A manual of bacteriology, clinical and applied / by R. Tanner Hewlett.

  • Hewlett, R. Tanner (Richard Tanner), 1865-1940.
Date:
1911
Catalogue details

Licence: In copyright

Credit: A manual of bacteriology, clinical and applied / by R. Tanner Hewlett. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    18/790 (page 2)
    and Koch will ever hold an honourable place in its annals. The study of micro-organisms must always be of considerable importance in general biology, for their vital phenomena arc comparatively simple, and throw much light on the more complex processes occurring in the higher orders of living beings. Weismann based his theory of heredity on the fundamental conception of the immortality of these unicellular organisms. Excluding accidents, they are immortal—they repro- duce themselves by a process of simple division, an individual dividing, and two daughter forms taking the place of the original parent one, and although the parent has disappeared yet there has been no death, no dissolution ; its protoplasm or living material is still existent in its progeny and is immortal, since this process of reproduction apparently may go on indefinitely. Moreover, the study of the mutability and possible transformation of species of micro-organisms is likely to throw light on the theory of evolution. Organisms such as bacteria multiply so rapidly that fifty or sixty generations may be developed in thirty hours, a, number which would take years to attain if even the most rapid breeder among mammals were the subject of experiment, and as they occur in vast numbers the opportunity for variation is extensive. These are some of the relations which micro-organisms have to general biology. In what may be termed the economy of nature micro-organisms are all-important ; without them there would be no putrefaction, no decay, and the dead remains of animal and vegetable life would so accumu- late as to encumber the earth, which would become sterile for the want of the organic matter originally derived from it, but of which there was no return. In