverings were also recorded.

The temperature at the middle of the potato heap showed a drift with time similar to that of mean air temperature. Deviations of mean air temperature from smooth trend, lasting for about a week, had no effect on the temperature of the potatoes; longerperiod deviations were reflected in the temperature of the potatoes after a lag of about a week. The difference in weekly mean temperature between potatoes and external air averaged about 1–5° C. in 1943–4. In 1942–3 it was greater, increasing to over 20° C. in April, because bacterial rotting of the potatoes following blight infection increased the rate of heat production and caused the clamp to collapse at the end of April.

The CO2 concentration in the atmosphere of a potato clamp varied between 0·06 and 0·86%. The sum of CO2 and oxygen concentrations remained approximately constant at 21%. The CO2 concentration increased with time from December to April. This was attributed to increase in the rate of respiration of the potatoes caused by rise of temperature. Wind blowing in the direction normal to the face of the clamp reduced the COa concentration, presumably by causing external air to flow through the clamp coverings. A multiple regression of CO2 concentration on temperature of the potatoes at the time of sampling, and on the mean component of wind velocity normal to the clamp face estimated over a period of 3 hr. before the time of sampling, accounted for 64% of the variance between sampling occasions.

Unsaturated compounds were detected in the clamp atmosphere by absorption in bromine; the concentration of these, expressed as ethylene, varied between 0·004 and 0·025%.

The magnitude of CO2 accumulation and oxygen depletion in the clamp atmosphere was too small to produce effects of practical importance on the storage behaviour of the potatoes. If the unsaturated compounds were ethylene, the concentration present was sufficient to cause appreciable retardation of sprouting.

Ghani's method for the partial fractionation of soil phosphorus has been simplified. From results obtained with soils and representative phosphatic minerals it has been shown that successive single extractions with 2·5% acetic acid-l% 8-hydroxyquinoline and 0·1 N-sodium hydroxide gives a good fractionation of the phosphate compounds present.

The relative effects of cupferron and 8-hydroxyquinoline as reagents for blocking the adsorption of phosphate were also investigated. Cupferron precipitated aluminium more completely than did 8-hydroxyquinoline at the pH used for the extraction. However, because of its instability and also because of indications that it may attack organic forms of phosphorus cupferron was considered to be of less value than 8-hydroxyquinoline in the fractionation of soil phosphorus.

The recovery of phosphate added to soil, the reaction of which had been varied by the use of sulphur or calcium carbonate, was almost complete at all reactions used (pH 4·5–8·2) for amounts of phosphate up to the equivalent of 500 parts of PO4 per million parts of soil. The distribution of this added phosphate between the acid and alkali soluble fraction showed that in acid soils the phosphate tended to be fixed mainly by adsorption or as a basic ferric and aluminium phosphates, while at an alkaline reaction most of the fixation was due to precipitation by calcium.

A study of residual phosphorus in soils resulting from the use of phosphate fertilizers has been made, using a simplification of Ghani's method for the fractionation of soil phosphorus.

In cultivated soils all the residual phosphorus was extractable by successive extractions with 2·5% acetic acid-1% 8-hydroxyquinoline and 0–1 N-sodium hydroxide, and practically all had remained in the inorganic form; very little, if any, change in organic phosphorus was recorded as a result of the application of superphosphate.

In pasture soils (uncultivated) the application of phosphatic fertilizers brought about an increase in both inorganic and organic phosphorus and, in addition, some of the applied phosphate may have entered a form not extractable by the two extractants. The increase in organic phosphorus was not directly proportional to the amount of phosphate applied, as were the increases in the extractable inorganic fractions. It tended to approach a constant value, irrespective of amount and nature of the phosphate applied.

A simplification of Ghani's method for the fractionation of soil phosphorus has been used to study relationships between soil and plant phosphorus in field and pot-culture experiments.

In pot-culture experiments with red-brown earth soils (pH 5·6–6·1) wheat derived approximately 60% of its phosphorus from the fraction of soil phosphorus soluble in 2·5% acetic acid-1% 8-hydroxyquinoline and 30% from the inorganic fraction soluble in 0·1 n-sodium hydroxide, even although the amount of acetic acid soluble phosphorus present in these soils was only about half that present as inorganic alkali soluble. Very little use was made of organic phosphorus.

In field experiments with similar soils there was a correlation between the percentage phosphorus in the plant material and the acetic acid soluble, the inorganic alkali soluble, and the sura of these two fractions of soil phosphorus. The sum of these two fractions was also correlated with the amount of phosphorus taken up by the crop.

In pot-culture experiments with a wider range of soil types there was good correlation between the total extractable inorganic soil phosphorus and both the phosphorus content of the plant and the phosphorus uptake. Correlations between individual inorganic extractable soil phosphorus fractions and plant phosphorus were influenced by the pH of the two groups of soils examined.

During 1947–9, field and pot experiments have been carried out first to assess the herbicidal properties of 2:4-dinitro-6-secondary-butyl-phenol, and secondly to determine its value for selective weed control in leguminous crops. In order to obtain precise estimates of the concentration required to produce a given percentage mortality of either weed or crops species, such experiments were so designed that the results are capable of probit analysis.

From the data of field experiments on thirteen species of annual weeds, it is evident that there are wide variations in the concentration required to produce a standard kill. Irrespective of the species, susceptibility is greatest in the young seedling stage and there is a rapid increase in resistance with age. For example, with Raphanus raphanistrum between the cotyledon and pre-flowering stage a sixfold increase in concentration is needed to give a 90% mortality.

Four experiments dealing with attempts to induce pregnancy in the anoestrous ewe during the summer of 1948 are described. While little has been accomplished towards a practical solution of the problem of regularly inducing such pregnancies, some light has been thrown on reasons for past failures and erratic results. The following conclusions are drawn:

1. In the absence of a spontaneous corpus luteum, ovulation without heat may be induced in anoestrus by 800 i.u. PMS.

2. In the presence of a waning corpus luteum ovulation with heat may be induced in anoestrus by 800 i.u. PMS.

3. In the presence of an active corpus luteum neither ovulation nor heat is induced in anoestrus by 800 i.u. PMS. Occasionally, however, heat may occur without ovulation and with the formation of grossly cystic ovaries.

4. In mid-anoestrus ovulation is not regularly induced by 800 i.u. PMS, due presumably to very low pituitary and ovarian activity.

5. Anoestrus in the ewe is a relative rather than an absolute quiescence, and it is suggested that there is a rhythm of pituitary activity roughly inversely related to the daylight/dark rhythm, deep anoestrus occurring about the time of the longest day. Thus at different stages of anoestrus, different response to the same treatment may be expected in accordance with the proportion of animals falling into the categories 1–4 above.

6. Artificially formed corpora lutea are apparently perfectly normal as regards size, colour and function.

7. Treatment with PMS alone is sufficient to cause follicular maturation, ovulation and corpus luteum formation. There is some evidence, however, that the anoestrous ewe has some difficulty in ovulating all the follicles matured. The subcutaneous use of Prolan does not alleviate this difficulty, but injection of stilboestrol at about the time ovulation is due, may have some effect.

8. The mean ovulation rate of ewes ovulating after 800 i.u. PMS is usually rather higher than the normal for the breed and many cases of definite multiple ovulation have been observed. For this to occur the presence of an old corpus luteum is not necessary. A maximum of six ova have been shed.

9. In mid-anoestrus Welsh ewes show a higher resistance to PMS action than do Suffolks, both as regards numbers ovulating and ovulation rates of those responding.

10. Injection of PMS in increasing divided doses is no more effective in inducing heat than is a single injection. Ovulation without heat occurs as soon as a certain threshold of stimulation (probably about 400 i.u.) is reached.

11. Previous findings have been confirmed that, unless modified by the presence of a spontaneous corpus luteum, ovulation will normally occur within 48 hr. of injection.

12. When 35 mg. testosterone propionate is administered 24 hr. before 800 i.u. PMS, heat, usually without ovulation, will occur in a high proportion of ewes. Where ovulation does occur it rarely coincides with heat.

13. When testosterone propionate is injected with or after PMS the results are much more variable, depending upon whether or not it is absorbed in time to play a role.

14. Testosterone propionate, while inhibiting ovulation, does not inhibit follicular development.

15. Testosterone propionate has no oestrogenic effect. Its action in inducing oestrus in conjunction with PMS has been discussed.

16. The low percentage recovery of fertilized ova following service is attributed to faulty timing between service and ovulation in some cases. In others it may be due to either the ova being potentially unfertilizable or to the uterine and tubal environments being unsuitable for transport of sperm and fertilization. The latter view is favoured.

17. When heat and ovulation occur as a result of PMS injection in the presence of a waning corpus luteum, normal service, sperm transport and fertilization occur.

1. Rumen contents of sheep given three different diets contained free bacterial α-amylase. The method of obtaining a cell-free rumen filtrate containing the enzyme is described.

2. Amylase potency in the rumen was highest in the sheep given a diet of flaked maize, intermediate in that given a mixed diet of hay and concentrate and lowest in that given a diet of casein.

3. The effect of rumen amylase on structural maize and potato starches has been investigated.

4. Absence of amylase from sheep saliva was confirmed.

5. Where flaked maize is fed, one of the organisms responsible for amylase production in the rumen of the sheep is Cl. butyricum.