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erally considered as the temperature at which most plant growth begins in spring and ends in fall, Mr. Kincer made maps showing the advance and retreat of the isotherm of 43° F. in the United States in spring and fall and of the length of the period between the date in spring when the normal mean daily temperature rises above 43° F. in spring and falls below it in autumn. This period he called the "vegetative period." These maps were then compared with the corresponding maps of last killing frost in spring, first killing frost in autumn and average length of the growing season (i. e., between killing frosts); and other maps were made to show the differences, which amount to about ten days in the North and thirty or more in the South, the vegetative period being the longer. Other maps show that the normal mean daily temperature on the average frost dates just mentioned are for most of the country between 50° and 57° F.; on the Great Lakes, the Pacific, and the Atlantic north of Hatteras, however, the corresponding temperatures are below 50° F. Mr. Kincer points out that protective measures against frost damage may be well worth while in the South, where the vegetative period usually continues for weeks after the first killing frost, but not in the North, where, in autumn for example, low temperatures would soon stop the growth of vegetation which might have been protected from the first killing frost.

Temperature Influence on Planting and Harvest dates (by J. B. Kincer, Mo. Weather Review, May, 1919, Vol. 47, pp. 312-323, 20 figs., inclu. maps).-This is based largely on a study of the maps in "A Graphic Summary of Seasonal Work on Farm Crops," in comparison with temperature data.

It is suggested that the mean temperature at which planting of a given crop can be accomplished be used as a base, or starting point, for any method that may be employed for temperature summation, instead of a general base for all crops (e. g., 6o C.). . . . Spring wheat seeding usually begins... when the normal daily temperature rises to 37° or 40° F. The corresponding temperature for spring oats is 43°, for early potatoes, 45°, for corn 55° and for cotton 62° F. Cotton and

corn are warm-weather crops and the areas in which successful production on a commercial scale can be accomplished are limited principally by both the general temperature conditions and the temperature at which planting may be accomplished. There is a close relation between spring temperatures and the condition of these crops to certain dates in the early stages of growth.

Alfalfa Hay and Seed Growing in South Dakota and Utah (separate papers by H. N. Johnson of Rapid City, S. Dak., and J. C. Alter of Salt Lake City, Mo. Weather Rev., May, 1919, Vol. 47, pp. 328-332, 5 figs.).— "Alfalfa seed is usually produced [in S. Dak.] when conditions are such as to retard the maturing of the first hay crop, and then in paying quantities only when there is a comparative shortage in the moisture supply, hence the weather conditions determine whether the second crop shall be cut for hay or left for seed. If there is considerable rainfall, the second crop is usually cut for hay, and a third crop is frequently possible." As rainfall conditions fluctuate widely on the Great Plains, the western South Dakota alfalfa farmer has in such an arrangement a fine insurance against drought or unusual amounts of rainfall. In Utah the seed-crop, which follows a cutting for hay, needs special weather conditions for the best yields: there should be

sufficient moisture during its early growth to produce a vigorous, healthy plant, but the weather should be dry and not too warm while the plants are in bloom. The dry spell must not be too extended, however, as the seed must have sufficient moisture while setting to give it size and weight. It takes nearly twice as long to grow and mature a seed crop as it does a hay crop. As the seed crop is not always ripe on the occasion of the first killing frost in fall, considerable importance is attached to frost and minimum temperature forecasts. On the receipt of frost warnings, the usual practise is to cut as large an area as possible; but as the first cold period is often followed by several weeks of fine ripening weather, and as the value of the seed is said to increase at the rate of nearly $5 an acre each 24 hours when ripening, efforts should be made to protect the plants from frost damage without cutting.

WASHINGTON, D. C.

CHARLES F. BROOKS

SPECIAL ARTICLES

WHITE CORN VS. YELLOW CORN AND A PROBABLE RELATION BETWEEN THE FATSOLUBLE VITAMINE AND YELLOW PLANT PIGMENTS

As the importance of the vitamines in the physiological economy of the animal is coming to be appreciated, observations on their occurrence and their distribution in nature are being rapidly accumulated in various laboratories. As is to be expected, with data on vitamine distribution available, there is a growing inclination to deduce therefrom, not only evidence as to their possible rôle in living organisms, but also a suitable working hypothesis enabling one to predict in an known whether the amount of vitamine is liable to be large or small. Furthermore, from the viewpoint of the chemist, it scarcely needs to be emphasized what a step in advance it would be if from their occurrence in nature an idea could be obtained as to their possible chemical character.

We are still far distant from this goal in the case of the anti-scorbutic and antineuritic vitamines, but in the case of the fatsoluble vitamine, the mere fact-as its name indicates that it is soluble in fats and also its solubility in many fat solvents excludes from consideration many compounds.

Two years ago the writer experienced some difficulty in getting rats to rear their young on a ration which, to a considerable extent, consisted of corn. Failure was often indicated by an inflammation of the eyes-a xerophthalmia, which Osborne and Mendel1 first indicated as evidence of a deficiency of the fat-soluble vitamine. No further attention was paid to this difficulty beyond modifying the ration to increase its content of this dietary essential. Later, however, rats were again put on a similar ration and no difficulty was experienced. With many other apparent inconsistencies arising in a colony of a thousand animals, and all of them bearing investigation no immediate attention was given to this matter.

1 T. B. Osborne and L. B. Mendel, Jour. Biol. Chem., 16, 431, 1913.

During the course of the past year a considerable amount of work dealing with the occurrence of the fat-soluble vitamine in roots was completed. It was indicated that, while the colored roots such as carrots and sweet potatoes are rich in this dietary essential, sugar beets, mangels, dasheens and Irish potatoes contain little or none of it. It was then recalled that at the time that the difficulty with female rats to rear their young had been observed, it had been impossible to obtain sound yellow corn on the local market and white corn had been used instead. This had been done in a part of the stock colony and as the conditions for its maintenance are fairly well standardized and not always under close personal supervision the relation between the slight modification in the ration and the disastrous results had not been detected.

It has now been conclusively demonstrated with eight different varieties of corn which are extensively grown in the middle west, that while white corn contains no demonstrable amounts of the fat-soluble vitamine, yellow corn may contain sufficient amounts to allow normal growth and reproduction in the rat. One rat has successfully reared her young after having been fed yellow corn suitably supplemented with vitamine-free protein and salts for seven months. On white corn, similarly supplemented, young rats usually die in three months with the typical symptoms of a fat-soluble vitamine deficiency.

These relations suggested the possibility of correlating other instances of the simultaneous occurrence of the fat-soluble vitamine and yellow plant pigments. We have at hand the interesting observation of Osborne and Mendel? that while the oleo oils contain the vitamine, the solid beef fats do not. They state specifically that the oleo oils were yellow while the solid fats were colorless. Furthermore, they were also able to separate the butter fats by fractional crystallization into an active fraction of the liquid fats-which was yellowand an inactive fraction-which was colorless.

2 T. B. Osborne and L. B. Mendel, Jour. Biol. Chem., 20, 379, 1915.

In an investigation of the nutritive properties of commercial oleos and their ingredients, the writer and coworkers have found a considerable difference in their vitamine content. It is significant that of the oleo oils those most highly pigmented were also the richest in fat-soluble vitamine and those least pigmented were the poorest. This, in view of the present prevailing conception of the importance of the vitamine content of certain fats in the diet, is a matter of such great economic significance that comment on it is reserved until the investigations now in progress shall have been completed. It is mentioned here merely to indicate why it is considered possible that the fat-soluble vitamine may be one of the yellow pigments or a closely related compound.

In scores of feeding experiments in which butter fat as prepared from ordinary butter has been used as the source of the fat-soluble vitamine we have repeatedly observed variations in the vitamine content. It has not been possible to correlate this with the degree of pigmentation-which is well known to vary with the feed and the breed of the dairy cowas the amount of natural pigment present had been concealed by the addition of butter color. One fact however appears particularly significant, and that is, that when butter fat is heated its vitamine is destroyed and simultaneously there occurs a destruction of its pigment. Whether this is an accidental coincidence or one and the same thing remains to be seen.

From the evidence submitted it appears reasonably safe, at least as a working hypothesis, to assume that the fat-soluble vitamine is a yellow plant pigment or a closely related compound, which view, moreover, is strengthened by the fact that we know through the work of Palmer and Eckles of the inability of the animal to synthesize the yellow pigments carotin and xanthophyll. From its occurrence in butter, in leaves, in carrots and in other materials known to be rich in carotin,

3 H. Steenbock, P. W. Boutwell and Hazel E. Kent, Jour. Biol. Chem., 35, 517, 1918.

4 L. S. Palmer and C. H. Eckles, Jour. Biol. Chem., 17, 211, 223, 237, 245, 1914.

it might be concluded that we were here concerned with carotin. Some data, that we have accumulated have answered this in the negative and it has been so reported, but it appears doubtful if much importance can be attached to these earlier results as we have since observed that carotin under certain conditions is a very labile compound. We do not desire to mislead our readers by indicating that we have conclusive evidence one way or another.

Provisionally, we are assuming that the fatsoluble vitamine is one of the yellow plant pigments, but we are not unmindful of the possibility that the reasons for the association of these properties in nature, viz., yellow pigmentation and this growth-promoting property may be a genetic one in some cases, while in others it may be indicative of mere similarity in physical if not chemical properties. If it is not a pigment, no doubt, instances will soon be found where it is found to occur liberally in non-pigmented materials. We already have indications that certain materials are as rich in the fat-soluble vitamine as is yellow corn, yet they are far less pigmented. Whether this can be explained in difference of kind of pigment which in yellow corn is known to be principally xanthophyll or whether we are dealing in these instances with the leuco compound remains to be seen.

It is scarcely necessary to elaborate on these findings or to point out their possible economic significance. Many investigations based on the general premises which we have here outlined are now in progress and will be reported as the evidence obtained seems to warrant a detailed discussion.

H. STEENBOCK LABORATORY OF AGRICULTURAL CHEMISTRY, UNIVERSITY OF WISCONSIN

THE AMERICAN MATHEMATICAL

SOCIETY

THE twenty-sixth summer meeting of the society was held at the University of Michigan, September 2-4, in conjunction with meetings of the Mathematical Association of America and the

5 H. Steenbock, P. W. Boutwell and Hazel E. Kent, Proc. Amer. Soc. Biol. Chem., 1919.

American Astronomical Society. On Thursday afternoon there was a joint session, at which the following papers were presented:

"Mathematics and statistics," retiring address of the president of the Mathematical Association of America, by E. V. HUNTINGTON.

"The work of the National Research Council with reference to mathematics and astronomy," by E. W. BROWN.

Reports on the international conference of scientists at Brussels, by FRANK SCHLESINGER and L. A. BAUER.

The following papers were presented to the society:

On wind corrections: PETER FIELD.

Cauchy's memoir of 1814 on definite integrals: H. J. ETTLINGER.

Expansion of any determinant in minors from rectangular panels: L. H. RICE.

Pseudo-canonical forms and invariants of systems of partial differential equations: A. L. NELSON. On the separation of complex roots of an algebraic equation: A. J. KEMPNER.

Some theorems on the zeros of solutions of homogeneous linear differential equations of the nth order: C. N. REYNOLDS, JR.

Some theorems on the zeros of solutions of selfadjoint homogeneous linear differential equations of the fifth order: C. N. REYNOLDS, Jr. Proof of the existence of distinct three-dimensional manifolds with the same group: J. W. ALEXANDER.

Certain determinants expressible as circulants or skew-circulants: E. D. ROE, JR.

A brief account of the life and work of the late Professor Ulisse Dini: W. B. FORD.

The resolvents of König and other types of symmetric functions: S. P. SHUGERT.

Form of the number of subgroups of prime-power groups: G. A. MILLER.

A generalization of a formula of Schubert in enumerative geometry: E. S. ALLEN.

Joint axis congruences with indeterminate developables: E. P. LANE.

A modification of an integral test for the convergence and divergence of infinite series: R. W. BRINK.

Certain types of involutorial space transformations (second paper): F. R. SHARPE and VIRGIL SNYDER.

Transformations of surfaces applicable to a quadric: L. P. EISENHART.

Transformations of cyclic systems of circles: L. P. EISENHART.

Differential equations containing arbitrary func tions: G. A. BLISS.

Functions of lines in ballistics: G. A. BLISS. On the relative positions of the complex roots of an algebraic equation with real coefficients and those of its derived equation: D. R. CURTISS. Urn schemata as a basis for the development of the theory of correlation: H. L. RIETZ. Projective transformations in function space (second paper): L. L. DINES,

On the invariants belonging to a hypernumber in an algebra of infinite order: J. B. SHAW. Conditions necessary and sufficient for the exist ence of a Stieltjes integral: R. D. CARMICHAEL. Note on convergence tests for series and on Stieltjes integration by parts: R. D. CAR

MICHAEL.

Note on a physical interpretation of Stieltjes integrals: R. D. CARMICHAEL.

An apparent anomaly in errors of interpolated values: H. A. HOWE.

Transformations of a Stieltjes integral potential: G. C. EVANS.

Note on sequences of Stieltjes integrals: T. H.
HILDEBRANDT.

Differential equations of motion of a projectile
regarded as a particle: W. H. ROEVER.
Certain properties of binomial coefficients: W. D.
CAIRNS.

On the shape of polynomial curves: A. J. KEMPNER. Abstracts of these papers and a fuller report of the meeting will be published in the November number of the Bulletin of the American Mathematical Society.

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SCIENCE

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ENGINEERING SCIENCE BEFORE, DURING AND AFTER THE WAR. II

IN coming to this section of my address I am reminded that in the course of his presidential address to section G, in 1858, Lord Rosse said:

Another object of the Mechanical Section of the association has been effected-the importance of engineering science in the service of the state has been brought more prominently forward. There seems, however, something still wanting. Science may yet do more for the Navy and Army if more called upon.

Comparatively recently too, Lord French remarked:

We have failed during the past to read accurately the lessons as regards the fighting of the future which modern science and invention should have taught us.

In view of the eminent services which men of science have rendered during the war, I think that we may be justified in regarding the requirement stated by Lord Rosse as having at last been satisfied, and also in believing that such a criticism as Lord French rightly uttered will not be levelled against the country in the future.

Though British men of science had not formerly been adequately recognized in relation to war and the safety of their country, yet at the call of the sailors and the soldiers they whole-heartedly, and with intense zeal, devoted themselves to repair the negligence of the past, and to apply their unrivalled powers and skill to encounter and overcome the long-standing machinations of the enemy. They worked in close collaboration with the men of science of the allied nations, and eventually produced better war material, chem

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