non, it is unnecessary to search for another. And this brings me to refer to the admirable drawing of the transverse section of the leaf, magnified 235 times, of Silphium laciniatum, given on page 157 of Botany by C. E. Bessey, professor of botany in the Iowa Agricultural College. He says, “Its chlorophyll-bearing parenchyma is almost entirely arranged as palisade tissue, so that the upper and lower portions are almost exactly identical in structure;" on page 103 he says, "there are in the true upper surface 52,700 stomata per square inch, and on the under surface 57,300 per square inch." This magnifying of a section of the leaf is a dissection, and thus there is no cause to suppose the existence of any spiral ducts such as are above referred to. Professor Bessey, living in the prairie region has the best possible opportunities to observe the compass plant. He says, page 515: "Its large pinnately lobed leaves twist upon their petioles, so as to present one surface of the blade to the east and the other to the west, the two edges being upon the meridian." This language applies to the leaves of the flowering plant, for in the growing of the radical leaf there is no cause for the twisting of the petiole in order that it may assume its meridional position. As to the history of the plant in Europe. The following is an extract from the article by Sir Joseph Hooker in the London Botanical Magazine for January, 1881, above quoted, which is preceded by a drawing of the flowering plant: "This noble plant was introduced into Europe in 1781 by Thouin and flowered for the first time in the Botanical Garden of Upsala in Sweden. It has been in cultivation in Europe ever since, though its name and fame as the compass plant of the prairies are of comparatively modern date, it having before that borne the popular names of turpentine plant and rosin weed, except among the hunters and settlers in the Western States. With regard to the history of its reputed properties as an indicator of the meridian by the position of its leaves, I am fortunate in having recourse to my friend Professor Asa Gray, now in England, who has most kindly furnished me the following very interesting account of this matter: "The first announcement of the tendency of the leaves of the compass plant to direct their edges to the north and south, was made by General (then Lieutenant) Alvord of the U. S. Army, in the year 1842, and again in 1849, in communications to the American Association for the Advancement of Science. But the fact appears to have long been familiar to the hunters who traversed the prairies in which this plant abounds. The account was somewhat discredited at the time by the observation that the plants cultivated in the Botanical Garden at Cambridge, U. S., did not distinctly exhibit this tendency.'" Nature for Feb. 1, 1877, contains the first of a series of articles by "A. W. B." on "Remarkable Plants," and begins with the compass plant as No. 1. It says: "Our illustration is taken. partly from the plate in Jacquin's 'Ecloga,' the only good drawing of the plant published, assisted by comparison with dried specimens in the Kew Herbarium." The full title2 of Jacquin's book, published in Latin in Vienna in, 1812, is, "Selections of rare and little-known plants, described from living plants with colored illustrations." Like the plant in Upsala, Sweden, in 1781, it was cultivated, but its true rarity, and its claims for interest and investigation, were quite unknown. If it is asked what remains for the observation of scientists in this connection, we answer, that besides the occasional torsion of 90° referred to by Dr. Gray, and the exceptions to the rule in which the whole leaf is east and west, to which we have briefly alluded, we will add: the whole subject of the reason (the entire rationale) of leaves turning towards the light is worthy of more full experiment and elucidation. I had written the above sentence when I was pleased to see in the American Journal of Science for March, 1882, a communication by Dr. Asa Gray, stating the substance of a paper by Francis Darwin, in Journal of the Linnæan Society, 1881, "On the power possessed by leaves of placing themselves at right angles to the direction of incident light." Dr. Gray concludes his abstract by saying: "The experiments varied in many ways, and with arrangements to eliminate epinastic and hyponastic ten 1 Dr. Gray adds: "The lines in Evangeline' were inspired by a personal communication made by Gen. Alvord to the poet Longfellow." This was in January, 1847. Sir Joseph Hooker adds in a note after quoting the lines, " I cannot congrat ulate the poet on the fidelity of the plant as a 'delicate one.'" The same criticism is made by the article in Nature. The truth is, I wrote Professor Longfellow after "Evangeline" first came out that the plant was not a "delicate" one, but on the contrary, stout and robust, and therefore a better image of faith. "Such in the soul of man is faith," &c., &c., and in all the later editions of "Evangeline," Mr. Longfellow calls it a "vigorous plant." But in England the first editions are most read. 2 Ecloga plantarum rariorum et minus cognitarum, quas ad vivum descripsit et iconibus coloratis illustravit. Fehr. Jos. Fry. Jacquin. Fasc. I-X. Fol maj. Wien, dencies, plainly bring out the conclusion that the power which leaves have of placing themselves at right angles to the incident light is due to a specialized sensitiveness to light, which is able to regulate or govern the action of other external forces, such as epinasty.'" Professor Bessey, in his recent admirable work on botany, page 193, says: "The explanation for heliotropism which is commonly given, is that the light retards the growth on the illuminated side, while the shaded side elongates, resulting in a tension which necessarily produces a curvature." This is the most plausible statement we have seen, but we are not informed how far it is founded on any actual experiment. It is satisfactory that Mr. Darwin has undertaken the task in such a careful and systematic manner. It is an interesting field of observation and worthy of being thoroughly examined by different persons and in different localities. LIST OF PAPERS ON THE COMPASS PLANT, ETC. BENJAMIN ALVORD, U. S. Army.-Proceedings of National Institute, Washington, D. C., 1842 and 1843. Proceedings of American Association for the Advancement of Science (page 12) at Cambridge, Mass., August, 1849. THOMAS HILL, LL.D.—American Journal of Science for November, 1863, p. 439. American Naturalist, 1870, p. 495. J. A. ALLEN.-American Naturalist, 1870, p. 580. W. F. WHITNEY.-American Naturalist for March, 1871, p. I. PROFESSOR ALFRED W. BENNETT, Lecturer on Botany at St. Thomas Hospital, Eng. Nature for Feb. 1, 1877, p. 298, with figure of the plant. DR. GEORGE ENGELMANN, of St. Louis.-American Association for Advancement of Science, St. Louis, Aug, 1878. PROFESSOR C. E. BESSEY.-American Naturalist for August, 1877, p. 486. Botany. Henry Holt & Co., N. Y., 1880, pages 103, 157, 515, with figures of section of leaf magnified. DR. ASA GRAY.-Ed. of 1880 of Botany of Northern U. S. -American Journal of Science for March, 1882, page 245. On Francis Darwin's paper in Journal of the Linnæan Society, No. 112, Vol. 18, pp. 42c455, June 1881, on "The power possessed by leaves of placing themselves at right angles to the direction of incident light." SIR JOSEPH D. HOOKER and DR. ASA GRAY.—London Botanical Magazine for January, 1881. -Gardeners' Chronicle, p. 276, for Feb. 26, 1881. "W. G. F.," or PROFESSOR W. G. FARLOW, of Harvard University.—American Journal of Science for February, 1882, p. 157, giving extracts from Stahl in the Jen. Zeitschrift, Germany. A THE DEVELOPMENT OF THE TREE-TOAD.' BY MARY H. HINCKLEY. RECORD of several seasons gives the appearance of Hyla versicolor in the spring, in Milton, Massachusetts, from about the Ist to the 10th of May. Tadpoles of this species I have found most abundant in the water of small, still, shadowy ponds near large trees. The eggs are attached singly and in small groups for a distance of one or two yards along the grasses which grow up and rest on the water. Unless the grass is parted they are not readily seen. The gelatinous substance surrounding the eggs is exceedingly thin. When first laid they are of a drab color on the upper surface, which becomes lighter after a few hours in the water. The under surface is white; the extent of this color varies; in some cases only a spot of drab is seen on an otherwise white egg. The period of egg-laying, according to my observations, extends from the first week in May to July. The development of the egg is rapid, being accomplished within fortyeight hours. When first hatched the tadpole is about a quarter of an inch long, of a pale yellow color, dotted with olive on the head and sides of the body. During the first week the external gills are developed and resorbed. At the same time the olive color gradually increases and deepens till it extends over the upper surface of the tadpole. A fine dotting of gold color also appears on both upper and under surfaces. In the water, however, they look black. The holders, at first so prominent, disappear within ten days. The head and body are short. The tail is broad and thick. The eyes are prominent, set widely apart, and of a brilliant flame color; the iris in some specimens is quartered by dark lines. The lips are broad. The nostril openings and two perpendicular lines on the muzzle, also a line from before the eyes down each side to the tail, are gold colored. Transverse bars of the same tint on the upper edge of the tail are sometimes seen. The tadpoles are shy and quick in movement as young fishes, moving through the water with the least perceptible motion of the tail. They do not collect together, but where there is room enough, each tadpole goes its own way independently. They are hardy, and probably owing in some degree to their quick move1 Abstract of a paper published in the Proceedings of the Boston Society of Natu ral History, Vol. XXI, Nov. 17, 1880. |