.THE SLIME-MOULDS. . 6 1 



Fig. 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 puflf-balls (Gastromycetes). How 

 ever, the characteristic cellular threads, or 

 hypha;, of a real fungus do not arise from 

 the germinal corpuscles, or spores, of the Myxomycetes, but 

 mei'ely naked masses of plasma, or cells, which at first swim 

 about in the form of Flagellata (Fig. 11), afterwards creep 

 about like the Amcebse (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-bj^, 

 the bladder-shaped fruit-body. Many of my readers prob- 

 ably know one of these plasmodia, the .^thalium septicum, 

 which in summer forms a beautiful yellow mass of solt 

 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-creeping Myxomycetes, 

 which live for the most part in damp forests, upon decaying 

 vegetable substances, bark of tx'ees, etc., are with equal justice 

 or injustice declai-ed 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 Ray-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 



