PROFESSOR I. M. KOLTHOFF, of the University of Utrecht, has accepted a professorship of analytical chemistry at the University of Minnesota and will begin his work in October. Dr. R. S. Livingston, of the University of California, has been appointed assistant professor of physical chemistry.

DR. CARL SNEED WILLIAMSON, formerly of the Mayo Clinic, Rochester, Minn., has been appointed head of the department of surgery at the University of Arkansas School of Medicine, Little Rock, and Dr. Oliver C. Melson, also of the Mayo Clinic, has been appointed head of the department of medicine.

AFTER many years' activity as lecturer on zoology at the institute for investigations in heredity in BerlinDahlem, Dr. Paula Hertwig, the daughter of the former professor of biology, Oskar Hertwig, has been given the title of professor.

DISCUSSION AND CORRESPONDENCE AGE OF THE "SATSOP" AND THE DALLES FORMATIONS OF OREGON AND

WASHINGTON

GEOLOGISTS have differed regarding the ages of the "Satsop" and the Dalles formations of the Columbia River Gorge region. Because of their bearing on the history of the Gorge and for other reasons their ages are important.

During a brief investigation of these beds under the auspices of the Carnegie Institution of Washington, the writers secured fragmentary mammalian fossil remains from the Dalles formation representing not a Quaternary, but approximately an upper Miocene or lower Pliocene stage. This age determination is corroborated by the lithologic resemblance of the Dalles beds to the middle Neocene Ellensburg formation of central Washington, by the apparently similar relations of these two formations to the Columbia lavas, and by the induration of the Dalles beds, which is equal to that of lower or middle Neocene deposits of the west, but much greater than that of Quaternary formations.

In interesting papers by J H. Bretz and by I. A. Williams the "Satsop" in the Columbia River Gorge has been considered Quaternary by correlation, mainly through lithologic similarity, with the fossiliferous marine Satsop on the Washington coast. In the eastern part of the gorge, however, the writers have found the "Satsop" gravels beneath the Dalles beds. Moreover, the "Satsop" gravels can be traced into central Washington where they lie at the base of the middle Neocene Ellensburg formation. Further, the induration of the "Satsop" is considerably greater than that of other Pacific Coast upper Pliocene or

Quaternary strata. For these three reasons the "Satsop" of the gorge is also believed to be approximately upper Miocene or lower Pliocene rather than Quaternary.

Since the "Satsop" of the gorge is not the correlative of the type Satsop on the coast, the new name, "Hood River Formation," is proposed for these rather unique conglomerate and sandstone strata. The type section may well be the beds so excellently exposed in the cut immediately east of the Columbia River Highway bridge across Hood River.

A more detailed statement of the evidence and of the bearing of these beds on the geological history of the region is in course of publication.

JOHN P. BUWALDA BERNARD N. MOORE

CALIFORNIA INSTITUTE OF TECHNOLOGY

MORE DATA

UNDER "Datum and Data" in the July 1 issue of SCIENCE, Mr. Blake says that "We speak and hence write English by ear and not by rules of grammar," and that "in ordinary use," data is not the mere plural of datum. It was, no doubt, recognition of these very unfortunate conditions that prompted the commendable letters of protest regarding the use of "data" in the singular.

There is no standard in the education of ears, and thus it becomes very difficult to eliminate "ain't" from spoken English. The old dictum that use is the law of language presupposes good usage, and the best existing criterion of good usage is a good dictionary. No reputable dictionary admits, or is likely to admit, "data" as a singular form.

But the correspondence which I have seen regarding the misuse of "data" entirely overlooks the chief abuse, which consists, not in using the word incorrectly as a singular, but in using it at all when the intended meaning can be more accurately expressed otherwise. Any one who cares to observe will find that, in probably nine cases out of ten, clearness can be gained by the substitution of "facts," "figures," "records," "values," "results," "information," or any one of perhaps a dozen other words which may more aptly fit the particular case. The general use of "data" for all such cases is due to the same slovenly thinking which causes a writer to use "etc." when he is at a loss for another word; or to use such expressions as "in regard to same" instead of repeating, or specifying just what he means by "same."

The laudable desire to adopt "new" words is to a considerable degree offset by failure to see that they are used accurately, and "data" is only one of a large number used erroneously more often than correctly. Though its use in the singular offends the intelligent

reader, the context usually reveals the true meaning. This seems to be less often true in the case of "strata"

(used less frequently, but with at least as high a percentage of error). The same desire for new expressions fills our reading matter with such words as "résumé" (for which "summary" is usually better) and "rôle," printed (newspaper style) without accents.

Strangely enough, many a worker who conducts his investigations with the strictest accuracy of which science is capable, publishes his results with little concern for accuracy of statement or nomenclature. Unfortunately, some of the errors escape the attention of even the most vigilant editor. A flagrant error which seems to be gaining ground is the expression "different than." Only two weeks ago it occurred in the Saturday Evening Post-one of our most carefully edited journals.

E. H. MCCLELLAND

CARNEGIE LIBRARY OF PITTSBURGH

ASSIMILATION OF FIXED NITROGEN BY HAVANA TOBACCO

EXPERIMENTS on the assimilation of different forms of combined nitrogen by Havana tobacco are being made at the Massachusetts Agricultural Experiment Station. Among results to date is the proof of ready assimilation of ureal nitrogen in the unchanged form. Plant growth, however, has not been as rapid with urea as a source of nitrogen as with sodium or calcium nitrate.

A more detailed report of the whole experiment will be made later. On account of the growing importance of urea as a commercial fertilizer, we make this progress report.

A. B. BEAUMONT G. J. LARSINOS

STANDARD MATHEMATICAL SYMBOLS A LIST of proposed American standard mathematical symbols has been prepared by a special committee of the American Engineering Standards Committee and the list has been submitted to the sponsor organizations. This list was noted in SCIENCE for August 12, 1927. It has been published in full in the following places: Jour. Engin. Educ., June, 1927; Jour. Soc. Auto. Engin., July, 1927; Mechanical Engineering, August, 1927. Since the American Association for the Advancement of Science is one of the sponsor organizations for this standardization project, the permanent secretary wishes to bring this matter to the attention of all members interested, with the request that they examine the list and send him their comments as as possible. The comments received will be

soon

placed before the executive committee of the association, which is asked officially to approve the list of proposed standard symbols.

BURTON E. LIVINGSTON, Permanent Secretary

QUOTATIONS

A PORTRAIT PAINTER OF BIRDS THE birds have lost their most devoted and faithful portrait painter in the tragic and untimely death of Louis Agassiz Fuertes. For he was not only a great ornithologist. He was for the birds what such an artist as Sargent was for men. There are not a few artists who have represented with more or less accuracy the color, form and pose of birds, but the portraits painted by Fuertes, who had a genius for individualizing every bird he saw even in its facial expression and in depicting what he saw with practiced vision that was as a sensitized plate, also revealed the character of the living creature. All birds of a feather look alike to the ordinary observer, but every owl and toucan painted by Fuertes, as Frank M. Chapman said in writing of him many years ago, had its individuality, was instinct with life, and differed from the drawings of the inexperienced or unsympathetic artist as a living bird from a stuffed

one.

Dr. Fuertes's opportunities for field study were greater than those of any other painter of birds, from the boreal birds of the Bering Sea to the flamingoes of the warmer regions. He studied the birds of Texas, California, Nevada, Jamaica, the Gulf of St. Lawrence, the Bahamas, Florida, Saskatchewan, Alberta, Yucatan, Mexico, Colombia and Abyssinia. He made thousands of drawings, many of which have been widely reproduced and have been of the greatest value in interesting the public, children especially, in bird life, and acquainting them with the characteristics, the habits and the migrations of birds and their relation to human life.

But the contribution that will be his permanent monument in this state is his collection of portraits of the birds of New York (made for the illustration of Eaton's great work on the "Birds of New York”), which was purchased by Mrs. Russell Sage and presented to the State Museum at Albany. The birds will come and go with the seasons through the years all unwitting of his absence, but they can not become wholly extinct, for they will be preserved there as in life. He whose skill has given them this sort of immortality, in season and out, needs "no trophy, sword or hatchment o'er his bones," for they in turn will preserve the memory of his genius and of his devotion to them.-The New York Times.

SOME LIMITATIONS OF WARBURG'S THEORY OF THE ROLE OF IRON IN RESPIRATION

THE construction of models of biological processes has occasionally contributed greatly to the knowledge of the mechanisms of vital phenomena. However, enthusiasm over the successful construction of a model that in part duplicates the reaction of living protoplasm often obscures the fact that the duplication is only partial and misleads the investigator into undue dependence on deductive reasoning. Caution must be observed in accepting theories of the organism derived from the behavior of models, for in attempting to isolate a single process in this manner the controls and correlations that distinguish the living from the non-living are lost. Obviously, the value of any theory derived from the behavior of a model depends on the extent of resemblance between the behavior of the non-living system and the facts and characteristics of the process of the living organism which it purports to simulate.

An examination of the characteristics of biological oxidations shows that the comprehensive theory of Warburg of the mechanism of oxidations in the cell,1 based largely upon the characteristics of his so-called models of respiration, is not free from the criticisms that have been levelled at other theories of biological processes similarly derived from models. On the contrary, the divergence between Warburg's theory and the actual facts is wide enough to justify regarding the theory as distinctly limited in application.

Briefly, Warburg has developed a theory of cellular oxidations in which iron in unknown combination with nitrogen is held to play the rôle of catalyzer. Molecular oxygen is said to enter into combination with the iron to form higher oxides of iron, and the iron-nitrogen is assigned the property of adsorbing and peculiarly loosening the bonds of amino acids. in the cell. In the oxidation of carbohydrates phosphates replace nitrogen, and in the oxidation of fats the presence of the SH group is necessary. A transfer of active oxygen is thus effected, and the iron is returned to a lower oxide. Unfortunately for the theory in its present form, the facts of cellular oxidations which Warburg cites in support of his theory are in some important details disputable.

The theory demands, and Warburg has shown in the case of the unfertilized sea urchin egg,2 that the oxygen absorption of disintegrated cells is equal to

1 Warburg, O., 1921, Biochem. Zeitschr., cxix, 134; 1923, ibid., cxxxvi, 266; 1923, ibid., cxlii, 518; SCIENCE, n. s., 1925, lxi, 575.

2 Warburg, O., 1911, Zeitschr. f. physiol. Chem., lxx, 413; 1914, Arch. f. ges. Physiol., clviii, 189.

that of intact cells. This is contradictory to sound evidence3 which shows that the chief energy-releasing oxidations in the cell are profoundly depressed by mechanical destruction of the cellular structure. This contradiction between the findings of Warburg and those of others shows that the experimental result which Warburg uses in support of his general theory is not a general but a particular case. The peculiar structure of the cell has thus been shown to be of great importance in its energetics. Warburg himself years ago demonstrated the importance of the cell boundary in regulating oxidative metabolism when he showed that dilute sodium hydroxide accelerates the oxygen consumption of the sea urchin egg without entering the cell interior.

According to Warburg, anesthetics decrease oxidations in the cell because they are adsorbed by the ironnitrogen, and are therefore described as general negative catalyzers of this reaction. However, there is abundant evidence that dilute solutions of many anesthetics accelerate oxidative metabolism. The powerful action of the cyanides in depressing oxidative metabolism, Warburg asserts, strongly supports his theory. The validity of this evidence is open to question. Within certain limits the depression of oxidative metabolism in cyanide solutions increases with increasing concentration of the cyanide, but, after maximum depression characteristic of the concentration has been reached, continuous exposure does not result in further depression of oxidations. Warburg holds that the action of cyanide in depressing oxidations in protoplasm is due to its combination with iron, converting it into a form incapable of transferring oxygen. He regards the reaction between the cyanide and the iron as stoichiochemical, and he shows that the activity of an iron-nitrogen model in oxidizing an amino acid is depressed 97 per cent. by the addition of M/1000 HNC. According to this, we should expect very complete extinction of oxygen metabolism in the presence of strong cyanide. The expectation is not realized. It has been shown that M/1000 and M/2000 KNC have approximately the same effect on oxygen consumption in

3 Fletcher and Hopkins, 1907, Jour. Physiol. xxxv, 247; Harden and Maclean, 1911, Jour. Physiol., xliii, 34; Batelli and Stern, 1914, Biochem. Zeitschr. lxvii, 443; Lund, E. J., 1921, Amer. Jour. Physiol., lvii, 336. See also discussion in R. S. Lillie's book, "Protoplasmic Action and Nervous Action," Chicago, 1923, page 52, et seq.

4 Warburg, O., 1910, Zeitschr. f. physiol. Chem., cxvi, 305.

5 Lillie, R. S., 1916, Biol. Bull., xxx, 311 and references; Buchanan, J. W., 1923, Jour. Exper. Zool., Xxxviii, 331 and references.

Planaria dorotocephala, and although M/1000 KNC is lethal within a few hours, there still remains an oxygen consumption of about ten per cent. of the normal to be accounted for.6 In Planaria agilis and in certain molluscan tissues the remaining oxygen consumption after maximum depression by cyanide I is twenty per cent. of the normal. Suitably diluted solutions of the cyanides appear to accelerate metabolism and in one case at least relatively strong soluitions are required to depress cellular respiration.8 It is also true that an oxidative enzyme has been isolated, the activity of which is not appreciably affected by cyanide. The wide discrepancy between the theory and the observed facts is obvious. Cyanide is therefore not a "specific negative catalyst" in the strict sense that Warburg's theory requires.

A slight recovery of oxidative metabolism in the presence of cyanide has sometimes been noted. This, Warburg says, is due to the oxidation of the cyanide itself by the catalytic action of the iron-containing i substance. Since the cyanide is said to render the catalyst incapable of transferring oxygen, a reasonable doubt arises that a catalyst can be instrumental in oxidizing a substance that has rendered it incapable of catalyzing an oxidative reaction.

de

The writer has recently studied the recovery period after depression by KNC more intimately than has been done heretofore.10 When Planaria are removed from a solution of KNC in which their oxygen consumption has been depressed fifty per cent., the oxyigen consumption rises above the normal during the first hour after removal from the cyanide. The extent of rise above normal is considerable, is independent of the duration of depression of KNC and persists, with gradual decrement, for at least six hours. To bring Warburg's theory into alignment with these facts it is necessary to assume that the quantity of active iron or of oxidizable materials in the cell increases during the period of depression. However, the fact that the extent of rise in rate of oxygen consumption above the normal is independent of the duration of depression renders these assumptions exceedingly improbable. A third assumption is possible, namely, that the catalyst, after being freed from the cyanide, becomes excessively active. Concerning this possibility there is no information available.

6 Hyman, L. H., 1919, Amer. Jour. Physiol., xlviii, 340. Allen, G. D., 1919, Amer. Jour. Physiol., xlviii, 93; Gray, J., 1924, Proc. Roy. Soc., Ser. B, xcv, 95.

8 Hyman, L. H., 1919, Amer. Jour. Physiol., xlviii, 340; Townsend, 1901, Md. Agri. Exper. Sta. Bull., No. 75, 183; Lund, E. J., 1918, Amer. Jour. Physiol., xiv, 365; 1921, ibid., lvii, 336.

• Dixon and Thurlow, 1925, Biochem. Jour., xix, 672. 10 Buchanan, J. W., 1926, Jour. Exper. Zool., xliv, 285.

Why anhydrous conditions are necessary for the action of the iron catalyst in commercial nitrogenfixing processes or why the reaction is strongly inhibited by minute quantities of carbon monoxide and other impurities is unknown, despite the vast amount of research that has been expended. The oxidative reactions in the living organism go on in a much more complicated system. Warburg's emphatic postulation regarding the action of cyanide on the system may be considered premature.

From the effects of cyanides on oxidation in living systems it is perfectly clear that the resemblance between Warburg's models and the oxidative mechanisms in the cell is distinctly limited. As Warburg states, the idea that iron is of importance in oxidative metabolism is not new. Warburg's results have yielded suggestions as to the possible nature of the rôle of iron. However, the universality of iron in biological oxidative mechanisms is not proven, and his theory as at present formulated is quite inadequate to explain many of the facts that are associated with changes in rate of oxidations in the living organism.

J. WILLIAM BUCHANAN

OSBORN ZOOLOGICAL LABORATORY, YALE UNIVERSITY

SPECIAL ARTICLES

VISIBLE RADIATION FROM EXCITED NERVE FIBER: THE REDDISH BLUE ARCS AND THE REDDISH BLUE GLOW OF THE RETINA

THERE is a singular phenomenon-one of the countless interesting entoptic phenomena discovered by Purkinje1-which has remarkable consequences. In a perfectly dark room you give yourself a band of red light any light of the spectrum, and white light as well, will give the phenomenon but it is rather more easy to obtain with red light. What you will see is not only the band of red light, but also stretching out from it on both sides big slightly reddish blue arcs-the bigger the further away you stand. They are not of the color of the rod pigment (visual purple), which is of a slightly bluish red. The angular size and the shape of these reddish blue arcs make

1 Purkinje: "Beobachtungen und Versuche zur Physi ologie der Sinne," 1825, ii. 74. This rare work of Purkinje so rare that Gertz reproduces the whole discussion which Purkinje gives of this phenomenon because so few of his readers will be able to see his book-has now been reproduced in Czecho-Slovakia: Purkinje, Johann Evangelista, Opera Omnia. Praze: C. Calve, 1919. My name for this phenomenon, "the reddish blue arcs" and "the reddish blue glow of the retina,'' has been very generally accepted.

it absolutely certain that what you are seeing is the fibers of the optic nerve which lie on the surface of the retina. Since the beautiful work of Vogt with blue-green (red-free) light2 these fibers can be plainly seen in any one's eye with the aid of the ophthalmoscope; until now they had only been seen by the anatomist and by means of the entoptic phenomenon here described.

But why are these fibers visible? The explanation hitherto given, by Gertz and by others, is that the action current of the optic nerve fibers which carry the red light excitation causes a "secondary excitation" in adjoining fibers. Such a nerve current as this, however, if it occurred, would not be provided with the right "place-coefficients"; no adjoining fibers, though stimulated, would enable you to actually "see" the nerve fiber in question, for they would have the place-coefficients of those rods or cones from which they come. It is with nothing but rods or cones, or bipolar cells, or ganglia, that the "seeing" of these reddish blue fibers could be done.

But there is an additional feature of this phenomenon which throws great light upon its nature: it is followed by an after-image. It has been shown by Lazareff directly (what was perfectly well-known before) that any production of a light sensation (whether chromatic or achromatic) due to the passage through the head of an electric current is followed by no exhaustion; the nerve is like the heart and the organs of respiration-the refractory period suffices for complete restoration. When, however, exactly the same sensation is brought about by the action of physical light upon the retina there is extreme exhaustion, as measured by the Nagel adaptometer. But what is exhaustion in the light-sensitive substance in the rods and cones? It is merely another name for the after-image.5 The specific residual image that follows, a whitish reddish blue sensation, would be in color a less bright yellowish green. A person who gets this after-image says at once "It is a dark olive,” which is correct both as regards brightness and chromatic quality. This fact excludes the possibility of any nervous structure whatever being the thing which is directly acted upon by the "blue arcs." Of this 2 Handb. der biol. Arbeitsment., 1922, Abt. V, Lief. 376.

55,

3 It has been necessary to introduce this new term; without it we have nothing but the wholly erroneous "local sign.'

4 Lazareff, Comptes rendues de l'Académie des Sciences, 178, 1100, 1924.

5 I have introduced the terms "persistent image” and "residual image" for positive after-image and negative after-image, respectively. They save the tired brain, in each case, one unnecessary syllogism.

the experiment of Lazareff (loc. cit.) is absolute proof. His experiment is this: it is found that exactly the same visual sensation (say a slightly reddish blue) can be produced (1) by physical light and (2) by an electric current, but that in case (1) there is extreme exhaustion (and a residual image), and that in case (2) there is no exhaustion (and no residual image). What can be the cause of this extraordinary difference? The sensation (and therefore the cortical process) is the same in both cases. All the conducting nerve-fibers are certainly stimulated in both cases. But there is the possibility of a difference in what takes place in the retina:

(1) There is no question that in the case of the physical light stimulus it is the light-sensitive substance in the cones (and the rods) that is acted on, and that it is the photochemical products of the dissociation produced by light that act then on the nerve-ends in the cones and rods. If the electric current acted on the light-sensitive substance (as it is hard to think that it could-it has not got the excessive specificity of the visible radiations) then there would be no possible difference between the two situations, and there could not be (1) the existence of the residual image in the one case, and (2) its non-existence in the other. Hence we must conclude that (1) with the existence of the residual image goes the stimulation by physical light and (2) with the non-existence of the residual image goes direct stimulation of nerve by the electric current. The "blue arcs" and the "blue glow" which belong in the case of the after-images make themselves seen therefore by physical light and not by any sort of a "secondary excitation."

But this is not so strange a situation as it appears to be at first sight. There is another case in which visual sensations of all kinds are produced, but without any residual images—that in which the optic nerve is directly stimulated by pressure. There are several (no less than six) different forms in which pressure can be applied to the optic nerve:

(a) The "pressure phosphenes"-rings produced by pressure with the finger on the corner of the eye.

(b) Light-sensations (all the colors of the rainbow) produced by pressure with the hand on the whole eyeball. (This is dangerous.)

(c) What I have called the pull-phosphenes (got by moving the eyeballs vigorously to one side and the other). One sees the exit point of the optic nerve.

(d) The so-called "self-light of the retina." This is now believed to be due to permanent pressure on the retina by the fluids of the eyeball.

(e) After a fall on the ice, if one hits the back of the head, one "sees stars."

(f) In case of enucleation of the eyeball, at the