4 VEGETABLE PHYSIOLOGY 



cell-membrane can also be observed in certain peculiar 

 fungi, which are to be found creeping over moist surfaces 

 without such appendages (fig. 4). These are known as 

 the slime-fungi or Myxomycetes. In many respects they 

 approach very near to one of the humblest animals, the 

 Amoeba. They have hardly any structure, appearing like 

 a lump of transparent jelly, the whole mass being called a 

 plasmodium. They have the power of extruding a certain 

 portion of their substance in the form of a blunt protrusion 



FIG. 4. PORTION OF A PLASMODIUM OF A Myxomycete. x 300. 

 (After De Bary.) 



known as a pseudopodium, and by means of these pseudo- 

 podia they can creep slowly over the surface on which they 

 are lying. The naked condition is, however, exceptional in 

 plants. In most of those which are unicellular the 

 living substance is covered by a delicate membrane or 

 cell-wall, and it may either fill the space inside the latter, 

 or may have in its interior a cavity or vacuole, which is 

 filled with a watery fluid. In the multicellular plants each 

 chamber during life contains its own protoplast or little mass 

 of protoplasm, whichjis connected, as already mentioned, 



