The Dynamics of Living Matter

into normal sea water divided as represented in these drawings. The division began (as was frequently the case) on one side (Fig. 10), and the protoplasm then flowed in the direction of the two arrows (Fig. u) in opposite directions toward the two nuclei. The connecting piece becomes empty of protoplasm and only the pigmented solid surface film is left (Fig. 12), and finally this also disappears (Fig. 13). It is, however, possible that contractile forces acting in a radial direction in an astrosphere might bring about similar results.

The process of the cell division proper seems to consist also of several phases. A reduction of volume seems to occur in this process, inasmuch as the combined volume of the two daughter cells appears immediately after the division, smaller than the volume of the mother cell. This diminution of volume may be due to a loss of water, or watery liquid, on the part of the cell. There may also be a process of gelation on the part of certain constituents of the cell, e.g. the nucleus, which at this stage appears to form a solid mass, or possesses at its surface a solid wall.

The first investigation of animal phosphorescence that was of any consequence goes back to Faraday, who showed that the phosphores- cent part of a glowworm continues to send out light if it be made into a pulp. This observation speaks against the view of Kolliker and Pfliiger that the phosphorescence of animals is a function of "living" matter, and even, in certain cases, under the control of the nervous system. They were led to their view by the observation that "stimu- lation" could call forth the process of phosphorescence, while poisons and high temperatures caused it to disappear. From this Pfliiger *

drew the conclusion that phosphorescent matter is irritable, and "irrita- bility" is considered a sign of life. We must not, however, overlook the possibility that stimulation of an animal may produce the process of phosphorescence indirectly, e.g. by causing motions on the part of the animal which bring the phosphorescent matter into contact with oxygen. Giesebrecht * has furnished an absolute proof for the fact that phosphorescence may be produced in animals by non-living mate- rial. He found that certain pelagic copepods, e.g. Pleuromma gracile and Leuckartia flaviensis show phosphorescence, and that this phe- nomenon is confined to definite points of their body, which correspond to the ducts of certain glands of the skin of the animals. These glands secrete drops of a greenish yellow substance. As long as the animals lie quiet there is no phosphorescence visible, but they show this phenom- enon when pressed or heated, or if brought in contact with ammonia, alcohol, or glycerine. This might easily be interpreted as signifying that the phosphorescence of these animals is a phenomenon, which is produced by the stimulation of the animal. Giesebrecht found, how- ever, that the phosphorescence occurs only when the secretion of the glands is brought to the surface of the animal, and comes in contact with the sea water. He proved, moreover, that the secretion even re- tains its power of phosphorescing after the death of the animal. Dead copepods, which had been preserved in a dry condition for three weeks, still showed the phosphorescence at the opening of the glands, whenever they were put into water. The above-mentioned "stimuli" caused the phosphorescence only indirectly, by causing the squeezing out of the secretion of the glands from the duct.

How the contact of the secretion with water can cause the phos- phorescence is not yet clear. Radziszewski f has found that a number of organic compounds show phosphorescence at a comparatively low temperature, e.g. 10° C., when they come in contact with atmos- pheric oxygen, and the reaction is alkaline. Among these substances are the soaps of oleic acid, a number of alcohols, etc. This author assumes that the phosphorescence of animals is caused in the same way. Traces of the phosphorescent substances and of oxygen suffice for the production of the phenomenon. We can readily understand that mo- tions of an animal are favorable for the production of phosphorescence, as they tend to bring the oxygen (e.g. in the tracheae of insects) in con- tact with new particles of the phosphorescent substance. Giesebrecht questions the importance of oxygen for this process, inasmuch as in

* Giesebrecht, Mittheilungcn aits der zoologischen Station zii Neapel, Vol. 2, p. 648, his experiments the animals also showed phosphorescence in boiled water; but as very little oxygen suffices for the phenomenon, it is possible that in Giesebrecht's experiments sufficient oxygen was present for the pro- cess. The experimenters agree, in general, that free oxygen is neces- sary for phosphorescence. It is possible, however, that the conditions for phosphorescence may vary with the nature of the substance.

When Galvani noticed that the muscles of the leg of a frog twitch when touched with two metals, he believed that this phenomenon indicated the production of electricity in living organisms. Volta subsequently showed that the nerve-muscle preparation only acts as a sensitive rheoscope. Thus a misunderstood biological observation became the germ for the development of electrochemistry. It was found afterward that living organisms produce indeed some electrical energy, but in spite of the most diligent search nobody has yet been able to prove that the electrical energy thus produced plays any role in an essential life phenomenon, although this may be the case.

The liquids of the body must be the cause of the differences of potential in the tissues as only the electrolytes dissolved in these liquids are capable of producing differences of potential. The most common instances of the production of a difference of electrical potential are the cases of an active or dying nerve or muscle. When an element of a nerve is active or injured, and one electrode of a galvanometer is applied to the active or injured spot (Fig. 14), an- other to the neighboring resting, or normal element of the nerve or muscle, a cur- rent of positive electricity travels through the galvanometer from the resting, or normal, to the active, or injured element of the nerve or muscle. The activity of the muscle, or its injury, is accompanied by a production of acid, i.e. carbonic, and possibly, lactic acid. According to Waller CO2 is also produced in the active nerve.* I concluded from this that these currents might be due to the formation of acid. The H-ions have a much greater velocity of migration than any anion, and hence,

* Waller, Lectures on Physiology, I. On Animal Electricity, London, 1897. if in an active or injured- element of the nerve or muscle acid is formed, the hydrogen-ions must migrate faster into the neighboring tissue than the anions. Consequently, the active element will have an excess of free negatively charged ions, while the neighboring resting elements will assume a positive charge (Fig. 14). I published this explanation of the origin of currents of action in a preliminary way in an address at the Naturalists' meeting in 1897.* Oker-Blom-f has since expressed a similar view in regard to the current of demarcation ; and he mentions that Tschagovetz has published a similar view in a Russian journal.

Ostwald J has pointed out that the semipermeable membranes may possibly be permeable for only one class of ions, positive or negative, and "not only the currents in muscles and nerves, but also the myste- rious effects of electrical fishes might find their explanation by such a property of the semipermeable membranes." Bernstein § and Briin- ings || have recently adopted this view. Bernstein pointed out that, in order to explain the above-mentioned current of action, a specific permeability of the semipermeable membranes for cations must be assumed. It is hardly possible that differences in electrical poten- tial can arise in any other way in the tissues than by a separation of anions and cations of the electrolytes dissolved in the tissues. As the difference in the rate of diffusion for different ions always exists, especially when acids or alkalies are formed, and as a difference of the permeability of the protoplasm for oppositely charged ions may also easily exist or arise, it is not difficult to understand that so many life phenomena are accompanied by electrical changes and currents, e.g. when light falls upon the retina, or when glands secrete.

Plants also show such currents, especially such plants, as are dis- tinguished by a comparatively quick conduction of stimuli, e.g. Mimosa or Drosera. This lends, perhaps, support to the idea expressed by Hermann that the current of action is the cause, or means, of the propa- gation of the nerve impulse. When a nerve or muscle is stimulated, the stimulated spot becomes negatively electrical as compared with the neighboring resting spot. In the next element of time this latter spot becomes the seat of activity, and now becomes negative toward the more distantly situated piece of nerve, etc. A region or wave of negative potential is thus propagated from the original seat of stimu- lation in both directions, through the nerve. Bernstein has found that this negative wave is propagated with the same velocity as the

nerve impulse, so that there exists a possibility that this difference of potential which originates upon stimulation is the cause, or the means, of propagation for the nerve impulse. Hermann has given a more detailed sketch of such an assumption.* The axis cylinder of the nerve is surrounded by a liquid conductor of electricity, i.e. a solution of electrolytes. If a certain element A of the axis cylinder be stimulated, it will assume a negative charge, while the neighboring parts B assume a positive charge. This leads to the formation of a microscopic cur- rent from B through the liquid conductor to A. This current may be considered as a stimulating current for the axis cylinder with an anode at A and a cathode at B. We shall see in a later lecture that if a current be made, the stimulation occurs at the cathode, while the anode is put into a condition of diminished irritability. Therefore, the region A now returns to a condition of rest, while B becomes active. Then the same process is repeated for B and its neighboring element, etc. Waller has been able to determine the beginning of life in the hen's egg and in seeds of plants by galvanometric tests; he has also deter- mined the cessation of life in the same manner. f These facts may serve as a further indication that all life phenomena are accompanied by electrical phenomena. We shall see later that salts play a great role in life phenomena ; and it is obvious that if changes in the nature and number of ions in a solution accompany life phenomena, electrical currents must also be a necessary consequence.

THE green plants are the factories in which the material for the nutrition for animals and fungi is prepared. The green plant, how- ever, manufactures also, as long as it grows, its own living matter out of the electrolytes of the soil and the CO2 of the air. The CO2 is util- ized for the formation of carbohydrates and probably fats; the salts of ammonia, nitrates, phosphates, and sulphates are used for the building lip of nitrogenous compounds. One of the nutritive solutions * which is most commonly used for phanerogamic plants is as follows : —

The whole is dissolved in from 3 1. to 7 1. of water. A few drops of ferric chloride are added to this solution. This solution may vary within certain limits. It contains besides the anions CO3, NO3, SO4, and PO4, which are necessary for the synthesis of the essential compounds of the plant, the cations K, Ca, Mg, which do not seem equally necessary for the synthesis of living matter. In addition to these, free oxygen is absolutely necessary for the formation of living matter in green plants.

For the fungi the nutritive solutions are similarly constituted, with this difference only, that they cannot make carbohydrates of CO2 ; and they are therefore compelled to get their sugar from plants or animals. If raised in a solution containing sugar or certain organic acids (e.g. acetic, tartaric acids) and certain salts, they can also make all the constituents of living matter, e.g. fats, proteins, nucleins. Raulin, a pupil of Pasteur, has investigated with unparalleled thor- oughness the optimal nutritive solutions for a fungus, Aspergillus niger. Raulin * determined which nutritive solution gave the great- est development of living matter from a given quantity of spores, and found that it possessed the following composition : —

Part of the free acid in Raulin's solution is neutralized by the HO- ions due to the presence of (NH4)3PO4 and K2CO3 in the solution. The sugar, fatty acid, ammonia, SO4, and PO4 are used for the build- ing up of living matter ; but it is not clear what the role of K, Mg, Zn, and Fe is. It is remarkable that Ca is not required, and it seems to be a general fact that Ca is not of great importance for the fungi, while it is of great importance for animals, and apparently also for the higher plants. But what is the role of the cations?

It has been noticed that the living tissues of plants, as well as of animals, possess a selective power for certain salts, especially for K-salts. Although in fresh-water streams the concentration of K-salts is often very low, the plants which live in it are capable of storing up a com- paratively large amount in their tissues. The muscle of animals shows the same phenomenon, inasmuch as it contains a much higher per- centage of potassium than the blood. This "selective power" admits of only one explanation; namely, that the potassium is used for the building up of more complex compounds in which the K cannot be dissociated as a free ion. If a tissue utilizes one kind of metals in this way, e.g. K, while another metal, e.g. Na, is chiefly used for the forma- tion of dissociable compounds with Na as a free ion, the consequence will be that the ashes of a tissue contain K and Na in altogether differ- ent proportions from what they are contained in the surrounding solu-

tion. I think we may take it for granted that, at least, K forms a nondissociable constituent of the protoplasm of a number of tissues of animals and plants, and that it therefore may be considered a building stone for living matter in the same sense as the above-mentioned anions. This fact explains the so-called oligodynamic effects. This term was applied to the fact that certain heavy metals like Cu, or, as I believe, traces of their salts, can produce a toxic effect. Obviously the Cu-ions form upon their entrance into the cell undissociable or practically undissociable compounds with protein substances, and thus their con- centration is kept lower in the cell than in the surrounding solution. The consequence is that in due length of time enough Cu may diffuse into the cell to act toxically. There is therefore no reason why we should continue to set aside the oligodynamic effects as a distinct group of phenomena in biology. It is quite possible that an ion may be utilized in two ways by a tissue; namely, for the synthesis of mole- cules from which it can no longer be dissociated as an ion, and in the form of salts, — possibly ion-proteids, — where the metal can disso- ciate as an ion.

What is true for the K may also be true for the Mg, but it can scarcely be so for the Zn in Raulin's solution, although, curiously enough, it is not so much less important for Aspergillus than K. Raulin found that if he allowed spores to develop on the above-mentioned solution, which contained all fourteen constituents, except K, the crop was only one twenty-fifth of the dry weight of that which he got when he added K. When the trace of Zn contained in that solution was omitted, the dry weight of the crop was only one tenth of that which he obtained when Zn was added. Raulin has made similar determinations for all the constituents of his nutritive solution. The figure following each sub- stance in the table below expresses how many times greater the dry weight of the crop was with the addition of the substance than without it.

It was to be expected that the omission of NH4 from the solution would reduce the crop considerably (to T^-g of its weight), inasmuch as it furnishes the material for the manufacture of the proteins. The PO4 is needed for the nucleins, and it is probable that the Mg is necessary for the building up of definite important compounds; but the Zn is no part of any compound of the plant. It is therefore obvious that the nutritive solution for a plant not only contains substances which are of importance for the building up of its living matter, but also sub- stances which do not enter into these compounds and are yet of im- portance. I am inclined to believe that the explanation of the latter facts takes us back to the antagonistic salt effects discussed in the previous lecture.

If we compare the nutritive solutions for animals with those of plants, we find in general that PO4-, NH4-, NO3-ions, which are of such im- portance for plants, are either of no importance for animals, or are directly poisonous, e.g. the NH4-ions. Inasmuch as the animals get all their proteins and carbohydrates directly or indirectly from plants, it is to be expected that they do not depend upon the CO2 of the air or the NH4, NO3, or PO4 of the soil. We meet, however, with another striking difference between animals and plants, which was not to be expected a priori; namely, the fact that Na, which appears neither in Knop's solution for Phanerogams nor in Raulin's solution, is one of the most, if not the most, important constituent of a nutritive solu- tion for animals. Next in importance for animals is Ca, which does not appear in Raulin's solution, although it seems to be important for phanerogamic plants.

We have already seen that the majority of marine animals, e.g. marine Gammarus, can only live in solutions which contain certain salts, NaCl, CaCl2, KC1, and MgCl2 in definite proportions. The lack of Mg is not so fatal as the lack of one of the other three metals. One anion is sufficient; namely, Cl. Without Na, K, or Ca the animal lives at the utmost but a couple of hours, as a rule a much shorter time; while in a mixture of NaCl, KC1, and CaCl2 it may live as long as two days, and still longer upon the addition of MgCl2.

Similar results were obtained in experiments on the substances which Tubularians need for regeneration and growth. These Hy- droids can only live in a solution which contains NaCl, KC1, CaCl2, and MgCl2. If one of these salts is lacking, no polyp can be regener- ated. In order to allow the polyp to grow, a substance must be added which keeps the reaction of the solution neutral; namely, NaHCO3* The conditions for the development of the eggs of the sea urchin,

Strongylocentrotus purpuratus, are similar.* NaCl, KC1, and CaCl2 are necessary: as without one of these salts no segmentation is pos- sible. For the complete development Mg and SO4 are also required, but these latter two constituents do not possess the same degree of importance as Ca, Na, or K. In addition, a substance is needed which keeps the solution neutral, e.g. NaHCO3. Other constituents of the sea water, such as PO4, Fe, are not required. This latter statement disagrees with the conclusions of Herbst. f

The same is true for Medusae : they will keep alive in solutions of NaCl, KC1, CaCL,, MgCl2, in the proportion and concentration in which these solutions occur in the sea water. In addition, a substance is required which keeps the sea water neutral, e.g. NaHCO3. I think these examples may suffice as the proof of the fact that for marine animals NaCl and CaCL, and KC1 are essential for the maintenance of life. It is questionable whether the substances which growing animals require for the manufacture of living matter are taken from the surrounding solution. Were this the case, only traces of any of these salts should be sufficient, while in reality the proportion of Na, K, and Ca can vary only within certain limits in the solution.

The tissues of marine animals seem to require a solution of the same character. Dr. Rogers has, at my suggestion, determined in which solution the heart of a marine crab beats longest. He found that sea water is an excellent "nutritive" solution for the heart, and that the same is true for a van't Hoff solution; namely, a solution of 100 molecules NaCl, 2.2 KC1, 2 CaCl2, 7.8 MgCl2, 3.8 MgSO4. To this should be added a trace of NaHCO3. The action of sea water becomes better if a little CaCL, is added, possibly on account of a slight antago- nistic effect between Ca and Mg.

It is remarkable that the tissues of fresh-water and land animals, e.g. the frog, the tortoise, and apparently the mammals, live longest in a solution which has the same constitution as the sea water, and differs from the latter only in its concentration. The optimal concen- tration of the solutions for frogs and land animals is about that of a •Q- solution of NaCl. In order to keep the isolated heart of cold-blooded animals alive, Ringer has recommended the following solution : — J

t Herbst, Arehiv fitr Entivickehitigsmechanik, Vol. 5, p. 649, 1897, and numerous other papers on the same subject. Herbst did not recognize the antagonistic effects of salts, and so concluded that if the elimination of one of the constituents of the sea water was injurious, this proved the neces- sity of the omitted substance for the animal. The above-mentioned observations on Fundu- lus show in m.y opinion the fallacy of this conclusion. Rusch has applied this solution with success for the isolated heart of warm-blooded animals, with the difference only that he added 8 g. instead of 6 g. of NaCl to 1000 g. of water.

Locke * recommends the following solution for the isolated heart of the rabbit: — The solution is said to be more effective if a little dextrose is added, Otherwise Locke's solution differs from Ringer's by a somewhat higher amount of KC1 and CaCl2. His figures for these latter salts are approximately those which Abderhalden found for the concen- tration of these salts in the serum of rabbits; namely, 0.024 per cent CaCl2 and 0.042 per cent KCl.f

If we express the percentage solutions of Ringer, Locke, or Abder- halden, in the values of grammolecular solutions, we find that it is approximately 100 molecules NaCl to 2 molecules of CaCl2. This is practically the proportion in which these salts exist in the sea water, and in which marine animals live longest. This proportion may vary a little for marine animals, and the same is true for the solutions in which the tissues of animals live best, as a comparison of the figures of Ringer and Locke shows.