Part 2 (1/2)

[Illustration: FIG 6--Blue-green slime (_Oscillaria_) _A_, le filament, 300 _C_, a piece of a filament that has become separated _s_, sheath, 300]

As a representative of the group, ill select one of the coreen slireen or blackish sliish water, in watering troughs, on damp rocks, or even on moist earth A search in the places mentioned can hardly 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 tie of the mass will show nureen color, radiating in all directions fro 6, _a_) The filaments are the individual plants, and possess considerable power ofthe mass remain undisturbed for a day or two, at the end of which time they will have formed a thin film over the surface of the vessel in which they are kept; and the radiating arrangement of the filaments can then be plainly seen

If the ht blue stain, due to the blue pigment in the cells of the fila a quantity of the dried plants, and pouring water over theed with a decided blue If now the water containing the blue pigment is filtered, and the residue treated with alcohol, the latter will extract the chlorophyll, becoreen

The microscope shows that the filale rows of short cylindrical cells of uniform diameter, except at the end of the filament, where they usually become somewhat smaller, so that the tip is more or less distinctly pointed The protoplash it, and is colored uniforreen No nucleus can be seen

If the filaenerally be detected a delicate, colorless sheath that surrounds it, and extends beyond the end cells (Fig 6, _c_) The fila division, this always taking place at right angles to the axis of the filament New fila into a nurows to full size

The naing movements that the plant exhibits Thefrom side to side, combined with a rotary motion of the free ends of the filaether like the strands of a rope If the filaments are entirely free, theymovement Just how these movements are caused is still a matter of controversy

The lowest of the _Cyanophyceae_ are strictly single-celled, separating as soon as for usually in inous substance that surrounds theher ones are filaments, in which there may be considerable differentiation These often occur injelly-like lu 7, _A_, _B_) They are soround, but more commonly attached to plants, stones, etc, in water The reen, and in size from that of a pin head to several centimetres in diameter

[Illustration: FIG 7--Forms of _Cyanophyceae_ _A_, _Nostoc_ _B_, _Glotrichia_, 1 _C_, individual of _Glotrichia_ _D_, Chroococcus _E_, _Nostoc_ _F_, Oscillaria _G_, _H_, _Tolypothrix_

All 300 _y_, heterocyst _sp_ spore]

In the higher forms special cells called heterocysts are found They are colorless, or light yellowish, regularly disposed; but their function is not known Besides these, certain cells beco cells (spores) for the propagation of the plant (Fig 7, C _sp_) In species where the sheath of the filaroups of cells slip out of the sheath, and develop a new one, thus giving rise to a new plant

The bacteria (_Schizo to their excessive inner They reseeneral structure and reen slimes, but are, with very few exceptions, destitute of chlorophyll, although often possessing bright pigments,--blue, violet, 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 war on, and are theents of decay, which is the result of their feeding upon the substance, as, like all plants without chlorophyll, they require organic matter for food Most of the species are very tenacious of life, and , and on being placed in water will quickly revive Being so extremely small, they are readily carried about in the air in their dried-up condition, and thus fall upon exposed bodies, setting up decomposition if the conditions are favorable

A si two test tubes and partly filling theanic substance (dried leaves or hay, or a bit of meat will answer) The fluid should now be boiled so as to kill any germs that may 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 closed vessel will reed indefinitely; but the other will soon becoiven off Microscopic exaer with various forms of bacteria

[Illustration: FIG 8--Bacteria]

These little organisms have of late years attracted the attention of very many scientists, froious diseases The germs of many such diseases have been isolated, and experiments prove beyond doubt that these are alone the causes of the diseases in question

If a drop of water containing bacteria is examined, we find them to be excessively sest lenses The larger ones (Fig 8) recall quite strongly the smaller species of oscillaria, and exhibit similar movements Others are so sest lenses A, rod-shaped or thread-shaped filaht or curved, or even spirally twisted Frequently they show a quick movement which is probably in all cases due to cilia, which are, however, too small to be seen in lena_ _A_, individual in the active condition _E_, the red ”eye-spot” _c_, flagellu, 300]

Reproduction is for the most part by simple transverse division, as in oscillaria; but occasionally spores are produced also

CLass III--GREEN MONADS (_Volvocineae_)

This group of the protophytes is unquestionably closely related to certain low aniellata_), hich they are so actively motile, and are either strictly unicellular, or the cells are united by a gelatinous envelope into a colony of definite for 9), anisae, and occasionally forarded as a plant, soated, someore its form to some extent The protoplasreen 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 iodine solution, which often will render the flagellu invisible while the cell is in motion The cells ellum is withdrawn, and a fir 9, _B_) The contents then divide into two or more parts, which afterwards escape as new individuals

Of the forms that are united in colonies[2] one of the best known is _Volvox_ (Fig 10) This plant is sometimes found in quiet water, 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 for some time in aquaria, and will sometimes multiply rapidly, but are very susceptible to extremes of temperature, especially of heat

[2] The term ”colony” is, perhaps, inappropriate, as the whole le one, and may properly be looked upon as an individual plant

[Illustration: FIG 10--_Volvox_ _A_,several s the cilia, 300]

The colony (Fig 10, _A_) is a hollow sphere, the nule layer on the outside