No very definite statement has yet been made as to the time when Mytilus edulis spawns at Plymouth. However, in 1911 records of spawning in the Laboratory tanks were made in January, February, and March, and in 1912 two specimens removed from the tanks spawned in early May.

An objection often raised to experiments on tissues treated with artificial solutions and isolated from nervous control is that results obtained under such highly abnormal conditions can be of no real value. This criticism arises essentially from a misconception as to the aim of the experiments in question, but it is encountered so frequently that it may not be out of place to consider briefly why it is necessary for the physiologist who would learn something of the more intimate mechanism of the cell to work with tissues under artificial conditions.

Colonies of Bowerbankia pustulosa, collected in July and August, 1911, in and near Plymouth Sound, contained a great many ovicells and produced numerous larvae, when kept in a flat glass trough and put under circulation during the night. The small yellowish larvae have a decidedly positive phototropism. They gather on the surface of the water on that side which is turned towards the light, from which position they sink to the bottom of the glass. Their movements slacken gradually in the course of a few hours, and at last are limited to revolving in a small circle until they fasten on the sides of the glass. Here they complete their metamorphosis, and in a few days the primary polypides are expanding their ciliated tentacles. The result was better when the just-hatched larvae were brought into a jar sterilised by hot water and filled with so-called outside water, i.e. water from beyond the Breakwater. This jar was fitted with a glass stand carrying a number of cover-glasses. When the larvae settled on these, it was easy to make total preparations of them without detaching them.

Having been engaged at intervals during the last few years in studying from a physiological point of view the coagulation of crustacean blood—Tait (08), (10, A and B), (11)—and finding more variation in this regard in different Crustacea than has hitherto been recognized, it suggested itself to me to inquire if the observed differences are correlated with any special physiological peculiarities, and, further, if they depend in marked degree on phylogenetic relationship. It is not a simple matter to settle either of these questions, and I make no pretence to have done so. At the same time, I have thought it worth while to put my observations on record, in the hope that the matter may thus sooner arrive at a satisfactory settlement.

During the summer of 1911 I conducted at the Plymouth Biological Station a series of experiments on the living active gas-gland associated with the bladder of certain marine fish, the results of which are recorded in a paper published in the Anatomischer Anzeiger for 1911 (Bd. XL, p. 225). Whilst so employed I incidentally made some observations on the structure and mode of action of the “oval” in fishes, and since my conclusions differ in several particulars from those of Nusbaum and Eeis (Bull. Acad. d. Sciences Gracovie, 1905, p. 778; Anatomischer Anzeiger, Bd. XXXI, 1907, p. 169), I think it as well to put them on record. Most of my observations were made on the Pollack. If a weight be attached to this fish so as to cause the gas-gland (oxygen gland) to become active and to pump oxygen into the bladder, it will be found that the oval strongly contracts, so as to prevent the additional gas forced into the bladder from escaping into the blood. The oval, it may be mentioned, is a large oval area usually situated in the dorsal posterior wall of the bladder. It differs from the rest of the bladder wall in that it alone is permeable to the contained gases, and, like the ductus pneumaticus in Physostomi, permits their escape when the conditions require it. In the Pollack the oval is normally widely open and is invisible to the naked eye, but on the gas-gland being caused to become active in an unusual degree, the oval becomes strongly contracted and is then a very conspicuous structure inside the bladder. This contraction of the oval is of course effected by muscles, and the result of it is to cause the thin-walled permeable area to become more or less completely shut off from the general bladder cavity, the walls of which, as just mentioned, are impermeable.

The American limpet, or slipper-limpet, known to naturalists as Crepidula fornicata, was introduced into England about 1880, being recorded at that time by Mr. B. S. Dodd in the Proceedings of the Malacological Society for 1893. Dodd, it is interesting to note, sounded even at that early time a warning note against the possible spread of this animal, and the probability of its becoming an enemy to the oyster farmer. There is no doubt that this limpet has been, and is probably still being introduced along with American oysters, on which it fixes itself. I have myself seen it unshipped along with oysters, but all the specimens I found had died recently. The spread of the limpet appears to have been very rapid on some grounds, as, for example, at West Mersea, where, since its appearance about eight years ago (from information obtained from local oyster fishermen), it has spread so that it is now more common than oysters.

Some fifty years ago a German investigator, Eeissner, discovered lying freely in the central canal of the spinal cord of the lamprey a very fine cylindrical rod, which he supposed, notwithstanding its unusual situation, to be a delicate nerve fibre. He failed, however, to learn anything concerning its connection with the central nervous system, and his discovery, although confirmed, seems to have attracted but little attention. The few observers who have since that time recorded observations upon Eeissner's fibre were almost all agreed that it was to be looked upon merely as an artifact produced by the coagulation of the cerebro-spinal fluid by the action of the fixing reagents employed.

The Amphipoda dealt with in this paper were collected in August, 1906, by Dr. Allen, to whom I am indebted for the opportunity of examining them.

The collection contained thirty-five species (belonging to twenty families), of which one only, Tryphosites alleni, is new to science. Five others, Stenothoe richardi, Syrrhoites walkeri, Syrrhoe affinis, Eusirus biscayensis, and Rhachotropis rostrata, are recorded for the first time since their original discovery. The geographical range of five species has been considerably extended, viz. Syrrhoe affinis, Tmetonyx similis, Sympleustes glaber, Epimeria parasitica, and Laetmatophihis tuberculatus; the four last forms have not been hitherto recorded with certainty south of Norway.

The significance of the colouration of various Actiniaria has been of much interest to me for some time, and particularly the extreme variability displayed by certain of the most abundant species. Descriptions of colouration and coloured plates help but little toward elucidating these problems, the examination of numbers of the animals living in their natural environment being absolutely essential before any conclusions can be drawn.

This species is described and figured by Gosse in his Actinologia Britannica, quoting its original discoverer Holdsworth, who obtained a number of specimens at the entrance of Dartmouth harbour from among the roots of Laminaria. In Section III of the Appendix, Gosse (p. 355) adds: “I have taken this at Torquay. It has also been found at Mizen Head, and sent me from Banff. The markings are true to the description, and leave no doubt of its distinctness as a species.”

In one of the tanks at the Plymouth Laboratory containing pipe-fish and sticklebacks, a whiting was found recently which exhibited black specks scattered over its pigmented areas and on the conjunctiva. The spots were fairly evenly distributed and averaged .5 to .1 mm. in diameter. Around each black point there was a clear unpigmented area.