Items related to Life histories of animals, including man; or, Outlines...
Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1876 Excerpt: ...of worms, in which there is no true stomach and intestines, but a simple short blind digestive sac leading from the mouth and pharynx, are known to multiply by fission, the Ik-.mi. body dividing into two. They also possess ovaries and male glands, and reproduce from eggs. We are not acquainted with the life-history of the Ehabdocoelous forms, such as Vortex, Prostomum, etc., except that we know that they produce eggs and spermatic particles. In Prostomum, an orbicular form, the yolk cells are formed in a gland (vitellogene) distinct from the true ovary or germforming gland (germogene). As an example of reproduction by fission may be cited the singular Catena quatema Schmarda, which occurs in fresh Catena uaterna water at the Cape of Good Hope. Fig. 131 represents two individuals in partial division, and a chain of four individuals, natural size. This form reminds us of the tape worm, in which the joints remain permanently attached. We know nothing further regarding the history of Catena except that it has been found as indicated in the figure here reproduced from Schmarda. Among the Dendrocoela, or Planarians, and in fact in the flat worms generally, fission takes place. If we cut the common fresh water Planarians into several pieces, each piece will become a perfect worm. All the fresh water flat worms are born as infusorian-like ciliated bodies which attain maturity without any metamorphosis. As an example of the mode of development of a Planarian worm, may be given the history of Planocera elliptica discovered by Girard in Boston and Beverly harbors. The spawning time lasts from the middle of May until the middle of June, the eggs being deposited in a thin viscid band on stones and sea weeds. The egg undergoes total segmentation in four or five days afte...
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