This paper brings together from all available sources records of marine mollusca indigenous to Orkney, together with notes on their local distribution. Besides incorporating the results of recent research it includes a brief account of work done in the islands by earlier conchologists. For convenience of reference the list of species follows the nomenclature and systematic arrangement used by the Conchological Society of Great Britain and Ireland in Winckworth's revised list of the British Marine Mollusca. The small section on local collecting grounds may prove useful to future workers. A commentary seeks to relate the molluscan fauna of the islands to a wider context of distribution and draws attention to the seemingly characteristic western influence present in Orkney waters. A brief note is added on the non-marine mollusca of the islands.

Drosophila melanogaster larvæ when cultured aseptically on a synthetic diet require exogenous ribose nucleic acid (RNA) for normal growth even though they can synthesize their own endogenous RNA from simple precursors. The optimum dietary supply lies between 0.4 and 0.7 per cent RNA. Individual bases, nucleosides and nucleotides which make up RNA cannot substitute for the whole polynucleotide, but adenine, adenosine, adenylic acid, guanosine and guanylic acid are used and stimulate growth to varying degrees. The pyrimidines and their nucleosides and nucleotides are not used when fed singly.

It is shown that the de novo synthesis of purines may be more difficult than that of pyrimidines, and that if a source of purines is supplied (as adenylic acid), then the nucleosides and nucleotides of both cytosine and uracil are utilized by the larvæ, whereas the free bases are not. Cytidylic and uridylic acids seem to be interchangeable, and together with an adequate supply of adenylic acid give as good growth as RNA. Orotic acid and 2—6-diaminopurine are not used by the larvæ under the conditions described, but hypoxanthine and inosine are: xanthine and xanthosine can also be shown to have an effect on growth.

Dose-response curves were determined for adenylic, guanylic, cytidylic and uridylic acids under conditions which allow the determination of the optimal supplies of each. These are found to be about 0.110, 0.080, 0.025 and 0.025 per cent, respectively. The requirement of RNA is therefore primarily a requirement of adenylic acid, since more than enough of the other nucleotides should be available when the supply of RNA is optimal. The optimal supply of adenine corresponds almost exactly with the optimal supply of adenylic acid, though a somewhat delayed larval development may be a result of energy utilization in the base-nucleoside-nucleotide conversion.

These results are discussed in the light of our knowledge of purine and pyrimidine utilization in other multicellular organisms, particularly the rat, and possible applications of the findings are considered.

Pharaoh's Ant, Monomorium pharaonis (L.), is arrhenotokously parthenogenetic, conforming essentially to the pattern of reproduction characteristic of Hymenoptera generally. The female is diploid, 2n = 22, the male haploid, n = 11, in certain somatic cells and in the gonia, though polyploidy exists in some larval tissues. The 11 discrete chromosomes of the male cells comprise a single genome, in which are distinctive only one large clubbed chromosome and at least one of intermediate size. Spermatogenesis is characterized by a first abortive division and a second equational division, resulting in two spermatozoa being derived from each haploid spermatogonium. Spermateleosis is described in some detail. Certain peculiar features are discussed, viz. the cytoplasmic buds appearing during spermatogenesis; unequal second spermatocyte divisions; the single chromosome sometimes observed as lying apart from the other chromosomes during first spermatocyte metaphase; the division and grouping of polar body chromosomes. For reasons given, several recent conclusions of Whelden and Haskins (1953) regarding the cytology of ants are regarded as mistaken.

The fossil plant described is a mould formed in a Clayband Ironstone nodule by the leaf cushions of a palæozoic arborescent Lycopod. It exhibits the unaltered three-dimensional shape of the surface of the tree-trunk. The description adds to the known facts about the leaf cushions and their diagnostic features. The specimen has been placed in a new species of the genus Sublepidophloios, Sublepidophloios ventricosus.

A new method of making casts from such fossil moulds is described which involves the use of an elastic, re-meltable plastic compound. An examination of casts made by this method indicates that the plant fragment described was fossilized with the minimum amount of compression and distortion.

The exact age of the basalts and intercalated tuff-beds of Iceland is still uncertain. Palæontological dating relies almost solely on plant fossils the occurrence of which is known from many different localities in western Iceland. No plant fossils have hitherto been found in eastern Iceland. In summer 1952 an expedition set out from Scotland to search for plant fossils and lignite deposits intercalated in the East Icelandic Volcanic Series. Such deposits were found on the northern flank of the mountain Tungufell.

Macroscopical remains of plants were rare and badly preserved as compared with the finds in western Iceland, but a microscopical investigation of the lignite yielded 22 types of pollen and spores and 19 species and varieties of diatoms. The flora differs from that known of western Iceland; macroscopical remains and pollen of Abietineæ are abundant in western Icelandic sediments but are entirely absent in the Tungufell flora. The Tungufell flora appears to be younger than the fossil flora of western Iceland; however, the possibility that the difference between the Tungufell flora in East Iceland and the flora found in West Icelandic deposits is due to different ecological factors cannot be excluded. Many further investigations are required before this question may be satisfactorily answered.

The larval tracheal system of Tabanus bisignatus is described and compared with the previous descriptions of Hœmatopota pluvialis by Cameron (1934) and of Tabanus, Chrysops and Hexatoma by Stammer (1924). Omissions in these descriptions are pointed out, and possible homologies of the tracheæ are discussed in terms of the generalized dipteran larval pattern deduced by the author from comparative studies of the tracheal system in certain larval Diptera (Whitten 1955). Attention is drawn to departures from this generalized pattern—departures which may be characteristic of family or of intra-familial segregates.

An account is given of the species Psilophyton robustius and the relevant literature is reviewed. There follows an illustrated description of a relatively well-preserved fertile, branched specimen. The morphological features of this specimen are discussed with reference to the earlier descriptions by Dawson and others. It has been found necessary to institute a new genus as Psilophyton is now apparently inappropriate for this species. The name given to this new genus is Trimerophyton, which includes the one species Trimerophyton robustius (Dawson) Hopping.

This note presents in summary the recorded occurrences of Potamopyrgus jenkinsi (Smith) in fresh waters in Scotland over the fifty years since it was first reported. Apart from isolated occurrences in the Outer Hebrides, in the Caithness-Orkney area, and in the Borders—Solway area, the records appear to reflect a gradual dispersal (1906—56) from an origin on the Tay, over the Tay and Forth drainage areas, and thence perhaps through the Midland Valley to the west coast. This dispersal has been slower than the rate of spread of the same species through England and Wales earlier in the century, but has been rapid compared with the rates of dispersal assumed for other molluscan species.

On the European continent, Uromyces punctatus is heterœcious and occurs on 35 species and 1 variety of Astragalus, 6 species of Oxytropis and 1 species of Onobrychis. There are 3 æcidial hosts recorded, the major one being Euphorbia cyparissias. At St Andrews, the uredo stage of the rust is confined to A. danicus and only uredospores and teleutospores have been found. Experiments conducted showed that the local population of the rust was capable of infecting 9 species of Astragalus and 1 species of Medicago, out of 27 species of Astragalus, 5 species of Medicago and 28 species of other legumes inoculated. No host specialization within the local population was evident. Attempts to germinate the teleutospores, using a variety of methods, failed, with the exception of a single spore. The major æcidial host, when inoculated with teleutospores, failed to show any signs of æcidial infection over a period of four years. Possible factors affecting the shortening of the life cycle of the rust are discussed.

Seldom, if ever, in the long histories of the Scottish Universities can there have chanced a centenary such as we now commemorate. In the same year, 1854, there died in Edinburgh two celebrated occupants of the Regius Chair of Natural History in the University, one full of years, with solid achievement and half a century of academic service behind him, the other in the first year of his Professorship, in the full tide of life, whose great accomplishment held promise of greater still; the one the master, the other his brilliant pupil and successor—Robert Jameson and Edward Forbes. Each of these men, in his own way, added enormously to the factual stock of knowledge, but the greater contribution was that each, by precept and example, helped to modify and mould the outlook of naturalists throughout the civilized world.

A typical poultry flock consists of offspring from a number of sires each mated to several dams. In choosing male parents in a selection programme no criterion of individual merit may be available and selection must usually be based on the performance of related females. The present report deals with the theoretical efficiencies of three systems of selection of males

(1) on the average performance of the dam family of a male's sisters.

(2) on the average performance of the sire family of a male's full- and half-sisters.

(3) on a weighted combination of sire family and dam family averages.

For traits of low heritability system (2) may offer marked advantages over system (1), the only type of family selection previously investigated. This should prove of importance in flocks where recording facilities are limited. Providing environmental effects can be minimised, efficient selection may be based on the average performance of sire families housed as units without individual recording.

The efficiency of system (2) declines with increasing heritability and is also subject to complications introduced by population size. In all cases, however, optimum gains may be obtained on system (3) when both dam family and sire family records are available.

In January 1956 a visit was made to North Ronaldshay, one of the Orkney Islands, to examine the rumen ciliate protozoa of the seaweed-fed native sheep. Rumen material from thirteen sheep was examined and the ciliate species identified. The numerical ratio of holotrich to oligotrich ciliates appeared to be much the same as in the hay-fed sheep's rumen; Isotriclia intestinalis Stein was, however, always absent. Certain experiments on the protozoan utilization of carbohydrates were carried out and the results compared with those of similar experiments on rumen liquor from hay-fed sheep. The holotrich ciliates of North Ronaldshay sheep were found to store amylopectin when the rumen liquor was incubated with laminarin, to a lesser extent when incubated with galactose and to be unaffected by mannose. These three results differ from previous experience with hay-fed sheep. No seaweed carbohydrate other than laminarin was utilized by the North Ronaldshay sheep holotrichs in vitro.

Floral ontogenesis has long been a preoccupation of morphologists. In trying to understand the physiological mechanism that underlies and determines the orderly formation of the several kinds of floral organs, it is essential to consider the organization and functional activities of the apex of the antecedent leafy shoot. The most general characteristic of the growing shoot apical meristem is that it gives rise to a succession of regularly spaced leaf primordia, sometimes of very variable form and structure, these having their inception in loci of special metabolism, or growth centres. The latter, typically originate in the sub-distal region of the meristem. The initial state of this region, which consists of equivalent embryonic cells, may be such that the reacting metabolic substances are homogeneously distributed in it. A contemporary chemical theory of morphogenesis envisages the possibility that a reaction system of this kind, in obedience to the laws of physical chemistry and mathematics, and on being activated, can give rise to a patternized distribution of metabolites, e.g. of growth centres, this constituting the chemical basis for the ensuing morphogenetic developments. This general property of the apex is maintained throughout the flora development, however much it may be modified in other ways. It is also known that the positions of new primordia are affected by those already present round the meristem.

Scotland's vital interest in the fisheries needs no stressing. Nor does her interest in marine research, for which reference to the pioneer work of Edward Forbes and the voyages of the Challenger and the Scotia alone are sufficient testimonial. Both in England and in Scotland many Commissions have been set up to try to deal with one fisheries problem or another. The setting up of the Board of British White Herring Fisheries in 1808 may be said to have been the beginning of a new phase; as a result Scotland has one of the best series of fishery statistics, those for the “cured” herring fishery, available to-day—and statistics are the foundation of fisheries research! Apart from this, perhaps Scottish fishery research, as distinct from marine research, may be said to have begun in 1836 when a Dr Knox “was asked, in order to solve a fishery problem in the Firth of Forth, to investigate whether the sprat and the herring were different species or not; and further, in 1842, Mr Henry Goodsir was employed to gain some definite information about the growth, food and habits of the herring. This was just one of many contemporary problems; a later one, of course, concerned the influence of the developing trawl fishery upon the conventional method of lining for demersal fish such as cod and haddock. The duties of this Board were the supervision of the fisheries (of which herring was the principal), the “branding” of herring and “cran” measures, securing the observation of the few international fisheries regulations of that time, guarding the territorial limits from the encroachment of foreign fishermen, and supplying to the Scottish Meteorological Society information about weather conditions in the fisheries.

A description is given of a new genus of mammal-like reptile, Mirotenthes, of which a remarkably complete and well-preserved skeleton was collected in 1936 by Professor Camp of the University of California, from the late Permian deposits of the South African Karroo.

Unlike the majority of Permian mammal-like reptiles, Mirotenthes was an agile form of small dimensions. Many of the skeletal characters exhibit a significant approach towards the mammalian threshold. The limb structure is very advanced and the digital formula is mammalian. The differentiation of ribs to form a definite rib-cage of mammalian type is particularly noteworthy and may indicate the presence in this genus of a mammalian respiratory mechanism.

The systematic study of this complete skeleton does much to bridge the gap between the primitive basal groups of mammal-like reptiles and the advanced Triassic groups from which the mammals derive. It has been known for many years that small, fast-moving carnivorous forms were present in the late Permian fauna, but the evidence has been fragmentary. The complete skeleton described in this paper throws new light on these hitherto poorly known genera.

Structural changes induced in male auxocytes after formaldehyde feeding were analysed cytologically. In comparison with the effects of X-rays (on mature sperm) there is: (1) a high proportion of mosaics; (2) an excess of repeats and deficiencies; (3) a shortage of translocations, and (4) fewer breaks in the heterochromatic regions.

The very high frequency of mosaics and the low ratio of inter- to intrachromosomal changes may be explained by the delayed opening of potential breaks which tend to open simultaneously in the same chromosome but at different times in different chromosomes. The high number of “isochromatid” breaks (repeats) points to some connection with the reduplication cycle.

The shortage of “eu-heterochromatic” changes in which “heterochromatic” breaks in salivary gland analysis are scored, can be similarly explained by a difference in the time of opening of potential breaks in the two types of chromatin.

Initial non random distribution of breaks as well as the conditions of rejoining in premeiotic cells may also play some role.

The subject is a very wide one and for the purposes of a single contribution some selection is essential. Much might be, indeed has been, said concerning the adaptations relating to sexual and reproductive behaviour in the Primates, notably in a long series of contributions by Zuckerman and his co-workers (especially in his summaries of 1932 and 1933). Attention might also be made to the structural adaptations associated with toilet habits. But I have restricted my remarks to three aspects alone, paying particular attention to behavioural patterns in which I have been personally interested, or structural details which I have myself made the subject of contributions to the literature.

I shall confine myself to I. Adaptations associated with the Arboreal Habit; II. Adaptations connected with Dietetic Habits; III. Adaptations correlated with Social Organization.

Notwithstanding its reported effect upon the levels of native auxin in plant tissues, 2, 3, 5-triiodobenzoic acid (TIBA) does not influence sex expression in Cannabis sativa, a dioecious species in which there is evidence that flower sexuality may be regulated by auxin levels in the neighbourhood of developing primordia. The total production of flowers is, however, increased in both sexes by TIBA, an effect possibly resulting from an alleviation of the correlative inhibition of lateral buds. Whilst hardly influencing morphogenetic activity at a cellular level at all, TIBA treatment leads to gross ontogenetic abnormalities, of which the common feature is a tendency for the elimination of localized growth and the substitution instead of generalized growth fields, resulting in the formation of infundibuliform and cylindrical foliar and floral structures. It seems probable that the bulk of the effects of TIBA in the plant may be due to an influence on auxin distribution, perhaps through interference with the mechanism of polar transport.

Details of what occurs in the interval between the hatching of amœbulæ from the spores of the Proteus group of amœbæ to the attainment of the adult condition (4–6 months) not hitherto known are described. The method consists in removing mature adults to petri dishes 4 in. in diameter, containing a dilute inorganic fluid which causes sporulation. The subsequent development of the hatching amœbulaæ can be traced in situ by means of a 4·4 mm. water immersion lens, and is seen to consist of feeding and growth alternating with periods of encystment. The time spent in cysts greatly exceeds that of activity.

Some account of what takes place when cultures of the Proteus group, allowed to dry to a brownish dust, and then wetted, is given. Only in the case of A. proteus have the amœbulæ, which hatch out from the spores, been grown to maturity. It has been shown that the dried cultures used may comprise (1) spores, (2) cysts of varying size from which arise amœbulæ likewise varying in size.