THURSDAY, NOVEMBER 5, 1903.

THIS

BLOOD AND IRON.

By

Plant Disease and its Relation to Animal Life. E. F. Wright. Pp. vi + 160. (London: Swan Sonnenschein and Co., Ltd., 1903.) Price 3s. 6d. THIS little book is with so alluring a title emphatically disappointing, and would appear to have been written by a compiler quite inadequately informed on the subject, especially in its botanical aspect.

The principal contention of the author seems to be that, because iron is necessary for the production of chlorophyll in the green plant, and is an indispensable ingredient in relation to the hæmoglobin of the blood in animals, these two bodies, chlorophyll and hæmoglobin, are the same. Thus on p. I we read, "Now what chlorophyll is to the plant, hæmoglobin is to the animal, the one being a red modification of the other," and, p. 69, "As hæmoglobin is allied to the proteids and a red modification of chlorophyll, it follows that the hæmoglobin of the animal varies as the chlorophyll or chlorophyll products vary in the plants eaten."

He then proceeds to argue that if an animal eats plants deficient in chlorophyll (i.e. chlorotic) it suffers the evils due to want of iron-e.g. (on p. 6) " animals eating chlorotic food must be deficient in sugar, fats and proteids," which would seem to indicate (since the author appears not to discriminate between chlorosis and etiolation) that people who are fond of cauliflowers, asparagus, endive, rhubarb, and the like, run risks hitherto unsuspected. For note this (p. 13), "if my contention is correct, the susceptibility to certain bacterial diseases is directly traceable to the use of chlorotic food." And on p. 15, "from which it follows that a chlorotic plant will contain less proteids than a plant containing the maximum quantity of iron." And, again, p. 28, "it is clear that there must be a large number of animals living entirely or partly on this chlorotic vegetable food, from which it follows that a large portion of animal life must be

more or less anæmic through eating this chlorotic food."

We have already stated that the author draws no distinctions between different forms of chlorosis and etiolation, and puts the former down simply to a lack of iron. Now let us see what he regards as the measure of this deficiency, bearing in mind that modern plant physiology teaches us that the traces of iron found necessary to develop the peculiar form of chlorosis in question are so minute that it is often somewhat difficult to ensure the absence of that element in experimental cultures.

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On p. 7 we read, "Yet there are many soils quite wanting in iron, and in the history of agriculture you never read of manuring with iron, excepting possibly in the case of some experimental plots, although some iron has been used of late years in the form of basic slag, which contains about 18 per cent. of iron," and, further on the same page, Unfortunately, much vegetation is deficient in iron, and consequently chlorotic, and it would seem simpler instead of washing with sulphate of iron, as is now occasionally done, to have recourse to manuring the ground with iron," all of which goes to show that the author's notions as to the relations between iron and plants are, to say the least of it, crude. Does he seriously suppose that basic slag is used as manure on account of the iron it contains?

But lest there should be any risk of misunderstanding the author's meaning here, we may quote the following from this amusing book. After describing how one lamb of a flock, too weak to proceed, was rescued and brought up by the children of a blacksmith, the author continues (p. 34), "This lamb. grew up by grazing on the grass growing round this [the blacksmith's] shop, and was shorn three times in three years," &c., and he explains the excellent condition of this lamb as follows:-" In the first place,. it is quite certain there would be plenty of iron in the soil for some distance round a country blacksmith's shop, owing to rusty iron being carried about, to say nothing of the scales of iron and iron filings," &c.

To show what gourmands for iron the author's animals are, we quote from p. 93 :-" And to show that

animals require iron, I have seen mules licking rusty iron, just as thousands of people have seen horses licking salt," to which valuable testimony he quotes an account of quails in Florida picking at the holes in the steel rails.

But to appreciate fully what a man of blood and iron we are concerned with, it is necessary to obtain some insight into his views of what his plants and animals do with these relatively enormous quantities of the metal.

We read on p. 5, "iron is the means of fixing the ammonia of the air in the soil to form nitrates. In any case I am sure there is a fixed law by which the ammonia of the air is fixed in the soil to form nitrates . . . ." Then, on p. 21, “it has been proved over and over again that iron is fatal to all fungi, consequently it is unreasonable to suggest that bacteria would attack a perfectly healthy animal, and destroy the blood containing a constituent which was a poison to them."

And, again, on pp. 98-99, "The distinct chemical difference between fungi and what we look upon as ordinary plants, is that the fungi contain no iron or nitrogen, while these constituents are essential to ordinary plant life. It is known that iron and nitrogen are fatal to fungi, therefore the more iron and nitrogen animal life takes up in its food the more likely it is to be immune to bacterial diseases."

It might not unreasonably be expected that we had here plumbed the depths, but the following shows that there are nether regions still, for on p. 42 we have the astounding statement, "It is fully recognised that iron and nitrogen in combination with the phosphates are the means by which the plant is enabled to take up the carbon of the air, . . ." and on p. 68, "it is admitted that the proteids are fatal to pathogenic bacteria.” Even these are not the only contributions of the author to the study of bacteria, for he states (p. 98) "it is recognised that all classes of bacteria can only live on foods corresponding in chemical composition to themselves," which pronouncement would appear to require some explanation in view of the previous one regarding proteids, for instance, and the following, quoted from p. 33:"it is admitted that pathogenic bacteria cannot live in the presence of proteids."

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What the author's idea of a proteid may be we have been unable to make out, but there is no hesitation needed in regard to some of his notions regarding immunity, of which the following is a specimen (p. (60):-" Another important factor in immunity is electricity, which is so closely connected with the chemistry of the animal that it is reasonable to think that an animal of normal chemical combination will be in a position to produce much more electricity than an animal chemically deficient.

Immunity is a fascinating but a very difficult subject, but the author is not deterred by the latter in his submission to the former attribute.

of constituting a great chemical difference." Indeed, we should think it would! But let us read on (p. 120), "if you have a field rich in all the essential mineral constituents, in an assimilable form, and a green crop be grown in this field and ploughed in, and then a cereal crop be grown, this cereal crop will be immune to rust, to say nothing of other parasitical diseases." Here it might be said that the author is merely claiming that high manuring renders a crop more immune, did not the context show that his ideas are by no means so simple, and if the continuation on p. 120 were overlooked, I while if in another field, very deficient in these assimilable mineral constituents, a green crop was grown of a chlorotic nature and ploughed in, then the cereal crop grown would not be immune owing to the imperfect chemical functions performed by what I may call a chlorotic humus."

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And this, after all the careful work that has been done on the cereal rusts and other parasitic diseases!

On p. 131 the author declares that "parasitic fungi and bacteria can only flourish when the plant (or animal) on which they feed is deficient in chlorophyll or chlorophyll matter, or their products.'

An interesting specimen of the author's quality appears in the following naive passage on p. 148:"Slugs, indeed, living as they do like the fungi mainly upon decaying vegetable matter, are not unlike creeping fungi, and I believe it can be shown that they are chemically of a similar composition." Again, p. 158: "I have now pointed out that there are forms of insect life that are to all intents and purposes simply an extension of the fungi."

These suggestive quotations will, we are of opinion, convince the reader that the present volume cannot be said to be of any use to a serious student of science.

MINES AND MINERALS OF THE UNITED STATES.

Calendar Mineral Resources of the United States. Year 1901. Pp. 973 and index. (Washington : Government Printing Office, 1902.) THIS is the eighteenth volume of the well-known

series issued by the United States Geological Survey, and, like those which have gone before, it is full of valuable information concerning the mineral output not only of the country itself, but also of the world generally. The book consists of a number of articles written by various experts; thus the production of iron ore is dealt with by Mr. Birkinbine, and the American iron trade by Mr. Swank. Mr. G. F. Kunz contributes some interesting pages upon precious stones, whilst the coal trade is reviewed by Mr. E. W. Parker. The consequence is that a more useful contribution to knowledge is made by the United States Geological Survey than by the British Home Office in its annual mineral statistics.

The introductory remarks written by Dr. David T. Day tell us that the total value of the minerals produced in 1901 is reckoned at 1,086,529,521 dollars, or about 223 millions sterling; this is more than twice the value of the mineral output of the United Kingdom last year. It must be pointed out, however, that the

American figures are swollen by taking the value of the metals and not the value of the ores, but even if the comparison with this country were made upon strictly identical lines, we should still be a long way behind.

In 1901 the United States produced more coal, copper, gold, iron, lead, salt and silver than any other country in the world. The yield of coal was about one-third of the world's supply. This mineral is mined in twenty-eight different States, Pennsylvania being, of course, by far the most important. Twentyfour States are producing iron ore, Minnesota heading the list with 11 million tons of red hæmatite.

Montana yields about two-fifths of the copper of the United States, the Lake Superior district about onequarter, and Arizona about one-fifth.

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Colorado has outstripped California, and is now the leading gold-producing State.

Mr. Oliphant's chapter upon natural gas is sure to claim much attention, and is of special import for those who are interested in our new supply in Sussex. The advantages of this cheap and economical fuel are lauded to the skies by the author, who reckons that the quantity tapped and supplied in 1901 exceeded one cubic mile in volume; 21,848 miles of mains, 2 to 36 inches in diameter, are employed in distributing the gas to consumers.

We learn from Mr. Struthers that the United States are the largest producers of borates in the world. Most of the borax is obtained by treating the colemanite of California.

According to Mr. Joseph Hyde Pratt, who deals with abrasives, artificial corundum is now being employed in the manufacture of emery wheels. It appears that bauxite is converted into corundum by means of great heat and pressure in an electrical furnace. The mineral monazite is far more widely distributed than was imagined when its name was chosen in allusion to its supposed rare occurrence; it derives its commercial value from the small percentage of thoria which it contains. The quantity washed from gravels and sands in North and South Carolina in 1901 amounted to 334 tons.

means

two volumes of the original work, which deal with special climatology, as it has been found "impracticable" to translate them. This is greatly to be regretted, for the generalisations which constitute the science of climatology cannot be satisfactorily treated without reference to the statistical data and the for verifying them. Moreover, a compendious review, in English, of the statistics of the various meteorological elements arranged according to geographical distribution is constantly wanted for many purposes, and either a translation of Dr. Hann's volumes, or a reproduction in an abridged form of Dr. Buchan's volume of the Challenger reports, is a necessity of which every student of meteorology must be aware. It is quite true that such a survey would be a work of reference, and would not serve as a text-book in a course of general climatology, and as that is Prof. Ward's purpose in preparing the translation, we must unfortunately wait for some other interest to prompt the translation of the two volumes of special climatology.

The translator himself explains the relation of the English version to Hann's first volume :—

"This translation, as it stands, essentially reproduces the original. Numerous references, especially such as will be most useful to English and American students, have been added, and changes have been made in the text in order to bring the discussion down to date. A natural temptation to expand the original has been yielded to in very few cases only. Practically all of the important publications which have been issued since the completion of the second German edition are referred to. Some new examples of different climatic phenomena have been added, chiefly from the United States. Most of the examples given, climatology of that continent has been studied more however, necessarily still relate to Europe, because the critically than that of any other region. A few cuts have been made where the discussion concerned matters of special interest to European students only."

Among recent works, references to which have been incorporated, Bartholomew's "Atlas" is conspicuous, but the remarkable Russian "Climatological Atlas,' published in 1900, is not, although it furnishes a large number of illustrations of climatological principles.

A distinction is drawn by Hann between climatology and meteorology, but when one deals with general climatology it is rather hard to maintain the distinction. In dealing with the analysis of climates into solar, or mathematical climate, and physical climate, with such subdivisions as mountain climate, continental and marine climates, forest climate, and such supplements as mountains as climatic barriers, geological changes of climate and periodic variations of climate, all of which are treated in the book, it is obvious that neither author nor translator would be content with the mere analysis of figures representing these different sections. The mode of classification at once suggests the causes of climate, and the investigation of such causes is practically general meteorology.

It is scarcely necessary to refer to the admirable way in which Dr. Hann arranged his introductory volume to include a survey of all the general facts about climate and its local variations, and to produce a book

LETTERS TO THE EDITOR.

(The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, or to correspond with the writers of, rejected manuscripts intended for this or any other part of NATURE. No notice is taken of anonymous communications.]

Variation of Atmospheric Absorption.

I SHOULD be pleased to know how far some observations on the change in the average absorption of the terrestrial atmosphere in this country during the last two years have been confirmed by observations elsewhere. The following table gives the mean of the best of these, made at Washington in the autumn of 1901, the spring and autumn of 1902, and in the winter, spring, and summer of 1903. Coefficients of Transmission for Zenith Sun.

not give its full heating power at first, but the heating effect rises to a maximum in the course of the first few hours. If the emanation is the cause of the heat, why this slow rise? Here again the effect seems proportional to the amount of excited activity present, and not to the amount of the emanation. The connection of heating power with the emission of a rays also requires further elucidation, and the information given by the authors is not, I believe, sufficient to prove their case. It is only with great diffidence that I address these remarks to you, because Prof. Rutherford knows the whole subject at first hand, and his judgment is more likely to be correct than mine. Nevertheless, one likes to know whether others have felt the same difficulty, and whether the apparent disagreement is one of misunderstanding or has some more deep-seated ARTHUR SCHUSTER.

cause.

The Owens College, Manchester, November 2.

Heating Effect of the Radium Emanation. THE very important and fundamental experiments described by Profs. E. Rutherford and H. T. Barnes in NATURE of October 29 will have been read with the greatest interest. Owing to the importance of the subject, I should like to direct the authors' attention to some points in their comment and explanation which do not appear to me to be quite clear, and if I can draw from them some more detailed discussion this letter will have served its purpose. The general conclusion arrived at by the authors is that "more than two-thirds of the heating effect is not due to the radium at all, but to the radio-active emanation which it produces from itself." If I understand the description of their experiments correctly, these seem to me, however, to point to the fact that it is the "excited activity" and not the emanation that is the cause of the heating. Apparently de-emanated radium gives out an amount of heat at a rate which falls in a few hours to a minimum and then slowly recovers. Now the emanation itself begins to form again at once, so that on the authors' hypothesis the heating effect should start with a minimum and then gradually increase. The activity of the radium measured by electric methods follows the course of the heating effect, and, as Messrs. Rutherford and Soddy have explained (Phil. Mag., April, not May as quoted by the authors), this is due to the fact that the de-emanated radium has still the excited activity attached to it, and this activity decays in the course of a few hours. When the excited activity is gone there is nothing but radium left, and the further changes are due to the re-formation of the emanation and its subsequent change into excited activity. During the course of the first few hours there is, therefore, very little emanation, but there is excited activity which falls to a minimum and then slowly grows again. Does not the explanation which holds for the activity also hold for the heating effect, and would it not follow that the parallelism of heating effect lies with the amount of the excited activity present, and should be assigned to it rather than to the emanation?

Similarly, the emanation, according to the authors, does

Radium and Plants.

THE sensibility of protoplasm towards the radiations of radium is a matter of so much importance that a few preliminary experiments I have carried out on plants may be of interest.

The first experiment I made in this direction was with cress seedlings. About 100 seeds were uniformly distributed over the surface of some moist sand contained in a flower saucer, and a tube containing 5 mgrs. of pure radium bromide supported at a height of 1 cm. over the centre of the sand surface. During the experiment the saucer, covered with a glass shade, was kept in the dark. It was hoped that this arrangement would show whether the radiations are harmful or not to the sensitive cells of seedlings, and at the same time indicate if they are able to act as a stimulus to evoke positive or negative

curvatures.

After the germination of the seeds, which took place within two days nearly simultaneously all over the sand, the growth of all the seedlings was nearly uniform. But close comparison showed that the seedlings immediately under the radium tube were to some small extent retarded in their development. The retardation was apparent in the seedlings situated within a radius of about 2 cm. from the radium bromide. Besides being smaller, these seedlings developed somewhat fewer and shorter root-hairs than those nearer the margin of the sand.

In the subsequent growth the presence of the radium evoked no curvatures in the little plants close by it, or in those more removed. Nor did it appear to exercise any noxious effects, other than the retardation just described, on the seedlings within the period of the experiment, viz. thirteen days. The plants grew up beside it and against the glass containing it, neither influenced by it nor hurt by it, so far as one could see.

This experiment was repeated on two other occasions (one experiment lasting three days after germination and the other lasting four days) with the same result, viz. no curvature was evoked, but the seedlings close under the radium bromide were slightly retarded in their growth.

In order to determine if motile organisms are sensitive to the radiations I enclosed the radium tube in a vessel of

water containing large quantities of Volvox globator. Extraneous light was cut off from the experiment. After twenty hours many of the Volvox colonies had sunk to the bottom of the vessel, but they were evenly distributed over the bottom, and were neither aggregated under the tube nor dispersed away from it. Those that were still swimming in the water were also uniformly distributed through it, some actually in contact with the radium tube and some far away from it, but showing no sign of being attracted towards it, or of being repelled from it.

It is apparent from these few experiments that the radiations emitted by radium bromide are not able to produce marked effects in a short time on these vegetable cells and tissues. Even the phosphorescent light (which is quite perceptible to the eye under suitable conditions) emitted by the radium bromide is too feeble to be effective in calling out a phototactic response. HENRY H. DIXON. Botanical Laboratory, Trinity College, Dublin.