A text-book of pathology for students of medicine / by J. George Adami and John McCrae.
- John George Adami
- Date:
- 1914
Licence: In copyright
Credit: A text-book of pathology for students of medicine / by J. George Adami and John McCrae. Source: Wellcome Collection.
31/904 page 35
![ever, be recalled that the dissociation of nucleic acid yields a j)entose (sugar) according to Levene and Jacobs, a hexose according to Stendel and Halliburton. From the dissociation of sugars energy is liberated, and on the contrary energy is conserved when they are stored as built-up glycogen molecules. GROWTH In all our previous considerations of the biophore we have dealt with metabolic activity, but we have made onH passing reference to growth. If we think a little it will be seen that the growth of living matter demands a process whereby two molecules exist where there was one before. Our conception of the biophore is as a ring, or a ring of rings, and growth occurs by increase first of the individual smaller groups or rings. These groups, from their very inception present a series of unsatisfied affinities, and each or any of the molecules is con- stantly attracting molecules of a like order, and on the first of these is built up a second and a third until the group is complete. Along these lines we can imagine the development of a new ring of which each individual component is the reflection of the components of the original ring: in its turn this ring attracts, and so builds up other rings in due order until eventually there is produced a completed compound molecule, reproducing the parent molecule. We use the illustration of the ring to indicate a degree of completeness; the ring can break, it is true, and in its repair, be enlarged or be made smaller, or it can join with another broken one, but the molecules of the formed ring are less likely to be attracted away just because they are in a ring, i. e., in a state of relative completeness. The Relation between Growth and Other Cell Activities.—The consideration of this subject demands a few words on the dynamics of the cell. In the performance of function of whatever kind, the cell is a machine discharging potential energy. The body warmth means that cells are liberating energy in the form of heat; the nerve cell liberates energy akin to electricity. On the other hand, growth and the accumulation of new molecules demand, not the evolution, but the storage of energy, and this comes from the food. The proteins, carbohydrates, and fats are carbon-containing bodies the ultimate result of whose decomposition is a yielding of much energy. The excreta of the organism, carbonic acid, water, urea, etc., on the other hand, store up comparatively little, and the cells acquire most of the difference. Strictly s])eaking, energy is not evolved in the dissociation of matter; but dissociation and the freeing of ions mean that combinations im- mediately occur which liberate far more energy than was lost in the dissociations of a moment before, so that the ultimate result of disso- ciation is, paradoxically, the production of energy. To give a familiar example; heat has to be ai)i)lied in the first i)lace to tlie wick of the](https://iiif.wellcomecollection.org/image/b28055172_0031.jp2/full/800%2C/0/default.jpg)
