/. RHIZOPODA: MJCETOZOA. 



199 



damp weather as networks of bright-red, orange or yellow slime on 

 decaying wood. They are giant Amc8ba3, several centimeters in 

 extent, of reticulate protoplasm containing many nuclei and much 

 foreign matter taken as food. They creep slowly by means of 

 pseudopdia (fig. 132). On drying the plasmodium encysts in a 



r < 1 



Fig, 133. 



Fig 13,3— (/i ( (i I i i Itff hk (After Strasburger.) o, dry spore; h, swollen in 

 witer c sp re with escaping contents; d, zoospore : t% amoeboid modification of 

 zrospjres which die uniting to form a Plasmodium; /, part of a Plasmodium; 

 in d and t, nuclei and contractile vacuoles. 



Fig. 133. — Spore-sacs of Arci/ria incarnattt. (After de Bary.) At the left the sporan- 

 gium ruptured by the expanding capillitium, which has discharged the spores. 



peculiar manner, and if at the proper stage of maturity, it forms the 

 reproductive bodies, the sporangia (fig. 133). These are firm-walled 

 vesicles, frequently stalked, the stalk sometimes extending into the 

 axis of the sporangium as a columella. The space between the 

 wall of the sporangium and the columella is filled with fine piowdery 

 spores and an exploding apparatus, either a network of fine fila- 

 ments (capillitium) or many spirally coiled threads (elators). 

 When wet, as by rain, the elaters or capillitium expand, rupture 

 the sporangium and scatter the sjDores. The sj^ores germinate in 

 water or on moist surfaces, and from each comes out a small 

 amoeba-like embryo, frequently famished with a liagellum (fig. 132). 

 Several of these embryos fuse to form a plasmodium : ^EflutUum 

 scpticum, flowers of tan, plasmodium yellow, on spent tanbark; 

 Comatriclui, Arcyria (fig. 133). 



