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easily examined. Until very recently no attempts have been made to extend observation and description to the subterranean parts of land plants, but excellent beginnings in this recondite province of botany are now available and enough has been accomplished to demonstrate that a well-rounded knowledge of plants or of any plant individual must include just as thorough study of root systems as has been devoted to the aerial parts.

Publication No. 292 of the Carnegie Institution of Washington is perhaps the most valuable contribution yet available in this new field. In this book Weaver presents the results of an enormous amount of detailed study devoted to the form and distribution of the roots of plants growing in the grasslands of the United States, this study being a continuation of the author's earlier volume on "The Ecological Relations of Roots." "Practically all of the grassland dominants have now been studied, many of them in two or more associations and under widely different conditions of environment." Descriptions of 38 new root systems of native plants are here presented and more than 80 examinations of the root systems of crop plants have been made in widely varying soil types and conditions of growth." The root systems have been excavated with painstaking care and their form and distribution are set forth by descriptions and by diagrams drawn to scale, being frequently also illustrated by reproductions of photographs.

The point of view is primarily that of what may be called the Nebraska school of ecology. with much emphasis on the concept of plant succession and on the practical value of a knowledge of native vegetation as an indicator of agricultural possibilities.

The phenomena of plant succession, whether ecesis, competition, or reaction, are controlled so largely by edaphic conditions and particularly by water-content [of the soil] that they can be properly interpreted and their true significance understood only from a thorough knowledge of root relations.

But the discussions involve much of the physiological, and the author's aim appears

generally to be a consideration of the individual plant as a machine operating under the controlling conditions of the surroundings, both above and below the soil surface.

Since the work of charting root systems is very arduous and since the physiological processes of agricultural plants deserve attention before native plants are to be thoroughly studied in this way, it is especially gratifying that a goodly number of crop plants have received attention at the author's hands. Some striking points are shown by the following illustrations (from p. 139): Sweet clover (Melilotus) 116 days old had tops 1.8 ft. high and roots about 5 ft. deep in lowland soil, while the tops were only 1.5 ft. high and the roots were mainly about 5.8 ft. deep in upland soil. Oats (Avena) 75 days old had tops 3 ft. high in lowland and 2 ft. high in upland soil, the corresponding "working depths" of the roots being 2.6 and 3.1 ft., respectively.

The presentation of the results of these valuable investigations might rather easily have been rendered more generally clear and more readily comparable with the results of other similar studies, if the author had employed a meter-stick instead of his foot-rule. He does not appear to be consistently opposed to the use of the metric system, for some measurements are recorded in millimeters, etc., and he has grafted the decimal characteristic of the better system on to the unit of the worse; he dealt primarily with feet and inches but reduced his final values to terms of the foot and its decimal fractions.

The root characteristics of a given species are found to be "often as marked and distinctive as are those of the aerial vegetative parts," in spite of profound differences frequently concomitant with marked differences in habitat conditions. Different species of the same genus are sometimes markedly different in their root characteristics.

The volume should be familiar to all who are interested in the relations that obtain between plants, on the one hand, and the soil and air conditions of their surroundings, on the other.

B. E. LIVINGSTON

NOTES ON METEOROLOGY AND

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CLIMATOLOGY

PHYSIOLOGICAL METEOROLOGY

IN opening his presidential address1 before the American Meteorological Society at Chicago in December, Professor Robert DeC. Ward directed attention to the fact that the Constitution of the Society states as its first object the advancement and diffusion of knowledge of meteorology, including climatology, and the development of its application to public health . . . ." He said further that, in spite of the intimate relations existing between meteorology and health, there are few physicians who have even an elementary training in meteorology, and perhaps fewer meteorologists who are competent to deal with the physiological and medical relations. It appears, however, that more and more thought is being given the subject, both at home and abroad; and this interest is finding its expression in various researches and numerous papers, these, in turn, being applied practically in the control of air conditions in hospitals, factories, and, in fact, in many other places where human health and mechanical efficiency must be maintained at their best.

Numerous papers bearing upon the subject of physiological meteorology have been published from time to time in the Monthly Weather Review, and among the most important of these is one by Dr. Leonard Hill of Essex, England, on "Atmospheric environment and health."4 Says Dr. Hill:

The body is fashioned by nature for the getting 1 "Climate and Health, with Special Reference to the United States.' "" Author's abstract in Monthly Weather Review, December, 1920, pp. 690691. Published in The Scientific Monthly, April, 1921.

2 See Huntington, Ellsworth, "The Importance of Air Control in Hospitals," The Modern Hospital, April and May, 1920, pp. 271-275 and 348353; noted in Monthly Weather Review, May, 1920, pp. 279-280.

3 Mount, Harry A., "Making Weather to Order, "Scientific American, March 5, 1921, pp. 188 and 198.

4 December, 1920, pp. 687-690.

of food by active exercise, and upon the taking of such exercise depends the proper vigorous function of the digestive, respiratory and vascular organs. Consequent on this, too, is the vigor of the nervous system and keen enjoyment of life. So, too, the healthy state of joints, muscles and ligaments, and freedom from rheumatic pains depend upon proper exercise of the body, neither over use nor under use, either of which may be associated with malnutrition and lowered resistance to infection. The hothouse conditions of life suitable for the failing powers of the aged, the injured in a state of shock and those in the last stages of wasting disease are mistakenly supposed to be suitable for the young and healthy. The traditional fear of cold is handed down from mother to children at her knee. For fear of their "catching cold," they are confined indoors and overclothed. They are debilitated and exposed at the same time to massive infection in crowded places. They require well-chosen food containing all those vitamines or principles of growth which are found in milk, the young green shoots of plants, grain foods with the germ and outer layers not removed by the miller. At the same time they require the stimulation of abundant open-air exercise to make them eat and metabolize their food. Household expenses will go up as more food is eaten by children excited by open-air exercise to keen appetite, but an immense national economy will result from a healthy, vigorous, efficient people.

But to obtain quantitative measures of the meteorological conditions most closely related to bodily comfort and health (these conditions being temperature, vapor-pressure, and velocity of air movement), recourse must be had to other devices than the familiar wetand dry-bulb thermometers. The thermometer, Dr. Hill points out, is a static instrument, while the body is dynamic, since heat is produced at a certain rate and must be lost at an equal rate. To meet this need, Dr. Hill, in 1913, devised the katathermometer, which has given excellent results. The katathermometers consists of "a large-bulbed spirit thermometer of standard size and shape, graduated between 100° F. and 95° F. The

5 Cf. Jacob, Robert A., "The Katathermometer: An Instrument to Measure Bodily Comfort,'' Monthly Weather Review, September, 1920, pp. 497-498, for history, description and photographs of the katathermometer.

bulb is heated in hot water in a thermos flask until the meniscus rises into the small top of the bulb. It is then dried, suspended and the time of cooling from 100° to 95° F. taken with a stop watch in seconds. The number of seconds, divided into a factor number (approximately 500, and determined for each instrument) gives the cooling power by convection and radiation on the surface of the "kata" at approximately skin temperature in millicalories per square centimeter per second. The operation is repeated with a cotton muslin finger stall on the bulb and the wet "kata" cooling power obtained, a cooling power due to evaporation, radiation. and convection. The difference between the two readings gives the cooling power of the evaporation alone.

It is shown by a table to what low values the cooling power can fall in stagnant air at even moderate temperatures-values that are much too low for any except the most sedentary occupations. And yet it is true that in many factories and mills where great heat is generated by rapidly moving machinery, or where workmen are subjected to high temperatures in engine rooms and about furnaces, no provision is made for the introduction of cool air, nor even for keeping the warm air in circulation. The result is that the proper vigorous activity of the respiratory and vascular organs is not maintained and illness, or general depression, with its consequent inefficiency results. An excellent example of the effect of providing proper means for cooling is that of a large steel tube factory in England, where air ducts supply air so cool that the men working before the huge furnaces actually feel cool when the furnace doors are shut. The effect is quite like the heating and cooling on a summer's day with passing clouds. It is said that the output of that factory is greater than that of any other of its kind, and there is no industrial unrest. Thus it is, that by reproducing as far as possible within doors the slight variations of temperature and air movement which outdoor workers experience, it is possible to make some progress in keeping the sedentary worker

in the same robust and vigorous physical condition in which the outdoor worker finds himself. The economic importance of giving attention to these considerations is obvious.

A study of the relations between weather conditions and the incidence of certain diseases in north Atlantic states has been made by Mr. John R. Weeks, U. S. Weather Bureau meteorologist at Binghamton, N. Y. From his studies he has drawn the following conclusions:

First, that a moderate degree of humidity, about 70 per cent., and a moderate temperature, about 68° F., should be maintained in dwellings;

Second, that crowding and mingling with persons having cough should be avoided; Third, that sunshine and plenty of interior light should be sought; and

Fourth, that schools for janitors should be provided in order that the heating and ventilation of public places may be properly cared for.

The objection that a relative humidity as high as 70 per cent. indoors in winter would be difficult to maintain with a temperature as high as 68° F. is, no doubt, a valid one; but such a temperature would probably be too high for comfort with that humidity. Since it would be much easier to maintain a high humidity with a lower temperature it probably would be possible to find a practicable combination of temperature and humidity which would be entirely comfortable. In an article by William E. Watt, principal of the Graham Public School, Chicago, on "How I run my school," it is found that a temperature of 60° F. is sufficiently high for comfort if sufficient humidity is maintained. By introducing live steam into his warm air ducts he found it possible to maintain such conditions, with beneficial results to teachers and pupils.

In addition to the necessity for local con6 Abstract and discussion in Bulletin of the American Meteorological Society, February, 1921, pp. 27-28.

7 The Ladies' Home Journal, September 1, 1910,

p. 20.

siderations of atmospheric conditions and health, there are the broader and more general aspects of climate and the treatment of certain diseases. Professor Ward, in the address earlier referred to, emphasized the correct understanding of the characteristics of climate and the judicious selection of climates to suit the particular ailments, for there is no 66 perfect" climate that will be equally beneficial for all ills.

Efforts have been made frequently to give graphical representations of climatic characteristics, especially with regard to temperature and humidity, and some of these have been very successful. Perhaps the climograph of Dr. Griffith Taylor, of Australia, is the most noteworthy example. Mr. B. M. Varneys says:

One scarcely need point out the great usefulness, to the geographer, the business man, the physician, the teacher, any device which helps to create living conceptions of the nature of climate and weather, so leading to a better estimate of the effect of a given atmospheric environment on human affairs.

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That is what the climograph seeks to do. It is a chart in which wet-bulb temperatures are plotted against relative humidity, or air temperature (dry-bulb) against relative humidity. Mr. Varney has chosen to mark certain regions of his climographs raw," "keen," "scorching," "muggy," etc., to indicate bodily sensation. The line joining the points in the diagram wanders about among these regions and thus indicates the characteristics of the weather or climate under consideration.

Dr. Carrol E. Edson, president of the American Climatological and Clinical Association, at the meeting of the Meteorological Society mentioned above, gave the following questions as being worthy of study by the meteorologist, and referred to them as gaps in present medical knowledge:

1. Is basic metabolism different in people liv ing at high altitudes from that of people living at 8"Some Further Uses of the Climograph," Monthly Weather Review, September, 1920, pp. 495-497.

low altitudes? A study of this might be called "Climatic physiology."

2. What is the effect of sudden changeschanges of altitude, temperature, moisture, wind, etc.? Experimental solution of this question is possible. This is "Physiologic meteorology."

3. Lastly, there is the study of the adaptability of the diseased mechanism to meet sudden changes: "Medical climatology.'

These are a few of the aspects of the relations between meteorology and health, and indicate what an extensive field there is for investigation, both for the meteorologist and the physician. C. LEROY MEISINGER

WASHINGTON, D. C.

SPECIAL ARTICLES

A NEW TYPE OF INHERITANCE

IN a recent contribution from the Carlsberg Laboratory,1 J. Schmidt has described a new type of inheritance found in "the millions fish," Lebistes reticulatus, from Trinidad. A conspicuous black spot occurs on the dorsal fin of the male in one race of this species, but it is wanting in all females of the species and also in males of a second race with which crosses were made. This spot was transmitted to all male offspring of the spotted fish, regardless of the mother's ancestry, but it was not found in the female offspring, nor did it reappear in the male offspring of such females, when they were mated with males which lacked the spot.

Further, sons of the spotted male, transmitted the spot to all their male offspring, not to half of them, as would be the case with an ordinary dominant Mendelian character. The inheritance of the character appears to be exclusively from father to son, females neither possessing nor transmitting it. Evidently the sperm is the sole vehicle of its transmission. It does not get into the egg at all. Moreover it is apparently transmitted by only half the sperm cells, those namely which are male determining in function. It therefore has, as Schmidt points out, exactly the distribution of a Y chromosome, and he suggests that a Y 1 C. R. Travaux Laboratoire Carlsberg, Vol. 14, No. 8, Copenhagen, 1920.

chromosome may be the vehicle of transmission, a matter which his colleague, Winge, has under investigation.

In all previously known cases of sex-linked inheritance, the egg as well as the sperm may serve as a vehicle of transmission. In Drosophila and man it is supposed that the X chromosome bears sex-linked characters, the female being in formula XX, so that every egg after maturation contains an X, a bearer of sexlinked characters; but in the same species the male is XY in formula, a Y replacing one of the X's found in the female. This X consequently will occur in only half of the sperm produced by the XY male, namely those which pass into female offspring, but the other sperms will contain Y instead of X and they will pass into male offspring. However, up to the appearance of Schmidt's paper, no characters had been observed to follow the path of a Y chromosome in transmission, so that Morgan characterizes the Y chromosome of Drosophila as "empty."

Before the mechanism of transmission of sex-linked characters had been worked out, I suggested in 19092 that the Y chromosome afforded a suitable vehicle for transmitting the secondary sex characters of males. But until Schmidt's publication was made this suggestion had found no support in known facts, and the demonstration by Morgan and others that characters which make their first appearance or are most often found in males, may nevertheless have their genetic basis in an X chromosome, seemed to discredit the Y chromosome as a possible organ of inheritance. The discovery of Schmidt leads me to call attention to my earlier suggestion, not for the mere satisfaction of saying "I told you so," but to renew the further suggestion which I then made and which still lacks verification, that the Y chromosome may contain the clew to the explanation of that other and very different type of sex-linked inheritance found in Abraxas and subsequently found to occur also in poultry.

2"A Mendelian View of Sex-heredity," SOIENCE Vol. 29, pp. 395-400, March 5, 1909.

Studies of sex-determination made in the last twenty years show unmistakably that in diœcious species the chromatin composition of the nucleus of the egg determines the sex of the individual into which the egg develops. Further, in many cases, if not in all, the quantity of chromatin is clearly decisive between maleness or femaleness in the individual which develops from the egg. Thus in parthenogenesis an egg which develops without chromatin reduction (in maturation) regularly develops into a female; but an egg which first undergoes chromatin reduction (usually by exactly half the total number of chromosomes), before it begins development into an embryo, if it remains unfertilized, now develops into a male. Yet if the egg, after undergoing chromatin reduction in maturation, receives a new complement of chromatin by being fertilized, it is restored again to the female status. Femaleness thus goes with the full chromatin equipment of the species, maleness with a less complete chromatin equipment.

It has further become clear through studies of sex-linked inheritance that not all kinds of chromatin are equally influential in determining sex, but that a particular chromosome called X is of preeminent, if not exclusive importance in determining sex. In the case first clearly worked out by Wilson, that of the squash-bug, the female bears in each cellnucleus a pair of X's, whereas the male contains but one. As the remaining ten chromosomes of this species are paired in both sexes, the total chromosome count for the female is 20+2X=22; for the male it is 20X21. The only discoverable difference between the two sexes is in the number of the X chromosomes. The number is two in the female, one in the male. The metabolic grade of maleness is attained when, in addition to the other ten pairs of chromosomes, a single X chromosome is present in the cell, but the grade of femaleness is attained only when the further addition of a second X is made. Every kind of chromatin of the species is present in the male, but a particular kind of chromatin is present in less

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