Volume 1

The principles of psychology / by Herbert Spencer.

  • Herbert Spencer
Date:
1897
Catalogue details

Licence: Public Domain Mark

Credit: The principles of psychology / by Herbert Spencer. Source: Wellcome Collection.

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    we call decomposition; the second isomeric transforma- tion. These forms of change are further distinguished in this, that the one is usually accompanied by a great dissipation of motion, whereas the motion given out or taken up along with the other is relatively insignificant. There is yet a third contrast. After decomposition the separated components cannot be readily made to resume their previous relations: often it is impossible to combine them again; and in most other cases it is difficult to do this. But in many instances of isomeric transformation, resump- tion of the original form may be produced by a very mod- erate change of conditions. Now the two kinds of molecular change thus strongly contrasted, are the two kinds of molecular change which we have reason to suspect are undergone by the two forms of nervous matter. While the protein-substance mingled with fat-granules in the vesicles, is habitually decomposed; the protein-substance forming the axes of the nerve-fibres is habitually changed from one of its isomeric states to another. Such, at least, is the assumption here made, in conformity with the conclusion drawn in the Principles of Biology (§ 302); where it was argued that the propagation of mole- cular disturbances from one place in an organism to another, tends so to modify the mingled colloidal substances as to produce, between the two places, a form of colloid that undergoes isomeric transformation when disturbed, and com- municates the disturbance in undergoing the transformation; and where it was argued that this easily-transformable colloid, having had such a change set up at one end of it and passed on to the other, giving out in the process some molecular motion and consequently falling in temperature, immediately re-absorbs from the adjacent tissues permeated by blood, an amount of molecular motion equal to that which was lost: thereupon resuming its previous isomeric state, and its fitness for again propagating a wave of transformation. Much as there is here of hypothesis, the indirect evidence
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