. A manual of zoology. Zoology. Fig. 227. Fig. 226.—Excretory system of Ceroaria. (After Albert Lang.) 7), limb of bladder ; ?/, same "with urinary concretions; cc, collecting canal; c.^, canals of ventral suclier; cr, collecting vacuole; e, eye; cp, excretory pore; I, lumen of tail; o^^ oral suclier ; v^^ ventral suclcer. Fig. 327.—Eggs of LiMiitiiiim nnilvlosurn. (After Schauinsland.) A, before develop- ment; B, later, the yolk broken down, d, yolk cells ; c), egg cell; €h\ ectoderm ; tw(, entoderm; )j, pigment spot. formation of the embryo and is the true ovum, while the yolk cells bre
. A manual of zoology. Zoology. Fig. 227. Fig. 226.—Excretory system of Ceroaria. (After Albert Lang.) 7), limb of bladder ; ?/, same "with urinary concretions; cc, collecting canal; c.^, canals of ventral suclier; cr, collecting vacuole; e, eye; cp, excretory pore; I, lumen of tail; o^^ oral suclier ; v^^ ventral suclcer. Fig. 327.—Eggs of LiMiitiiiim nnilvlosurn. (After Schauinsland.) A, before develop- ment; B, later, the yolk broken down, d, yolk cells ; c), egg cell; €h\ ectoderm ; tw(, entoderm; )j, pigment spot. formation of the embryo and is the true ovum, while the yolk cells break down and furnish food to the growing embryo (fig. 237, B). Class I. Turbellaria. The Turbellaria are small, only a few being measured by inches, while many are almost microscopic in size. The name Turbellaria has reference to the currents produced by the ciliated ectoderm which covers the Ijody, the cilia arising from the single layer of columnar epithelial cells (fig. TiS). This ectoderm serves at once for motiou and for respiration. Most sjiecies are aquatic (fresh water or marine), only a few land planarians living in moist earth. In the water they cither creeji slowly over stones or plants on their ventral surface, or they swim freely. In swimming the larger species progress by nndalations of the body, the smaller by means of the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929. New York, H. Holt and Company
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