CHAPTER VI 



IVISION I. THALLOPHYTA 



60. Classification of the Thallophyta. — The Thallophyta com- 

 prise a multitude of plants that include the most primitive and 

 simple forms of vegetation upon the earth. They range in size 

 from single microscopic cells to forms that are comparable in 

 bulk to some of our shrubs and trees. They are all of simple 

 structure and do not possess roots, stems and leaves in the sense 

 of the seed plants. Such a type of plant body is called a thallus 

 and it assumes a variety of forms. The absorption and manu- 

 facture of foods is carried on, as a rule, by any and all of the 

 cells and this is equally true of the reproductive process. It 

 would be impossible, however, to give in a short space a general 

 idea of the nature and character of this division which includes 

 many groups of widely different forms. For the purpose of 

 study the Thallophyta may be divided into five subdivisions: — 

 (i) Myxomcyetes or Slime Moulds; (2) Schizophyta or Bacteria 

 and Blue green Algae; (3) Diatomeae or Diatoms; (4) Euphy- 

 ceae or Algae; (5) Eumycetes or Fungi. 



Subdivision 1. Myxomycetes or Slime Moulds 



61. The Life History of a Slime Mould. — In one stage of their 

 life the slime moulds have a motility and mode of feeding sug- 

 gestive of some of the lower animals, while on the other hand 

 the final stage of their existence is more suggestive of the fungi. 

 For this reason it has often been suggested that they are inter- 

 mediate between plant and animal life. These plants are widely 

 distributed over the earth and may frequently be found on de- 

 caying logs and rotting twigs and leaves in forests. A common 

 form, resembling a miniature, brownish puffball, is often seen on 

 stumps and fallen logs (Fig. 87). Other kinds are illustrated in 



Fig. 88. They range in size from scarcely a pin head to nearly 



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