Biological Studies (Classic Reprint) - Softcover

Sedgwick, William Thompson

Softcover

ISBN 10: 1330455517 ISBN 13: 9781330455517

Publisher: Forgotten Books, 2019

Synopsis

Excerpt from Biological Studies

Paramecium aurelia, according to Maupas, differs from P. Cau datum in the following points: It is smaller (70 to 290 p, as against 120 to 32 5 p. In P. Caudatum); its posterior end is rounded, while P. Caudatum has an attenuated end (hence caudatum); it has two small micronuclei (3 to 5 u in diameter), while P. Caudatum has but one (8 to 10 u); in conjugation its macronucleus becomes rib bon-shaped at an earlier period than in P. Caudatum; and after conjugation its cleavage nucleus gives rise to four corpuscles, whereas in P. Caudatum there are eight. In deciding which of these forms to call caudatum and which aurelia, Maupas could not determine which type Miiller had seen, and went back therefore only to Ehrenberg, who' in naming P. Caudatum had noted the attenuated posterior end. Hence it turns out that the more common form of Para mecium has become widely known as P. Caudatum, while the less common form bears the original name P. Aurelia. If the two are only variants of the same species, it follows from the rules of zo ological nomenclature that the common and well-known name Para mecium caudatum must be given up and P. Aurelia substituted. That this must be the case follows, as I believe, from the observa tions here described. In the following description the names P. Caudatum and P. Aurelia will be used for those variants of the organ isms which agree with Maupas' Specific characteristics.

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Edition details

• Publisher: Forgotten Books
• Publication date: 2019
• Language: English
• ISBN 10: 1330455517
• ISBN 13: 9781330455517
• Binding: Paperback
• Number of pages: 346