We thus arrive at an explanation of antagonism. The theory attempts to ac count for the following facts.

1. Why both NaCl and CaCl, are toxic.

tion of certain fundamental problems of biology.

Reference has been made to the suggestion that calcium antagonizes sodium by

Time in Hours

38 NaCl +62 CaCl2

2. Why when mixed in the proper proportions their toxicity is greatly diminished (antagonistic action).

3. Why they have opposite effects on permeability.

4. Why the decrease of permeability produced by CaCl, must be followed by an increase when the exposure is sufficiently prolonged.

5. Why all toxicity disappears in sea water. This is accounted for by supposing that in sea water A is formed as fast as it decomposes.

The theory gives a quantitative explanation of the toxicity of all the mixtures and enables us to predict the resistance (and permeability) in any mixture at any moment during exposure.

It likewise emphasizes the fact that life processes consist largely of consecutive reactions and that analysis of the dynamics of such reactions is indispensable for the solu4 Cf. Proc. Am. Phil. Soc., 55: 533, 1916.

preventing it from entering the cell. This explanation encounters a difficulty in the fact that even in a balanced solution the salts penetrate the cell. This difficulty disappears if we adopt the point of view which has just been presented, for it is evident that on this basis we do not regard antagonism as due to prevention of penetration. Nor is there any reason to suppose that the penetration of salts will have an unfavorable effect provided that as they penetrate into the cell the balance between them is preserved.

There is another aspect of the subject which is of considerable interest. It is usually found that when antagonistic substances are mixed in various combinations there is one proportion which is more favorable than others. If we increase the concentration of one constituent it is necessary to increase the concentrations of the others in like proportion in order to preserve the optimum condition. This law of

direct proportionality has been identified with Weber's law by Loeb, who says:

Since this law underlies many phenomena of stimulation it appears possible that changes in the concentration of antagonistic ions or salts are the means by which these stimulations may be brought about.

we can see why the most favorable proportion must remain approximately the same in spite of variations in concentration, and we thus arrive at a satisfactory explanation of Weber's law.

There are other ways in which perme

tions it seems desirable to ascertain what mechanism makes one proportion better than others and preserves this preeminence than others and preserves this preeminence in spite of changes in concentration.

Precisely this kind of mechanism is involved in the theory just outlined. It is easy to see that such a mechanism must exist if the formation of Na,XСaCl, takes place at a surface. In a surface substances

usually exist in a different concentration from that which they have elsewhere in the solution. If NaCl and CaCl, migrate into the surface, so as to become more concentrated there than in the rest of the solution, their concentration in the surface must increase, as their concentration in the solu

tion increases, up to the point where the surface is saturated. Beyond this point an increase in their concentration in the solution produces no effect on their concentration in the surface.

When this stage has been reached the formation of Na2XCaCl, if it takes place in the surface, will not be affected by an increase in the concentration of the salts in the solution. It will, however, be affected by changes in the relative proportions of the salts. The number of molecules in a unit of surface will remain nearly constant, but if the proportion of NaCl in the solution be increased some of the CaCl, in the surface will be displaced by NaCl. Below the saturation point the relative proportions of the salts will be of less importance than their total concentration: this is the case at low concentrations in the region of the so-called "nutritive effects."

It is evident that if we adopt this theory

lation. One of these has to do with anesthesia. Typical anesthetics decrease permeability. This accords with the idea that stimulation depends on the movement of

ions in the tissue. Such movement would be checked by decrease of permeability.

Another has to do with mechanical stimulation. It is well known that the effects of certain kinds of stimuli can be referred

directly to chemical changes which they produce in the protoplasm, but there are other kinds which appear to operate by physical means only. In the latter category are such stimuli as contact, mechanical shock and gravitation. While their action appears at first sight to be purely mechanical, they are able to produce effects so

much like those of chemical stimuli that it appears probable that in every case their action must involve chemical changes.

The chief difficulty which confronts a theory of mechanical stimulation appears to be this: How can purely physical alterations in the protoplasm give rise to chemical changes? It would seem that a satisfactory solution of this problem might serve to bring all kinds of stimulation under a common point of view, by showing that a stim ulus acts in every case by the production of chemical reactions.

An answer to this question is suggested by some observations on the cells of the marine alga Griffithsia. When one of the larger cells is placed under the microscope and touched near one end a change occurs in the chromatophores directly beneath the spot which is touched. The surfaces of the chromatophores in this region become per

meable to the red pigment, which begins to diffuse out into the surrounding protoplasm. This change begins soon after the cell is touched. As the red pigment diffuses through the protoplasm it soon reaches neighboring chromatophores and it may be seen that their surfaces also become permeable and their pigments begin to diffuse out. In this way a wave-which may be compared to a wave of stimulation-progresses along the cell until the opposite end is reached.

The rate of propagation of this wave corresponds to that of the diffusion of the pigment. It would seem that at the point where the cell is touched, pigment, and probably other substances, are set free, diffuse out and set up secondary changes as they progress. These changes are doubtless chemical in nature.

The important question then arises: How does the contact initiate the outward diffusion of the pigment or other substances? It would seem that this may be due to a mechanical rupture of the surface layer of the chromatophores which is either not repaired at all or only very slowly. Many cases are known in which the surface layers of protoplasmic structures behave in this way. If, therefore, such structures exist within the cell, it is evident that any deformation of the protoplasm which is sufficient to rupture their surface layers will permit their contents to diffuse out into the surrounding protoplasm. A great variety of cellular structures (plastids, vacuoles, "microsomes," inclusions, etc.), possess surface layers of great delicacy and it is easy to see how some of these may be ruptured by even the slightest mechanical disturbance.

If these processes occur it is evident that purely physical alterations in the protoplasm can give rise to chemical changes. Responses to contact and mechanical stim

IT is as a human being ever striving upward that I would portray John Muir.

From his early boyhood to his old age this spirit dominated him. As a child in Scotland, at every opportunity, in spite of parental prohibitions, and notwithstanding the certainty of punishment upon his return, he would steal away to the green fields and the seashore, eagerly interested in everything alive.

Illustrating this trait, I quote his boyhood impressions of the skylarks:2

Oftentimes on a broad meadow near Dunbar we stood for hours enjoying their marvelous singing and soaring. From the grass where the nest was hidden the male would suddenly rise, as straight as if shot up, to a height of perhaps thirty or forty feet, and, sustaining himself with rapid wing-beats, pour down the most delicious melody, sweet and clear and strong, overflowing all bounds, then suddenly he would soar higher again and again, ever higher and higher, soaring and singing until lost to sight even in perfectly clear days, and oftentimes in cloudy weather "far in the downy cloud' . . . and still the music came pouring down to us in glorious profusion, from a height far above our vision, requiring marvelous power of

1 Address delivered upon the occasion of the unveiling of a bronze bust by the sculptor C. S. Pietro, at the University of Wisconsin, December 6, 1916.

2"The Story of My Boyhood and Youth," John Muir (Houghton-Mifflin Co., 1913), pp. 46 and 47.

wing and marvelous power of voice, for that rich, delicious, soft, and yet clear music was distinctly heard long after the bird was out of sight.

At the age of eleven Muir with his father came to America to a farm beside a lake a few miles from Portage. His interest in the life of the wilderness, new to him, was thrilling. When first on Fountain Lake meadow he saw the lightning bugs, he thought to himself3

that the whole wonderful fairy show must be in my eyes; for only in fighting, when my eyes were struck, had I ever seen anything in the least like it. But when I asked my brother if he saw anything strange in the meadow, he said: "Yes, it's all covered with shaky fire-sparks.'' Then I guessed it might be something, outside of us.

Again when first he heard partridge drumming he thought,*

It must be made by some strange disturbance in my head or stomach, but as all seemed serene within, I asked David whether he heard anything queer. "Yes," he said, "I hear something saying boomp, boomp, boomp, and I'm wondering at it." Then I was half satisfied that the source of the mysterious sound must be in something outside of us, coming perhaps from the ground or from some ghost or bogie or woodland fairy.

Every boy who has grown up in Wisconsin and has a tinge of the love of nature will appreciate how accurately does John Muir tell of the feelings inspired in the heart of the lad, after the long cold winter, by the first migrating birds and the early spring flowers. The robin and the bluebird declare that spring is approaching, and the pasque flower shouts that spring has arrived.

Muir became intimately familiar with the southern Wisconsin flowers. He knew the gorgeous white water lily, the deliciously perfumed, delicate lady's slipper, white, pink and yellow, the scarlet painted cup, the nodding trillium and all the other beautiful early spring flowers so dear to the Wisconsin country children.

The life of the boy on the farm in pioneer days was one of hard work, and that of Muir

8The Story of My Boyhood and Youth," p. 71. 4 Ibid., p. 72.

was exceptionally hard; but he differed from the majority of his fellows in that he was not content simply to become a plowboy. Notwithstanding the prolonged physical labor, his inner spirit expressed itself, in the summer by his love of out of doors, and in the winter by study and mechanical invention.

After leaving school in Scotland at the age of eleven, Muir had little further opportunity as a boy for formal instruction. He succeeded, however, in persuading his father to get for him a higher arithmetic; and in the ends of the afternoons and in the evenings after the day's work he mastered the book; he followed this by algebra, geometry and trigonometry.

From the neighbors, and in various ways, he possessed himself of Scott's novels and the volumes of a number of the poets, including Shakespeare and Milton; and also he read the "Pilgrim's Progress," Josephus and similar works.

In the winter, immediately after prayers, he was required to go to bed; but the elder Muir, one night in repeating the order added, "If you will read, get up in the morning and read. You may get up in the morning as early as you like." From that time throughout the winter Muir was up at one o'clock. Although his father protested, he was held to his promise. In this manner Muir gained five hours each day, the time being used partly with his books and partly in the mechanical inventions in which he became interestedthermometers, barometers, hygrometers, pyrometers and clocks.

His more complicated clock told not only the hour of the day, but the day of the week and the month, and also had attachments which upturned his bedstead, setting him on his feet at the required hour in the morning, and other attachments to start the fire or light the lamp.

The ingenuity which young Muir displayed. in mechanical construction, had he followed this talent, undoubtedly would have given him a great career as an inventor. But such a life would never have satisfied his inner impulses. Hearing of a state fair at Madison, Muir

At Madison, Muir worked at any sort of thing, earning a few dollars. Of this he said:5

I was thus winning my bread while hoping that something would turn up that might enable me to make money enough to enter the state university. This was my ambition, and it never wavered, no matter what I was doing. No university, it seemed to me, could be more admirably situated, and as I sauntered about it, charmed with its fine lawns and trees and beautiful lakes, and saw the students going and coming with their books, and occasionally practising with a theodolite in measuring distances, I thought that if I could only join them it would be the greatest joy of life. I was desperately hungry and thirsty for knowledge and willing to endure anything to get it.

Of his admission to the university he says: With fear and trembling, overladen with ignorance, I called upon Professor Sterling, the dean of the faculty, who was then acting president, presented my case, and told him how far I had got on with my studies at home, and that I hadn't been to school since leaving Scotland at the age of eleven years, excepting one short term of a couple of months at a district school, because I could not be spared from the farm work. After hearing my story, the kind professor welcomed me to the glorious university-next, it seemed to me, to the Kingdom of Heaven. After a few weeks in the preparatory department I entered the fresh

man class.

Doing odd jobs during the term and working in the harvest fields in the summer, Muir maintained himself at the university for four years; but pursued those studies toward which he was attracted rather than a regular course. He was interested in all the sciences, and particularly in botany and geology. It was in his botanical studies about these Madison lakes that he first learned to wander. Upon leaving the university Muir says:7

5 Ibid., p. 274.

Ibid., pp. 275-76.

"My Boyhood and Youth," pp. 286-287.

From the top of a hill on the north side of Lake Mendota I gained a last wistful, lingering view of the beautiful university grounds and buildings where I had spent so many hungry and happy and hopeful days. There with streaming eyes I bade my blessed Alma Mater farewell. But I was only leaving one university for another, the Wisconsin University for the University of the Wilderness.

John Muir's life work was that of an explorer and a student of nature. His travels, beginning in the region of the Great Lakes shortly after leaving the university, extended throughout the world, and continued to old age. His journeys carried him to Russia, Siberia, Africa, Australia, South America, and other remote regions little visited by the ordinary traveler. But his contributions to knowledge were mainly due to his studies in California and Alaska.

It was inevitable that after reaching California Muir should be drawn by an irresistible attraction to the Sierra Nevada. His first visit filled him with burning enthusiasm; and during some ten years he studied the flora, the fauna, the glaciers, and the topography of that superb range. His study of animals and plants was not that of systematic biologythe interior structures or methods of life growth-indeed was very unlike that in the biological laboratories of the present day. His interests were rather in the habits of the plants and animals and their relations to their neighbors and to their environment. Each animal or plant as an individual was a subject of interest to John Muir. The mighty silver firs, the sugar pines, the Douglas spruces and the gigantic sequoia were ever inspiring him; and he never ceased to write of their beauty and their majesty. However, he was no less moved by the dwarf cedars, pines and oaks, which near the timber line carried on a brave struggle through the years against the terrific storms and prolonged cold of the heights.

The wonderful variety and beauty of the With enthusiasm he sought and admired each flowers of the Sierra also deeply stirred him. species, whether found for the first time or an old friend.

The animals and their habits thrilled him with delight. There have been no more ap