THE SLIME-MOULDS, 61 
Fic. 15.—A stalked fruit-body (spore-bladder, filled 
with spores) of one of the Myxomycetes (Physarum 
albipes) not much enlarged. 
roundish bladder, often several inches in 
size, filled with fine spore-dust and soft 
flakes (Fig. 15), as in the case of the well- 
| known puff-balls (Gastromycetes). How 
ever, the characteristic cellular threads, or 
hyphe, of a real fungus do not arise from 
the germinal corpuscles, or spores, of the Myxomycetes, but 
merely naked masses of plasma, or cells, which at first swim 
about in the form of Flagellata (Fig. 11), afterwards creep 
about like the Amcebe (Fig. 10 B), and finally combine 
with others of the same kind to form large masses of “slime,” 
or “plasmodia.” Out of these, again, there arises, by-and-by, 
the bladder-shaped fruit-body. Many of my readers prob- 
ably know one of these plasmodia, the Aithalium septicum, 
which in summer forms a beautiful yellow mass of soft 
mucus, often several feet in breadth, known by the name of 
“tan flowers,” and penetrates tan-heaps and tan-beds. At 
an early stage these slimy, freely-creepmg Myxomycetes, 
which live for the most part in damp forests, upon decaying 
vegetabie substances, bark of trees, etc., are with equal justice 
or injustice declared by zoologists to be animals, while in the 
mature, bladder-shaped condition of fructification they are 
by botanists defined as plants. 
The nature of the Iay-streamers (Rhizopoda), the eighth 
class of the kingdom Protista, is equally obscure. These 
remarkable organisms have peopled the sea from the most 
ancient times of the organic history of the earth, in an 
