History has little of note to relate regarding cereal rusts in South Africa. G. W. Thompson (1) in his Travels and Adventures in South Africa informs us that the wheat crops during 1708—1710 were severely attacked by rust. Theal (2) nevertheless maintains that rust in wheat was not known in the country before the year 1727, when the epidemic was so bad that the crops were almost a complete failure, although he states that rust in rye had been known before 1727. The year 1820, however, is reported as one notorious for the severity of the rust attack.

The F2 generation of crosses between a number of varieties of wheat susceptible to the attacks of Yellow Rust (Puccinia glumarum) and “American Club.” which shows an extraordinary degree of resistance to the attacks of this parasite showed in the year 1906 obvious segregation into immune and susceptible forms. The immunity was further found to be independent of any recognizable morphological feature. An analysis of these F2 generations demonstrated the fact that the immune plants were present to the extent of 25 per cent., that is that the property of resisting the attacks of Yellow Rust behaves as a recessive character to the property of being susceptible. The plants which proved susceptible showed, however, very varied degrees of susceptibility. Many were as covered with rust pustules as Michigan Bronze, one of the extremely susceptible varieties used as a parent. Others on the other hand were relatively slightly attacked and between these extremes all degrees of susceptibility appeared to exist. Nilsson-Ehle who has also observed the segregation of this pair of characteristics has also noted the wide differences in susceptibility in plants of the F2 and succeeding generations.

Investigations on the various products of the action of lime on copper sulphate, including ordinary Bordeaux mixture, led to the conclusion that the efficacy of such substances as fungicides depended on the proportion of copper in them which is rendered soluble by the carbon dioxide of the air, and, that if a deficiency of lime is used to start with, one of the lower basic sulphates of copper is obtained, from which carbon dioxide liberates a much larger proportion of copper than it does from the more highly basic sulphates present in ordinary Bordeaux mixture. The lowest basic sulphate is, owing to its physical condition, unsuitable for spraying purposes; but this is not so with the compound 10 CuO, SO3, obtained by adding lime-water to copper sulphate just short of alkalinity, and this substance has been put on the market under the name of Woburn Bordeaux Paste. In the absence of secondary reactions, carbon dioxide should convert one-tenth of the copper present in it into soluble copper sulphate, 2 (10 CuO, SO3) + 9 CO2 = 9 (2 CuO, CO2) + 2 CuSO4, whereas with ordinary Bordeaux mixture, any copper sulphate formed in this way, would be decomposed by the excess of lime present, and that ultimately remaining undecomposed would be very small in amount.

In undertaking a survey of the soils of a given district the methods of analysis and the classification to be adopted (which in its turn shapes the scheme of the work) must be determined by the purpose before the investigator at the outset. His end may be scientific–to assign the soils in question to their types, or practical–to give information to the cultivator by showing him the area over which a given method of treatment may be expected to succeed. Much will depend upon the extent of the area under investigation and on the character of the climate prevailing.

In the following pages the author gives a preliminary account of his attempts to improve the methods commonly in use for the separation of the products of the hydrolysis of proteins.

The results of all the experiments above described may be shortly summarised as follows.

Nitrites have been shown by Molisch, M. Schultz, and by Perciabosco and Rosso to be assimilated by various plants from sufficiently dilute solutions. Perciabosco and Rosso found that plants supplied with nitrogen in this form contain higher percentages of nitrogen than with nitrates as source of nitrogen. This is also the case, as was already shown, when plants take up all, or most, of their nitrogen as ammonium salts.

Experiments with other inorganic forms of nitrogen—amidosulphonic acid, hydroxylamine, hydrazine and azoimide—have all given negative results up to the present time.

As regards organic compounds the majority have given negative if not uncertain results. The results in which at least 1 milligram of nitrogen was assimilated are set out in Table I, p. 291.

In Part I of the current volume of this Journal Green and Ampt make certain assumptions regarding the factors which control the rate of flow of water and air through soils, the basis of which is that the channels in a soil may be regarded as a bundle of capillary tubes, and that the velocity of flow of a liquid will consequently conform to Poiseuille’s formula. Such an assumption cannot however be maintained. Poiseuille’s formula was deduced from the ascertained rate of flow of liquids through straight tubes of approximately uniform diameter; the latter being 1 mm. or so. The formula is not however really accurate even under these limited conditions, as was shown by Thorpe and Roger, who found it necessary to add the correction – ρV/8πlt. But the passages through the soil are not straight or of uniform diameter for any measurable distance, in fact they are wholly irregular, which Green and Ampt recognise, for they describe them as “irregular in area, length, direction and shape.” But this being the case, Poiseuille’s formula obviously cannot be expected to apply.

The study of two years' hay crops indicates that the composition of the hay steadily changes throughout the period commonly covered by the hay-making season.

The nature of the change depends to some extent upon the character of the season. In the summer of 1909 when the climatic conditions favoured steady growth there was a steady production of protein and fibre and a considerable assimilation of ash ingredients, notably silica. In the following summer the effects of a severe climatic set-back in the later part of June was seen in an almost complete suspension of growth, and notably in the production of protein.

In both seasons there was a steady fall all round in the digestibility of the hay, which in the end more than counterbalanced the increase in weight of the crop.

In both seasons the best results were obtained by cutting about the beginning of July. A fair amount of latitude in the time of cutting —say, a week or 10 days—may be allowed, however, without very seriously impairing the nutritive value of the crop. There was evidence, nevertheless, in each year of appreciable deterioration after the middle of July.

Much work has been done in America, on the Continent and in this country, to determine the effect of different finely-ground naturally-occurring phosphatic substances on plants of various natural orders, grown under differing conditions as to the character of the soil and the use of other nutrient substances. In a few cases results or conclusions appear to conflict. Not nearly so much attention has been devoted to the effect of artificially prepared insoluble salts of phosphoric acid on the growth of plants. When these are employed in the absence of ammonium salts, and acid soil substances, definite information should be obtained as to the powers possessed by plants themselves of utilizing insoluble phosphates. With the object of making a contribution to such knowledge, oats, peas and swede turnips were grown in artificial soils made up of white sand and pure chalk, and the particular salt of phosphoric acid under investigation. The other essential nutrient substances were supplied in a dilute solution of salts.

In discussing among men of science the subject of diseases caused by bacteria, it is quite unnecessary, at this date, to argue the question as to whether there are or are not bacterial diseases of plants. A knowledge of the literature of the past fifteen years and of the character of the researches which have been carried out in this branch of phytopathology, establishes the point beyond all doubt. But it may be useful to consider briefly some of the reasons which accounted for the scepticism prevalent in earlier days.