In connection with the metabolism of mineral salts, an interesting view has been presented by Benjamin Moore. He declares that the living cell from the physio-chemical point of view may be looked upon as a machine through which is passing a constant flow of energy, which is distributed in other forms without the integrity of the cell being to any obvious extent affected. These supplies of energy always come to it in the form of organic compounds capable of being oxidised in the cell substance. For the preservation of this capacity to oxidise, it is essential that its own substance be preserved in an unimpaired state, and this is dependent on the presence of the ions of certain simple inorganic salts in the cell and its surrounding fluid media. If this supply of inorganic ions is not maintained, then the. physiological activity of the cell is interfered with much more than if the supply of organic nutritive material be defective, because the cell can always use those stored up within its own substance or even actually utilise its own substance for this purpose.

If an isolated heart muscle be immersed in a solution of distilled water and dextrose, it will cease to beat instantaneously, but in a solution of NaCl isosmotic with the natural serum of the animal from which it was taken, the beating will persist for some minutes. This isosmotic solution prevents the cells being suddenly disrupted, but cannot continue to preserve the integrity of the heart muscle, because NaCl solution has a zero pressure for certain ions indispensable to the activity of the heart. The ions of potassium and calcium are then slowly diffused out, and the cells are then unable any longer to draw upon their stored up energy, but the addition of 1/10000 part of KC1 and even less Ca to the NaCl solution enables the heart-beat to be continued for hours.

This is an effective demonstration of the labile equilibrium between the colloids of the cell protoplasm and the osmotic pressure or concentrations of the inorganic ions and other crystalloid constituents. If to the above solution of NaCl, KC1 and Ca, dextrose be now added, then the heart-beat is prolonged for a much longer period of time.

Bioplasm is composed of an aggregation of the variously constituted protein bodies, loosely combined with fats and carbohydrates and the ions of the inorganic salts, to form a united system. The attachment of these different parts to each other remains constant by varying "the organic oxidis-able substance, viz., the protein bodies themselves, the fats and carbohydrates which suffer temporary molecular disruptions, during which the oxygen also held in the bioplasm comes into union with them, and the oxidised products as they increase in pressure are shed off from the cell." Heating with alkalis or acids under pressure causes the proteins to take up the element of water and yield simpler organic compounds, the process known as hydrolysis. On the other hand, by dehydration or condensation, union is effected amongst the organic radicles of the proteins.

These organic radicles are of three classes: (1) purely organic bases, (2) purely organic acids, (3) amino-acids which possess the properties of both in a modified degree. These last; undergo condensation or conjugation with one another, or with other organic bodies, to form long chains in single series, or main chains with side or branch chains arising from them, a process easily effected if we will only remember that many of them contain more than one basic group or more than one acidic group, so that ramification can take place in all three dimensions of space. This goes on until equilibrium is reached between the synthetic or building up and the disrupting forces.

In this process a number of poles of opposite types are left capable of being satisfied with substances of opposite polarity held in loose attachment. This form of union by residual affinities is spoken of as adsorption, and every grade of affinity for union may exist, between the double decomposition which constitutes chemical combination and the physical union of an infinitely weaker type which is entitled adsorption. In this last state stability is only possible so long as a certain pressure or concentration is maintained. When this diminishes disruption takes place.

In this way new proteins are formed by the union of protein radicles with carbohydrate radicles, and in the same manner fats are synthesised from carbohydrates.

The selective power of each tissue varies. Thus the tissue cells and the blood corpuscles are rich in potassium and phos-phatic ions and poor in sodium and chlorine, whereas the converse obtains in the fluids bathing the cells. This is due to the fact that the proteins of the cells have affinities for absorbing potassium and phosphorus, bub not sodium and chlorine, whilst the fluids have an opposite tendency.

This theory of the peculiar distribution of the salts is much more satisfactory than that the cell wall is a membrane with varying resisting power to the passage of the various ions. It does not destroy the argument for osmosis, but only denies the existence of a membrane and postulates the whole chemical structure of the cell as the osmotic machine. The bioplasm holds the crystalloids in loose union in the cells, preventing their escape or diffusion, and yet permitting their still further ability to attach other molecules by residual affinity.