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Microscopical researches into the accordance in the structure and growth of animals and plants / Translated from the German of Dr. Th. Schwann ... by Henry Smith.

  • Schwann, Theodor, 1810-1882.
Date:
1847
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Licence: Public Domain Mark

Credit: Microscopical researches into the accordance in the structure and growth of animals and plants / Translated from the German of Dr. Th. Schwann ... by Henry Smith. Source: Wellcome Collection.

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    opinion still maintained its ground, even when the structure of the tissues became more accurately known. Nor did the plant-like growth of the component parts of the ovum abolish the assumed essential difference of the growth of the vascular tissues. A very important advance was made in the year 1837, when an actual growth of the elementary particles of epithe- lium was proved to take place without vessels. Henle (Sym- bole ad anatomiam vill. intest. Berol. 1837) showed that the cells in the superficial layers of epithelium are much more ex- panded than those in the deeper strata, a fact which leaves scarcely any doubt as to their true plant-like (1. e. non-vascular) growth. Henle’ says (l. c. p. 9), “Hoc in loco (in planta pedis) cellularum (retis Malpighii) diametrum extrorsum augeri, seepius repetita observatione pro re certa affirmare audeo. Quas retis cellulas non minus in foetu suillo sensim increscentes transire in cellulas epidermidis, nunguam non inveni.” Purkinje and Raschkow (Meletem. circa mammal. dentium evol. Vratisl. 1835) had made the following obser- vations upon the development of the epidermis: “Im primis evolutionis periodis—squamule—epithelii nondum ita con- formate sunt ut in illa periodo, que partui precedit, sed parenchyma plantarum cellulis simillimum ostendunt, cum queeque squamula, que postea talis apparet, tunc temporis tanquam cellula polyedrica e membrana tenacissima constans globosamque guttulam continens in conspectum veniat. Pressu applicato rumpebantur iste cellule atque lymphaticum liquo- rem effundebant, que cellule, procedente evolutione, verisimile complanatz in illas polyedricas squamas mutantur.” Henle, when quoting this passage, adds (l. c. p. 9): “ Hee illa num vero sola compressio in causa esse possit, ut parva cellula ! Henle’s observations are detailed at page 76 of this treatise. The researches of Turpin and Dumortier could not be quoted, as [ only became acquainted with them at the conclusion of my work.