873. A SYSTEM OF CLASSIFICATION IS SAID TO BE ARTIFICIAL WHEN, disregarding the real nature of the subjects classified, it rests merely on some obvious external circumstance. As when the books of a library are arranged on shelves according to their size, octavo, duodecimo, etc., or as when the words in a language are arranged in dictionaries, alphabetically, forming thu3 class A, class B, etc. In either case the books or the words constituting any group may be quite diverse in charactor, having nothing in common except their octavo size or initial letter. The only use of such an arrangement is convenience of reference.

874. Carl von Linne (Linnaeus) of Sweden, born in 1707, everywhere honored as the father of systematic and descriptive botany, was the author of that renowned artificial system which bears his name. For well nigh a century it continued in almost universal use, and was regarded by his followers with far more respect than by Linnaeus himself, who designed it simply as an index or clue to the vegetable kingdom. For ho says (Philosophia Botanica) "Methodi Naturalis fragmenta studio3e inquirenda sunt. Primum et ultimum hoc in Botanicis desideratum est."

875. Considered as a system, the Linnaean arrangement totally fails to exhibit those true relations and affinities of plants which render the knowledge of each kind a guide to that of the others, and combine all into one consistent whole. It can not, therefore, properly be regarded as a system.

876. Considered as an index or key to the vegetable kingdom, it is by no means reliable, for the stamens and styles often vary numerically in the same plant; and secondly, the species of the same genus often vary in these respects, thus obliging us to violate even specific affinities; and again, when the stamens or pistils are accidentally marred, or lost, or immature, the index must also fail of its purpose. For these reasons this arrangement has fallen into disuse, having been superseded by the Natural System, and by other arrangements better adapted to the present advanced state of the science. Yet being intimately connected with the history of botany, and having largely contributed to its early progress, its outlines at least demand a record in our pages.

877. The Linnaean System proposes to arrange all the known genera of plants under twenty-four classes, each based on some special character derived from the essential floral organs, as follows:

§ 1. The first thirteen classes comprehend all such plants as have their flowers all perfect, their stamens unconnected and and of equal length, or at least neither didynamous nor tetra-dynamous. Class I. Monandria,-one stamen to each flower (Saltwort, etc.). Class II. Diandria,-two stamens (Circaea, Veronica). Class III. Triandria,-three stamens (Iris. Nearly all the Grasses. Class IV. Tetrandria,-four stamens (Galium, Plantago). Class V. Pentandria,-five stamens (Vitis, Conium). Class VI. Hexandria.-six stamens (Lily, Tulip, Luzula). Class VII. Heptandria,-seven stamens (Trientalis). Class VIII. Octandria,-eight stamens (Erica, OEnothera). Class IX. Enneandria,-nine stamens (Rheum, Sassafras). Class X. Decandria,-ten stamens (Dianthus, Rhododendron). Class XI. Dodecandria,-twelve to nineteen stamens (Asarum). Class XII. Icosandria,-twenty or more stamens, perigynous (Rosa). Class XIII. Polyanjiria,-twenty or more stamens, hypogynous (Ranunculus, Papaver). § 2. The next two classes are founded on the relative length of the stamens, the flowers being perfect and stamens generally unconnected. Class XIV. Didynamia,-four stamens, two long and two short, by pairs, as in

Antirrhinum, Prunella. Class XV. Tetradynamia,-six stamens, four long and two short, as in the wall-flower and the Cruciferse generally. § 3. The next four classes are determined by the connection or union of the stamens. Class XVI. Monadelphia,-stamens united by their filaments into one set, as in Malva, Geranium. Class XVII. Diadelphia, - stamens united by their filaments into two sets

(Polygala, pea, Lathyrus). Class XVIII. Polyadelphia, - stamens united by their filaments into three or more sets (Hypericum). Class XIX. Syngenesia, stamens united by their anthers, as in the Asters and other Compositae. § 4. The next class depends for its character upon the adhesion of the stamens with the pistil. Class XX. Gynandria, - stamens and styles united, forming a column, as in Orchis, Asclepias. § 5. The next three classes include all plants with diclinous flowers, some with pistils, some with stamens only. Class XXI. Monoecia, - staminate and pistillate flowers, both upon the same plant (Pinus, Arum, Hazel). Class XXII. Dioecia, - staminate and pistillate flowers on separate plants (Wil low, Hemp, Hop, Smilax). Class XXIII. Polyoamia. - staminate, pistillate and perfect flowers either on the same or on different plants, as in Acer, Acacia, Veratrum). § 6. The last class includes flowerless plants.

Class XXIV. Cryptogamia, - plants in which the organs of fructification are concealed as the name implies) as in ferns, mosse3, seaweeds.

818. The Linnaean orders. Each class is subdivided into orders, and these also are founded on some condition of the essential organs. The orders of the first thirteen classes are determined by the number of styles (or stigmas when the styles are wanting) in each flower.

Order 1.

Monogyma,

1 style.

Order 2.

Digynia,

2 styles.

Order 3.

Trigynia,

3 styles.

Order 4.

Tetragynia,

4 styles,

Order 5.

Pentagynia,

5 styles.

Order 6.

Hexagynia,

6 styles.

Order 1.

Heptagynia,

1 styles.

Order 8.

Oetogynia,

8 styles.

Order 9.

Enneagynia,

9 styles.

Order 10.

Decagynia,

10 styles.

Order 11.

Dodecagynia,

12 styles.

Order 12.

Polygynia,

more than 12.

879. The orders of class XIV. depend upon their seed vessels. Order 1. Gymnospermia - Fruit four achenia, as in the Labiatae.

Order 2. Angiospermia - Fruit inclosing several seeds.

880. The orders of class XV. also depend on the fruit Order 1. Siliculosa - Fruit a sillicle, as in pepper-grass.

Order 2. Siliquosa - Fruit a silique as in wall-flower.

881. The orders of classes XVI., XVII, XVIII. are distinguished by the number of stamens and named like the first classes.

Order 1. Triandria - three stamens united by their filaments. Order 2. Pentandria - five stamens united by their filaments.

882. The orders of class XIX are five, as follows: Order 1. Equalis - Florets of the head all perfect (♀)•

Order 2. Superflua - Florets of the disk $♀, of the ray? . Order 3. Frustranea - Florets of the disk ♀, ray abortive. Order 4. Necessaria - Florets of the disk ♂,. of the ray ? . Order 5. Segregata - Each floret with a separate involucre.

883. The orders of classes XX., XXL, XXII. distinguished in the same way as the first thirteen, the XVI., XVII., XVIII. classes; as

Order 1. Monandria - one stamen. Order 2. Diandria - two stamens. Order 3. Triandria - three stamens, etc.

884. The orders of class XXIII. are founded on the position of the flowers relatively, thus:

Order 1. Monoecia - Flowers ♀, ♂, ♀ on the same plant (Acacia).

Order 2. Dicecia - Flowers ♀ on one plant, ♀, ♀, on another (Chamerops).

Order 3. Trioecia - Flowers ♀ , ♂, and? , each on separate plants.

885. The orders of class XXIV. are the same as in the Natural System, and can not be defined by a single character.

Order 1.

Felices,

ferns.

Order 2.

Musci,

mosses.

Order 3.

Hepaticae,

liverworts.

Order 4.

Lichens,

lichens.

Order 5,

Fungi,

mushrooms.

Order 6.

Algae,

seaweeds.