the quantity of oxygen absorbed and the amount of carbonic acid exhaled by a plant placed in the light and under natural conditions, it will easily be understood why we refrain from making any comparison until we are in possession of all the data necessary to carry out the calculation. (9) The facts which precede convince me that the seeds of uncultivated plants germinating in the light are, all other conditions being equal, better distributed than the seeds of cultivated plants; that they possess a greater germinating power, an advantage which increases their chances for ulterior development. Chapter III. THE TEMPERATURE OF THE SOIL. OBSERVATIONS AT HOUGHTON FARM AND GENEVA, N. Y., BY D. P. PENHALLOW. In reference to the value of soil temperatures, Penhallow states (Agr. Sci., Vol. I, p. 78): A proper knowledge of the temperature of the soil must serve to guide us in reference to the time of planting particular seeds and the depth at which they should be planted, as determined by the condition and character of the soil. When the farmer gently packs the earth over the planted seed he derives a measure of benefit in the higher temperature of the soil at that place, whereby germination is accelerated. Similarly, we can understand that cultivation during periods of excessive heat must tend to avert some of the evil results otherwise following from an excess of temperature. Moreover, in seasons of great or even of ordinary dryness a judicious system of irrigation must be of the greatest advantage, not only as supplying needed fluids for the general functions of growth, but as reducing the otherwise high temperature of the soil to a degree that is well within the danger limit and consistent with normal growth. Penhallow also shows from observations at Houghton Farm and at Geneva, N. Y., that all layers of the soil within 3 inches of the surface have temperatures that depend not merely upon absorption of solar heat but also upon the cooling due to radiation and evaporation. The depression due to evaporation amounts to about 8° C. on the average of the warmer half of the year and is even more than this when hot days and strong dry winds produce an excessive evaporation. OBSERVATIONS BY E. S. GOFF. E. S. Goff adduces observations to show that the temperature of the water at the time when it enters into the roots from the soil has some relation to the temperature of the stem of the plant for a short distance above the surface soil, and that the distance up the stem to which this temperature is felt depends upon the rapidity of the flow of the sap, and therefore ultimately on the rapidity of transpiration from the leaves. (Agr. Sci., Vol. I, p. 134.) OBSERVATIONS OF TEMPERATURE OF MANURED SOILS IN JAPAN BY GEORGESON. Soil temperature must to some extent be affected by the heat given out by decaying manure and vegetation. On this subject Mr. C. C. Georgeson describes some experiments being made at Tokyo, Japan (Agr. Sci., Vol. I, p. 251), from which it appears that the temperature immediately after applying the manure was from 2° to 5° F. higher than in the unmanured soil, and this excess steadily diminished, but was still appreciable at the end of two months. The 2° of excess occurred when the manure was applied at the rate of 10 tons per acre, and the 5° of excess when applied at a rate of 80 tons per acre. INFLUENCE OF RAIN ON TEMPERATURE OF THE SOIL AT The study of the earth temperatures at considerable depths is a problem for terrestrial physics, but for agricultural purposes we need only consider the temperature of the soil within 4 or at most 8 feet. The work of Karl Singer (1890) is sufficiently instructive to justify the presentation of his general results for use in studying the phænological phenomena of Europe. In a simple diagram Singer summarizes at a glance the mean temperature of the soil at any depth between 1 and 7 meters for any day of the year, as it results from an average of thirty years of observations at the observatory at Bogenhausen, near Munich, Bavaria. The series of observations includes, in fact, four sets of earth thermometers, two of which were on the northwest side of the observatory and the other two on the southeast side; the diagram and the following summary of results relate to the average of the pair on the southeast side. Each set of thermometers consisted of five, whose bulbs were buried at depths of 4, 8, 12, 16, and 20 Bavarian feet, respectively, or 1.2, 2.4, 3.6, 4.8, and 5.9 meters, respectively. The lines given in this diagram are thermal isopleths, viz, curves of equal temperature for successive depths and days, the days being represented by vertical lines and the depths by the horizontal lines. The following paragraphs express the general results of Singer's work as far as it bears upon the growth of plants: (1) The normal mean temperature of the earth for twenty-five years (1861-1885) at Bogenhausen, near Munich, at certain depths, is as follows: (2) The mean temperature of the earth at a depth of about 1 meter below the surface exceeds the mean temperature of the air [at a meter above the surface] by more than 20. The important influence. of the considerable altitude above sea level of the place of observation is to be recognized in this result. (3) The decrease of the annual amplitude with increasing depth for the adopted interval of 4 Bavarian feet, or 1.17 meters, amounts to 12.18° C, or very nearly one-third of the original amplitude of the atmospheric temperature. The amplitude AP in centigrade degrees at the depth P in meters is represented by log P=1.26200.1508 P. Whence we compute the amplitudes given in the last column of the preceding table. (4) The epoch of the occurrence of the extreme and mean temperatures for the highest thermometer, No. I, are: Minimum, 2d of March; first mean, 21st May; maximum, 24th August; second mean, 15th November. These are therefore separated from each other by intervals of about 23, 3, 23, 33 months, respectively. For each step downward of 4 feet, or 1.2 meters, in depth, the occurrence of the epoch of extreme temperature is retarded on an average 21 days and that of the mean temperature 24 days; therefore an almost uniform distribution of these dates is brought about down to a depth of 20.2 feet, or 6 meters, where the minimum occurs on the 23d of May, the first mean on the 24th August; the maximum 17th November, and the second mean on the 24th February. (5) The actual temperatures of the ground from 1861 to 1889, at the upper stage of 4.2 feet, or 1.3 meters, or thermometer No. I, did not fall below 2° C. or rise above 17° C. At the lower levels they ranged between 4° and 14°, 5° and 13°, 6° and 12°, 7° and 11°, respectively. (6) By a careful consideration of the state of the weather it is possible in every case to account for the connection between the fluctuations of the temperature of the air and that of the earth. The following generalizations refer to the climate of the South Bavarian Plateau only and to the four seasons of the year: (7) In mild and, as usual, rainy, winter months, there is no material rise in the temperature of the earth relative to the average temperature curves, particularly at great depths, but generally a lowering of temperature. (8) Mild, and at the same time dry, winters are associated with a tendency of the earth temperature to rise above the average. (9) The earth temperatures exhibit a tendency to fall, if not already too low, during winters in which, with alternate freezing and thawing, the mean temperature is below the normal. (10) In the same way even a covering of snow can only to a limited extent prevent the cooling of the earth when severe cold follows the mild and rainy weather of the first part of winter. (11) In continuous severe winters, on the contrary, when even December generally brings a permanent covering of snow, the negative departure of the earth temperature is either limited to the higher strata or is unimportant. (12) A warm spring, which, as a rule, brings only a moderate quantity of rain, causes a relatively decided rise of the earth temperature. (13) When a cold and rainy late winter is directly succeeded by warm spring months, the temperatures of only the upper strata of the ground rise, while those of the lower strata may fall still further below their normal values. (14) In certain warm and at the same time rainy springs the earth temperatures remain on an average unchanged with respect to the normal for the cold rain counterbalances the warm weather. C. A. (15) An exceptionally cold spring, which is generally distinguished by heavy snows, is, with few exceptions, accompanied, and to a considerable depth, by a notable lowering of the temperature of the ground in comparison with its normal temperature. (16) In cold and at the same time dry spring weather the relative lowering of the temperature of the ground will generally be inconsiderable if it has not been preceded by an immediate very rainy season. (17) A warm summer is always accompanied by a high temperature of the ground or by a rise of its temperature. The increase is the more decided the more the excess in the temperature of the air is accompanied by a large quantity of rain or has been immediately preceded by it. In warm and comparatively dry summers the rise of the earth's temperature does not perceptibly exceed the normal. (18) The relative lowness of the temperature of the soil which follows without exception a cool summer generally extends down only to a comparatively moderate depth, scarcely to 4 meters. Those months in which we find it extending to 6 meters will be found to have been at the same time rainy months. (19) A warm autumn, with very few exceptions, causes a corresponding small rise in the temperature of the soil, but this may even, on the contrary, become a fall when the late autumn, by reason of much rain, resembles a mild type of winter. (20) Low air temperature is generally accompanied in autumn by an excess of rain, the consequence of which, as regularly and frequently observed, is a falling in the temperature of the earth. (21) In the rarer cases of cool and dry autumns there is observed only a very inconsiderable influence on the temperature of the earth. (22) The dampness of the soil is (under the climatic influences prevailing in Munich) sufficient to allow the variations in the temperature of the air in winter and spring to exercise a decided influence upon those of the soil, whereas in summer an excess of rain would be |