60 STRUCTURAL AND SYSTEMATIC ZOOLOGY 



are terrestrial in habit, being often found in sum- 

 mer slowly crawling upon 

 stumps, logs, and leaves. 

 In their nonmotile stage 

 of development they re- 

 semble the spore-bearing 

 organs and spores of cer- 

 tain Fungi, but in their 

 locomotor phase they ex- 

 hibit the structure and 

 physiology of amoeboid 



FIG. 3. Germination of a spore of a Myceto- , n 11 4. 



zoan (Trfchia), showing the development and flagellate 

 of the amoeboid stage. Much magnified. SOTTlPtimPS 



forming large, multinucleated masses of 

 'protoplasm which crawl about and ingest 

 solid food (Fig. 3). 



CLASS 3. Mastigophora 



The distinctive character of the ani- 

 mals in this group is the presence of 

 one or more flagella, long, whiplashlike 

 threads of protoplasm used for locomo- 

 tion and for obtaining food. Some kinds, 

 like Euglena (Fig. 4), live as independent 

 organisms, while others, as Volvox and 

 Dinobryon, form colonies (Fig. 5). The 

 latter two are of some sanitary impor- 

 tance, since either one, when present 

 in large numbers in a water supply, is 

 likely to cause unpleasant tastes and 



. FIG. 4. Euglena: /, 



odors. JVoctiluca, a marine form, is one flageiium; g, guiiet; 



r , i r i i A!_ P s t pigment spot or 



of the causes of phosphorescence in the e y e" ; cv, contrac- 

 sea. Some of the higher kinds, e.g., tiievacuoie: r.reser- 



voir ; /, paramylum 



Codosiga (Fig;. 6\ are interesting; for bodies; r, chlorophyll 



bodies. Much mag- 



the reason that they bear a peculiar struc- nified. 



