16 BOTANY. 



If the mass is allowed to dry on the paper, it often leaves a 

 bright blue stain, due to the blue pigment in the cells of the 

 filament. This blue color can also 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 water containing the blue pigment is filtered, and the resi- 

 due treated with alcohol, the latter will extract the chlorophyll, 

 becoming colored of a yellow-green. 



The microscope shows that the filaments of which the mass is com- 

 posed (Fig. 6, B) are single 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 

 protoplasm of the cells has a few small granules scattered through it, and 

 is colored uniformly of a pale blue-green. No nucleus can be seen. 



If the filament is broken, there may generally be detected a delicate, 

 colorless sheath that surrounds it, and extends beyond the end cells 

 (Fig. 6, c) . The filament increases in length by the individual cells under- 

 going division,- this always taking place at right angles to the axis of the 

 filament. New filaments are produced simply by the older ones breaking 

 into a number of pieces, each of which rapidly grows to full size. 



The name " oscillaria " arises from the peculiar oscillating 

 or swinging movements that the plant exhibits. The most 

 marked movement is a swaying from side to 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 entirely free, they may often be observed to move 

 forward with a slow, creeping movement. Just how these 

 movements are caused is still a matter of controversy. 



The lowest of the Cyanophycece are strictly single-celled, sep- 

 arating as soon as formed, but cohering usually in masses or 

 colonies by means of a thick mucilaginous substance that sur- 

 rounds them (Fig. 7, Z>). 



The higher ones are filaments, in which there may be con- 

 siderable differentiation. These often occur in masses of con- 

 siderable size, forming jelly-like lumps, which may be soft or 

 quite firm (Fig. 7, A, B). Th*y are sometimes found on 



