In any field of corn the population-density or number of plants per unit length of row is very fluctuating. Accidental circumstances may result in considerable stretches being empty or thinly populated. Quite apart from this, the population of successive short lengths is sharply and characteristically inconstant. Where plants are few tillering is profuse and there is thus a tendency towards constancy in yield per unit length of row. Specific ascertainment has, in earlier experiments, suggested that the tendency is by no means marked. In consequence fluctuation of population-density in the sense here used, reduces yield in typical field crop substantially below the potential maximum appropriate to the soil and other circumstances. From short lengths of row, low in plant-population, yields are low. In aggregate these sparsely populated lengths are a feature of considerable economic importance.

(1) Digestibility trials with wheats, carried out with White Leghorn cockerels, indicate that “weak” and “strong” wheats are equally suitable as sources of supply of food nutrients for poultry.

(2) In the production of wheat for poultry feeding, yield rather than strength should be the primary aim of the grower.

(3) Further research work on the Katayama method of estimating the digestibility of poultry feedingstufls is indicated.

(1) Digestibility trials with “whole” maize and “flaked” maize indicate that steam cooking by commercial processes considerably increases the digestibility of the food nutrients in maize. (2) The view held that the fowl is akin to the pig so far as its powers of digestibility of low fibre foods are concerned is substantiated by the results of the trials here reported.

Prof. T. B. Wood in the November issue of the Journal of the Ministry of Agriculture discussing the known methods of estimating the nutritive values of foodstuffs says, “there is a method which is within the scope of any experimenter and is capable of yielding accurate results of great practical value,” and he goes on to give examples, in the estimating of the nutritive value of swedes, kale, etc., using the results of an experiment which entailed the use of 40 to 120 animals. From these experiments he gets results showing a very satisfactory agreement between experiment and calculation, notwithstanding that there must be a slight experimental error in the calculation of food consumed.

1. When a peat, as obtained from the bog, is dried, considerable changes occur in the amount of ammoniacal nitrogen removable by distillation with magnesia under reduced pressure.

2. Removal of water causes a relative increase in the amount of ammonia extractable by water. This is due to a reduction in the absorptive colloidal properties of the peat.

3. A partial recovery in the absorptive power takes place on prolonged contact with water.

From the results presented it may be permissible to point out the following:

Fungi are responsible for the fixation of very small quantities of nitrogen, while the Azotobacter and B. amylobacter groups are the important nitrogen fixers in the soil.

B. amylobacter is able to fix from 4 to 5 mg. of nitrogen per gm. of dextrose consumed.

B. amylobacter has an optimum range of pH. between 6·0 and 7·0, and Azotobacter between 7·0 and 8·4.

Azotobacter utilises the organic acids produced during the fermentation of dextrose as sources of energy for nitrogen fixation in the absence of dextrose. B. amylobacler does not, or does only to a limited extent, utilise such products.

Large quantities of dextrose do not favour an efficient nitrogen fixation, as large quantities of the organic acids produced effect the reaction of the media rendering the organisms inactive.

The nitrogen fixing organisms seem to be equally well represented in the heavy and light soils.

1. Variations in growth of sugar beet on certain soils from north-east Scotland were investigated by examination of the soils with regard to field conditions, mechanical composition, pH value, lime requirement, readily extractable calcium and humified organic matter.

2. Field conditions and mechanical composition did not account for the variations in growth of the beet.

3. A certain degree of correlation was found between pH value, readily extractable calcium and growth of beet. In general when the pH was below 5·3 and extractable calcium below 0·12 per cent., growth was poor or failed. Above these figures it was good, but only relatively so, since all the soils were below 6·2 in pH value.

1. A historical review of the dye adsorption method for the estimation of soil colloids is presented, and the method is criticised chiefly from the point of view of the isoelectric theory.

2. A procedure for the detection of hydrous alumina in soils is described, involving the demonstration of the isoelectrio point of hydrous alumina by means of preferential dye adsorption in suspensions of various pH values.

3. Satisfactory results were obtained with a mixture of acidic Biebrich Scarlet and basic Iodine Green. The former is adsorbed by hydrous alumina only on the acid side of its isoelectric point, and the latter only on the alkaline side.

4. The characteristics of an ideal dye for use in studies such as those described are tabulated.

5. The applicability of the mixture of dye-stuffs finally selected is demonstrated for a series of soils of varying basic ratio, and including examples of lateritic soils and clays.

An attempt was made in a recent communication (1) to propound a theory in connection with the digestion of cellulose in the ruminant organism which should be compatible with Kellner's findings as to the value of digestible fibre in the fattening of ruminants. It was shown that the generally accepted theory, that cellulose is digested by bacterial agency in the rumen with the production of organic acids and gaseous products, such as methane, hydrogen and carbon dioxide, failed entirely to account for the equal values of digestible fibre and starch for fat production in the ruminant animal. This could only be explained by assuming that glucose (or some other sugar capable of hydrolysis to glucose) was formed as a primary product of the action of bacteria on cellulose, and that, as with digestible carbohydrates originally present in the food, only about 8 per cent, of the sugar so formed underwent further bacterial breakdown into organic acids and gases, the remainder being available for absorption into the organism in the form of glucose. On this assumption, it would follow that every gram of fibre so digested would yield to the organism as much glucose as would a gram of starch, and in this way Kellner's practical finding would be capable of explanation.

(1) The possibility of using acetic acid as a reagent for extracting exchangeable calcium from carbonate-free soils is discussed, and experimental results are given showing that calcium is quantitatively precipitated from an acetic acid medium.

(2) A method for determining exchangeable calcium using 0·5 N acetic acid is described, and figures are given comparing this proposed method with the Hissink method.

(3) A modification of the proposed method is suggested in the case of heavy clay soils owing to the impervious nature of these soils which probably does not allow the acid to penetrate through the whole mass of the soil when leached on the filter paper.

A new and improved type of dynamometer is described which by a simple interchange of parts can be used with the same percentage accuracy for all types of work from the lightest to the heaviest.

The instrument consists of (a) an hydraulic link weighing 16 1b. and placed in the hitch, (b) a recording mechanism weighing 15 lb. carried on any convenient part of the implement, and (c) a control box weighing 4 lb. carried by the operator. When packed in a stout box for transit and with all accessories the total weight is less than 100 lb. The instrument is of robust construction and has a minimum number of moving parts. Adjustments for stylus pressure, etc., are provided, but the necessity for using them hardly ever arises.

The instrument operates by recording the amount of movement in a Bourdon tube filled with oil and connected by narrow bore copper tubing to the oil in the hydraulic link.

In a previous paper Quinlan(1) published the results of his observations on a flock of sheep which had been vasectomised for two years. The present paper contains a résumé of the data already published, to which an additional twelve months' observations have been added. This paper gives the data available from observations carried out on the flock over a period covering three years, or a period of time which allowed full skeletal development to take place.

In a former number of this Journal (1), there appeared a report on the mechanical analysis of soils by this sub-committee of the Agricultural Education Association. The report contained proposals for certain modifications of the earlier A.E.A. (1906) method, of which the most important were the introduction of hydrogen peroxide as a dispersive agent in the preliminary treatment, the use of the pipette method for the actual mechanical analysis, and the abolition of the fine gravel (3 mm.–1 mm.) fraction. This report was officially adopted by the A.E.A. and the method of mechanical analysis therein proposed was accepted as the new standard to replace the 1906 method. The full details were published in the Journal of the Association (2).

1. The interaction of Bordeaux mixture with lead arsenate and with calcium arsenate has been studied by an examination of the effects which are produced:

(a) When hydrated lime is added to the arsenical compounds.

(b) When copper sulphate is added to the arsenical compounds and hydrated lime.

2. The nature of the interaction of calcium hydroxide and diplumbic hydrogen arsenate has been shown to be most complex and to result in the complete decomposition of part of the lead arsenate and th e formation of basic calcium arsenates.

3. Support is not given to the view that calcium carbonate decomposes diplumbic hydrogen arsenate with the production of soluble arsenic compounds.

4. When the lead arsenate, in water, is allowed to interact for long periods with excess of hydrated lime, the amount of basic calcium arsenates formed is such that large quantities of arsenic are brought into solution by the action of carbon dioxide.

5. Under conditions when the calcium hydroxide is rapidly converted to the carbonate the amount of arsenic rendered soluble is slight.

6. The conclusion is formed that in actual spraying there is a definite reduction of the risk of arsenical injury when hydrated lime is added to lead arsenate and to calcium arsenate.

7. It is concluded that when the conditions are such that the addition of hydrated lime brings about a reduction of arsenical injury, the use of an “equal-lime” Bordeaux mixture containing an equivalent amount of calcium hydroxide will prove far more effective.

Numerous attempts have been made to devise an experimental method that, applied to a variety or a series of soils, enables them to be placed in an order closely reflecting their field behaviour or their most important physical characteristics. They are called “single-value” determinations as they endeavour to specify the soil by a single number, in distinction to the group of figures obtained, for example, from a mechanical analysis. A number of these methods are discussed in the present paper which contains an account of a detailed investigation on 39 soils of certain single value determinations.

The methods selected for study were chosen because (i) they required only simple apparatus, and (ii) they appeared to be related to some distinct soil characteristic.

The list of measurements was as follows:

Percentage of clay.

Moisture content of soil in equilibrium with atmosphere of 50 per cent, relative humidity (the ordinary “air-dry moisture content” which was also determined, is close to this value).

1. The formation of colloidal CaHPO4 by the interaction of CaCl2 and Na2HPO4 in the presence of neutral casemates has been demonstrated.

2. The colloidal CaHPO4 is shown to be non-diffusible across a membrane of cellophane.

3. A theory is outlined which will account for the secretion of the high concentrations of calcium and phosphorus in milk from the low concentrations of these elements in the blood.

1. Four White Leghorn cockerels were fed with widely varying quantities of a Sussex ground oats and milk mixture without material alteration in the coefficients of digestibility of the digestible nutrients.

2. The amounts fed varied from a sub-maintenance ration of 50 gm. to a “limit of appetite” ration of 150 gm. A slight depression in the coefficients of digestibility of the organic matter, the crude protein and the N-free extract, and a slight increase in the coefficient of digestibility of the ether extract was obtained, but the differences shown are attributed to normal fluctuations in digestibility due to individual variation and not to differences in the quantity of food given.

3. In feeding experiments carried out with fowls, in which variable amounts of food are fed, these experiments indicate that it may safely be assumed that the coefficients of digestibility of the food nutrients are not materially affected by the variations in the amounts of food fed.

Four years ago one of us(1) propounded a method of computing rations for all classes of farm animals on the basis of a maintenance ration related to the animal's live-weight plus a production ration estimated in accordance with the amount and kind of product—such as live-weight increase, work, milk—which the animal is expected to produce. This method is on the same lines as the modern method of computing rations for milch cows which is based on Kellner's work (2). It has been used in practice for the last four years and has been found to be successful, not only as a practical method of computing rations, but more especially as a logical and intelligible method of teaching students. For this latter purpose it is a great advance over the learning of standard rations since it appeals rather to the reasoning powers than to the memory. In view of these considerations, the method has been incorporated in Rations for Livestock (3). Much of the time of the Staff of the Cambridge Animal Nutrition Institute has been devoted, during the last four years, to investigations designed to fill the gaps in our knowledge of the basal metabolism, the maintenance requirement, and the production requirement of farm animals.

A Recent statistical survey of the records of premium stallions by Sanders (1) draws attention to the fact that the breeding efficiency of the horse is much below that of the other domesticated animals and that it has apparently declined within recent years. For example, between 1887 and 1889 the average number of mares served by Light Horse stallions and which produced foals was about 59 per cent, of the total mares served. Between 1904 and 1910 this figure had fallen to about 56 per cent, and at the present time is not much above 50 per cent. While this decline may in part be due to the record of infertile services being kept more strictly now than formerly, and perhaps also to the more rigorous conditions to which travelling stallions are subjected, the figures are sufficient to indicate that much loss is actually occasioned by low breeding efficiency and also that there might be considerable improvement on the present standard.

The respective effect of the period of lactation and the age of the cow on the yield and quality of the milk have previously been studied separately (see J. Agric. Sci. 17, PtI, p. 118, “The Influence of the Stage of Lactation and the Breed of the Cow on the Yield and Quality of the Milk,” and 17, Pt III, p. 420, “The Influence of the Age of the Cow on the Yield and Quality of the Milk”), and an analysis of the data has now been made with regard to the joint influence of these factors.