Beginners' zoology . Fic;. 22. — Section of fresh-water sponge(enlarged). 17 i8 BEGINNERS ZOOLOGY. Fig. 23. — Eggs and spicules of fresh-watersponge (enlarged). surface of the sponge rough or smooth? Do any of the skeletalspicules show on the surface? (Fig. 21.) Does the sponge thinout near its edge? The egg of this sponge is shown in Fig. 23. It escapes fromthe parent sponge through the osculum, or large outlet. As in most sponges, the firststage after the egg isciliated and free-swim-ming. Marine Sponges. —The grantia (Fig. 24) isone of the simplest ofmarine sponges. What is the j-/i<7/(?
Beginners' zoology . Fic;. 22. — Section of fresh-water sponge(enlarged). 17 i8 BEGINNERS ZOOLOGY. Fig. 23. — Eggs and spicules of fresh-watersponge (enlarged). surface of the sponge rough or smooth? Do any of the skeletalspicules show on the surface? (Fig. 21.) Does the sponge thinout near its edge? The egg of this sponge is shown in Fig. 23. It escapes fromthe parent sponge through the osculum, or large outlet. As in most sponges, the firststage after the egg isciliated and free-swim-ming. Marine Sponges. —The grantia (Fig. 24) isone of the simplest ofmarine sponges. What is the j-/i<7/(? of grantia? What is its lengthand diameter? How does the free end differ from the fixed end?Are the spicules projecting from its body few or many?Where is the osculutn, or large outlet? With whatis this surrounded? The osculum opens from a centralcavity called the cloaca. The canals from the poreslead to the cloaca. Buds are sometimes seen growing out from thesponge near its base. These are young sponges formedasexually. Later they become detached from theparent sponge. Commercial Sponge.
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1921
