Histology; normal and morbid.
- Dunham, Edward K. (Edward Kellogg), 1860-1922
- Date:
- 1898
Licence: Public Domain Mark
Credit: Histology; normal and morbid. 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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![1. The cytoplasnij which usually makes up the chief bulk of the cell, especially in those varieties which have active metabolic functions, appears to be the part of the cell in which the assimilated food is utilized in the production of chemical substances, either fresh cytoplasm or some other product, or in the execution of movements or the libe- ration of energy in other forms. Most of the active processes that are obvious seem to be carried on in the cytoplasm during the greater part of the life-history of the cell. 2. The nucleus appears to preside over the assimilative processes Avithin the cell. If a cell be subdivided so that the uninjured nu- cleus is retained in one of the portions, that portion may grow and become a perfect cell. But the portions that are deprived of a nu- cleus do not grow, and while they may retain life for a considerable time, utilizing the assimilated food they retain, eventually perish. Aside from this assimilative function, the nucleus appears to be the carrier of hereditary characters from the parent cell to its prog- eny during the division of the cell. This will become clearer when the process of cell-division is described. 3. The centrosome appears to be the organ presiding over the division of the cell. It inaugurates those activities in nucleus and cytoplasm which result in the production of new cells, and seems to guide them, at least during the greater part of the whole process. It is evident, from these statements, that the cell has an exceed- ingly complex organization, which a simple microscopical study can- not wholly reveal. Notwithstanding this fact, obvious microscopical differences are presented by cells which have be(iome specialized in different directions, and we must know something of the visible structure of the primitive cell before we can appreciate these depart- ures from it. The cytoplasm is not a simple substance. Its constitution is so com- plex that our present means of research are not adequate to reveal its structure. We know that its solid constituents are chiefly ])ro- teids, together with relatively small quantities of carbohydrates, fats, and salts. To these is added a large proportion of water wliich, while not entering into a definite chemical union with the other constituents, is so intimately associated with them as to form an integral part of the cytoplasm. The visible structure of cytoplasm differs somewhat in different cells, even among those that appear to be comparatively unspecial- ized. In the fixed cells of the higlier animals and man it appears](https://iiif.wellcomecollection.org/image/b21223841_0028.jp2/full/800%2C/0/default.jpg)
