104 PLANT MORPHOLOGY 



phyll, presence of cilia in some members, and character of the rest- 

 ing cell. 



2. MYXOMYCETES 



The Myxomycetes, or slime molds, are peculiar organisms that, like 

 the flagellates, are claimed by both botanists and zoologists, the latter 

 calling them Mycetozoa (fungus-animals). They are a widely dis- 

 tributed group, living in damp, shady places as saprophytes on humus, 

 decaying wood, bark, fallen leaves, etc. All lack chlorophyll. The 



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I 



Fig. 81. Plasmodium of Didymitim, a slime mold, X30. {From Gilbert M. Smith.) 



Myxomycetes number over 400 species. Some of the common genera 

 are Lycogala, Stemonitis, Fuligo, Arcyria, and Trichia. 



Plant Body. The vegetative body of a myxomycete is a Plasmodium, 

 which is a naked mass of multinucleate protoplasm (Fig. 81). The 

 nuclei, like those of the higher plants, are well organized. The Plas- 

 modium is without definite form and may attain a diameter of several 

 centimeters, or even a meter in some myxomycetes. The Plasmodium 

 moves by the formation of pseudopodia and engulfs solid particles of food 

 as it passes over them, digesting them within food vacuoles. In these 

 respects it resembles an amoeba. It also absorbs food material in solu- 

 tion through the plasma membrane. Depending on the species, the 

 Plasmodium may be white or some shade of yellow, orange, red, brown, 

 or violet. The Plasmodium tends to move toward moisture but shows an 

 avoiding reaction to light, appearing at the surface of its substratum 

 only at night. In times of drought it retracts itself into a waxy mass and 



