MORPHOLOGY 



regarded as plants or animals. Those who incline to the view that they 

 are animals use the term Mycetozoa (fungus animals) for the group. It 

 should not be surprising to find at the lower confines of the plant and 

 animal kingdoms organisms which do not appear to belong to either. 



The lowest slime molds are aquatic, but most of them are terrestrial, 

 being common in forests on humous soil, decapng wood, fallen leaves, 

 etc., and one of the largest occurs on spent tan bark. The body contains 

 no chlorophyll, and this fact has induced many to regard slime molds 

 as fungi. The absence of chlorophyll means inability to manufacture 

 food, and hence a dependent habit, slime molds being for the most part 

 saprophytes (see p. 6i). 



Plant body. — The characteristic body is called the Plasmodium, 

 which is a naked mass of protoplasm (the living substance) with a 



creeping motion, putting out and 

 withdrawing regions of its body 

 (pseudopodia) like a gigantic amoeba 

 (see p. 444). This slimy body is 

 for a time very sensitive to light, in 

 the case of the slime mold of tan, 

 for example, shrinking away from it 

 into the crevices of its substratum. 

 Within the body there are found em- 

 bedded many nuclei (protoplasmic 

 organs), and streaming movements 

 in the cytoplasm (the general proto- 

 plasm) may be observed (fig. i). 

 The most unplantlike behavior of 

 the Plasmodium is its habit of engulf- 

 ing solid food instead of admitting 

 it in solution, and within the body 

 may be seen engulfed bacteria and 

 other minute organisms. Under 

 certain conditions, the whole Plas- 

 modium or parts of it become en- 

 cysted, the surface becoming hardened 

 and often crusty and inclosing a mass of resting protoplasm of waxlike 

 consistency. These hardened masses are called sclerotia, and are won- 

 derfully resistant, being capable of renevidng their activity after re- 

 maining dry for years. 



Fig. 1 . — A small portion of tiie Plas- 

 modium of a slime mold (Fulign), highly 

 magnified; the cytoplasm is very vacuo- 

 late, so that it appears as a network of 

 strands of varying width, in which numer- 

 ous nuclei may be observed. — Adapted 

 from Lister, 



