138 



KINGDOMS MONERA AND PROTISTA: 



forms plant-like sporangia which later form spores. In 

 some circumstances the Plasmodium does not form 

 sporangia immediately. If food and/or moisture are 

 limited, a resting stage {sclerolium) is assumed until 

 the return of favorable conditions. 



Most slime molds feed upon dead and decaying 

 materials. Unfortunately, the forms are rarely ob- 

 served. These creatures are quite intricate and 

 beautiful, but to appreciate this fact one must first 

 recognize and know where to find them. They gen- 

 erally range from the size of a dime to that of a din- 

 ner plate. When growing, they appear slimy and 

 moldy to the naked eye. More specifically, they are 

 a naked mass of usually yellowish or whitish slimy 

 protoplasm that moves in a slow creeping motion. 

 Although such a description is unlikely to imply 

 much in the way of beauty, appropriate magnification 

 (in some cases even a hand lens) reveals an intricacy 

 of pattern that is pleasing to the eye. However, this 

 is neither the only nor the most pleasing structure of 

 these fungi. When dry, they tend to assume a lacy 

 pattern and have erect spore-producing structures 

 arising from this pattern. 



To find slime molds, one must look through dead, 

 preferably decaying, leaves and wood. An especially 

 likely site is the interior of a decaying, wet log. These 

 habitats are an indication of the most likely areas, 

 namely below the substrate, where these creatures 

 can be found. Their habitat is explained on the basis 

 of their lacking chlorophyll and any type of photo- 

 synthetic nutrition. Also, it appears that they shun 

 open areas because such situations would promote 

 more rapid drying of the unprotected plasmodium or 

 other stages. 



Structure: without organization into definite cells; 

 conspicuous phase vegetative (feeding but not re- 

 productive), typically a yellowish visible mass (plas- 

 modium), usually observed flowing slowly over a 

 substrate; produce spores in a definite sporangium or, 

 rarely, on other structures (Figure 8.9). 



Plasmodium is a multinucleate mass of protoplasm 

 containing contractile vacuoles and bounded by an 

 indistinguishable jelly-like covering that is instru- 

 mental in forming a slime trail; without photo- 

 synthetic pigments of any kind. 



Sporangia are 1/25 to 2/5 inch long; often stalked, 

 the stalks and sporangia are said to constitute fruit- 

 ing bodies. 



.Nutrition: holozoic, mostly ingesting bacteria, and 

 saprophytic on decaying vegetation. 



SLIME MOLDS 



Ceratiomyxa (X 10) 



Fuligo (X 1) 



Hemitnchia (X 10) 

 Sporangia Types (enlarged) 



Stemonitis (X 1) 



Figure 8.9 Representative slime molds, showing plosmodio with spo- 

 rangia or other spore-forming structures. 



Life cycle: typically with a sequence of stages (see 

 Figure 8.8). 



Occurrence: terrestrial in moist situations, mostly 

 in decaying vegetation (especially inside dead wood 

 or within dead surface leaves) or in the dung of 

 herbivorous animals; rarely seen upon the surface 

 except when approaching or within the sporangia- 

 bearing stage; also a few parasitic forms mostly 

 upon vascular plants but also algae and true fungi; 

 about 500 species. 



EUMYCOPHYTA (True Fungi) 



Fragmentary fossils imply the presence of the first 

 fungi some two billion years ago during the "Age of 

 Monera." The same fossils could include flagellates 

 but the remains do not definitely establish their 

 presence at that time. Therefore, fungi may be more 



