Under laboratory conditions the mucilage is unattacked by the digestive enzymes, and even when fed to a non-ruminant animal 75 per cent. can be shown to pass through unchanged. As far as such a point can be demonstrated by laboratory experiments, it is however probable that the mucilage is attacked by intestinal bacteria, and, in ruminants especially, largely broken up in this way, with the evolution of gases and certain volatile acids among other products. This behaviour while unexpected at the beginning of the investigation is not inconsistent with its chemical character as a hydrated cellulose. A similar case is perhaps found in the substance agar-agar, which is readily attacked by bacteria, but is stated by Armstrong in his article on “Carbohydrates” in Allen's Organic Analysis to be practically indigestible by the human organism.

1. The first lactation shews greater variability than the second, third, fourth or fifth.

2. The estimation of one lactation from another cannot be made with great accuracy, since the correlation coefficient between even successive lactations does not rise above + ·6.

3. It is necessary, in classing a cow, to decide on one lactation that shall represent her mature capability. It is suggested that the maximum lactation is the most suitable one to chose.

4. The correlation coefficient with the maximum lactation increases from ·394 for first to ·762 for fifth lactation.

5. The mean of the first and second lactations however gives a correlation coefficient of ·526 with maximum lactation, which is higher than any of the first three taken separately.

§ 1. In Part I. (vol. IV. pp. 1—24) it was shown that the intrinsic permeability of a soil when measured with water was less than when measured with air as the experimental fluid, and that the ratio of the two values varied with the amount of colloidal matter present. It was desirable to determine accurately whether the values would be identical for soils composed of pure sand or other uniform and non-colloidal particles.

The problem of immunity to disease in plants is now receiving a large amount of attention from plant-pathologists. It has long been known that different varieties of the same species of plant may differ in their susceptibility to the attacks of fungi and possibly other parasites, but even now practically nothing is known of the factors which determine whether a plant will prove immune to a disease or not. The following paper is a record of investigations which it was hoped would contribute something towards the solution of this problem, or which might at least suggest lines of further research on this subject.

The experiments of Russell and Hutchinson1 have shown that the micro-organic population of ordinary soils is not working at a maximum efficiency; there exists a biological factor, provisionally identified with the soil protozoa, detrimental to bacteria and limiting their numbers and activities. It follows that any change in the conditions of the soil that is more favourable to the harmful organisms than to the bacteria will disturb the normal equilibrium between these two sets of organisms and lead to a relative reduction in bacterial numbers and activity. We shall therefore expect to find that causes not in themselves harmful to bacteria may bring about a reduction of bacteria through favouring the development of the detrimental factor.

The following brief summary may be given on the aetiology of drought resistance as exemplified by the conditions obtaining in 1911.

From an agricultural point of view the value of a plant as a drought-resister is seen to be measurable by two standards: (1) Its power to give a good yield all through the period of drought; (2) its ability through living through the summer without materially adding bulk to the herbage to recuperate when the conditions become less severe. It has been shown that the phenomenon of drought-resistance is not associated with any one set of morphological characters, but that various growth forms are met with amongst the most successful plants. Further, a number of plants have shown themselves very tolerant, although having no apparent modifications to assist them, in which case there can be no doubt that their power of resistance is a simple outcome of their inherent vitality. Consequently it is perhaps dangerous to assign too great an importance to the possession of apparently useful modifications. A fair correlation is however seen to exist between a plant's manner of resistance and its growth form, as the following classification shows.

During the past few years we have grown a large number of plants in partially sterilised soils alongside of others in untreated soils, in order to compare the total weights of dry matter produced. While the experiments were in progress certain qualitative differences in growth and habits of the plants revealed themselves; we propose in this paper to record these differences and to set out certain of the hypotheses that have been put forward to account for them. It was soon found that several distinct problems in plant physiology were concerned, and that any attempt to test the hypotheses experimentally would involve us in a number of side issues and lead us away from our main purpose. We therefore for the present confine ourselves to a statement of the facts observed, leaving their more complete elucidation for later work.

The rain analyses summarised in this paper bring out very clearly the marked difference in the purity of the atmosphere between the industrial-rural area to the west and south and the purely agricultural area to the north and north-east of Leeds.

They show that the sulphur-content of the rain falling at a given station affords a fairly reliable diagnosis of the degree of pollution of the atmosphere by smoke, provided the observations be prolonged over several months. Further, evidence has been obtained in confirmation of that adduced by earlier observers, that the sulphur-content of the leaves of trees may afford useful assistance in the diagnosis of smoke-pollution. In preliminary tests the proportion of sulphur present in the leaf as sulphate gave a sharper grading of the pollution in different districts than the total sulphur.

The rain analyses show further that appreciable smoke-pollution still remains throughout the agricultural area at distances of seven miles from the city, the rate of improvement of the atmosphere on passing away from the city into the purely agricultural areas being appreciably slower in the direction of the prevailing winds than in other directions.

In a general way the analyses tend to show that the smoke, though in greater quantity, is in a higher state of oxidation in the dirtier or more industrial districts—due to more efficient combustion of the coal.

Throughout the industrial-rural area abundant evidence of damage to leaves was found, and there can be no doubt of the consequent check to growth.

Under digestive conditions cyanogenesis is likely to be inhibited by acids and alkalies, digestive juices, cellulose, glucose, and molasses, salt and many other feeding-stuff constituents and adjuncts.

Owing to the time the food remains in the digestive tract before coming to the true stomach or the acid secreting portion of the stomach, normal inhibition is caused by the alkaline character of the salivary juices. This is likely to be the chief cause of the innocuous character of linseed cake.

In the case of sheep fed with linseed cake shortly before being killed small amounts of hydrocyanic acid were to be found, chiefly in the rumen.

Cyanogenetic feeding-stuffs are most likely to be poisonous when fed with acid containing or acid producing food-stuffs, or where the hydrocyanic acid is pre-formed, as in the case of an improperly made linseed gruel.

The small quantities of hydrocyanic acid normally produced from cyanogenetic feeding-stuffs may possibly have a strongly beneficial action.

In a recent number of this Journal, T. B. Wood and F. J. M. Stratton have discussed the probable error of field and feeding experiments, but in the latter case their investigations included only cattle and sheep.

The following work was undertaken as a necessary preliminary to a series of pig feeding experiments which are in contemplation. It is published at once in the hope that the results obtained may be of use to others who may be engaged in planning similar feeding trials.

The present paper is an account of observations and experiments in connexion with Silver-leaf Disease which have been made since the publication of my paper on the same subject in the Journal of Agricultural Science for 1911. I am indebted to the Board of Agriculture for giving a grant to assist this work and to the Cambridge University School of Agriculture for placing at my disposal a plot of land on its farm for most of the fruit trees used in the experiments. I have also to thank Mr R. I. Lynch, Curator of the Botanic Gardens, Cambridge, for providing accommodation for other trees.

The conclusions reached in our previous paper have been confirmed and extended. Fresh evidence is adduced that bacteria are not the only inhabitants of the soil, but that another group of organisms occurs, detrimental to bacteria, multiplying more slowly under soil couditions and possessing lower power of resistance to heat and to antiseptics.

In consequence of the presence of these detrimental organisms the number of bacteria present in the soil at any time is not a simple function of the temperature, moisture content and other conditions of the soil. It may, indeed, show no sort of connection with them; thus rise of temperature is found to be ineffective in increasing the bacteria in the soil; increase in moisture content has also proved without action. The number of bacteria depends on the difference in activity of the bacteria and the detrimental organisms.

1. The numbers of bacteria and fungi in a newly-made Stilton may rise to the enormous number of 1000 to 3000 millions per gram in the first week.

2. There is a gradual fall in the numbers up to the time of ripeness (100 to 150 days old), when 50 to 100 millions only are found.

3. In the early stages lactic acid bacteria are most abundant. When the cheese is ripe the lactic acid bacteria are few and weakened in physiological power; Penicillium glaucum and a form of Torula are then abundant.

4. Five characteristic organisms are found in all Stilton cheeses examined, viz.:—(1) Streptococcus lacticus, (2) a short rod-shaped form of Bs. acidi lactici, (3) a species of Tyrothrix, (4) Penicillium glaucum, and (5) a round form of Torula, sometimes accompanied or replaced by an oval form.

In cheeses where starters have been used we find a large celled form of Streptococcus lacticus present.

5. Penicillium glaucum is checked in its growth by the Tyrothrix.

In a previous paper on the “Interpretation of Milk Records” the following points were dealt with:

I. Selection of a figure definitive of a cow's milking capability.

II. The influences affecting such a figure.

(a) The usual methods of describing a cow by her total yield per calendar year, per lactation, or per average week are inconvenient both for practical breeding on a large scale and for definite enquiry on the inheritance of milk yield or its possible correlation with other characters. The figures are inconvenient because a variety of circumstances which affect them must be stated for every individual case before such figures can be reliable. Chief of these circumstances are age of cow, length of lactation, number of weeks dry before calving, interval between calving and subsequent service, and time of year of calving.

It is shown that whereas the platinum chloride method of estimation is uncertain and liable to give varying results, the perchlorate method described is at once more simple in manipulation and more uniform and exact in its results. An improvement has been introduced which consists in washing the perchlorate precipitate with 95% alcohol saturated with potassium perchlorate by means of which any error due to the solubility of the precipitate is obviated. This is of importance when dealing with small quantities of precipitate. The following other advantages may here be enumerated:

Black pigment is very frequently, but not invariably present in the mammary tissue of Large-Black, Berkshire and other dark-coloured sows. It is stated that the presence of this pigment (apart altogether from the question of the pigs being “on heat”) renders the bacon less saleable, owing to its discoloured or “seedy” appearance. If this is the case, it ought to be possible to remedy this fault, by breeding from individuals in which this pigment is absent, and so building up a strain of increased commercial value.

If on the other hand it be the case that the presence of black pigment is not in itself objectionable, but that the changes in the mammary area due to the occurrence of heat are what are not desired, the remedy is to be sought in spaying, a practice which must be carried out on a sufficient scale and be efficiently performed. That imperfect spaying (in which one, or a part of one, ovary is left behind, while the bed is wholly or partly removed) sometimes happens is shown by the facts described in this paper.

The expenses of the investigation described in this paper have been very largely defrayed by a grant made by the Development Commissioners through the Board of Agriculture and Fisheries.

Expression is frequently given to an apparently widespread belief that irrigated in comparison with non-irrigated fruits are flat in taste and less resistant to the various agencies which effect decay. In support of that belief this statement in substance is almost invariably advanced: “The irrigated fruits contain abnormally high percentages of water and consequently low percentages of solid or dry matter; they are, therefore, deficient in the particular compounds upon which taste and body or solidity of structure depend.” We do not presume to say that from analyses alone can the many questions relating to quality in fruits be definitely settled, but since those alleged characteristics of irrigated fruits are charged by this statement to radical deficiencies in certain compounds, it would seem that analytical data would be of material service in the settlement of questions relating to quality. This view of the matter and the fact that here in the north-west, in both the irrigated and the non-irrigated sections, the hardy fruits are grown extensively and shipped to distant markets induced us to undertake some two years ago extensive analyses of fruits grown with and without irrigation. We wish to report here in summarised form the results of that work on the apple; for it, in point of commercial importance, stands pre-eminent among all other fruits grown in the north-west.

The present paper deals with the results of an investigation on a serious and common disorder of cider, generally known as cider sickness. The account here given is concerned with its characteristic features, its cause, and, as far as present knowledge permits, methods for its prevention. The disorder is due to the action of a bacterium. It is proposed to give a detailed account of the organism and its chemical activities in a supplementary paper.

The practical advantages accruing from the use of lime are now generally recognised, but on account of the complexity of the changes induced it is by no means easy to determine, in the case of a field soil, the exact extent to which one effect or set of effects has contributed to the general improvement of the soil in relation to its crop-producing power.