The results of our first experiment in applying fertilizers to a small sealoch, Loch Craiglin (Gross, 1947; Marshall, 1947; Orr, 1947; Raymont, 1947; for references see No. V), were sufficiently encouraging to justify an extension of the work to a larger area. Loch Craiglin provided a good site for preliminary investigations because it could be easily enclosed and, for all practical purposes, isolated from the main loch. The conditions in Loch Craiglin were, however, atypical in many respects, and it seemed desirable that the results obtained there should be tested by investigations in a body of water (1) sufficiently large to reduce the extreme fluctuations in salinity, pH and other factors, encountered in Loch Craiglin; (2) sufficiently deep to reduce the proportion of seaweed to phytoplankton in the productivity of the cultivated area; and (3) with its connection with the main loch or the sea left undammed, to test the possibilities of fertilizer application in open, i.e. not artificially enclosed, sea-lochs.

Extracts of green peas stimulate penicillin formation by Penicillium notatum, and fractions have been prepared by treating the juice with ethanol to find the constituents present which have a stimulating action. The mould has been grown as a surface culture on a basal medium containing NaNO3, KH2PO4, MgSO4, NaCl and lactose to which the various fractions have been added. One chemically complex fraction containing a large number of amino acids (demonstrated by paper partition chromatography and estimated micro-biologically), carbohydrates and mineral matter (containing a number of trace elements) gives high yields of penicillin. The types of penicillin produced on this medium have been determined by micro-chromatography.

Chemically defined media have been formulated, and information has been obtained on the sources of carbon and nitrogen that permit growth and penicillin formation.

The amounts of carbohydrate and salts in the medium influence the formation of penicillin. Excess of carbohydrates such as glucose cause an increase in growth of the mould and a decrease in the production of penicillin.

The significance of the results in relation to the formation of penicillin is discussed.

I am privileged to-day in having been invited to give this address, but I feel that I am particularly privileged also in that, so far as I can discover, this is the first occasion in the annals of the Royal Society of Edinburgh on which a veterinarian has been asked to address the Society on matters concerning the diseases of animals.

The Veterinary profession has long been recognised as a handmaid of Agriculture but, like her sister profession Medicine, her services, until comparatively recently, have been based on knowledge acquired by long experience derived from trial and error, as distinct from planned experiment based on scientific principles.

Two series of logarithmic expansion systems are described, with × 1·6 as the rate of increase in numbers of new monotypic genera correlated with a rate of × 2·0 for increase in total numbers of species. These series are discussed in relation to current numbers for monotypic genera, total genera, and total species in 36 of the largest 45 families of flowering plants.

The Rowett Institute for research on animal nutrition had its origin under a scheme for promoting scientific research in agriculture adopted by the Development Commission in 1911.

The Governing Body, which originally consisted of an equal number of members appointed by the Court of the University of Aberdeen and the Governors of the North of Scotland College of Agriculture, was constituted in 1913. Within recent years it has been expanded to include persons nominated by the Secretary of State for Scotland, the Royal Society, the Royal Society of Edinburgh, the Agricultural Research Council, and the Medical Research Council. Research work was begun in temporary accommodation in Marischal College in 1914, under the direction of Dr John Boyd Orr—now Lord Boyd-Orr—who continued as Director until his retirement in 1945.

1. The site (Kyle Scotnish) of an experiment to test the effect of the addition of chemical fertilizers (N and P) to an arm of a sea-loch is described.

2. Certain physical conditions of the loch are recorded, including the tides, which were of a peculiar form.

3. Methods used in the measurement of water movements are described, and the results used to calculate the rate of exchange of Kyle Scotnish water with the water outside the loch. At spring tides this exchange was estimated at less than 8 per cent, of the volume of Kyle Scotnish.

4. The additional corroborative evidence obtained by tracking marked water masses within the loch is presented.

5. The quantities of fertilizer used are tabulated, and results given which demonstrate its rapid removal from the water.

6. The significance of the low rate of water exchange is discussed. This low rate of exchange makes possible the increase in productivity of Kyle Scotnish, brought about by the addition of chemical fertilizers.

Marking experiments have demonstrated that certain of the rings appearing as surface sculpture on the shells of the lamellibranch Venerupis pullastra are valid as a measure of annual growth. From measurement of these rings the mean monthly and the mean annual growth increments have been calculated. The length-age relationship curve is similar to that of most other lamellibranchs. Reasons for the variation in the mean monthly rate of growth have been examined. The height-length and the thickness-length ratios for various sizes have been calculated and found to follow a simple and direct tangent relationship.

The Golgi material of the neurones of the central nervous system of normal fowl and of birds affected with spontaneous cases of Neurolymphomatosis gallinarum (fowl paralysis) is described. Material was prepared according to the methods of Kolatchev and of Aoyama. The Golgi material of normal pyramidal cells of the cerebral cortex, the Purkinje cells of the cerebellum, the multipolar cells of the spinal cord, and the cells of the spinal ganglia, is present as rods, irregular bodies and filaments. Compact net-like Golgi material is present in the small cells of the spinal ganglia.

In the neurones of fowl affected with Neurolymphomatosis gallinarum the Golgi material undergoes hypertrophy, followed by clustering of the Golgi elements and fragmentation. The intensity of the morphological changes and the number of neurones affected in a particular region of the central nervous system varies considerably, except in the spinal ganglia where all the cells examined exhibited marked changes. It was not possible to determine whether the changes were primary or secondary in nature. The literature of the subject is discussed.

In the year 1815 an anonymous article appeared in Thomas Thomson's Annals of Philosophy (1) entitled “On the Relation between the Specific Gravities of Bodies in their Gaseous State and the Weights of their Atoms “. Its introductory paragraph illustrates the hesitancy of the writer in its exposition: “The author of the following essay submits it to the public with the greatest diffidence; for although he has taken the utmost pains to arrive at the truth, yet he has not that confidence in his abilities as an experimentalist as to induce him to dictate to others far superior to himself in chemical acquirements and fame. He trusts, however, that its importance will be seen, and that some one will undertake to examine it, and thus verify or refute its conclusions. If these should be proved erroneous, still new facts may be brought to light, or old ones better established, by the investigation; but if they should be verified, a new and interesting light will be thrown upon the whole science of chemistry.”

From the proportion of first births in any year it is possible to calculate the average size of fertile family which would be produced if the rate of reproduction remained constant and equal to that of that year. From marriage age and total married fertility rate the corresponding size of all families may be estimated. The relation of these two figures gives the percentage of fertile unions corresponding to the aforesaid reproduction rate. The proportion of fertile unions in various countries during the two wars, and under the varying economic conditions of peace, has been studied, and the great variations demonstrated. The importance of these variations is considered.

A system of twelve stages of expansion from one primary monotypic genus is described and elaborated, using as two correlated parameters the rate of x 1·5 for the number of new monotypic genera arising (rGi) when the rate of X 2·0 is taken for the increase in generic size or numbers of species within any one genus (rSz). Too much stress should not be read into the precision of the positions indicated for known numerical data; an approximate fitting is all that can be reasonably expected even if these theoretical expansions are something like the historical truth.

1. The phytoplankton in Kyle Scotnish and Sailean More, two parallel arms of Loch Sween, was studied and the seasonal variations described.

2. Artificial fertilizers were distributed in Kyle Scotnish and their effects on the phytoplankton were followed up. It was found that on some occasions the phytoplankton increased rapidly after the distribution of fertilizers, but that on other occasions there was no apparent response.

3. The zooplankton populations in Kyle Scotnish and Sailean More were studied and the seasonal variations described.

4. It was found that after fertilizers had been distributed the zooplankton in Kyle Scotnish became considerably richer than that in Sailean More, and its density remained higher until it was reduced in September 1945 by the feeding of young herring. Even so, the average density in Kyle Scotnish was twice that in Sailean More.

5. Experiments were done to determine the effect upon the phytoplankton of the grazing of the zooplankton. It appears that the zooplankton removed a large portion of the phytoplankton by grazing, and that the apparent lack of response of the phytoplankton to the distribution fertilizers was at least on some occasions due to the effects of grazing.

6. It was shown that the productivity of Kyle Scotnish, in terms of plankton, has been doubled by the distribution of fertilizers.

This paper was assisted in publication by a grant from the Carnegie Trust for the Universities of Scotland.

The application of fertilizers to an enclosed sea-loch (Loch Craiglin) led to a marked increase in the density of the bottom fauna (Raymont, 1947, 1949). The rise in the bottom fauna was slow, and this was to be expected, since first a considerably increased density of plankton had to be built up, and only then would the relatively slowly reproducing bottom fauna have a chance to increase in numbers. It seemed clear also from the later work in Loch Craiglin that the beneficial effects of fertilization on the bottom fauna lasted for a considerable time after application of fertilizers had ceased.

This paper is a first report on the Echiurids and Sipunculids of Zanzibar, and deals with the material collected by Dr J. D. Robertson during the years 1948–1950 on the shores of Zanzibar, supplemented with a few dredgings. These collections contained two species of Echiurids and eighteen species and varieties of Sipunculids. Of these, one Echiurid (Ochetostoma zanzibarense) and two Sipunculids (Dendrostoma robertsoni and Phascolion robertsoni) are described as new species. Six others are recorded from the area for the first time. The list of species now described from the Zanzibar area contains eight species of Echiurids and twenty-four species and varieties of Sipunculids. Rich as the area is in species, it is even more remarkable for the numbers of individuals, some species being dominant forms in the population.

The genetical studies on ring-chromosomes in Drosophila show that there is no interlocking of chromatids at mitosis.

Dicentric ring-chromosomes formed at meiosis on being pulled apart do not become broken with subsequent reunion of the broken ends. This may be due to the failure of these chromosomes either to rejoin or to become broken at all.

The results make it probable that there is a gene or genes located in one of chromocentral regions of the X-chromosome of Drosophila, probably in the region at the distal end, which has a function in ensuring the orderly segregation of the chromatids in the early cleavage stages of the fertilised eggs. Hence the absence of this chromosome region results in a tendency to gynandromorphism.

Results indicate the incorrectness of the view that the inviable zygotes and the patroclinous males found in the ring-chromosome stock arise from different kinds of eggs (single cross-over and progressive double cross-over respectively, as proposed by L. V. Morgan). Both arise from eggs that have for any reason failed to receive a monocentric X-chromosome. This result occurs in all cases of digressive double crossing-over and in half the cases of progressive double crossing-over. Such virtually X-less eggs, when fertilised by an X-bearing sperm, form patroclinous males, and when fertilised by a Y-bearing sperm, form inviable zygotes. The classes thus found are therefore equal in number.

The form and structure of the uterus of the albino laboratory rat are described. Cyclical vascular changes are noted, and attention is drawn to the presence of spiral arteries in the endometrium. A common lower cervical canal is described.

In each of three years studied, the spring hatching period for a flock of Brown Leghorns has been divided into two sub-periods such that a number of matings are represented by offspring in each sub-period. Analysis of variance of age at sexual maturity reveals statistical interaction between family means and hatching period, the ranking of family means varying with date of hatch. Consequences of this are discussed with reference to current methods of correcting age at maturity for date of hatch, the method of multiple shift progeny testing, and the general question of improvement by selection in the presence of non-additive combinations of genetic and environmental effects.

Measurements of comb growth in maturing pullets reveal a seasonal retardation, possibly reflecting retardation in sexual maturity, and in line with environmental effects causing cessation of production in older birds. It is suggested that rapid changes in day length during September and October may play a large part in determining the retardtions and interactions displayed, and that measurements of comb growth may be of value in recognising consistently superior genotypes for age at sexual maturity.

Fishing with both a shore seine net and a small otter trawl in the summer of 1943 and the spring of 1944 showed that the native fish population was very sparse. No estimate of the size of fish population was attempted in 1944. Estimates undertaken in 1945 and 1946 will be discussed later (p. 120). Fishing in the period June to September 1945 produced small numbers of fish tabulated on p. 110, and some plaice and flounders which will be dealt with separately.

In addition there were fairly large numbers of gobies, sticklebacks, pipe fish and sand eels which, however, were not usually recorded in our catches. Shoals of young herring appeared only in the summer and autumn of 1945.

The common strain and six specialised strains of Phytophthora infestans have been employed in testing potato varieties and seedling progenies bred from the wild species S. demissum for resistance to the disease. Resistance, due to the hypersensitive condition of the protoplasm, is manifested in the presence of major genes, and four such genes have been identified, viz. R1, R2, R3 and R4. Each gene induces in the plant a hypersensitive response to infection with the common strain and with a particular group of specialised strains of the parasite. The genes are inherited independently in simple Mendelian fashion, but in the segregations three different types of deviations from standard disomic ratios occur due to (a) unpaired chromosomes, (b) incompatibility factors, and (c) partial autosyndesis. A series of minor genes modify the phenotypic expression of the major gene system and so differentiate grades of hypersensitivity or of susceptibility as the case may be.

The common strain of P. infestans appears to be a population persisting at an equilibrium determined by host range and environmental conditions. Mutations frequently occur, but new forms survive only when host genotypes, to which they are specially adapted, are available.

The common strain A of the blight fungus (Phytophthora infestans) and two new strains, B and C, have been employed in testing potato varieties and seedling progenies, bred from the wild species S. demissum, for resistance to the disease. The reactions of seedlings to infection with strain C are compared with those of strains A and B. The C strain is shown to be more virulent than A, since it attacks some A resistant as well as all A susceptible plants. Likewise the B strain is more virulent than A. The difference between the pathogenicity of strains B and C, however, is not one of degree of virulence; one plant may be B resistant-C susceptible, while another may be B susceptible-C resistant. This difference is essentially of a qualitative nature. Resistance to these strains, which is manifested by the hypersensitive condition of the plant's cells, is produced in the presence of three major independent genes, Re, Rb and Rbc, which confer resistance to strains A and C, A and B, and A, B and C respectively. Segregations in each case are similar in type, and are characterised by an excess of recessive individuals.