About the same time or but shortly after the Negrito reached southern Asia there was taking place a larger movement of yellowbrown population from the more westward drying up regions into eastern Asia and over southern Siberia. This population gradually spread over the whole Asiatic continent north of the Himalayas and, multiplying, began to extend in all directions—through the Negrito area to the south and southeastward, peopling the southeastern parts of the continent with Malaysia; it peopled the Nippon Archipelago; and as food was diminishing or pressure behind became greater, it extended along the coast northward to the northeastern limits of the continent, whence it passed on gradually and repeatedly, over the various practicable routes, still further eastward, reaching and eventually peopling America. Still later the surplus of this brown population in the south, admixed already to some extent with the Negrito as well as with a more important contingent of the more recent near-white-man types from the west, peopled Micronesia and Polynesia. Meanwhile the older and darker yellow-brown wave was, according to all indications, followed by successively lighter, though still yellow-brown waves of people from the west, which, penetrating among and mixing with the old population, gave us such actual ethnic units as the Chinese, Japanese, Koreans and Tatars. Remnants of the oldest brown wave are still discernible in the living population in many parts of this vast region, particularly in Mongolia, Thibet, the Saghalien and the Formosa Island, as well as in parts of Siberia.

All these yellow-brown people could have had but one farback parentage-that of the early Neolithic western Asiatics, and with these that of the Paleolithic Europeans. They unquestionably must proceed from the same source as the white race, but they separated from the mother stock before or during the earlier parts of the period of its differentiation into the white Europeans.

A word at the conclusion about the origin of the Negrito and Negro. They too, upon a critical examination, present ample evidence of original identity with the old Mediterranean and European stock. They are no separate species, and the main physical differences between them and the rest of mankind are but skin deep. Their forebears must have separated from the general parent

stock at a distant and yet not excessively distant period-not earlier in all probability and rather later than the second half, the latter Neanderthal part, of the Paleolithic period; and passing deeper into Africa they eventually became modified through environmental influences into the smaller and the taller Negro.

The cradle of humanity therefore, according to present indications, was essentially southwestern Europe, with later on the Mediterranean Basin, western Asia, and Africa. It is primarily from Europe and secondarily from these regions that the earth was peopled. And its peopling, so far as can now be determined, appears on the whole to be a matter of comparative recency.

That earlier man was not able to people the globe before was in all probability due to his insufficient effectiveness. Up towards near the end of the glacial times and his old stone culture, he had evidently all he could do to preserve mere existence. Only after he advanced mentally and in culture so far that he could control his environment sufficiently to secure a steady surplus of births over deaths was he able, and in fact became obliged, to extend over other parts of the earth.

The cause of man's peopling the world, it may well be assumed, was not a mere wish to do so, but chiefly necessity arising from growing numbers and correspondingly diminishing supply of food. It was this in the main which led him to spread; it was this which eventually led him to agriculture. And his spread-for it was a spread rather than "migrations"-followed the three great laws of spread of all organized beings which are: (1) movement in the direction of least resistance; (2) movement in the direction of the greatest prospects; and (3) movement due to a force from behind, to compulsion.

The peopling of Asia is a key to the problem of the peopling of all that part of the world lying east and southeast of that continent, in particular of the Americas; and even our imperfect knowledge of the events shows how vain it would be to expect to find in this latter part of the world traces of man of any great antiquity.

PROC. AMER. PHIL. SOC., VOL. LX., JJ, MARCH. 20, 1922.

AN ELECTRO-CHEMICAL THEORY OF NORMAL AND CERTAIN PATHOLOGICAL PROCESSES.

By G. W. CRILE, M.D.

(Read April 23, 1921.)

That electro-chemical processes play an important rôle in living processes has long been held by bio-chemists and bio-physicists.

Du Bois Reymond held that the action current is an electric current; and Crehore and Williams have put forward strong evidence in favor of the identity of the action current and electricty.

Burdon Sanderson demonstrated that motor plants such as venus' fly trap and the sensitive plant show electric variations during their specific response to stimulation. Waller extended these observations and called these electric variations "blaze currents of action." Bose has found evidence of the identity of vegetable and animal activity, and having demonstrated by most ingenious experiments that the activities of plants are attended by electrical phenomena he concludes that electricity plays an important rôle in vital phenomena.

Piper showed that sound waves originate an electric current in the auditory nerve of fish; and Einthoven and Jolly confirmed the discovery made by Holmgren in 1866 that when light falls on the retina, an electric current is produced in the optic nerve.

Gotch and Horsley have shown that during electric stimulation of the cortex, causing muscular action of the leg, a sustained electromotive force is present in the spinal cord during the continuance of the stimulation. Not only did they demonstrate an electric wave, but they were able to pick out the conduction paths in the spinal cord over which this wave travelled, showing that the current found its way along the intricate pathway from the cortex to the muscles, passing over the various synapses with accuracy. Gotch and Horsley also demonstrated a persistent negative variation in the cord during electric stimulation of the Rolandic area.

Nernst supposed that the electrolytes in the axis cylinder lie within membranes which are impermeable to certain ions; and that when an electric current is passed through a nerve, it is conveyed by the dissociated electrolytes, causing an accumulation of positive ions at one point and of negative ions at another: when the concentration reaches a certain point, excitation occurs. A. V. Hill supports Nernst's general theory; and McClendon, Bayliss, Lillie and others take a similar view. Lillie has developed an analogy between the local electrical effects in metals and in living tissue, as exemplified by the passive state in metals and in nerve conduction. He considers that the phenomena in each case are due to the formation of local electrical currents, resulting in the case of metals from local changes in surface tension; and in nerve tissue from local changes in the permeability of the surface film or membrane. In each case the phenomena are subject to rapid "spreading" as a result of electrical polarization, the rate of "spreading" depending upon the rate of the reaction which initiates it. He states that in nerve tissue" a relation of direct proportion should thus exist between the electric conductivity of the medium and the rate of propagation of the excitation wave."

By microchemical methods MacCallum showed that since it contains a greater concentration of electrolytes, the axis cylinder is a better conductor than the medullary sheath.

Meyer found that alteration in the concentration of electrolytes in the seawater in which the nerve of a marine animal was suspended altered equally the rate of electric conductivity of the water and the rate of nerve conduction.

Tashiro has demonstrated that as the result of the passage of the normal action current down a nerve fiber, carbon dioxid is given off and oxygen is consumed. He has shown also that when a nerve is stimulated by electricity, the same phenomena are observed; i.e., carbon dioxid is given off and oxygen is consumed. Moreover, whether in the case of the normal or of the eletcrical current, no heat is produced. A. V. Hill has confirmed Tashiro's findings as to the absence of heat; and Benedict was unable to demonstrate heat resulting from mental activity.

Following the lead offered by the above-cited investigators and by

many other bio-physicists, we propose to offer further evidence in support of the hypothesis that man is an electro-chemical mechanism, as gained, first, from a general consideration of the structure and arrangement of the central nervous system; second, from laboratory findings; and third, from observations and experience in the clinic.

STRUCTURE AND ARRANGEMENT OF THE CENTRAL NERVOUS SYSTEM.

The nerve cell consists of two highly differentiated parts, the nucleus and the cell body, which are separated from each other by a semi-permeable membrane. Sir Frederick Mott has shown that the so-called Nissl bodies during life are globules covered by a lipoid film on which oxidation occurs. The nucleus and the cellbody cannot be sharply stained with the same stain, but differential stains are required. This fact indicates a difference between the composition and function of these two parts of the cell. Two colloidal solutions, one acid and the other neutral or alkaline, separated by a semi-permeable membrane, constitute a battery. The nerve cell, therefore, is a battery. Electricity travels from areas of higher to areas of lower potential. In the animal organism the nerve-cell batteries are connected by microscopically fine prolongations of the nerve cells. Constant discharge of the artificial electric battery used in the laboratory is prevented by "make and break" keys; constant discharge of the nerve-cell battery is prevented by a "make and break" mechanism called a synapse.

According to this hypothesis, the unit structure of animals consists of a nerve-cell battery (or electric cell), its prolongation or nerve fiber to the synapse or key, the connecting nerve fiber from the synapse to the muscle cell or gland, by whose discharge upon receipt of an electric current from the nerve-cell battery, action is effected. Electricity alone can close the synoptic "key," complete the circuit and fire the "charge."

GENERAL AND LABORATORY OBSERVATIONS OF THE ELECTRO

CHEMICAL REACTIONS OF THE ORGANISM.

If we are correct in assuming that each nerve-muscle and each nerve-gland unit is a part of a biologic electro-chemical system, all of which collectively make up the organism, then we would expect