Licence: Public Domain Mark
Credit: The surgery of the head and neck / by Levi Cooper Lane. 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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![Bacterial organisms are cells which have an average diam- eter of one-thousandth of a millimeter. The cell consists of a wall within which is a homogeneous or granular protoplasmic material. The cell is ordinarily colorless. From contact with water the cell wall may hecome gelatinoid; and in this condition the cells may cohere in chain form, or aggregate in the irregular masses named zoogloca. The ]nost of bacteria are capable of locomotion, in which they are seen to rapidly move in the containing fluid from place to place, in a very irregular manner. Other bacteria, instead of progression exhibit vibratory movements, dependent on molecular movement of the cellular content. Rod-shaped bacilli are some- times provided with cilia-like appendages, which are attached to the ends or sides, and these appendages, like fins, may aid in propulsion. They may also aid the microphyte in getting its nutriment. Bacteria placed in proper conditions have the endowment of rapid multiplication; and reproduction may occur by segmenta- tion or sporulation. Reproduction of the coccus by segmentation, in four different stages, is shown in Figure 2. And segmentation Figure 2. Divibion ot coccus. (After Mace.) of a bacillus, in its five successive stages, is shown in Figure 3. Figure 3. Division of a bacillus. (After Mace.) Instead of development by simple division, bacterial repro- duction may occur by means of spores, which correspond to the seeds of ferns. Most bacilli grow by njeans of spores. There are two ways in which the growth by spores may occur: in one, the embryo appears within the mother-cell; and this mode of reproduction is named endosporous; and in a second wa}^ the offspring appears as an appendage to the mother; and this mode is named arthrosporous. These modes of development, which are also respectively named endogenous and exogenous, are shown in Figure 4 on page xviii. If sporulation be intra-cellular, the spore may appear at any point within its progenitor. It begins as one or several granules within the parental protoplasm ; and this, enlarging and acquir-](https://iiif.wellcomecollection.org/image/b21215406_0021.jp2/full/800%2C/0/default.jpg)
