Now, excepting some particular cases, such as those described by Mr. Scoresby, and by Cook, Horsburgh, Pe rouse, and other voyagers, where such minute animals were found in immense colonies in the wide ocean, we have reason to think that they are far more numerous near land than in the open sea. In our own observations on the coasts of Scotland, this was invariably the case. Within eight or ten miles of land, they always appeared to become more numerous, and in harbours they were still more abundant. \Vith few exceptions, also, we found them in the greatest quantity and variety in narrow creeks, among rocks, or under high cliffs, where the water was sheltered from the sea and wind, and when, at the same time, it was least disturbed. A large proportion of them seemed in deed to be exclusively limited to situations of this nature, as we never observed them at all in the open sea, or at any considerable distances from the shore. Many of them also seemed peculiarly to affect those shallow and rocky places where sea-weeds abound. It was only at the end of the season, in which our principal observations were made, that we happened to be thus situated ; and we dis covered thus, in one day, as many species as we had found before in the course of a whole fortnight. Not to specify more minutely the places where these observations were made, we shall only say that they were confined to a few of the lochs on the west coast of Scotland, to one or two places on the coast, north of Inverness, and to some of the bays of Orkney and Shetland. These are the situations, then, and that chiefly in summer weather, and in calm seas, where the naturalist who may undertake this pursuit is most likely to meet with success.
Some of these species, however, seem utterly to disre gard boisterous weather ; while there were many, on the contrary, that almost invariably disappeared on the coming on of a fresh gale, and were only found again when the weather moderated. In the same manner, other changes of wind or weather, even when there was not a strong breeze, or perhaps no wind at all, caused them to disap pear entirely in the course of a few hours. It is probable that these animals, like the leech and many others, are highly sensible to atmospheric changes, and that they retire to the deeper water from some warning which they have of that which might be injurious to them ; probably to avoid that agitation, which, to many of the larger kinds, would be fatal from their tenderness and bulk. We have no doubt that many of them are destroyed, in bad weather, by the agitation of the sea at the surface. These hints, like the others, will be useful to the naturalist in his labours.
But, besides this, these remarks will serve to throw light on that part of the subject, which relates to the un certainty and the apparently capricious occurrence of the phosphorescence of the ocean. That this is very variable, is well known, even from day to day, or indeed from hour to hour, when we are sure that the animals cannot have had time to remove to any distance, and when we know that they were abundant but a short time before. Thus, when the sea has been quite dark, or sparingly luminous, or exhibiting only a few sparks, it will on a sudden be come bright and crowded with lights ; and, in a contrary manner, a bright sea will become dark, even though no change from calm to storm, or the reverse, should happen.
This, among others formerly enumerated, has been one of the causes which has served to mislead observers ; and which has induced them to imagine that the phosphorescent property belonged to the water, and that it was under the influence of the atmosphere. It has equally given rise to many of the prognostics relating to the weather, which, whether they are just or not, are the prophecies of living animals, and neither those of the water nor the air.
We already noticed that seamen were accustomed to draw their own prognostics from these appearances, and we then professed to disregard them as founded in erro neous views of the phosphorescence of sea water. \Ve have not, however, the least doubt that some true prog nostics might actually be drawn from such phenomena, provided all the collateral causes were duly considered, as may be done by studying the motions of leeches. But we are quite sure that the popular ones are unfounded ; while it is equally plain that many things must be considered. before we could hope to arrive at true conclusions on this subject. Thus the mere abundance of these animals at one time, and their absence at another, would, to an incau tious observer, seem to foretel the same changes as those which are indicated by their appearance at the surface, or by their retiring, or else by their showing or obscuring their light in consequence of other causes. It is from this last circumstance that is derived the erroneous opinion, that a very luminous state of the sea is the forerunner of bad weather. This, however, is a consequence of the mere agitation of the water, which always excites the luminous action of these animals ; so that a luminous sea is the concomitant, and not the forerunner, of an agitated one. So far indeed is the prognostic from being true, that it is by no means uncommon for the sea to be ex tremely brilliant in a calm, and to become dark at the ap proach of a gale of wind ; the animals retiring to the deeps, for the reasons stated above. But even in calm weather, and when we can ascertain that these animals are actually present, and that also in abundance, there is often no light to be seen ; another circumstance which has equally led to fallacious prognostics, as well as to unfounded opinions respecting the seat of the light. Very often we have found the water crowded, even with the large medusze, yet scarcely betraying themselves by an occasional twinkle, when the dash of an oar, or any accidental agitation, was sufficient to involve the whole water in a blaze of light. Many other circumstances already mentioned, as well as this, prove that the light is under the guidance of the animal's will ; and all our observations concur in confirm ing this opinion. We have often observed the usual loco motions performed by millions of these animals, of all kinds, for a whole night, without the slightest indication of their presence ; or perhaps some one individual might emit an occasional spark, when the least alarm excited, even by mere noise in some cases, was sufficient to render the whole luminous.