150 



LIFE OF A SLIME MOULD 



form, resembling a miniature, brownish puffball, is often seen on 

 stumps and fallen logs (Fig. 87). Other kinds are illustrated in 

 Fig. 88. They range in size from scarcely a pin head to nearly 

 a foot in diameter and from spherical to cylindrical and cake-like 

 masses. Not infrequently they are of great beauty owing to their 

 coloration and lace-like structures. These small sacs or spor- 

 angia (sing, sporangium) as they are commonly called, repre- 

 sent but one stage in the life of the slime moulds. If we begin 

 with an examination of the dust that floats away from these 



FIG. 87. FIG. 88. 



FIG. 87. The sporangial stage of two common slime moulds: A, Ly co- 

 gala. B, Arcyria. C, sporangia rupturing, hair-like structures (the capil- 

 litium) and spores protruding. D, sporangia emptied. 



FIG. 88. Open types of sporangia: A, Stemonitis, at left a single spo- 

 rangium enlarged, showing net-like structure formed by capillitium radiating 

 from the central stalk of the sporangium. B, Cribaria. 



sacs every time they are tapped, the life history will be found to 

 be about as follows: Under the microscope the particles of dust 

 are seen to be minute cells or spores (Fig. 89, ^4). You may think 

 of a cell as a cube, a sphere or as assuming almost any form, 



