stimulating tone and its frank acknowledgment of our ignorance in regard to many matters of fundamental importance. So valuable a work should have been printed on much better paper, but the exigencies of the war probably made this impossible. One could have wished also that the author had provided the volume with an index and had seen fit to give careful citations of the many interesting works to which he refers.

W. M. WHEELER

SPECIAL ARTICLES

ON THE PROTEIN CONTENT OF WHEAT WHEATS of the Pacific coast states are conspicuously low in protein, so much so that western millers are obliged to ship in large quantities of high protein wheat to mix with their domestic wheats in order to manufacture flour of good baking qualities. The cause of the low protein content of western wheats has been the object of considerable investigation on the part of interested agronomists and plant physiologists for the last two decades. Results obtained from these investigations have led to a rather common belief, that the cause of the low protein content of Pacific coast wheat is primarily attributable to peculiar influences of climate.

In an investigation by the writer on the effect of applications of certain forms of soluble nitrogen to plants at different growth phases, results obtained with wheat, one of the plants studied, throw new light upon this protein question. In this paper, only that part of the plan and the results that pertain to the subject under discussion, need be given. These are essentially as follows:

Glazed stone jars were filled with a soil very low in nitrogen. This soil, as taken from the field, had a very low crop-producing power when cereals were planted, but upon receiving a moderate application of soluble nitrogen salt would yield large crops. This soil was planted to a pure strain of White Australian Wheat. Two hundred and fifty milligrams of nitrogen per jar, that is, at the rate of 100 pounds of nitrogen per acre, were added in single applications to different jars,

at dfferent times during the growng period of the plants. The nitrogen was added in two forms, NaNO, and (NH),SO, respectively, for two different series that were tested. Every application was made in triplicate. The first application of nitrogen to the first set of triplicates of each of the two series was made at the time of planting, the second was made to other jars 17 days after planting and so on at intervals until the last sets in each of the NaNO, and (NH),SO series received their nitrogen application 110 days after planting. Every application of nitrogen made to the several sets in the series was, therefore, made at different ages of the plants and obviously represents more or less different growth phases of the plants. The tabulated data for a NaNO, series will serve as an example of the plan of the investigation and gives the results obtained.

It will be noted that the data show a decided increase (about 77 percent.) in the protein content of wheat obtained from the plants that received nitrogen when they were 110 days old over those that were treated with nitrate at the time of planting. The protein content of the wheat obtained from these two different treatments are respectively 15.2 per cent., and 8.6 per cent. The data show that for each of the different applications of nitrate made after the time of planting, there was a corresponding increase in the protein content of wheat. As these increases in the

protein content of wheat correspond with the length of the period of the different deferred applications of nitrate made after planting, this would indicate a significant relation between the state of development of the plant and when nitrate can be most effectively utilized by the plant in the production of high protein wheat. This emphasizes that the physiological status of the plant, as indicated in its different growth phases, is a factor of great importance in the utilization of plant food available to it.

Not only was the protein content of the wheat increased by all of the deferred applications of nitrogen, but the yield of produce, excepting that obtained by the latest application, was much larger from the plants that received nitrogen for the period of 33 to 72 days after planting than those that received nitrogen during the early growing period. The best quality wheat as determined by commercial grading was secured from the plants that received nitrogen 72 and 110 days after planting. This means that the high protein wheat berry was likewise plump and well filled.

A much fuller account of the investigation with ample analytical data and a critical review of other investigations relating to the subject will shortly appear. It is felt that the results obtained in this investigation do show that the low protein content of Pacific states wheats is not due primarily to the climate as such, but so far as the investigation with this one soil is concerned, is due to insufficiency of available nitrogen at certain growth periods of the plants. That climate is not without effect upon the availability of the plant food in the soil is obvious, but the emphasis to be laid on the climatic complex is that it affects the nutrition of the plant. This can be both in the kind and quantity of each of the different nutrients that may be available to it. That this availability is an important factor in affecting the composition of plant products is shown by the results of this investigation.

W. F. GERICKE

UNIVERSITY OF CALIFORNIA

THE VITAMINE REQUIREMENTS OF THE RAT ON DIETS RICH IN PROTEIN, CARBOHYDRATE, AND FAT RESPECTIVELY1 IN 1913, one of us (C.F.) showed that the onset of the symptoms of beriberi in pigeons could be hastened by increasing the amount of polished rice fed. This led to the conclusion that the anti-beriberi vitamine-vitamine B-plays an important rôle in carbohydrate metabolism. This observation was confirmed shortly afterwards by Braddon and Cooper and others, although Eijkman and Vedder have denied the validity of this finding.

In a second series of experiments, in which the diets varied as shown in Table I., it will be noticed that beriberi developed in the following order: starch, sugar, casein, and fat.

The rats on the protein diet did not require the addition of extra vitamine (autolyzed yeast) at all. This may be regarded as the "sparing action of protein on the vitamine requirement." On the other hand, the rats on the fat diet took the extra vitamine with great avidity, but showed only a small advantage over the controls. The replacement of some of the fat by butter was without any significance, no improvement being noted.

On the starch diet, the rats actually needed extra vitamine (about 2 c.c. per day) in order to resume growth. This was likewise true of the rats on the sugar diet except that they appeared not to require as much vitamine for growth as those on the starch diet. On these diets we occasionally observed sudden large increases and losses in weight, suggestive of edema, though no external evidence was seen. As regards the general appearance of the animals, those on the protein diet and those getting extra vitamine looked very healthy, while the others appeared to be in poor shape with the usual evidences of improper nutrition. The rats on the high fat diet, without extra vitamine, presented the poorest appearance.

Out of thirty rats, only one developed keratomalacia, and this rat was getting five per cent. cod-liver oil. The eye condition cleared 8 In this instance, the figure represents the increase after 60 days, and is practically the same after 80 days, since most of the animals had already attained full size.

4 Vitamine given during last 55 days.

up on giving autolyzed yeast (about 2 c.c. per day).

The findings reported here show conclusively that although the qualitative food requirements of a well balanced diet have been pretty well established, this can not be said of the quantitative relationship between the dietary constituents necessary for proper nutrition. It is quite conceivable that under the abnormal conditions existing durng the war period and after, the usual ratio between the protein, carbohydrate, and vitamine constituents have been so changed as to present conditions analogous to those described by us in rats.

Theoretically at least, the above conditions could be corrected in either of two ways—(a) by increasing the protein and decreasing the carbohydrate intake, or (b) by supplying extra vitamine. The curative experiments of edema in rats reported by Miss Kohmann, and also the condition described as pellagra in a monkey, by Miss Chick, may be viewed in the above light. In view of the complications presented by the "sparing action of animal protein on the vitamine requirements," it may be just as well for the present to leave the question open, as to whether or not pellagra and war edema are avitaminoses. Of all the theories regarding pellagra, that expressed by Goldberger in which he states the facts and leaves the matter open for further investigation, appears to us to be the most satisfactory. Our complete results will be published in detail later on. CASIMIR FUNK, HARRY E. DUBIN

FRIDAY, NOVEMBER 12, 1920

CONTENTS

THE PROTEINS AND COLLOID

CHEMISTRY1

I

THE proteins, like certain other constituents of protoplasm, are colloidal in character, i. e., they are not able to diffuse through animal membranes which are permeable to crystalloids. For this reason a number of authors have tried to explain the behavior of proteins from the viewpoint of the newer concepts of colloid chemistry. Foremost among these concepts is the idea that the reactions be tween colloids and other bodies are not determined by the purely chemical forces of primary or secondary valency but follow the rules of "adsorption." Although a number of authors, during the last twenty years, e. g., Bugarszky and Liebermann, Hardy, Pauli, Robertson, Sörensen, and others, have advocated a chemical conception of the reactions of proteins, their experiments failed to convince the other side since these experiments could just as well be explained on the basis of the adsorption theory. There were two reasons for this failure. First, the experiments did not show that ions combined with proteins in the typical ratio in which the same ions combine with crystalloids. This proof only became possible when it was recognized that the hydrogen ion concentration of the protein solution determines the amount of ion entering into combination with a protein, and that therefore the ratios in which different ions combine with proteins must be compared for the same hydrogen ion concentrations. Since the former workers were in the habit of comparing the effects of

1 Address delivered before the Harvey Society, October 16, 1920. The writer's experiments, on which this address is based, have appeared in the J. Gen. Physiol., 1918-19, I., 39, 237, 363, 483, 559; 1919-20, II., 87; 1920-21, III., 85.

the same quantities of acid or alkali added instead of comparing the behavior of proteins at the same hydrogen ion concentration they were not able to furnish the final proof for the purely chemical character of the combinations between ions and proteins, and nothing prevented chemists from assuming that proteins formed only adsorption compounds with acids, bases, and neutral salts.

The second reason for the failure to prove the purely chemical character of the protein compounds lay in the so-called Hofmeister series of ion effects. Hofmeister was the first to investigate the effects of different salts on the physical properties of proteins, and he and his followers observed that the relative effects of anions on the precipitation, the swelling, and other properties of proteins was very definite and that the anions could be arranged in definite series according to their relative efficiency, the order being independent of the nature of the cation. Similar series were also found for the cations, though these series seemed to be less definite. These Hofmeister series were a puzzle inasmuch as it was impossible to discover in them any relation to the typical combining ratios of the ions, and this lack of chemical character in the Hofmeister series induced chemists to explain these series on the assumption of a selective adsorption of these ions by the colloids.

To illustrate this we will quote the order which, according to Pauli, represents the relative efficiency of different acids on the viscosity of blood albumin,

HCI > monochloracetic > oxalic > dichloracetic citric acetic > sulfuric > trichloracetic acid, where HCl increased the viscosity most and trichloracetic or sulfuric least. In this series the strong monobasic acid HCl is followed by the weak monochloracetic acid, this is followed by the dibasic oxalic acid; later follows a weak tribasic citric acid, then the very weak monobasic acetic acid, then the strong dibasic sulfuric acid, and finally again a monobasic acid, trichloracetic. Pauli is a believer in the chemical theory of the be

havior of proteins but it is impossible to harmonize his series of anions with any purely chemical theory of the behavior of proteins.

The ion series of Hofmeister are no more favorable for a chemical conception. Thus, according to Hofmeister, gelatin swells more in chlorides, bromides and nitrates than in water, while in acetates, tartrates, citrates, or sugar it swells less than in water. R. Lillie arranges ions according to their de pressing effect on the osmotic pressure of gelatin solution in the following way,

C1 > SO > NO, > Br > I > CNS.

4

These series again betray no relation to the stoichiometrical properties of the ions. As long as these Hofmeister ion series were believed to have a real existence it seemed futile to decide for or against a purely chemical theory of the behavior of colloids since even with a bias in favor of a chemical theory the Hofmeister series remained a puzzle.

The writer believes to have removed these difficulties by using protein solutions of the same hydrogen ion concentration as the standard of comparison. In this way he was able to show that acids, alkalies, and neutral salts combine with proteins by the same chemical forces of primary valency by which they combine with crystalloids, and that, moreover, the influence of the different ions upon the physical properties of proteins can be predicted from the general combining ratios of these ions. The so-called Hofmeister series have no real existence, being the result of the fact that the older workers failed to measure the most important variable in the case, namely the hydrogen ion concentration of their protein solutions, a failure for which they can not be blamed since the methods were not sufficiently developed.

II

Pauli and a number of other workers assume that both ions of a neutral salt are adsorbed simultaneously by non-ionized protein molecules. If we consider the hydrogen ion concentration of the proteins we can show