PS.OTOPEYTA. 



123 





is presented by some of the members of this group, viz. by 

 the formation of spores (Fig. 233). 



156. As representatives of this division (Protophyta), 

 the Myxomycetes, or Slime-Moulds, are the most re- 

 markable. During their growing, or vegetative stage, they 

 consist of a homogeneous mass of colored (but never green) 

 protoplasm, which has received the name o( plasmodium. 

 There is no cell-wall ; there is a streaming or circulation in 

 the mass of protoplasm, and the latter can, by constant 

 change of form, move slowly around on the damp decaying 

 wood, or vegetable mould, 

 where these plants are 

 often to be met with. In 

 their vegetative state they 

 are so much like the 

 lower animals {Monera) 

 that they were, for a long 

 time, considered as belong- 

 ing to the animal king- 

 dom. If they are brought 233 

 to rest by absence of proper moisture and temperature, they 

 become changed into rounded masses, and secrete a cellu- 

 lose wall. This is called the sderoiium stage. Upon re- 

 turn of suitable conditions, the plasmodium form is again 

 assumed. The reproductive stage is also one of rest ; the 

 mass becomes compact, heaped up into definite shapes (Fig. 

 233, J) surrounded by cellulose; the protoplasm within 

 becomes separated into multitudes of spores (Fig. 233, F), 

 which, in many species, are commingled with an irregular 

 net-work of (often ornamented) filaments, called the eapU- 

 liiium (Fig. 233, III, IV). Under proper conditions the 



Fig. 23.1, Arcyria pom{/ori}us,2^ Slime- llnuld ; c, capiUitium ; j^, sporangium ; 

 /, plant, natural size; //and ///, magnified sixteen diometets ; IV, capiUitium; 

 V, spores, more highly magniiied. 



