70 



BOTANY 



cakelike, or irregular roundish structures, or they may assume a 

 constant form characteristic of different genera. Thus in the com- 

 mon genus Stemonitis (Fig. 50, B) the sporocysts are cylindrical 

 bodies borne upon a long stalk, prolonged upward into the axis of 

 the cylindrical sporocyst. Other genera, e.g. Arcyria, have pear- 

 shaped or oblong stalked sporocysts, while in ^Ethaliurn and similar 

 forms (Fig. 50, A) the irregular, densely crowded sporocysts are 

 packed together into a solid cakelike mass (^Ethalium), which is 

 covered with a sort of crust which protects the underlying sporo- 

 cysts. The wall of the sporocyst is often colored, and there may 

 be a heavy deposit in it of carbonate of lime, which also sometimes 

 occurs in the active plasmodium. 



FIG. 50. A, aethalium of Enteridium splendens (X 1). B, two sporocysts of 

 Stemonitis fusca ( X 3) . C, sporocysts of Leocarpu/s fragilis, attached to a stalk 

 of grass (X 24). D, a single sporocyst more enlarged. E, capillitium and spores 

 of the same species (X 500). F, end of a capillitial filament of Trichia favoginea. 

 G, sporocyst of Dictydium cancellatum (x 25). (A and G after MACBRIDE.) 



Spore-formation. The protoplasm within the sporocyst divides into many 

 small globular cells, each containing a nucleus, and developing about it a mem- 

 brane which usually is colored, and is marked with characteristic sculpturing, 

 much like the spore-membranes of the higher plants. These spores do not 

 completely use up the protoplasm, but a part remains to form a system of 

 threadlike structures, the Capillitium, which are often of peculiar form. The 

 capillitium may be composed of solid, more or less confluent threads (e.g. 

 Stemonitis), or it may be made up of separate (Trichia) JOT united (Arcyria) 

 hollow tubes, with spirally thickened walls. 



Germination. The ripe spores germinate quickly under proper conditions. 

 The early stages may often be seen by placing the spores in water ; but for the 

 further development a proper nutrient solution is necessary. The spore ger- 



