Outlines of scientific anatomy : for students of biology and medicine / by Wilhelm Lubosch ; translated from the German by H.H. Woollard.

  • Wilhelm Lubosch
Date:
1928
Catalogue details

Licence: Public Domain Mark

Credit: Outlines of scientific anatomy : for students of biology and medicine / by Wilhelm Lubosch ; translated from the German by H.H. Woollard. Source: Wellcome Collection.

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    separation surfaces (disperse system). Both the substances of such a system are described by the peculiar expression, which has quite another meaning, “phases.” This phase in itself can be solid, liquid, and gaseous, so that a system of complex combinations can arise. They all fall under the name of “solution” wTerein the solution medium (dispersant, dispersing phase) stands opposite to the dissolved substance (dispersum, disperse phase). Of all possible combinations, the suspensions (solid in fluid) and emulsions (fluid in fluid) are the most important for us since between them stands the colloidal solution according to which type the organic body is fashioned physically. Whilst in the suspensions the distribution of the dispersum is made in quite large elements so that they remain visible (droplets), they grade into the colloidal solutions so far that particles of submicroscopic size arise (transitions, suspensoid colloid) until they can be compared to molecules (emulsion colloid). If the dispersion continues right up to the molecular stage then we get true solutions. The colloids coming into consideration for the aggregate state of protoplasm are the emulsion colloids, which in many characters show their near relation to true solutions. The most important of the general features is that the dissolved phase, if it becomes concentrated by dehydration, can always take up water again. It can always return to its starting point. Emulsion colloids are, like true solutions, re¬ versible (hydrophile). This reversibility of water-acceptance and water-loss is an indispensable condition for the maintenance of life. If the dispersum is dissolved, there arises a sol (sol-ution) within the solution medium, in nature mostly water, therefore hydrosol (-ution). From this solution it can be separated by coagulation, precipitation, etc., and be brought into a more solid state. It may then be a jelly, and the system falls into a dispersant and gel. The form of a colloid disperse system is complicated, because each phase can be again formed as colloidal (complex colloidal solution), as it certainly is in protoplasm, in a very complex form. Of the morphologically finer forms the ultramicroscope provides a glimpse. This rests on the principle that if dissolved substances become illuminated laterally through a sharp cone of light, and this illuminated field of the fluid is viewed through a microscope, we can observe them in the same manner as we see the dust in a sunbeam in a darkened room with the naked eye. The dark-ground illumination effected through a special condenser on an unstained object works similarly. What are here visible in the microscope are not the individual disperse particles, since their distances from one another are smaller than 0'2 ^ [cf. para. 100]. However, wre see the displace¬ ment of the cone of light starting from the particles themselves which have become illuminated. The difference between the picture granted by a glimpse through an ultramicroscope and that given by
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