354 VEGETABLE PHYSIOLOGY 
and not excited by any stimulation from without. The 
phenomenon is often spoken of as ciliary motion. 
Of a somewhat similar character is the curious creeping 
movement of the Myxomycetous Fungi. In a few cases the 
zoospores of these organisms are furnished with cilia or 
flagella, resembling those of the zoospores already men- 
tioned, but more frequently each consists of a minute mass 
of naked protoplasm, which makes its way over the 
surface of its substratum by putting out blunt processes 
of its own substance, known as pseudopodia (fig. 148). 
Fig. 148.—Staces in ConsTRUCTION OF THE PLASMODIUM OF a 
Myxomycete, 
After a while a number of these zoospores become fused 
together to form a large jelly-like mass, known as a 
plasmodium. This colony of protoplasts then makes its 
way slowly over its substratum by similar pseudopodial 
movements. Hach pseudopodium is a protrusion of .the 
ectoplasm, and the more fluid endoplasm is in some way 
drawn into the different protrusions, so that the rest of 
the cell or of the plasmodium follows the extension of the 
pseudopodium and is dragged after it. Which part of 
the operation corresponds to the act of contraction is 
disputed, but it seems probable that it is the second, and 
that the first protrusion is of the nature rather of relaxa- 
tion, The movement, like that of ciliary action, is a 
