180 



PROTOZOA 



wall massive, the terminal opening the only communication with the exterior. 

 Miliola (fig. 131). B. PERFORATA. Shell perforated by many pores; terminal 

 opening may be lacking. Polystomella, Rotalia (fig. 118), bottom dwelling; 

 Globigerina bulloides (fig. 130), pelagic. Among the fossils the Nummulites 

 need mention. 



Possibly the XENOPHYOPHORA of the deep seas belong near the For 

 aminifera. These are large biconcave discs or fan-like plates 2 to 7 cm. across, 

 formed of delicate tubes, sometimes arranged in a network, sometimes branched 

 like antlers, and between them a skeleton of foreign bodies, the 'xenophya.' 

 The fine tubes (granellare) are filled with a polynucleate protoplasm; the larger 

 tubes (stercomare} contain large balls, interpretated as fa?cal The animals 

 have not been studied in the living condition. 



Order VI. Mycetozoa (Myxomycetes). 



The Mycetozoa or slime animals are regarded by some as animals, by others as 

 plants (slime moulds). The first view is supported by the structure of the motile 

 stage, the plasmodium, the second by the reproductive bodies, resembling those 

 of many fungi. The plasmodia appear in damp weather as networks of bright- 

 red, orange or yellow slime on decaying wood. They are giant Amoeba? of 

 reticulate protoplasm several centimeters in extent, containing many nuclei and 





FIG. 152. FIG. 133. 



FIG. 132. Chondrioderma difforme (after Strasburger). a, dry spore; b, swollen 

 in water; c, spore with escaping contents; d, zoospore; e, amceboid modification of 

 zoospores which are uniting to form a plasmodium;/, part of a plasmodium; in d and e, 

 nuclei and contractile vacuoles. 



FIG. 133. Spore-sacs of Arcyria incarnata (after de BaryV At the left the sporan- 

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



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

 dopodia (fig. 132, /). On drying, the plasmodium encysts in a peculiar manner, 

 and forms the reproductive bodies, the sporangia (fig. 133) and the 'car pome.' 

 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 cf 

 the sporangium and the columella is filled with fine powdery spores and an 

 exploding apparatus, either a network of fine filaments (capillitium) or many 



