Première leçon de zoologie : adapté pour utilisation dans les écoles . f division. (Fortement agrandie.) c'est donc-contractile et (2) effectue des mouvements auto-matic ; aussi, comme les animaux supérieurs (3), nourriture itswallows ; (4) des changements chimiques dans l'alimentation lieu:en d'autres termes, il digère sa nourriture, i.e, sépare ou secretesthe partie nécessaire de nourrir son corps de ceux por-tions qu'elle excrète ou rejette comme des déchets ; (5) Il peut également être dit de respirer, les changements associés à l'alimentation L'AMCEBA ET D'AUTRES B00T-ANIMAL0ULE8. 15 en particulier l'oxygène, causant la production et de l'excrétion d'ofcarbonic

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First lesson in zoology : adapted for use in schools . f division. (Highly magnified.) it is thus said to be contractile—and (2) performs auto-matic movements; also, like the higher animals (3), itswallows food; (4) chemical changes in the food take place:in other words, it digests its food, i.e, separates or secretesthe portion necessary to nourish its body from those por-tions which it excretes or rejects as waste; (5) it may alsobe said to breathe, the changes involved in taking food THE AMCEBA AND OTHER B00T-ANIMAL0ULE8. 15 especially oxygen, causing the production and excretion ofcarbonic acid; (6) and finally, it can reproduce its kind.Thus we haye foreshadowed in this exceedingly simplebeing all the important functions of animal life. Besidesthe Amoeba, which is a representative of this class, thereare a number of fresh-water forms which are protected bysimple, silicious shells; but in the sea there are thousandsof species whose shells are partitioned into chambers, andare usually perforated with holes like a sieve, through which. Fig. 9.—a Foraminifer. Globigerina, magnified 70 diameters. the animal protrudes its false feet or pseudopods. Theseshelled Rhizopods are called Foraminifera (Latin, foramen, a hole or aperture;/ereMS, bearing. Figs. 9 and 10). Theyhave the same power as snails and clams to separate orsecrete from the sea-water the lime or silica dissolved in it, and to build up a shapely, graceful, and strong shell; whileothers gather with their finger-like processes graiils of sandor bits of shell and form them into houses of stone-work.Many Foraminifera float in calm weather on the surface ofthe sea, and when they die their shells slowly sink to thebottom. They are exceedingly abundant, and the shells atthe bottom accumulate in such (juantities as to make a gray 16 FIBST LES80N8 IW ZOOLOGY. mud or ooze, forming the bottom of the ocean at greatdepths: this soft, deep mi^d is called Globigerina ooze.Chalk is largely made up of the calcareous shel

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• bookcentury1800
• bookdecade1890
• booksubjectzoology
• bookyear1894