An osmotic growth also shows indications of movements which are connected with its nutrition, and these movements are rhythmic, like those of respiration or circulation in a living organism. The growth of an osmotic production shows itself not as a continuous process but periodically. The water traverses the membrane, raises the pressure, and distends the cell; at first the cell wall resists by reason of its elasticity, it then suddenly relaxes, yielding to the osmotic pressure and bulging out at a thinner spot on the surface; the internal pressure falls suddenly, and there is a pause in the growth. This rhythmic growth may be best observed by sowing in a solution of a tribasic alkaline phosphate, pellets composed of powdered calcium chloride moistened with glycerine, to which has been added 1 per cent. of monobasic calcium phosphate. The experiment is so arranged as to bend or incline the growing stems which shoot out from these grains. This may be done by carefully pouring above the mother liquor a layer of water, or a less concentrated solution. As the internal osmotic pressure rises, the drooping extremity of the twig will become turgescent and gradually lift itself {157} up, and then suddenly fall again for several millimetres. We have frequently watched this rhythmic movement for an hour or more--a slow gradual elevation of the extremity of the twig and a rapid fall recurring every four seconds or so. It may be objected that the substance of an osmotic growth is continually undergoing change, whereas a living organism transforms into its own substance the extraneous matter which it borrows from its environment. The distinction, however, is only an apparent one. The substance of a living being is also continually undergoing chemical change; it does not remain the same for a single instant. We see an evidence of this change in the evolution of age; the substance of the adult is not that of the infant. In some living organisms such as insects, especially the ephemeridae who have but a brief existence, this change of substance is even more rapid than that in an osmotic growth. It has been objected that osmotic productions cannot be compared with living organisms since they contain no albuminoid matter. This is to consider life as a substance, and to confound the synthesis of life with that of albumin. If albumin is ever produced by synthesis in the laboratory it will probably be dead albumin. All living organisms contain albumin; this is probably due to the fact that albuminoid matter is particularly adapted for the formation of osmotic membranes. Our osmotic productions are composed of the same elements as those which constitute living beings; an osmotic growth obtained by sowing calcium nitrate in a solution of potassium carbonate with sodium phosphate and sulphate contains all the principal elements of a living organism, viz. carbon, oxygen, hydrogen, nitrogen, sulphur, and phosphorus.