CLASSIFICATION OF PLANTS. 



15 



splitting of the cells, whence their name. There are two pretty 

 well-marked orders, the blue-green slimes (Cyanophycece) and 

 the bacteria (Schizomycetes) . They are distinguished, primarily, 

 by the first (with a very few exceptions) containing chlorophyll 

 (leaf -green), which is entirely absent from nearly all of the 

 latter. 



The blue-green slimes : These are, with few exceptions, green 

 plants of simple structure, but possessing, in addition to the 

 ordinary green pigment (chlorophyll, or leaf -green), another 

 coloring matter, soluble in water, and usually blue in color, 

 though sometimes yellowish or red. 



As a representative of the group, we will select one of the 

 commonest forms (Oscillaria) , known sometimes as green slime, 

 from forming a dark blue-green or blackish slimy coat over the 

 mud at the bottom of stagnant or sluggish 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 speci- 

 mens for study. If a bit of the slimy mass is transferred to 

 a china, dish, or placed with con- 

 siderable 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). The filaments are the in- 

 dividual plants, and possess con- 

 siderable power of motion, as is 

 shown by letting the mass re- 

 main 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. * 



FIG. G. Blue-green slime (Oscil- 

 laria). A, mass of filaments of 

 the natural size. B, single fila- 

 ment, x 300. C, a piece of a fila- 

 ment that has become separated. 

 s, sheath, x 300. 



