Buckmaster's Elements of animal physiology / by John Angell.

  • Angell, John.
Date:
1866
Catalogue details

Licence: Public Domain Mark

Credit: Buckmaster's Elements of animal physiology / by John Angell. Source: Wellcome Collection.

    17/384 (page 5)
    force, to form proximate principles; these again, under its influence, are built up into tissues \ the tissues are elaborated into organs \ and the organs together form the perfect animal. Development.—All animals originate in 2, germ, or cell. The germ, cell, or ovum from which the higher animals, including man, originate, differs but little in form and structure from those out of which the lower animals, or even vegetables, are developed. Life would, therefore, appear not so much to depend upon as to detemiine organization ; since all the higher forms of organization are developed from the lower. There is, first, the simple cell; this, by a pro- cess of development, or differentiation, divides and sub- divides into other cells; these unite to form tubes, vessels, fibres, &c., which again unite and constitute organs. The extent to which this process of differen- tiation, or development, can proceed, or, in other words, the number of the organs and functions—that is, the high or low organization of the animal—there- fore, seems to be dependent on the vital principle inherent in the original germ-cell. All views regarding life as a distinct principle are, however, purely theoretical. They do not aid us in our studies, and are probably rather suggested by sentimental and metaphysical considerations than by the spirit of true scientific induction. Low Organization.—When an organized being is possessed of but few organs performing distinct functions, or is made up of a repetition of similar organs performing similar functions, it is said to be of loiv organization. If such animals be injured, or por- tions of them be cut off and removed, the life of the animal is not endangered, but the part removed will, in many cases, as in that of the hydra, or fresh-water