THE MYCETOZOA 



INTRODUCTION 



The Mycetozoa, Myxomycetes, or Slime-Molds, as they are 

 variously named, are an interesting group of organisms that have 

 both animal and vegetable characteristics, yet are not definitely 

 intermediate. They produce fruiting bodies with spores, which 

 resemble certain fungous growths, and the formative processes of 

 these bodies are similar to those of some of the fungi. The spores 

 when wetted, however, germinate into small amoeboid bodies 

 which develop flagella, move, feed, and multiply by division, and 

 are regarded by zoologists as Protozoa. After some transforma- 

 tions, they fuse in great numbers into a mass of naked protoplasm, 

 with many nuclei, called the plasmodium. The plasmodium 

 moves by extending pseudopodia in the direction of its movement, 

 feeds on bacteria and other organic material, and increases in size 

 by the division of the nuclei. It may grow to a size of several 

 feet across, functions somewhat like a giant amoeba, and is re- 

 garded by many as an animal. The plasmodia vary in color and 

 size in different species, and are sometimes confined to a particular 

 habitat; otherwise, there is no way of differentiating between 

 various plasmodia. This vegetative phase, as it is called, may 

 continue for weeks or months, until the time arrives — depending 

 on several factors — when the plasmodium must go into fruit in 

 order to perpetuate the organism. It then emerges from its 

 habitat (wood or ground) and by changes which closely resemble 

 fungous processes produces fruiting bodies which simulate vege- 

 table growths, but which perform no further living functions, and 

 are dead except for the germ of life contained in each individual 

 spore. The process occurs usually at night, and in the morning 

 the area close to the last position of the plasmodium is covered by 

 the sporangia or fruiting bodies, often in great numbers. The life 

 cycle is then repeated through the germination of the spores. 



The unprotected plasmodium is delicate and subject to destruc- 

 tion in dry or cold weather. Under such conditions, the mass 

 may transform itself into a hard, brittle substance, known as 

 sclerotium, which is inactive, but which will revive with warmth 

 and water. In this condition, plasmodia will survive the winter 

 months or other unfavorable periods. 



The fruiting bodies, excepting in one species which produces 



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