The ability of some types to subsist on simple inorganic substances (CH,, NH, and CO2) without the aid of sunshine, and the sensitiveness of all bacteria to the action of sunlight suggest their existence on this planet prior to the appearance of plant life or the penetration of the rays of the sun through the volcanic vapors.

We may perhaps agree that an organism which can develop without organic compounds of any kind, utilizing inorganic compounds exclusively, would probably be primitive. There is no proof, however, that the original bacteria were any more sensitive to the sun's rays than are plant cells in general at the present day. It is not improbable that the purple sulphur forms are among the most primitive of our modern bacteria, and these, as is well demonstrated by the work of Molisch and others, grow only in the presence of light, and the motile forms show a very marked positive phototaxis. Most animal cells are equally sensitive to sunlight with most bacteria, but this does not argue that these animal cells are primitive. Finally, the assumption that life must have originated on earth while the earth was still bathed in volcanic vapors, and the earth's surface was dark, has little to substantiate it. It is quite as probable that we must account for the development of life upon earth on the basis of Chamberlain's accretion theory as on the theory of a once molten globe. It is not argued that either hypothesis of earth origin must be accepted, but Dr. Kligler's assumption is rather an insecure basis for the erection of his complex superstructure.

It is rather difficult to follow Dr. Kligler's reasoning through the succeeding paragraph. The thesis to be proved apparently is: "The intimate dependence of both plants and animals on bacteria and their activities tends to strengthen the conviction that these microorganisms must have preceded the others." The statement may well be accurate, but the examples adduced are not in all cases fortunate. For example: "Plants can not subsist without nitrates" is misleading, for many of the higher plants, fungi, yeasts, alge, etc.,

utilize ammonia quite as well as nitrates, in some cases utilizing ammonia in preference. To state that in arid regions where plant life is absent bacteria are also absent is simply to affirm that both bacteria and higher plants require water for their growth, or are killed by an excess of salts in the soil rather than that the higher plants are dependent upon the bacteria. The author's examples of the necessity of bacteria for the growth of animals are likewise not convincing as proof.

Attention is next called to the fact that with the bacteria evolutionary changes may be physiological as well as morphological, and the point is made that these "adaptive modifications" should be traced.

The statement that "Bacteria need only minute amounts of nitrogenous food but require a relatively enormous quantity of energy-yielding (carbon) compounds" is doubtless true for many of the fermentative types, but there seems to be no more reason for this assertion for primitive bacteria than for higher plants, or the fungi. Then it is argued since most bacteria, at least the saprophytes, can utilize nitrogen either as NH,, or NO, and show the most diverse ability to use various carbohydrates, then the first path of early evolution must have been increasing ability to use a variety of carbohydrates, and only later, when a higher scale of development is reached do we find increasing power to utilize complex nitrogenous compounds. No evidence is adduced that the primitive organisms were furnished with abundance of carbohydrates before they had opportunity to attack considerable quantities of protein or other comIt should be

plex nitrogenous substances. emphasized that carbohydrates in the sense used and in quantity needed would probably be produced only by higher plants. But all plants contain protoplasm, and in their decay organisms have access to proteins as well as to carbohydrates. In spite of the array of supporting evidence, it seems that there is no adequate proof that utilization of carbohydrates is any more primitive a function than is proteolysis.

The point is made that there are four principal types of primitive oxidizing bacteria,

those which oxidize C, N, S and Fe, then follows the statement:

It seems fairly certain from the important part played by carbon compounds in the vital activities of our common bacteria, especially as a source of energy, that the carbon oxidizers are the forerunners of the bacteria of to-day.

The author then concludes that the most primitive types must be those capable of oxidizing methane, followed by those which oxidize carbon monoxid, and, most astounding, those capable "of utilizing CO,." A careful scrutiny of the text will lead to no conclusion but that "utilizing" is here used to indicate "oxidizing." This inference is strengthened by a second statement even more surprising.

Since the ammonia and nitrate oxidizers (or nitrifiers) also assimilate large amounts of carbon-dioxide (Jensen) they would seem to fall in line along with the organisms capable of obtaining their energy from carbon dioxide.2

By what mystic process an organism may secure energy from CO, is not explained. The assumption that carbon-oxidizing forms are most primitive is scarcely proved. In fact, study of the oligocarbophilous organisms, that is, forms which can utilize CO, in the building up of food or protoplasm indicates that the more primitive of the modern types may be among the nitrifying and the sulphur bacteria. An analysis of the conditions upon the earth in early times as postulated by the author and elaborated by Osborn would seem to indicate that they would be even more favorable to the development of ammonia or sulphur oxidizers than for methane oxidizers. It should be emphasized that all organisms of types not using organic carbon must have some source of energy which will enable the protoplasm to take up CO,, replace the oxygen in part with hydrogen and build up complex organic compounds. The energy for this transformation might have come from the oxidation of ammonia or sulphur. Certainly ground waters laden with hydrogen sulphide must have reached the surface of the primitive earth much as they do to-day. Furthermore, the consistent development of the pig2 Italics not in original.

ment bacteriopurpurin by most members of the modern large group of sulphur bacteria, together with the marked phototaxis of this group, might be interpreted as evidence that the sun's rays had some influence almost from the beginning in the explanation of energy source in CO, assimilation. In other words, early coordination of photosynthesis with chemosynthesis can not be ignored as a possibility.

It may be noted further that to discuss primitive bacteria as capable of utilizing formic acid, acetic acid and alcohol is somewhat anachronistic. These substances are the results of the growth or fermentative power of organisms which stand higher in the scale of evolution. Where could the primitive organisms find these complex compounds to work on? The author next calls attention to the fact that certain organisms changed their habit of life from that of obligate aerobes, using atmospheric oxygen, to that of facultative anaerobes, "utilizing combined oxygen for intracellular combustion." The statement is made that the "prototrophic denitrifying bacteria are most probably the progenitors of this group." The statement requires some analysis. One would infer that prototrophic denitrifiers are common and well known. As a matter of fact, the denitrifying organisms are almost without exception anything but prototrophic. When one wishes to demonstrate denitrification in the laboratory it is customary to add a suitable organism to an aqueous solution of nitrate and organic carbon compounds. Under anaerobic conditions the oxygen is removed in whole or in part from the nitrogen, and used for oxidizing the carbon compounds present. The only exception to this rule known to the writer is the peculiar organism described by Beijerinck which will grow in the presence of free sulphur, nitrate and carbon dioxide in the absence of atmospheric oxygen, oxidizing the sulphur and using the energy thus gained apparently in the assimilation of CO2. It would seem that such a form would be much more closely related to the Thiobacteria than to the other denitrifiers. To make his point, Dr. Kligler should cite some examples of "prototrophic denitrifiers."

If descriptions of such organisms are nonexistent in the literature is it necessary to assume that they have not been discovered or that they once existed but have disappeared? Is it so evident that

The line of descent from the prototrophic denitrifiers is entirely clear.

The statement is made that next in series following the prototrophic denitrifiers probably came the aerogenes type of organism, one indication of relationship being that it can live "in simple inorganic media and under certain conditions, even to fix atmospheric nitrogen." The present writer has been unable to find any evidence that the aerogenes group can ever grow in a medium devoid of organic matter. It is true that inorganic nitrogen compounds may be used, but this, as was above indicated, has no particular significance, as many bacteria, yeasts, molds, algæ and even flowering plants have the same power. Any close relationship of aerogenes to a prototrophic form certainly has not been proved. However, the author's claim for close relationship between aerogenes and coli and through the series to the typhoid, dysentery and possibly even to the hemorrhagic septicemia groups has much to commend it, and is a generally accepted hypothesis at present among bacteriologists.

It is possible that the relationship assumed to exist between B. proteus and the sporebearing rods is a real one, but the structural modification incident to the development of the power of endospore production is so great that mere association of organisms in putrefactive processes and common property of producing proteolytic enzymes does not prove close affinity. It should be borne constantly in mind that proteolytic enzymes are commonly produced by cells. Every cell has protoplasm consisting largely of protein. in general after death undergo autolysis. Every cell then contains an autolytic proteolytic enzyme. The step to the production of an extracellular proteolytic enzyme would therefore seem not to be a difficult one to make, and one which may have been made independently by different groups. It might be mentioned, however, that Kligler has ig

Cells

nored one point of morphology which would tend to show relationship better than proteolysis, this being the diffuse arrangement of the flagella in both groups. Apparently organisms showing peritrichous flagella constitute a group rather distinct from the forms with polar flagella.

The type of pigment produced, and the general cultural and physiological characters would seem to argue quite as close a relationship between the Rhodococcus and Micrococcus and the rods producing red or yellow pigment, as between the latter and the spore-bearers or B. proteus. Many more resemblances than differences will be found, for example, between Rhodococcus roseus and the organism usually known as Bacillus prodigiosus.

The effort to derive the gram positive streptococci from the aerogenes types seems rather strained. Differences are more marked than resemblances. The products of fermentation are very distinct in the two groups. This fact together with decided differences in morphology, relationship to oxygen and cultural characters, counterbalance the presence of capsules of similar composition, ability to ferment inulin (in fact a variable character in aerogenes) and localization in the same organs of the animal body. However, it should be granted that the author's emphasis on relationship between the streptococci and the aciduric bacilli is probably well placed.

Kligler's characterization of Azotobacter as a form not only fixing atmospheric nitrogen but oxidizing nitrogen to nitrates is apparently not well founded. It may be noted that there is an apparent tendency to consider Azotobacter prototrophic, an assumption which is quite unwarranted. The statement "the Azotobacter can assimilate free nitrogen more readily if glucose and a small amount of ammonia are supplied" is misleading. Apparently Azotobacter is wholly incapable of growing, certainly incapable of fixing atmospheric nitrogen, without an abundance of soluble carbohydrate food. By oxidation of this carbohydrate, energy is secured for the fixation of sufficient atmospheric nitrogen for the needs of the cell, but there is apparently no nitrogen changed into the form of nitrates.

Furthermore it should be emphasized that this organism has very high fermentative powers, producing large amounts of CO, and H2O.

That the organisms of the nodules of the legumes are closely related to Azotobacter is not improbable, but that there is any close relationship between Rhizobium and the acidfast bacteria and the Actinomycetes is not so clear. It is true that the latter contention has been supported by several writers, but the fact that Rhizobium produces nodules on the plant roots and the tubercle bacillus causes tubercles to develop in animal tissues is no more of an argument for their inter-relationship than to claim that the nematodes producing galls on plant roots are related to the tubercle bacillus or to the Rhizobium for the same reason. The differences between the motile (polar flagellate) gram negative, Rhizobium, fixing atmospheric nitrogen, and the acid-fast gram positive, non-motile tubercle bacillus incapable of fixing nitrogen are very marked and tend to outweigh the remote resemblance of the branched bacteroids to branched tubercle bacilli.

The relationship indicated between the tubercle bacillus and the Actinomycetes is not at all improbable, in fact, intermediate forms have been described.

The use by the author of the name Sporothrix for a group of bacteria is unfortunate, and will tend to confusion.

It is surprising to find the Micrococci and Staphylococci at one extreme and Streptococci at the other of the classificatory scheme that is worked out. The concept is unusual, to say the least, and is scarcely supported by adequate proof to be convincing.

It would seem that the family tree of the bacteria suggested by Dr. Kligler is based upon many misconceptions and misinterpretations and can scarcely be accepted without much more adequate proof. However, there is much in the article to provoke thought and discussion, and if this is accomplished and some conclusions eventually reached, the effort put forth can scarcely be said to have been in vain. R. E. BUCHANAN THE BACTERIOLOGICAL LABORATORIES, IOWA STATE COLLEGE

THE AMERICAN MATHEMATICAL

SOCIETY

THE one hundred and ninety-sixth regular meeting of the society was held at Columbia University on Saturday, February 23, extending through the usual morning and afternoon sessions. Seventeen members were in attendance. Professor H. S. White occupied the chair. The following were elected to membership: Miss M. F. Chadburne, Smith College; Mr. Mervyn Davis, Equitable Life Insurance Company of Iowa; Mr. T. C. Fry, Western Electric Company; Dr. J. E. McAtee, University of Illinois; Dr. Norbert Wiener, Albany, N. Y. Four applications for membership were received.

The following papers were read at this meeting: J. F. Ritt: "Proof of the multiplication formula for determinants by means of linear differential equations.''

Olive C. Hazlett: "On vector covariants.'' P. R. Rider: "On the problem of the calculus of variations in n dimensions.''

A. R. Schweitzer: "On the iterative properties of an abstract group."

A. R. Schweitzer: "On certain articles on functional equations.'

A. R. Schweitzer: "On iterative function equations.''

J. R. Kline: "A new proof of a theorem due to Schoenflies.''

R. L. Moore: "A sufficient condition that a system of arcs should constitute a surface.''

J. L. Walsh: "On the location of the roots of the Jacobian of two binary forms, and of the derivative of a rational function."

O. E. Glenn: "Covariant expansion of a modular form.'

J. F. Ritt: "Polynomials with a common iterate."'

L. P. Eisenhart: "Transformations of applicable conjugate nets of curves or surfaces.''

S. E. Slocum: "The romantic aspect of num

bers.''

The San Francisco Section of the society will hold its semi-annual meeting at Stanford University on April 6. The Chicago Section will meet at the University of Chicago on April 12-13; this meeting will include a symposium on divergent series and modern theories of summability. The regular New York meeting will be held at Columbia University on April 27.

F. N. COLE, Secretary

GEOLOGY IN EDUCATION 1

WHAT Would be the result if those who are interested in education could come de novo to the question of the content of an ideal curriculum of study? It probably is safe to say that one of the results would be a shock to those whose opinions on this matter have been shaped by the prejudices which accompany our inheritance. That evolution is a slow process is illustrated nowhere better than in educational circles.

Let it be assumed that the consideration of what is most valuable in education could be approached by a jury which has an intelligent grasp of all subjects, as now understood, and of these subjects in their proper relations. Let it be assumed further that the jury is unprejudiced by tradition or by pronounced personal bents in favor of or against individual subjects. What conclusions would they reach? To this question there is of course no categorical answer. Wisdom would decree that there is no one model curriculum-that there should be various types of curricula, each susceptible of adaptation to individual needs.

The classes of subjects whose claims would need to be considered in such a study as that here suggested fall into several general classes. It goes without saying that their values would be differently gauged by different men, and that their values are different for different men.

Without presuming to make an exhaustive classification, it is clear that one great

1 Address of the vice-president and chairman of Section E-Geology and Geography-American Association for the Advancement of Science, Pittsburgh, December, 1917.