During the last eighty years the Mycetozoa have attracted the attention of numerous investigators, largely on account of the striking differences in structure which are exhibited at successive stages in the life-history. The fact that during the early stages of their development they consist of naked masses of protoplasm and closely resemble certain lowly animal forms, while later on in the sporangial condition they assume plant-like characters, has given rise to numerous discussions as to their position in the classification of living organisms.

In the Transactions of the Royal Society of Edinburgh, Vol. LIV, Part III, No. 11, 1926, the author published an account of the anatomy of the head of an African Elephant fœtus, 21 cms. in length. The present paper deals with the voluntary muscles (except those already described) of the same fœtus. The author intends to prepare later an account of the skeleton and internal organs, so that a complete description of the anatomy of this rare specimen will be available.

The section which treats of the head will henceforward be referred to as Part I; the present paper, therefore, becomes Part II.

The body muscles were investigated under the Zeiss Binocular Dissecting Microscope, and the work was facilitated by rapid staining with a weak solution of saffranin. Owing to long preservation, the muscles, nerves, and blood-vessels of the specimen were quite colourless. The saffranin gave a certain amount of differentiation which lasted for several hours, and the advantage of the method is that the colour disappears entirely when the specimen is put back into the store jar between one working period and the next.

The investigation of which the results are embodied in this paper was undertaken in an attempt to gain an insight into the problem of the propagation of Clematis by means of stem cuttings.

In order to be able to interpret the phenomena of regeneration induced by isolating portions of a plant, it is essential to investigate the normal anatomy in some detail. In any severed portion of a plant, the first signs of abnormal cell activity in the tissues depart only slightly from the normal, and unless they can be detected and identified at their initiation, it is impossible to define exactly the time and place of origin of the new growth.

Accordingly the first part of the paper will deal with the normal stem-anatomy of the genus. The second part, with the changes in the anatomy resulting from vegetative propagation, and the third part with some experimental modifications of the regeneration-response.

It is well known that in many orders of typically winged insects species occur which in the adult stage are apterous or have the wings so reduced in size that flight is impossible. Sometimes the reduction of wings affects one sex only, as in the case of the females of certain moths, but in the majority of cases it is exhibited by both sexes. In many instances wing dimorphism occurs irrespective of sex, one form of the species having fully developed wings and the other greatly reduced wings. In some species the wings are polymorphic. The problem of the origin of reduced wings and of other functionless organs is one of great interest from the evolutionary point of view. Various theories have been advanced in explanation, but in the majority of cases the various aspects of the subject are too little known to warrant discussion. More experimental work is required to show how far environmental conditions on the one hand, and hereditary factors on the other, are responsible for this phenomenon. Those species which exhibit alary dimorphism afford material for the study of the inheritance of the two types of wings, but only in a few cases has this method of research been utilized.

The district shown on the plate at the end of this paper belongs to an elevated portion of the much-dissected tableland known as the Highlands of Scotland. It stretches from the eastward-draining Dee to the southward-draining Shee and Isla. The watersheds between these three rivers determine the county boundaries of Aberdeen in the north, and Perth and Forfar in the south-west and south-east. They often rise well above 3000 feet, and where they meet in Glas Maol (I of Plate) they attain to 3502 feet. In the valley bottoms, Braemar on the Dee and the Spittal of Glen Shee both stand a little above the 1000-foot level. A connecting road, with a famous hairpin bend known as the Devil's Elbow (J), passes the Aberdeenshire frontier half a mile east of the Cairnwell at a height of 2199 feet. Its course furnishes an ideal geological traverse of the district considered as a whole.

A glance at a geological map of Middle Deeside shows that below Cambus O'May the valley is floored by a belt of metamorphic rocks flanked on both north and south by high hills of Younger Granite, of a date later than the regional metamorphism. The area of metamorphic rocks here considered extends from Cambus O'May down river to Banchory, but in the eastern half of this region the geological problems concern injection rather than tectonics. The cordon of Younger Granites enclosing the Deeside Schists is breached on the west near Cambus O'May by a mile-wide gap through which the metamorphic rocks escape to connect with those of the east side of Glen Muick. In this latter district the schists of as far south as the Aberdeenshire-Forfarshire watershed are considered in detail. Adjacent regions farther south and south-east are dealt with only in so far as they concern the correlation of the Deeside Schists.

Various selective agents exert their influence on the processes governing the survival of new forms within an established plant group. As the balance of these agents changes so also will the genetic composition of the plant group change. Environmental conditions undoubtedly permit and direct evolution, but apparently the action of the environment is mainly selective in nature, and, although not directly concerned in the production of new growthforms, it aids the survival of suitable forms by establishing a certain amount of genotype isolation. Amongst the various selective agents whose action is confined to the direct selection of genotypes, or phenotypes and therefore indirectly of genotypes, there is the important question of pollination and fertilisation. As the very existence of individuals depends on compatible fertilisation, the investigation of the problem of pollination and fertilisation obtaining within a plant group is essential preparatory to any study of the survival of individuals within that plant group.

The characters of the sporangium have been widely used in the phyletic treatment of Ferns, and one of the most important features has proved to be the nature and position of the annulus. As Professor Bower has pointed out, the position of the annulus has long been regarded as an important character in the systematic treatment of Ferns. In the more advanced groups the annulus forms a very precise dehiscence mechanism consisting of a single layer of indurated cells passing round the sporangium in different positions in the various groups. With very few exceptions, notably found in the Gymnogrammoid circle of affinity, the structure and position of the annulus is constant in any one species. In the more primitive groups of Ferns, however, the dehiscence mechanism is much less precise, and a re-examination of the sporangia of the Osmundaceæ has shown that these are by no means constant in structure and that, in particular, they show considerable variation in the characters of their annulus. These latter variations have proved to be of interest in relation to two questions:

1. The systematic placing of certain fossil sporangia.

2. The evolution of the more definite annulus of the higher Leptosporangiate Ferns.

Other points of interest emerged, such as the occurrence of abortive sporangia in this group, and certain facts relating to the position of the sporangia with relation to the margin of the frond.

A description of the sporangia of a number of species of Osmunda and Todea will first be given. The bearing of these facts on the problems above mentioned will then be discussed.

Chirocephalus diaphanus, the Fairy Shrimp, feeds on minute suspended particles and organisms that it separates from water currents produced by its limbs. According to Lundblad (1920, p. 41), in the closely similar form, Tanymastix stagnalis (L.), an orally directed current is produced along the mid-ventral line between the trunk limbs which actually carries food particles to the mouth, the current itself being produced by the sweeping action of the anteriorly directed basal parts of the proximal endites of the trunk limbs. According to Storch (1925a, p. 387), the particles are not carried forwards on a current but are swept forwards from limb to limb until they reach the mouth.

The following investigation was commenced, in the first place, to provide information for class use, for, in spite of the fact that thousands of specimens of Squalus acanthias and S. sucklii are used every year in North America, there appears to be no satisfactory account of the blood vascular system of either species available. As the work proceeded, various problems arose which necessitated references to the conditions in other species and the preparation of more detailed dissections than are usually made in class work. It is well known that there is considerable confusion in the nomenclature employed by different authors for even some of the main vessels, and it was soon evident that this is not merely individual preference but, in part, due to a more fundamental lack of agreement as to the precise morphological significance of the vessels themselves. More recent embryological investigations by other workers have, we consider, given a key to the solution of the most important of these problems and have shown that, in so far as the blood-vessels are concerned, the Elasmobranchs lie closer to the other gnathostomatous vertebrates than is generally recognised, and indeed furnish a primitive and generalised type. The time seemed ripe, therefore, to provide a connected account of the vascular system in an Elasmobranch, viewing it in the light of the researches just referred to, and of what is known of the distribution of the various vessels in the sub-class in general. It was hoped that this would provide an epitome that would serve as a basis for future work in the sub-class, and also for comparison with the conditions in higher vertebrates.