. The biology of the protozoa. Protozoa; Protozoa. REPRODUCTION 221 ing all of the differentiated parts of the entire adult organism. By regeneration, therefore, such a cut individual replaces the charac- teristic structures of the posterior end by the anterior fragment and the characteristic structures of the anterior end by the posterior fragment (Fig. 113). By their usual method of transverse division the ciliates have quite a different inheritance than do flagellates which divide longitudinally. In the latter the highly differen- tiated anterior ends and the less differentiated posterior e
. The biology of the protozoa. Protozoa; Protozoa. REPRODUCTION 221 ing all of the differentiated parts of the entire adult organism. By regeneration, therefore, such a cut individual replaces the charac- teristic structures of the posterior end by the anterior fragment and the characteristic structures of the anterior end by the posterior fragment (Fig. 113). By their usual method of transverse division the ciliates have quite a different inheritance than do flagellates which divide longitudinally. In the latter the highly differen- tiated anterior ends and the less differentiated posterior ends are equally divided so that the daughter cells have a like inheritance (p. 95).. Fig. 111.— Uronychia Iransfuga with giant cirri, membranelles used in swimming, ten macronuelear segments, and single micronucleus. (After Calkins.) The processes through which the filiate cell passes during division indicate that the organism is restored to a generalized condition practically equivalent to an encysted cell. Except for the cyto- stome the entire array of complex cortical organs is withdrawn and a new set is formed from the cortical protoplasm. This significant process first described by Wallengren (1900), later by Griffin (1910) in hypotrichous ciliates, has been observed in many forms and is probably characteristic of the entire group. It is most clearly established in the Hypotrichida wThere the highly specialized and conspicuous motile organs furnish suitable material for study. According to Wallengren's description the membranelles of the adoral zone slowly decrease in length as the process of absorption. 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 Calkins, Gary N. (Gary Nathan), b. 1869. Philadelphia, Lea & Febiger
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