THALLOPHYTA 



SUB-DIVISION A, :^IYXOMYCET^ 



33 



The slime-moulds are sticky masses frequently occurring on 

 decaying logs and leaves in a forest. They so combine the 

 characters of plants and animals as to make it doubtful with 

 which they should be classed. They live upon decaying organic 

 matter, have active locomotion, and possess no chlorophyl, but 

 they are terrestrial (sub-aerial) in habit and reproduce by spores 

 which are very much like those of certain fungi. They possess 

 no parts capable of preservation after death, and are not known 

 in the fossil state. 



SUB-DIVISION B, SCHIZOPHYTA 



One-celled plants reproducing by simple division into two more 

 or less equal parts, hence called fission-plants. They are sub- 

 divided as follows, — 



1. Bacteria. ^One-celled plants, jo^^o^ inch or less in dia- 

 meter. These are of great economic importance as agents of 

 fermentation, decay and disease ; they are now the chief agents 

 in the decomposition of organic matter and unquestionably 

 were similarly active in disintegrating the dead vegetation of 

 past ages, as is indicated by fossil evidence. Certain fossilized 

 plant tissues of the Pennsylvania coal-beds show a destruction 

 of cell w^alls which has been ascribed to this cause. But for their 

 activity it is probable that ancient plant and animal remains 

 would have been preserved in greater abundance. 



2. Blue-green algae. — Unicellular plants, occurring in slimy 

 masses in the presence of damp, decaying organic matter. When 

 present in enormous numbers they often produce a discolora- 

 tion of the water, as in the Red Sea. Some are lime-secreting 

 and thus are important as rock builders. To their agency, for 

 example, is due the formation of oolite grains on the shores of 

 the Great Salt Lake, the Red Sea, and elsewhere ; these grains 

 are blow^n landward into dunes and thus form continental 

 depasits, Oscillatoria is a blue-green alga which is one of the 



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