. Beginners' Zoology . ction.—This, as in the amoeba,is by division, the constriction being inthe middle, and part of the nucleus goingto each half. Sometimes two individ-. uals come together with their mouth-grooves touching andexchange parts of their nuclei(Fig. 16). They then separateand each divides to form twonew individuals. We thus see that the Para-mecium, though of only onecell, ts a vuicJi more comp/ex and advancedaniina/ tJian the cmceba. The tiny paddles,or cilia, the mouth-groove, etc., have theirspecial duties similar to the specialized organsof the many-celled animals to be stud
. Beginners' Zoology . ction.—This, as in the amoeba,is by division, the constriction being inthe middle, and part of the nucleus goingto each half. Sometimes two individ-. uals come together with their mouth-grooves touching andexchange parts of their nuclei(Fig. 16). They then separateand each divides to form twonew individuals. We thus see that the Para-mecium, though of only onecell, ts a vuicJi more comp/ex and advancedaniina/ tJian the cmceba. The tiny paddles,or cilia, the mouth-groove, etc., have theirspecial duties similar to the specialized organsof the many-celled animals to be studied later. If time and circumstancesallow a prolonged study, sev-eral additional facts may beobserved by the pupil, ^.Does the paramecium swimwith the same end alwaysforemost, and same sideuppermost .-* Can it movebackwards ? Avoid obsta-cles ? Change shape in anarrow passage ? Does refuse fig. 19. —shell of a raoiolarian. Fig. 17. — VoRTi-CELLA (or bellanimalcule), twoextended, onewithdrawn. Fig. l6 BEGINNERS ZOOLOGY matter leave the body at any particular place ? Trac«^movement of the food particles. Draw the paramecium. Which has more permanent parts, the amccba or Para-mecium ? Name two anatomical similarities and three dif-ferences ; four functional similarities and three differences. The amoeba belongs in the class of protozoans calledRhizopoda, root footed. Other classes of Protozoans are the Infusorians (in thebroad sense of the term), which have many waving cilia(Fig. 17) or one whip-Hke flagellum (Fig. 18), and theForanmiifers, which possess a calcareous shell pierced withholes (Fig. 19). Much chalky limestone has been formedof their shells. To which class does the parameciumbelong } Protozoans furnish a large amount of food to the higheisniraals. CHAPTER III SPONGES Suggestions.—In many parts of North America, fresh-watersponges may, by careful searching,be found growing on rocks and logsin clear water. They are brown, creamy, or greenish in
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