CHAPTER VI 

 DIVISION 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. This 

 Division is not a natural one in that some of the subdivisions are 

 not related so far as we know. Several of the groups represent 

 distinct lines of development and they are placed together 

 simply because they are all simple forms of plant life. So it is 

 impossible 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 Thallo- 

 phyta may be divided into five subdivisions: (i) Myxomycetes 

 or Slime Moulds; (2) Schizophyta or Bacteria and Blue green 

 Algae; (3) Diatomeae or Diatoms; (4) Euphyceae or Algae; 

 (5) Eumycetes or Fungi. 



Subdivision i. 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 



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