The essentials of anatomy, physiology, and hygiene : A text-book for schools and academies / By R.S. Tracy.

  • Tracy, Roger Sherman, 1841-1926.
Date:
1884
Catalogue details

Licence: Public Domain Mark

Credit: The essentials of anatomy, physiology, and hygiene : A text-book for schools and academies / By R.S. Tracy. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    ing that the dead one is motionless. A living cell, minute as it is, frequently possesses the power of independent motion, or at least is able to change its form (Fig. 4). It also can take up nourishment into its mass, and can propagate itself. The move- ments of the cell can be beautifully seen in the white cells of the blood, which will be described hereafter. 8. Growth of Cells.— A cell propagates itself in several ways; one of the most common is by divid- ing into two parts. This operation has been often watched under the micro- scope by skilled observers. The change is seen to begin in the nucleus, and, as that divides by a line through its center, the protoplasm of the cell ar- ranges itself in halves around each part of the nu- cleus, its surface dipping in toward the center, until finally the approaching surfaces meet and the Fig. 4.—White cells in motion. Fig. 5.—Cell dividing and forming two new cells. cell is divided into two new cells, each with its nu- cleus, and in every way complete (Fig. 5). This division goes on with great rapidity. The secre- tion from the throat and nose in nasal catarrh is composed mainly of cells, which are thrown off by millions during an inflammation.