Structural and Physiological Botany and Vegetable Products,, Part H.- Descriptions of Southern Plants. Arranged on the Natural System. Preceded by a Linnaen and a Dichotomous Analysis. By Prof. John Darby, A. M. New York, Cincinnati and Savannah. 1855.

It is no part of the mission of the Horticulturist to enter extensively upon minute Botanical descriptions; but it has a duty to perform by keeping its readers informed regarding the sources of information, and with this view we notice with pleasure the appearance of Professor Darby's new and important work. It forms an admirable introduction to Botany; as such it is adapted and intended for the assistance of learners, and may safely and profitably be introduced into schools. Its descriptions and instructions are brief and clear, perhaps the most so of any work that has fallen under our notice, having the advantage, too, of being fully up to the knowledge of the present day on the subjects of which it treats; as an instance we refer to the chapters on Fertilization and Fruiting, which are treated of in a popular manner. Witness the following:

"The constitution of the fruit differs materially in its ripe from what it was in the green state. Water and lignine diminish, and sugar increases. Water diminishes from two to ten per cent. in different kinds; lignine generally in a greater proportion. Sugar increases in Currants from 0.52 to 6.25, it being twelve times the quantity in a ripe from what they possessed in a green state. This the remarkable changes in taste would lead us to suppose without analysis. In many cases we know that sugar is produced at the expense of starch, but no starch can be discovered in those fruits which generate the greatest amount of sugar, such as Currants, Apples, Peaches, etc. That it takes place at the expense of the other proximate principles, aided by water, is certain, since it goes on without any increase of weight, and even when separated from the parent stock, and also in the process of cooking. It is a well known fact in chemistry, that the action of various vegetable substances on each other, aided by moderate heat, will produce the saccharine principle. The vegetable acids, with gum and mucilage, will produce this effect.

These principles are contained in all succulent fruits, tartaric acid, malic acid, gum, and various other substances peculiar to each fruit The act of ripening, therefore, is a chemical process, which consists in converting the various unpleasant and injurious principles of the green fruit into the most nourishing and healthy of vegetable products.

Although the above conveys the general principles on which, we believe, the ripening of fruit proceeds, yet in some cases these substances from which we suppose the sugar to be formed increase at the same time; yet we believe that in all cases either the acid or the other principles diminish, and never both increase or remain stationary in the same fruit If the acid increases, the other principles diminish. If the other principles increase, the acid diminishes.

For these processes to go on, an atmosphere containing oxygen is necessary; showing that this active agent is required in these operations, and performs some necessary office in the conversion of the crude materials of green fruit into the palatable one of the ripe".

The chapter on "Germination" will reward an attentive perusal. We are embarrassed in selecting extracts, so uniformly interesting is the portion of the work which treats of Physiological Botany, but must be indulged with the following:

"The principal food of plants is water and carbonic acid and ammonia, which are received through the roots in a liquid state, and through the leaves in a gaseous form. Besides these various salts enter in a greater or less decree into the composition of vegetables.

To determine the food of plants, it is an important element in the investigation to know of what the plant is composed. This has been determined by various philosophers with great accuracy. The following is the constitution of some of the most common plants, taking 1000 parts of the dry vegetable:

Carbon.

Hydrogen.

Oxygen.

Nitrogen.

Ashes.

Wheat........................

455

57

430

35

23

Oats.......................

507

64

367

22

40

Peas.....................

465

61

401.

42

31

Turnips................

429

56

422

17

76

Potatoes....................

441

58

439

12

50

Quice a uniformity will be observed in these elements; about one half being carbon, less than half oxygen; about one-twentieth hydrogen, less than one-twentieth nitrogen, with a much greater variation in the ashes, which consist mostly of potash, silex, lime, sulphur, prosphorus, and some other elements in minute quantities.

The first four elements are called organic elements, or organogens ; the materials of the ashes, inorganic elements. The most abundant element is carbon, and no organic product exists without it, although either of the others may be absent.

The plant derives its carbon from carbonic acid, C02. It cannot take up carbon in an uncombined state, as it is solid, and it can obtain it from no other compound of carbon, as no other exists in sufficient quantities. The carbonic acid in the air, the result of respiration of animals, the combustion of wood and coal, and the decay of carbonaceous substances, and that contained in the soil from the action of manure, affords the plant its carbon. It is chiefly derived from the air. Numerous facts prove this position. Originally, before there was any vegetation, there could have been carbonic acid nowhere else. Plants grow in the sir and deposit carbon. The growth of plants increases the carbonaceous matter in the soil where they grow. Plants will grow and increase in carbon in distilled water. These well-known facts prove that carbonic acid in the atmosphere supplies most of the carbon to plants".

The following carious table will interest many of the readers of the Horticulturist:

"Schubler and Kohler have made many interesting observations on odors as well as colors. They found that, of the various colors of flowers, some are more commonly odoriferous than others, and that some colors are more commonly agreeable than others.

Color.

No. of species.

Odoriferous.

Agreeable.

Disagreeable.

White . - -

1193

187

175

12

Yellow -

951

75

61

14

Red -

923

85

76

9

Blue ....

594

31

23

7

Violet

307

23

17

6

Green

153

12

10

2

Orange ...

50

8

1

2

Brown- - - -

18

1

0

1

The white most odoriferous and agreeable, the yellow and brown most disagreeable." We could profitably employ many pages with further extracts, did not imperative demands on our space prevent. The portion of country especially included in this most valuable Flora, which occupies a large portion of Professor Darby's laborious work, is from latitude 30° to 35° north, longitude 80° to 90° west from London, including South Carolina, Georgia, Alabama, and parts of North Carolina, Florida, and Mississippi - a section of country of the highest interest to the Botanist. It will answer as a text-book equally for all the Southern States, including as it does four great Botanical regions: the mountainous regions of the north, the coast region on the east, the partially tropical region on the south, and the upland or plane region of the middle portion. In short, no more important manual can be recommended to the lover of information and the seeker after knowledge in this department of natural history.