The Story of the Living Machine / A Review of the Conclusions of Modern Biology in Regard / to the Mechanism Which Controls the Phenomena of Living / Activity

by H. W. Conn

Consciousness.—It may be well here to refer to one other factor in the problem, because it has somewhat recently been brought into prominence. This factor is consciousness on the part of the animal. Among plants and the lower animals this factor can have no significance, but consciousness certainly occurs among the higher animals. Just when or how it appeared are questions which are not answered, and perhaps never will be. But consciousness, after it had once made its appearance, became a controlling factor in the development of the machine. It must not be understood by this that animals have had any consciousness of the development of their body, or that they have made any conscious endeavours to modify its development. This has not always been understood. It has been frequently supposed that the claim that consciousness has an influence upon the development of an animal means that the animal has made conscious efforts to develop in certain directions. For example, it has been suggested that the tiger, conscious of the advantage of being striped, had a desire to possess stripes, and the desire caused their appearance. This is absurd. Consciousness has been a factor in the development of the machine, but an indirect one. Consciousness leads to effort, and effort has a direct influence in development. For example, an animal is conscious of hunger, and this leads to efforts on his part to obtain food. His efforts to obtain food may lead to migration or to the adoption of new kinds of food or to conflicts with various kinds of rivals, and all of these efforts are potent factors in determining the direction of development. Consciousness, again, may lead certain animals to take pleasure in each other's society, or to recognize that in mutual association they have protection against common enemies. Such a consciousness will give rise to social habits, and social habits are a very potent factor in determining the direction in which the inherited variations will tend; not, perhaps, because it effects the variations themselves, but rather because it determines which variations among the many shall be preserved and which rejected by natural selection. Consciousness may lead the antelope to recognize that he has no chance in a combat with a lion, and this will induce him to flee. The habit of flight would then develop the power of flight, not because the antelope desired such power, but because the animals with variations which gave increased power of flight would be the ones to escape the lion, while the slower ones would die without offspring. Thus consciousness would indirectly, though not directly, result in the lengthening of the legs of the animal and in the strengthening of his running muscles. Beyond a doubt this factor of consciousness has been a factor of no little moment in the development of the higher types of organic machines. We can as yet only dimly understand its action, but it must hereafter be counted as one of the influences in the evolution of the living machine.

But, after all, these are only questions of the method of the action of certain well demonstrated, fundamental factors. Whether by natural selection, or by the inheritance of acquired characters produced by the environment, or whether by the effect of isolation of groups of individuals, the machine building has always been produced in the same way. A machine, either through the direct influence of the environment, or as a result of sexual combination of germ plasm, shows a variation from its parents. This variation proves of value to its possessor, who lives and transmits it permanently to posterity. Thus step by step, one part is added to another, until the machine has grown into the intricately adapted structure which we call the animal or plant. This has been nature's method of building machines, all based upon the three properties possessed by the living cell—reproduction, variation, and heredity.

Summary of Nature's Power of Building Machines.—Let us now notice the position we have reached. Our problem in the present chapter has been to find out whether nature possesses forces adequate to explain the building of machines with their parts accurately adapted to each other so as to act harmoniously for certain ends. Astronomy has shown that she has forces for the building of worlds; geology, that she has forces for making mountain and valley; and chemistry, that she has forces for building chemical compounds. But the organism is neither a world, nor a mass of matter, nor a chemical compound. It is a machine. Has nature any forces for machine building? We have found that by the use of the three factors, reproduction, variation, and heredity, nature is able to produce a machine of ever greater and greater complexity, with the parts all adapted to each other. Now the difference between a machine and a mass of matter is simply in the adaptation of parts to act harmoniously for definite ends. Hence if we are allowed these three factors, we can say that nature does possess forces adequate to the manufacture of machines. These forces are not chemical forces, and the construction of the machine has thus been brought about by forces entirely different from those which produced the chemical molecule.

But we have plainly not reached the bottom of the matter in our attempt to explain the machinery of living things. We have based the whole process upon three factors. Reproduction, variation, and heredity are the properties of all living matter; but they are not, like gravity and chemism, universal forces of nature. They occur in living organisms only. Why should they occur in living organisms, and here alone? These three properties are perhaps the most marvellous properties of nature; and surely we have not finished our task if we have based the whole process of machine building upon these mysterious phenomena, leaving them unintelligible. We must therefore now ask whether we can proceed any farther and find any explanation of these fundamental powers of the living machine.

It must be confessed that here we are at present forced to stop. We can proceed no further with any certainty, or even probability. We may say that variation and heredity are only phases of reproduction, and reproduction is a property of the living cell. We may say that this power of reproduction is dependent upon the power of assimilation and growth, for cell division is a result of cell growth. We may further say that growth and assimilation are chemical processes resulting from the oxidation of food, and that thus all of these processes are to be reduced to chemical forces. In this way we may seem to have a chemical foundation for life phenomena. But clearly this is far from satisfactory. In the first place, it utterly fails to explain why the living cell has these properties, while no other body possesses them, nor why they are possessed by living protoplasms alone, ceasing instantly with death. Indeed it does not tell us what death can be. Secondly, it utterly fails to explain the marvels of cell division with resulting hereditary transmission. For all this we must fall back upon the structure of protoplasm, and say that the cell machinery is so adjusted that the machine, when acting as a whole, is capable of transforming the energy of chemical composition in certain directions. These fundamental properties are then the properties of the cell machine just as surely as printing is the property of the printing press. We can no more account for the life phenomena by chemical powers than we can for printing by chemical forces manifested in the burning of the coal in the engine room. To be sure, it is the chemical forces in the engine room that furnishes the energy, but it is the machinery of the press that explains the printing. So, while chemical forces supply life energy, it is the cell machinery that must explain the fundamental living factors. So long as this machine is intact it can continue to run and perform its duties. But it is a very delicate machine and is easily broken. When it is broken its activities cease. A broken machine can not run. It is dead. In short, we come back once more to the idea of the machinery of protoplasm, and must base our understanding of its properties upon its structure.

It is proper to state that there are still some biologists who insist that the ultimate explanation of protoplasm is purely chemical and that life phenomena may be manifested in mixtures of compounds that are purely physical mixtures and not machines. It is claimed that much of this cell structure described above is due to imperfection in microscopic methods and does not really exist in living protoplasm, while the marvellous activities described are found only in the highly organized cell, but do not belong to simple protoplasm. It is claimed that simple protoplasm consists of a physical mixture of two different compounds which form a foam when thus mixed, and that much of the described structure of protoplasm is only the appearance of this foam. This conception is certainly not the prevalent one to-day; and even if it should be the proper one, it would still leave the cell as an extremely complicated machine. Under any view the cell is a mechanism and must be resolved into subordinate parts. It may be uncertain whether these subordinate parts are to be regarded simply as chemical compounds physically mixed, or as smaller units each of which is a smaller mechanism. At all events, at the present time we know of no such simple protoplasm capable of living activities apart from machinery, and the problem of explaining life, even in the simplest form known, remains the problem of explaining a mechanism.

The Origin of the Cell Machine.—We have thus set before us another problem, which is after all the fundamental one, namely, to ask whether we can tell anything of nature's method of building the protoplasmic machine. The building of the higher animal and plant, as we have seen, is the result of the powers of protoplasm; but protoplasm itself is a machine. What has been its history?

We must first notice that no notion of chemical evolution helps us out. It has been a favourite thought with some that the origin of the first living thing was the result of chemical evolution. As the result of physical forces there was produced, from the original nebulous mass, a more and more complicated system until the world was formed. Then chemical phenomena became more and more complicated until, with the production of more and more complicated compounds, protoplasm was finally produced. A few years ago, under the impulse of the idea that protoplasm was a compound, or at least a simple mixture of compounds, this thought of protoplasm as the result of chemical evolution was quite significant. Physical forces, chemical forces, and vital forces, explain successively the origin of worlds, protoplasm, and organisms. This conception has, however, no longer much significance. We know of no such living chemical compound apart from cell machinery. A new conception of protoplasm has arisen which demands a different explanation of its origin. Since it is a machine rather than a compound, mechanical rather than chemical forces are required for its explanation.

Have we then any suggestion as to the method of the origin of this protoplasmic machine? Our answer must, at the present, be certainly in the negative. The complexity of the cell tells us plainly that it can not be the ultimate living substance which may have arisen from chemical evolution. It is made up of parts delicately adapted to act in harmony with each other, and its activity depends upon the relation of these parts. Whatever chemical forces may have accomplished, they never could have combined different bodies into linin, centrosomes, chromosomes, etc., which, as we have seen, are the basis of cell life. To account for this machine, therefore, we are driven to assume either that it was produced by some unknown intelligent power in its present condition of complex adjustment, or to assume that it has had a long history of building by successive steps, just as we have seen to be the case with the higher organisms. The latter assumption is, of course, in harmony with the general trend of thought. To-day protoplasm is produced only from other protoplasm; but, plainly, the first protoplasm on the earth must have had a different origin. We must therefore next look for facts which will enable us to understand its origin. We have seen that the animal and plant machines have been built up from the simple cell as the result of its powers acting under the ordinary conditions of nature. Now, in accordance with this general line of thought, we shall be compelled to assume that previous to the period of building machinery which we have been considering, there was another period of machine building during which this cell machine was built by certain natural forces.

But here we are forced to stop, for nothing which we yet know gives even a hint as to the method by which this machine was produced. We have, however, seen that there are forces in nature efficient in building machines, as well as those for producing chemical compounds; and this, doubtless, suggests to us that there may be similar forces at work in building protoplasm. If we can find natural forces by which the simplest bit of living matter can be built up into a complicated machine like the ox, with its many delicately adjusted parts, it is certainly natural to imagine that the same forces may have built this simpler machine with which we started. But such a conclusion is for a simple reason impossible. We have seen that the essential factor in this machine building is reproduction, with the correlated powers of variation and heredity. Without these forces we could not have advanced in this machine building at all. But these properties are themselves the result of the machinery of protoplasm. We have no reason for thinking that this property of reproduction can occur in any other object in nature except this protoplasmic machine. Of course, then, if reproduction is the result of the structure of protoplasm we can not use this factor in explaining the origin of this protoplasm. The powers of the completed machine can not be brought forward to account for its origin. Thus the one fundamental factor for machine building is lacking, and if we are to explain nature's method of producing protoplasm from simpler structures, we must either suppose that the parts of the cell are capable of reproduction and subject to heredity, or we must look for some other method. Such a road has however not yet been found, nor have we any idea in what direction to look. But the fact that nature has methods of machine building, as we have seen, may hold out the possibility that some day we may discover her method of building this primitive living machine, the cell.