identical with one of the genus Agamonema, found in fresh water turtles.

Mr. Potts exhibited a specimen of the sponge to which the unfitness for use of the Boston drinking water had been attributed. The specimens were composed in part of a Meyenia and in part of a Spongilla. The Meyenia was new, and he proposed for it the name of M. acuminata. He believed that a sponge is usually the product of many statospheres, and that hybridism was, from the manner of germination of the statospheres, probably of frequent The speaker stated that he had never yet been able to detect the ciliated chambers that have been described in sponges.

occurrence.

Dr. Parker stated that the effect of colloids upon crystalline substances was to retard growth except in the direction of the axes. He believed that the various forms of spicules were caused by this retarding influence of the sarcode, acting with greater or lesser intensity.

Mr. Potts stated that in all spicules of sponges there was an axial space, branching towards the spines; moreover, the larger spicules can be seen to be formed of a series of annular layers.

NEW YORK ACADEMY OF SCIENCES, April 10.—Mr. F. J. G. Wiechmann read a paper on the fusion-structures in meteorites (illustrated with microscopic sections).

April 24.-Professor J. J. Stevenson read a paper on the economic importance of the mineral resources of Southwest Virginia. May 1.—Dr. B. N. Martin read a memorial notice of the life and works of the late Professor John W. Draper.

May 8th.-Professor H. Le R. Fairchild lectured on the methods of animal locomotion.

May 22.-Dr. A. A. Julien presented notes and observations made during a recent visit to the islands of Curaçoa, Buen Ayre and Aruba, W. I. Mr. J. C. Russell read a paper on sulphur deposits in Utah and Nevada.

June 5-Dr. W. Miller, read a paper on the prevention of tubercular disease in men and animals by Vaccination. Mr. N. L. Britton remarked on a glacial "pot-hole" near Williams Bridge, N. Y.

BOSTON SOCIETY OF NATURAL HISTORY, General Meeting, April 19. Mr. Frederic Gardiner, Jr., described the methods of propagating salmon, and Dr. W. S. Bigelow spoke on the study of Bacteria and allied forms.

Annual Meeting, May 3.-The curator, secretary and treasurer presented their annual reports on the condition and work of the society during the past year. The officers for 1882-83 were elected, after which the discussion of the general question of glacial erosion suggested by recent communications on the formation of lake basins was opened with a paper by Mr. W. M. Davis.

Mr. S. H. Scudder spoke of an interesting discovery of older fossil insects west of the Mississippi.

GEOGRAPHICAL SOCIETY OF THE PACIFIC, San Francisco, March 29.-The secretary read a letter from the president of the Board of Trade, requesting the Geographical Society to discuss the merits of the Nicaragua Interocean canal The following gentlemen were appointed a committee to act thereon: Captain Oliver Eldridge, Andrew McFarlane Davis, William Aldrich, B. B. Redding and Thomas E. Slevin. A paper entitled "Memoir on the River and Harbor of Guayaquil," was then read by Thomas E. Slevin, LL.D. The president gave notice that a paper would be read at the next meeting by B. B. Redding on the Gallapagos islands.

AMERICAN GEOGRAPHICAL SOCIETY, April 13.-The president, Chief Justice C. P. Daly, delivered an address upon Spain, Straits of Gibraltar and Tangiers in 1881.

MIDDLESEX INSTITUTE, March 14 and 21.-Mr. R. Frohock delivered the third and fourth lectures of the course on the "Morphology of Leaves," and the "Arrangement of leaves on the

stem

March 28 and April 4.-Mr. F. S. Collins lectured on the "Arrangement of flowers," and the "Morphology of the flower; calyx and corolla."

April 11.—Mrs. A. J. Dolbear explained the "Morphology of stamens and pistils" and "Estivation."

April 12, Regular Monthly Meeting.-Informal remarks were made by President Dame and others. Resolutions of respect to the memory of Professor Thomas P. James were read, ordered to be placed on record, and a copy to be sent to the family of the honored deceased. A committee on floral exhibitions for the current year was appointrd, and the executive committee instructed to arrange with the Essex Institute for a joint field excursion in the Middlesex fells in June.

BIOLOGICAL SOCIETY OF WASHINGTON, May 26th.-The following communications were made:-Exhibition of Eskimo carvings of animals by E. W. Nelson. Appeal for an exploration of the molluscan Fauna of the District of Columbia by Wm. H. Dall. Exhibition of a rare Arctic bird, the Spoonbilled Sandpiper (Eurynorhynchus pygmæus), by T. H. Bean, M. D. Air sacks of vertebrates, by R. M. Shufeldt, M. D. About mules, by Professor M. G. Ellzey.

APPALACHIAN MOUNTAIN CLUB, May 12.- The report of Mr. J. B. Henck, Jr., the delegate of the Club to the Alpine Congress, held at Milan last summer, was read.

Mr. W. M. Davis read a paper on the little mountains east of the Catskills.

A paper by Henry L. Stearns, entitled "An Ascent of Pike's Peak," was read.

THE

AMERICAN NATURALIST.

VOL. XVI. AUGUST, 1882. - No. 8.

SINCE

ON THE COMPASS PLANT.

BY BENJAMIN ALVORD.

INCE the publication of my paper on the compass plant, Silphium laciniatum (see page 12 of "Proceedings of American Association for Advancement of Science at Cambridge, Mass., in August, 1849"), I have made no communication concerning it to any scientific journal, constantly hoping that my army station would bring me where I could make more satisfactory experiments. In the meantime it has been made the topic of several papers (about fourteen in all) which will be enumerated at the end of this article.

The Silphium laciniatum is a perennial plant of the order Compositæ; the first year it bears only radical leaves, the second year and after, it is a flowering herb with four or five leaves on the stem; very rough bristly throughout; leaves pinnately parted, petioled but clasping at the base. Root very thick. Flowers yellow. Found on rich prairies of the Mississippi valley from Minnesota to Texas, not found on the Pacific slope. Stem stout, from three to five feet high; leaves ovate in general outline, from twelve to thirty inches long.

It was first seen by me in the autumn of 1839, on the rich prairies near Fort Wayne in the north-eastern portion of the Cherokee nation, near the Arkansas line. I felt assured that its curious properties had not been made known to the scientific world, and after I had explored all those regions on horseback, and satisfied myself of the verity of the peculiarity, I made it known to the National Institute in Washington, the officers of the army having been requested by that enlightened Secretary of War, Joel R. Poinsett, to aid that society as opportunity should

offer. The first communication was dated August 9, 1842, when I delivered in person to the Secretary of the Institute, Francis Markoe, Jr., a dried specimen of the plant. My second letter, published, like the first, in the Proceedings of the Institute, was dated January 25, 1843.

My principal object now is to record the various experiments which have, from time to time and in different places, been made by me or under my direction, to demonstrate that the meridional position of the plane of the leaf is due to the action of light.

Silphium laciniatum, or Compass Plant of the Western prairies. Radical leaf from twelve to thirty inches in height.

The property is best exhibited in the radical leaf, which presents its faces to the rising and setting sun. The flowering plant also exhibits the property, though imperfectly, but its leaves take a medium position between their normal and symmetrical arrangement in reference to the stalk, and the tendency to point toward the north. But I have been not a little surprised to find the figures of the plant, as given by A. W. B. (Professor A. W. Bennet) in Nature, Feb. 1, 1877, and by Sir Joseph D. Hooker in the London Botanical Magazine for January, 1881, present not the

radical leaf, but the flowering plant. The reader of those journals will look in vain at the drawings to comprehend the polarity

of the plant.

The experiments to which I refer were made on the radical leaves, which grow to the height of from one to two feet, and are strong and robust, and not easily disturbed by winds or other extraneous objects, and therefore the more useful as a guide on the prairies.

These experiments have been made since my paper was read in 1849 to the American Association. By them I became satisfied that Dr. Gray was right, in 1849, in attributing the peculiarity to the action of light.

Ist. I applied a very delicate galvanometer to the points of the leaves, so delicate that it should have detected the minutest quantity of magnetic or galvanic action, and no deflection was apparent.

2d.-Powerful magnets did not appear to deflect the leaves.

3d. The plant was grown in a box, and after the leaves presented their edges north and south, the box was turned ninety degrees, and in a few days the leaves were seen to struggle to get back to their former meridional position.

4th. Neither J. W. Bailey, LL.D., professor of chemistry at West Point, nor Professor John Torrey, at Princeton, after careful analysis in 1842, could detect any traces of the magnetic oxide of iron in the plant, or iron in any shape.

Mr. Edward Burgess, by request of Professor Asa Gray at Cambridge, about 1870, examined with a microscope the two surfaces of the leaf of the S. laciniatum, and found the structure of the epidermal tissue of the two, surfaces to be similar, and also the number of stomata in each face to be about equal. Leaves generally turn toward the light, and the under surface in such cases is more "copiously furnished with stomata, or breathing pores as they are often inaccurately termed, which serve to promote a diffusion of gases between the external air and the intercellular cavities within the tissue, and especially an abundant exhalation of aqueous vapor" (W. F. Whitney in AMERICAN NATURALIST for March, 1871).

My theory is this: all leaves will turn their upper faces toward the light. But in the compass plant (I speak now of the radical leaf) the stem comes up vertically and stiffly from the root.