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the fluid, the secretion of the appendices pylorica-the testpaper being applied to any one of those tubes after having been divided transversely, when a little liquid commonly exuded.

In connection with these observations, I have made a few on a subject nearly allied to them, viz. the action of the gastric juice, and of the other fluids supposed to be concerned in digestion after death, on the secreting organs and parts adjoining them, an action first observed and described by John Hunter in the instance of the human stomach.

In the common trout, the stomach of which is so rarely without food or without a free acid, indications of the action in question must be familiar to every angler in the habit of opening the fish he takes. According to what I have observed, several hours commonly intervene between the capture of the fish and the witnessing the effects, varying as to time with the temperature of the air and other circumstances of a less appreciable kind. The organs or parts most liable to suffer I have found to be not the stomach itself, but the parieties of the ribs on the side contiguous to the appendices pylorica and the upper portion of the intestinal canal. These bones have been seen bare and projecting internally, with softening, and often a breach of the intestine, and yet the stomach, at the time, has been little changed-softened only in a slight degree. The only instances that I can recall to mind of its having been partially dissolved and ruptured have been of young fish, especially the young of the salmon, the parr, taken at a season when they were feeding greedily.

These remarks on the trout are applicable to the charr and the grayling; in fish of each kind I have witnessed effects similar to the preceding.

The observations I have made on the salmon and sea trout, in relation to this action, have been fewer than I could wish; and it has so happened that they have been confined to those the stomachs of which were empty, and showed no acid reaction. In all but one, no post mortem effect was perceived; it was one of seven sea trout taken on the 10th September, and opened on the following day. In this exceptional one, the bones contiguous to the appendices pylorice were par

NEW SERIES.-VOL XI. NO. II.-APRIL 1860.

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tially laid bare, as if from solution of their covering. Neither in the stomach of this fish nor of the other six was there any food found, or any traces of acidity. I may mention the results of a comparative experiment made with the common trout and the sea trout, showing the marked difference of effect in the two instances. The subjects of the trial were a trout of the common kind, from the river Rothay, of about half a pound, and a sea trout from Maryport of three pounds. After a ligature had been applied to the gullet and also to the lower portion of the intestine of each, the viscera of both were taken out, and placed in a glass vessel and covered. The temperature of the air was little variable, about 65°. After twenty-four hours an examination was made. In the stomach of the common trout, pultaceous food was found with an acid reaction; its coats were but slightly softened; the intestine was reduced to a shreddy state, most remarkable in its upper portion, and its contents had escaped; these showed an alkaline reaction. The stomach of the sea trout was empty, with the exception of a little adhering milk white mucus, as were also the intestines, with the exception of a little yellow slime. The stomach was neutral; the intestine slightly alkaline. Neither exhibited any appearance of softening.

As some of the conclusions deducible from the preceding observations, I would beg to submit the following for consideration :

1. That the gastric juice, and probably the other fluids concerned in the function of digestion in fishes, are not secreted till the secreting organs are stimulated by the presence of food-a conclusion in harmony with a pretty general physiological law, and in accordance with what has been best ascertained respecting the gastric juice in other animals.

2. The probability that the gastric fluid-a fluid with an acid reaction-is less potent in the instance of fishes as a solvent than the alkaline fluid of the appendices pyloricæ ; and that even as regards the gastric fluid, its acidity is not essential to it, as its action does not appear to be arrested when it is neutralised by the presence of articles of food abounding in carbonate of lime.

Lastly, as a corollary from the first, may it not be inferred

that the migratory species of the salmonidæ, such as the salmon and sea trout, which attain their growth and become in high condition in the sea, there abundantly feeding and accumulating adipose matter, though not always abstaining in fresh water, which they enter for the purpose of breeding, are at least capable of long abstinence there without materially suffering? And may not this be owing to none of their secretions or excretions, with the exception of the milt of the male and the roe of the female, being of an exhausting kind? And, further, owing to the empty and collapsed state of the stomach and intestines, are they not, when captured, less subject to putrefaction, and thus better adapted to become the food of man ?

REVIEWS AND NOTICES OF BOOKS.

The Plant-Covering of the Earth; a Popular Exhibition of Botanical Geography for Well-informed Lovers of Nature, composed from the Newest Sources. By LUDWIG RUDOLPH.*

Die Pflanzendecke der Erde Populäre Darstellung der Pflanzengeographie für gebildete Naturfreunde nach den neuesten und besten Quellen zasammengestellt und bearbeitet VON LUDWIG RUDOLPH, Zweite vermehrte Ausgabe. Berlin: Nicolaische Verlagshandlung (G. Parthey)

1859.

Geographical botany, phyto-geography, or plant-geography, is the systematic arrangement of all facts connected with the mutual action and reaction between the vegetable covering of the globe and meteorological agencies, together with the modifications effected by man for the purposes of agriculture and horticulture, so as to affect the aspects of nature on a large scale. Hence it appears, that plant-geography is an important part of physical geography farther developed on account of its influence upon the weal, the woe, and the enjoyment of man.

If we attempt to assign to phyto-geography its right position

*This Review has been transmitted by a foreign correspondent, and hence there is some peculiarity in the idiom.-Ed. Phil. Jour.

in relation to the totality of sciences, we are led to the following considerations :

Science is the organic system of cognate truths, and philosophy is the organic system of all sciences. Hence it appears, that philosophy, strictly so called, cannot logically be co-ordinated to other sciences, since they are all contained in the idea of philosophy, to which they must be logically subordinated. This subordination may be effected in various ways, and it may assume different forms, e.g., the following :

All sciences are either formal or material: formal, if they consist entirely in the right conformation of thought; material, if they require, in addition, the correct observation of facts. The formal sciences do not contain the ideas of any given substance, matter, existence, or facts placed externally to the thinking mind; consequently the formal sciences may be called in preference demonstrative sciences, or sciences of hypothetical necessity, because they show that if one truth is admitted, other truths must necessarily follow. Logic and mathematics are formal sciences. The fundamental idea of logic is mental congruity, and the fundamental idea of mathematics is quantity, either numerical or continuous. Numerical quantity is the fundamental idea of arithmetic, and continuous quantity that of geometry.

In contradistinction to the formal sciences are the materialobserving, or monstrative sciences, in which all demonstration is more or less ased upon stubborn facts. These facts may be either transitory or continuous. Transitory facts are the basis of political history and biography, which never relate two facts in every respect alike. Natural history is based upon continuous facts, because it relates what continuously may be observed.

Political history and biography are related to natural history and the description of natural objects, as arithmetic to geometry. In history and biography, the dates are numerical. So in arithmetic the quantities are numerical. In natural history the dates are continuous; and so are the quantities in geometry. The events to which natural history refer are not regarded as past, but as continually present.

Natural history, in its widest sense, embraces the universe, and may be divided, according to its objects, into the branch relating to the cosmic bodies above the earth, i. e., astronomy, and into the branch relating to the earth, i. e., geography. Both branches may be divided into the observing and the calculating, which latter arises from the application of mathematical considerations to either astronomical or geographical observation. Geography may again be subdivided according to its objects, which may be inorganic (mineral), or organic (animal or vegetable). In this case we have phyto-geography, describing the plant-covering of the globe in its largest features.

In plant-geography we expect to find the following materials: First, A description of those plants which, by their massive forms, or by the frequency of their occurrence, give character to the countries; and Second, A description of the countries themselves, according to their botanical characteristics. As to the plants, they may be either of spontaneous growth, or spread by the cultivation of man.

Those of spontaneous growth are, for example, the forest-trees, with large leaves; the myrtaceous and other evergreens; the coniferous trees; the heaths, mimosas, ferns, palms, agaves, bromeliaceæ, pandanus, musæ, cannæ, gramineæ, cactus, liliaccæ, climbers, loranthaceæ, pothos, orchis, mosses, and lichens.

The cultivated plants to be considered are those which furnish food, raiment, and luxuries: plants of nourishment are Cerealia, such as wheat, rye, barley, oats, rice, maize, sorghum, panicum or millet, and buckwheat. Or tubers and roots, as mangold, potatoes, arums, turnips, carrots, cassava, batatas, yams. Or fruit-trees, like the breadfruit, coco-nut, date-palm, sagopalm, oil-palm, olive, mulberry, chestnut, and many others. Or plants yielding luxuries and medicines, as the vine, sugar-cane, coffee, tea, pepper, indigo, tobacco, opium-poppy, catechu, and gambir. Or raiment, like flax and cotton.

In describing the physiognomy of the countries, the following botanical zones have been adopted: 1. The equatorial zone; 2. The tropical zones, north and south; 3. The sub-tropical, north and south; 4. The warm temperate; 5. The cold temperate; 6. The sub-arctic; 7. The arctic; 8. The polar zones. These divisions are to be subdivided according to the various quarters of the globe, Europe, Asia, Africa, America, and Australia, Mr Rudolph has followed the plan here detailed.

Linnæus, in his Flora Lapponica, 1737; his Flora Suecica, 1745; and in his Coloniæ Plantarum, Amanitates Academica, vol. viii., p. 1; and Gmelin, in the preface to his Flora Sibirica, may be considered the first authors before Humboldt, who, by their observations, introduced, or at least foreshadowed, the study of phyto-geography. Mr Rudolph does not mention these early originators of the eighteenth century.

But the merits of Alexander von Humboldt are so great, that they need not to be enhanced by concealing or forgetting what Carolus a Linne taught half a century before him, viz. :-Sapientissimus creator, qui globum convestivit terraqueum plantis diversissimis, iisque prope modum innumeris, has pro suâ etiam stupendâ ac admirabili œconomiâ, modo usque singulari disposuit, ut unaquæque amoenissimæ hujus cohortis in suâ tanquam patriâ habitaret, loco ipsi adsignato. Sic nimirum India plurimas acceperunt Palmas; temperati coeli regiones Herbas inprimis; septentrionales moderate Graminum multitudinem; frigida

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