Hand-book of physiology / by W. Morrant Baker and Vincent Dormer Harris.

  • William Morrant Baker
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: Hand-book of physiology / by W. Morrant Baker and Vincent Dormer Harris. Source: Wellcome Collection.

    27/910 (page 3)
    fHAp. r.] THE PROPERTIES OF PROTOPLASM. cells it was called Protoplasm by Mulder, while Kemak applied the same name to the substance of animal cells. As the presumed formative matter in animal tissues it was termed Blastema, and in the belief that, vvherever found, it alone of all substances has to do with generation and nutrition, Beale has named it Germ inal matter or Bioplasm. Of these terms the one most in vogue at the present day, as we have already said, is Protoplasm, and inasmuch as all life, both in the animal and vegetable kingdoms, is associated with protoplasm, we are justified in describing it, with Huxley, as the physical basis of life, or simply living matter. A cell may now be defined as a nucleated mass of protoplasm,^ of microscopic size, which possesses sufficient individuality to have a life-history of its own. Each cell goes through the same cycle of changes as the whole organism, though doubtless in a much shorter time. Beginning with its origin from some pre- existing cell, it grows, produces other cells, and finally dies. It is true that several lower forms of life consist of non-nucleated protoplasm, but the above definition holds good for all the higher plants and animals. Hence a summary of the manifestations of cell life is really an account of the vital activities of protoplasm. Protoplasm.—Physically, protoplasm is viscid, varying from a semi-fluid to a strongly coherent consistency. Chemically, living protoplasm is an extremely unstable albuminoid substance, insoluble in w^ater. It is neutral or weakly alkaline in reaction. It undergoes heat stiffening or coagulation at about 130° F. (54*5° C.), and hence no organism can live when its own tempera- ture is raised beyond this point. I Many, of course, can exist for a time in a much hotter atmosphere, since they possess the means of regulating their own temperature. Besides the coagulation produced by heat, protoplasm is coagulated and therefore killed by all the reagents which pro- duce this change in albumen (see Appendix). If protoplasm be subjected to chemical analysis, the chief substances of which it is found to consist belong to the class of bodies called Proteids or albumins. These are bodies made up of the chemical elements C. H. N. 0. and S., in certain slightly varying propor- tions. They are essential to the formation of protoplasm, for * In the human body the cells range from the red blood-cell in.) to the ganglion-cell in.). R 2