PROTOZOA 



189 



"eye spot," which probably enables the creature to dis- 

 tinguish differences in illumination, though it is quite . 

 unable to see any distinct object. In its simplest form 

 the eye is a spot or area of coloring matter, which is 

 changed by light and stimulates the living protoplasm. 

 One of the marine flagellates is occasionally so abundant 

 off the coast of California as to color the sea red, and to 

 kill many fishes and other animals by clogging their 

 gills. The Noctiluca is a relatively large flagellate, 

 quite visible to the naked eye, which floats in the ocean 

 near the surface, and when disturbed produces a bril- 

 liant light, so that the wake of an ocean steamer at night 

 is often resplendent as though with fireworks. Other 

 flagellates, such as the Trypanosoma, are parasitic within 

 the bodies of animals. 



4. The Mycetozoa, often regarded as plants, arise from Slime molds 

 a firm-walled spore, which in water gives birth to a 

 swarm cell. These swarm cells are produced in great 

 numbers, and are flagellate, resembling the Masti- 

 gophora. They swim about, feeding on bacteria. After 



B 



Draving by R. Weber 



FIG. 38. Sporangia of Mycetozoa (after Lister). A, Sporangium of Didymium, on 

 a fragment of a leaf ; much magnified. B, Compound sporangium, or sthalium, of 

 Spumaria, on grass ; about twice natural size. C, Group of sporangia of Trichia, 

 on wood ; about four times natural size. 



