Facts and Arguments for Darwin - With Additions by the Author (Paperback)

Excerpt: ...is presented by the Hyperinae which usually live upon Acalephae. In these the young and adults often have a remarkably different appearance; but even in these there is no new formation of body-segments and limbs, but only a gradual transformation of these parts. ( In the young of Hyperia galba Spence Bate did not find any of the abdominal feet, or the last two pairs of thoracic feet, but this very remarkable statement required confirmation the more because he examined these minute animals only in the dried state. Subsequently I had the wished-for opportunity of tracing the development of a Hyperia which is not uncommon upon Ctenophora, especially Beroe gilva, Eschsch. The youngest larva from the brood-pouch of the mother already possess THE WHOLE of the thoracic feet; on the other hand, like Spence Bate, I cannot find those of the abdomen. At first simple enough, all these feet soon become converted, like the anterior feet, into richly denticulated prehensile feet, and indeed of three different forms, the anterior feet (Figure 44) the two following pairs (Figure 45) and finally the three last pairs (Figure 46) being similarly constructed and different from the rest. In this form the feet remain for a very long time, whilst the abdominal appendages grow into powerful natatory organs, and the eyes, which at first seemed to me to be wanting, into large hemispheres. In the transition to the form of the adult animal the last three pairs of feet (Figure 49) especially undergo a considerable change. The difference between the two sexes is considerable; the females are distinguished by a very broad thorax, and the males (Lestrigonus) by very long antennae, of which the anterior bear an unusual abundance of olfactory filaments. Their youngest larvae of course cannot swim; they are helpless little animals which firmly cling especially to the swimming laminae of their host; the adult Hyperiae, which are not unfrequently met with free in the sea, are, as is...

General

Imprint:	Cambridge UniversityPress
Country of origin:	United Kingdom
Series:	Cambridge Library Collection - Darwin, Evolution and Genetics
Release date:	November 2014
Authors:	Fritz Muller
Translators:	William Sweetland Dallas
Dimensions:	216 x 140 x 9mm (L x W x T)
Format:	Paperback - Trade
Pages:	158
ISBN-13:	978-1-108-07866-5
Languages:	English
Subtitles:	German
Categories:	Books > Science & Mathematics > Science: general issues > History of science
LSN:	1-108-07866-4
Barcode:	9781108078665

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