Elements of Structural and Systematic Botany

ur knowledge of many forms is still very imperfect, any classification we may adopt must be to a great extent onl

cepted: I. Sub-kingdom (or Branch); II. Class;

gs. The gymnosperms may be further divided into several subordinate groups (orders), one of which, the conifers, or cone-bearing evergreens, includes our plant. This order includes several families, among them the fir family (Abietine?), including the pines and firs. Of the sub-divisions (genera, sing. genus) of the fir family, one of the most familiar is the genus Pinus, which embraces all the true pines.

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and resemble so remarkably certain low forms of animal life as to be quite indistinguishable from them, at least in certain stages. Indeed, there are certain forms that are quite as muc

up of spore cases of a slime mould (Trichia), of about the natural size. E, two spore cases, × 5. The one at the right has begun to open. F, a thread (capillitium) and spores of Trichia, × 50. G, spores. H, e

vegetable nature, are nevertheless very diffe

es: I. The slime moulds (Myxomycetes); II. The

-The Sli

eness toward light. The plasmodium, as the mass of protoplasm is called, may be made to creep upon a slide in the following way: A tumbler is filled with water and placed in a saucer filled with sand. A strip of blotting paper about the width of the slide is now placed with one end in the water, the other hanging over the edge of the glass and against one side of a slide, which is thus held upright, but must not be allowed to touch the side of the tumbler. The strip of blotting paper sucks up the water, which flows slowly down the surface of the slide in contact with the blotting paper. If now a bit of the substance upon which the plasmodium is growing is placed against th

In one common form (Trichia) these are round or pear-shaped bodies of a yellow color, and about as big as a pin head (Fig. 5, D), occurring in groups on rotten logs in damp woods. Others are stalked (Arcyria, Stemon

processes which differ much in different species. The fibres also differ much in different genera. Sometimes they are simple, ha

protoplasm (Zo?spore) with a nucleus, and often showing a vacuole (Fig. 5, v), that alternately becomes much distended, and then disappears entirely. On first escaping it is usually provided with a long, whip-like filament of protoplasm, which is in active movement, and by means of which the cell swims acti

r of these am?ba-like cells run together, coalescing when they come in contact, and for

pores transferred to this drop with a needle previously heated. By these precautions foreign germs will be avoided, which otherwise may interfere seriously with the growth of the young slime moulds. After sowing the spores in the drop of culture fluid, the whole should be inverted over a so-called "moist chamber." This is simply a square of thick blotting paper, in which an opening is cut small enough to be entirely covered by the cover glass, but large enough so that the drop in the centre of the cover glass will not touch the sides of the chamber, b

I.-Schi

ly almost entirely by simple transverse division, or splitting of the cells, whence their name. There are two pretty well-marked orders,-the blue-green slimes (Cyanophyce?) and the bacter

possessing, in addition to the ordinary green pigment (chlorophyll, or leaf-green), another c

of the natural size. B, single filament, × 300. C, a piece

y fail to secure plenty of specimens for study. If a bit of the slimy mass is transferred to a china dish, or placed with considerable water on a piece of stiff paper, after a short time the edge of the mass will show numerous extremely fine filaments of a dark blue-green color, radiating in all directions from the mass (Fig. 6, a). T

so be extracted by pulverizing a quantity of the dried plants, and pouring water over them, the water soon becoming tinged with a decided blue. If now the wa

eter, except at the end of the filament, where they usually become somewhat smaller, so that the tip is more or less distinctly pointed. The

ig. 6, c). The filament increases in length by the individual cells undergoing division, this always taking place at right angles to the axis

side, combined with a rotary motion of the free ends of the filaments, which are often twisted together like the strands of a rope. If the filaments are en

as soon as formed, but cohering usually in masses or colonies by me

ke lumps, which may be soft or quite firm (Fig. 7, A, B). They are sometimes found on damp ground, but more commonly attached to plants, stones, etc.

, individual of Gl?otrichia. D, Chro?coccus. E, Nostoc. F, Osci

own. Besides these, certain cells become thick-walled, and form resting cells (spores) for the propagation of the plant (Fig. 7, C. sp.). In species whe

let, red, etc. It is one of these that sometimes forms blood-red spots in flour paste or bits of bread that have been kept very moist and warm. They are universally present where decomposition is going on, and are themselves the principal agents of decay, which is the result of their feeding upon the substance, as, like all plants without chlorophyll, they require org

8.-Ba

y be in it; and while hot, one of the vessels should be securely stopped up with a plug of cotton wool, and the other left open. The cotton prevents access of all solid particles, but allows the air to enter. If proper care has been taken, the infusion in the clo

t that to them is due many, if not all, contagious diseases. The germs of many such diseases have been

oscillaria, and exhibit similar movements. Others are so small as to appear as mere lines and dots, even with the strongest lenses. Among the common forms are small, nearly globular cells; oblong, rod-shaped or th

ion. E, the red "eye-spot." c, flagellum. n, nucleu

le transverse division, as in oscillaria;

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ata), with which they are sometimes united. They are characterized by being actively motile, and are eith

uglena (Fig. 9), may

in color; but the forward pointed end of the cell is colorless, and has a little depression. At this end there is a long vibratile protoplasmic filament (c), by means of which the cell moves. There is also to be seen near this end a red speck (e) which is probably sensitive to light. A nucleus can usually be seen if the cell is first killed with an

taining several smaller ones (x), × 50

, where it floats on or near the surface as a dark green ball, just large enough to be seen with the naked eye. They may be kept fo

to be somewhat pear-shaped (Fig. B), with the pointed end out. Attached to this end are two vibratile filaments (cilia or flagella), and the united movements of these cause the rolling motion of the

t found in many higher plants; but as it only occurs at cert

forming a flat square; Pandorina and Eudorina, with sixteen cells, forming an oval or globular colony