The Entomostraca recorded here were collected by the S.Y. Scotia on its way to and from the Antarctic, and also while carrying on investigations there during the years 1902 to 1904. The Entomostraca in these collections belong chiefly to the Copepoda, but the Cladocera and Ostracoda are also represented, the last by a considerable number of species. These three groups are described below in the order mentioned.

Although the amount of active research that has been carried on during the past few years on the question of chromosome reduction and relative problems has been very great, the nuclear activities here concerned are still far from being understood. We are not yet in a position to draw general conclusions in regard to meiotic phenomena. It therefore seems to me desirable that all observations of fact and rational interpretations should be placed on record, so that when it becomes possible to generalise, all lines of evidence may be available.

There are a number of gaps which exist in our knowledge of the temperature changes which occur in fresh-water lakes. The broad lines on which the changes occur are fairly well known, but on almost every point there is a lack of detailed knowledge, and every investigation shows new problems requiring attack. One of the most interesting of these problems is the causation of the temperature seiche, and the effect of varying meteorological conditions. The problem is a difficult one, as the factors to be taken into consideration are so numerous, and the data from which to form conclusions are difficult to procure. We must first obtain an accurate knowledge of the changes which are occurring in the body of water under consideration—not only at one point but at all points, and this necessitates observations at frequent intervals of time, at numerous depths, made from several points on the surface of the loch. As yet there are no satisfactory self-recording instruments by means of which we can record the temperature of water at a considerable depth below the surface, and recourse must be had to the reading of mercury thermometers.

Recent investigations have profoundly modified our conception of the value of the histological elements of the nervous system. Conflicting opinions are still held on many points of primary importance, perhaps the chief of which is the relation of the nerve fibre to the nerve cell. The origin of the nerve fibre is a problem of vital interest not only to the embryologist, but also to the physiologist and the pathologist. It has long been the subject of controversy, and, in spite of numerous valuable researches, we are still far from knowing the relation of the nerve fibre to the central neuroblast, a relation of essential importance in the understanding of all neuro-pathological questions.