Identifier: philtrans06129108 (find matches)
Title: A Preliminary Account of the Development of the Free-Swimming Nauplius of Leptodora hyalina (Lillj.)
Year: 1901 (1900s)
Authors: Warren, E.
Subjects: Proceedings of the Royal Society of London Philosophical Transactions of the Royal Society
Publisher: Royal Society of London

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er nauplius; it is a little posterior to A.Differentiation of end-sac and part of glandular tube can be seen in the dorso-lateral swelling. 214 Prof. E. Warren. On- the Development of tin which will form muscle, are considerably larger than the rest of themesoderm cells and stain more deeply; they become arranged inparallel cords. By the arrangement of the primitive muscle, thesegmentation of the abdomen is marked out quite early in the life ofthe nauplius. The cells which will form the heart, can be distinguished at anearly period. In the thoracic region, the dorsal portion of the mesodermbands consists of two closely applied layers of flattened cells (fig. 3).These layers gradually grow up over the yolk-sac, and those of one sidemeet their fellows of the other side in the mid-dorsal line. Separationof the two layers now occurs, and the sac thus formed is the heart(figs. 4 and 5). The pericardial space originates by two processes— Heart End Sac. N&ociU&ry Gland.Pericardium.
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MesoderntgsLBand. Fig. 4.—A. Longitudinal vertical section through the dorsolateral swelling ; it is-taken at some distance from the mid-dorsal line (see fig. 2).B. Similar section taken close to the mid-dorsal line. 1) the gradual separation of the ectoderm from the heart-sac, and (2) thedisintegration of the deeper layers of this thick ectoderm (figs. 2, 4, 5, *),.There appears to be a definite floor to the pericardial space, consistingof flattened cells continuous with those of the heart (fig. 5, B), but-the roof would seem to be simply the general dorsal ectoderm of thethorax. Free-swimming Nauplius of Leptodora hyalina (Lilly.). 21; L> The blood-corpuscles are large and frequently spherical. I think itis probable that they are budded off from the compact mesoderm atthe posterior end of the body, but it is very difficult to be certain about their origin. Pericardium. MuscLe. 1<3t^^GLand.philtrans06129108

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