Grassland, like any other kind of vegetation, represents a balance between the requirements of certain plants on the one hand, and the conditions of the environment on the other. It is a result of Nature's demand and supply. An examination of the environmental conditions which determine the existence of grassland is therefore necessary if we wish to make it and maintain it, or to improve its production. Experimental work has demonstrated that grassland is capable of being improved as to grazing qualities, but the results so obtained can hardly yet be said to be capable of being safely applied to areas beyond those actually experimented upon. Few can say with confidence that such and such a treatment will succeed here, and another treatment there. In other words, we have no basis for classifying or valuing grasslands. Assuming that our present outlook is too narrow, too economic, it may be that by taking a broader, if more philosophical view, some progress may be made.

The estimation of phosphate in soil extracts presents certain difficulties owing to the small amount usually present. Practically all the methods make use of the phospho-molybdate precipitate. Hehner's method based on the weighing of this precipitate was adopted by Dyer, and has been recently investigated by. Auld.

In a previous communication we have summarised the results obtained by us in a study of the nature and extent of atmospheric pollution in different parts of the city of Leeds and in further studies of some of the effects of smoke upon plant growth.

In the scheme of analysis of plant extracts described in a former paper (Davis and Daish, J. Agric. Sci., 1913, 5, 437), before it is possible to calculate the proportion of dextrose and laevulose an allowance must be made for the pentoses present; it therefore became necessary to ascertain the exact value of the cupric reducing power of these sugars under the standard conditions adopted—namely those defined by Brown, Morris and Millar. Value s of the cupric reducing power of xylose have been given already by Stone, Weiser and Zeitschek, and of arabinose by the latter workers and by Ost; but as they were obtained under conditions different from those specified by Brown, Morris and Millar, they are unsuitable for the present purpose, and it became necessary to make a fresh series of determinations. Xylose and arabinose are the only pentoses which are at all readily obtainable and in the present paper attention is limited to these.

The study of the fluctuations in the amounts of nitrate present in arable soils is important both from the practical and the scientific points of view. The nitrate supply in the soil is very commonly a limiting factor in crop production in Great Britain, so that any process which increases the nitrate supply tends to increase productiveness, and vice versa. From the scientific point of view the interest is even wider. No soil constituent, not even the moisture, shows such great fluctuations as the nitrates, and none is so susceptible to external influences. Further, the nitrate represents the end point in one chain of decompositions and the amount formed over a given period is therefore a measure of the extent to which this particular decomposition has proceeded.

After a consideration of the ways in which the fertility of domestic animals is controlled some of the factors which limit it have been investigated. Various circumstances control the number of ova shed at each heat period. Data are presented which show that the low fertility of young as compared with adult sows is due to the fact that not so many ova are shed at each period.

Counts have been made of the number of corpora lutea present in the ovaries and number of foetuses present in the uteri of pregnant rabbits and pigs. The results show that many more ova are shed at the heat period than young are produced at birth. Some ova possibly may be lost but many after fertilization atrophy at some period of their development and undergo absorption in utero.

While the occurrence of atrophic foetuses only causes reduced fertility in animals which have many young at birth yet their occurrence in animals producing only one young would give rise to sterility so that the problem of the cause of the atrophy becomes an important one.

Investigation points to the conclusion that the atrophy is not bacterial in origin since frequently healthy and atrophic foetuses lie side by side in the uterus. Moreover no bacteria could be found either in the foetus or foetal membranes.

Evidence is given to show that nutrition cannot be the cause of the atrophy although it may affect to a certain extent the size of the young.

No conclusion has yet been arrived at as to the cause of the atrophy, and the several possibilities suggested are still under investigation.

The life history of the black currant mite, Eriophyes ribis, Nal. is of a simple character from the month of May, when the buds of the current year's growth are entered, till March of the following year. During this time the mites live and multiply in the embryonic leaves producing the abnormal growth familiar to fruit growers as “big-bud.” From the end of March onward, however, the buds so attacked gradually die, and the mites which have lived in them for the past nine months are forced to find other plant food. At this time the buds of the black currant which the mites will eventually live in are rudimentary and it is the end of May before they are sufficiently developed for the acarids to enter.

In two previous communications a summary has been given of the results obtained in determinations of the relative degree of atmospheric pollution, firstly in various parts of the city of Leeds, and secondly in the surrounding semi-urban and rural areas, to a distance in some directions of seven miles from the centre of the city. The results obtained in the latter series indicated clearly the presence of extensive atmospheric pollution, showing the characteristics of coal smoke, in all parts of the area investigated. The degree of pollution was found to fall rapidly on passing in a northerly direction from the centre of the city into an area free from smoke-producing industries, but less rapidly on passing into similar areas to the north-east and east of the city, owing to the greater dispersion of the city smoke in these directions by the prevailing winds. On the opposite side of the city, from north-west round by south to south-east, smoke pollution was found to be very high in all quarters.

During the last few years a good deal has been heard of the estimation of colloids in soils by means of dye solutions.

Evidence is brought forward to show that free pentoses exist in the alcoholic extracts of foliage leaves of different plants. Their amount can be estimated with a fair degree of accuracy by the ordinary distillation process or by the reducing power of the purified liquor after other sugars have been fermented away.

When, however, small amounts of pentose have to be estimated accurately in presence of large quantities of other sugars, it is advisable, as suggested by Kluyver, to ferment away these sugars before applying Kröber's process.

Solutions were made by extracting the soils from certain of the Rothamsted plots on which wheat and barley had been grown for 60 years and upwards. Wheat and barley were grown in these solutions, which were renewed fortnightly. The comparative growth in the solutions was closely parallel to the growth of the crop on the plots in the field and corresponded to the composition of the solutions. The composition of the solutions as regards phosphoric acid and potash corresponded to the past manurial treatment of the soils and to the amount of phosphoric acid and potash they now show on analysis. Growth in the soil solutions agreed with the growth in artificial culture solutions containing equivalent amounts of phosphoric acid and potash. Growth in the soil solutions from imperfectly manured plots was brought up to the level of that in the solutions from completely manured plots on making up their deficiencies in phosphoric acid and potash by the addition of suitable salts. The phosphoric acid and potash content of the soil solutions was of the same order as the phosphoric acid and potash content of the natural drainage water from the same plots.

Wheat grew as well as barley in the solutions of the wheat soils, and vice versâ. In a similar set of solutions from the same soils the growth of buckwheat, white lupins and sunflowers corresponded with that of wheat and barley. Boiling effected no alteration in the nutritive value of the soil solutions.

In nutritive solutions of various degrees of dilution the growth of plants varied directly, but not proportionally, with the concentration of the solution, though the total plant food present in the solution was in excess of the requirements of the plant. When the nutrient solution was diffused as a film over sand or soil particles, as in nature, there was no retardation of growth due to the slowness of the diffusion of the nutrients to the points in the liquid film which had been exhausted by contact with the roots. Growth in such nutrient solutions forming a film over sand particles was much superior to the growth in a water culture of equal concentration, but the growth in the water culture was similarly increased if a continuous current of air was kept passing through it.

Last season (1912) it was noticed that gooseberry trees were being seriously deformed by an attack of Eriophyes. Specimens of the mite were sent to Dr Nalepa and they were identified by him as Eriophyes ribis, the mite responsible for the disease known as “big-bud” in black currants.

Caustic lime is found to have two distinct effects on the soil:

1. A partial sterilisation effect,

2. A chemical action, decomposing some of the soil organic matter.

The amount of caustic lime necessary to induce specific changes in the flora and fauna of the soil depends very largely on the character of the soil. The light sandy Millbrook soil, poor in organic matter and in carbonate, reacted sharply with 0·2 to 0·3 per cent. caustic lime; the Rothamsted clay soil, poor in organic matter but rich in carbonate, was found to react to 0·3 to 0·4 per cent.; the acid Woburn soil required an amount between 0·5 and 1·0 per cent., as did also the rich Chelsea garden soil, which already contained carbonate; the Craibstone soil, with a high organic and a low carbonate content, failed to react even to applications of 1·0 per cent, caustic lime.

It is shown that contrary to the statements of Kluyver and others, maltose undergoes slight hydrolysis (to the extent of about 2% when 1% solutions of maltose are used) when heated with hydrochloric acid under Herzfeld conditions. It is preferable therefore to adopt 10% citric acid, under the conditions formerly laid down, in estimating cane sugar in plant extracts when maltose is likely to be present.

The necessity for a method of comparing and, if possible, distinguishing chemically between the different classes of peat, and especially between alkaline or normal peats and acid peats, was suggested by a collection of soils received at the Rothamsted Laboratory.

Every growing crop results in the formation of a substance which is toxic to the growth of other plants, and still more so to itself.

By oxidation this toxin loses its toxic properties and enhances the fertility of the soil. The plants previously poisoned eventually outstrip those which had not been subjected to the poisoning, except in cases where the toxic effect has been sufficient to produce a permanent stunting.

The toxic effect must necessarily vary considerably with the different conditions obtaining, both as to the nature of the soil, the plant affected, and the vigour of growth of the plant producing the toxin.

There is no reason for assuming the excretion of any toxic matter from a plant, the debris from the growing roots is probably sufficient to account for the formation of the toxin.

The heating of a soil produces toxic matter from the organic substances present in it, and in much greater quantities than that produced by the growth of a crop. In both cases the toxin, after oxidation, increases the fertility of the soil.

1. The Sachsse method of estimating starch is unreliable in the case of plant material; not only does the presence of pentosans falsify the results as pentoses are formed during the hydrolysis, but actual destruction of dextrose occurs during the prolonged treatment with dilute acid.

2. O'Sullivan's method gives low results owing to the loss of dextrin which occurs during the purification of the solution after the conversion by diastase.

3. A method is described for estimating starch based on the use of taka-diastase; under suitable conditions this converts the starch into maltose and dextrose only and no loss of these sugars occurs when the solution is treated with clearing agents such as basic lead acetate.

4. The necessity of removing substances soluble in water, such as gums, etc., which are optically active and thus cause error in the estimation of starch in plant material is emphasised. Special care is also necessary in sampling.

The method at present in use for the estimation of tannin in apple juice and cider is that used by Lloyd. It is a modification according to Kraus of Löwenthal's method, and consists in titrating the cider directly with potassium permanganate in presence of indigo as an indicator. The permanganate is standardized by means of “pure tannin,” it being assumed that both this and the tannin present in the apple are digallic acid, and have the composition C14H10O9. It is apparent that all the permanganate reducing substances present in the cider will be included in the tannin content; moreover the amount of indigo used is not sufficient to retard noticeably the oxidation of the non-tannins for which purpose it was originally used in Löwenthal's method. The results obtained by this method are therefore only comparative.

1. The characteristics of true partial sterilisation have been found to be common to a large number of antiseptics and are

(a) An initial decrease in the numbers of bacteria followed by a large sustained rise.

(b) The killing of protozoa and nitrifying organisms. In no case have we observed all the usual partial sterilisation phenomena without the death of the larger protozoa which occur abundantly in cultures made from our soils.

With the extension of soil survey work and an increasing recognition of the importance, from chemical, physical and biological considerations, of the presence of calcium carbonate in the soil, it has become necessary to be able to determine accurately and with comparative ease the amount of carbonate in any given soil. During the past few years the methods adopted for this purpose have varied considerably, partly on account of inaccuracies which were only too apparent in comparative work, and also because of the need for greater convenience in manipulation.