are indigenous to the state. 124 species are, therefore, introduced, of which 113 come from Europe, and probably many of them directly from Germany. The list is prefaced by some remarks on the topography and climate of the county. It does not seem to be founded upon preserved specimens, which is unfortunate.

A PRELIMINARY catalogues of the vascular plants growing within a hundred miles of New York City has been issued by the Torrey Botanical Club. The boundary line is quite an arbitrary one, but probably limits the work as well as if it was more natural. A list of ballast plants is also included, and presents a formidable array of foreigners who have landed upon our shores, the great majority of whom, it is to be hoped, will find no welcome. The noticeable thing about the catalogue is its innovations in respect to specific names, for which, we are told, the subcommittee on nomenclature, consisting of Messrs. Britton, Sterns and Poggenburg, "alone are responsible."

NOTES AND NEWS.

DR. CHARLES E. BESSEY, of the University of Nebraska, sails for Europe June 16 to spend the summer.

THE FIRST PART of the seventh volume of Saccardo's Sylloge Fungorum is issued, and will hereafter receive suitable notice.

MR. M. S. BEBB describes (with plate) Salix balsamifera in Bull. Torr. Bot. Club (May), and gives an account of its discovery in the White Mountains.

ARCHEOPHYTON NEWBERRYANUM is the name of a supposed Archæan plant described (with plate) by Dr. N. L. Britton in Annals N. Y. Acad. iv., 123.

RECENTLY FIGURED North American plants in Garden and Forest are Roza minutifolia Eng. (April 25), Hymenocallis humilis Watson (May 2), H. Palmeri Watson (May 16).

DR. H. H. RUSBY, of Columbia College, has distributed a reprint of his interesting paper, "Coca at home and abroad," published in the Therapeutic Gazette for March and May.

MR. GEORGE MASSEE has published a revision of the genus Bovista in Journal of Botany (May). The genus is credited with thirty-nine species, four of which are described as new.

THE REVISION of Scotch Sphæropsideæ and Melanconies by Prof. J. W. H. Trail is brought to a close with 223 species in the Scottish Naturalist for April. It is a list of species and habitats with a key to the genera, but without descriptions of the species.

Preliminary Catalogue of Anthophyta and Pteridophyta reported as growing spontaneously within a hundred miles of New York City. Compiled by a committee of the Torrey Botanical Club. xviii and 90 pp., with map. New York, 1888. Price, $1.

AN INDEX of the habitats of the fungi in Ellis' North American Fungi, cent. XI to XX., has been compiled and published by W. C. Stevenson, Jr. It will prove a great service to users of the work.

THE KEW BULLETIN for May contains information concerning ipecacuanha, Brazilian gum-arabic, Trinidad coffee, patchouli, Cochin China vine, Madagascar ebony and Shantung cabbage.

DR. CHAS. E. BESSEY has published a pamphlet entitled "Grasses and Forage Plants of Nebraska." It is of great interest to the farmers of that country, and contains twenty plates of the common grasses.

DR. HUBERT LEITGEB, well known for his classical researches on the Hepatica, professor of botany and director of the Botanical Institute at Graz, died on the 5th of April, in the fifty-third year of his age.

IN THE Italian Journal of Botany (April 7) there are described numerous cases of teratology, illustrated with four plates, thus bringing together a large amount of information for those interested in this subject.

A SUPPLEMENTAL list of works on North American fungi, by Dr. Farlow, has been issued as No. 31 of the bibliographical contributions of the library of Harvard University, being a continuation of No. 25.

THE PARTS Comprising the Gamopetale of Gray's Synoptical Flora have been collected and issued in one volume, as No. xxxi of the Smithsonian Miscellaneous Collections. Corrections have been made, as far as could be done upon the electrotype plates.

DIRECTIONS for preparing twenty-three fungicide solutions or powders are given in a special bulletin of the section of vegetable pathology of the Department of Agriculture. The value of most and the best time and methods for applying them remain to be tested.

THE BULLETIN of the Botanical Department of the State Agricultural College of Iowa for 1888 has been issued. It contains the account of a large amount of work done by Dr. B. D. Halsted and his pupils. Almost every region of botany is touched upon, from bacteria to Iowa weeds.

A NEW Peronospora, P. Lapponica, from Lapland, on Euphrasia officinalis, is described in the last Botaniska Notiser (p. 49). It differs from P. densa on the same pest by its larger and colored conidia, and more closely resembles P. sordida. It should be looked for by collectors in America.

THE "Gray Memorial Botanical Chapter" of the Agassiz Association has a good constitution and ought to be a very successful organization. Its members are scattered through several states, the president being G. H. Hicks, of Grayling, Mich., the secretary E. L. Byington, of Colorado Springs, Colorado.

DR. C. WARNSTORF, of Neuruppin, Germany, has begun the issue of a collection of European Sphagnacea. The first century contains numerous new forms. The labels bear not only the usual data, but descriptions of the new forms, with critical remarks and drawings of the branch and stem-leaves, sections of the branch-leaves, etc.

DR. JULIUS ROLL, of Darmstadt, accompanied by Mr. Albert Purpus, has undertaken a collecting tour along the line of the Northern Pacific Railroad. Dr. Roll will give special attention to collecting mosses, and hopes to bring back a valuable collection. Vancouver Island is their first objective point, whence they will gradually work back to St. Paul.

VOL. XIII. No. 7.-BOTANICAL GAZETTE.-JULY, 1888.

Spore-dissemination of Equisetum. 1

F. C. NEWCOMBE.

(WITH PLATE IX.)

The subject of spore-dissemination of Equisetum may be considered under three heads:

I. Elongation of the axis of the spike.

II. Structure of the sporangium-wall and its mode of dehiscence.

III. Structure and action of the elaters.

Unless otherwise stated, these notes are wholly on Equisetum arvense preserved in alcohol.

1. Elongation of the axis of the spike.-In the immature spike the peltate scales which bear the sporangia on their inner surfaces are closely united edge to edge, forming an unbroken wall; but as the spores are nearing maturity the axis of the spike and the stalks of the peltate scales rapidly elongate, causing each scale to become separated by a considerable space from its neighbors. By careful comparison of cellular structure, this elongation seemed to be due to increase in length of cells. Longitudinal sections from the axis and scale-stalks of several spikes in which the scales were about to separate were made, and similar sections from the corresponding parts of spikes with separated scales. In each comparison the difference in length of cells was easily perceptible, the cells of the fundamental tissue in the different axes giving as the result of many measurements of length the ratio of 3 to 4. Thus, by the separation of the scales, resulting in the drying of sporangium-wall and spores, and furnishing a means of escape for the spores after they have left the sporangium, the first step in spore-dissemination is accomplished.

II. Structure of the sporangium-wall and its mode of dehiscence.-Each of the numerous scales of the spike is attached by a stalk running from the center of the scale to the main axis. Around the stalk and attached to the scale are from five to ten sporangia, arranged in a single row.

1Contribution from the botanical laboratory of the University of Michigan.

sporangium is shaped like the finger of a glove. The dehiscence extends the whole length of the sporangium, and is always along the surface which is directed toward the stalk of the scale.

Examined with the microscope, the sporangium wall is seen to be composed of several layers of cells. The attention is first caught by the appearance of the external layer of cells. These are found to have a definite arrangement, as indicated diagramatically in fig. 1. For convenience the surface of the sporangium which is nearest the stalk may be designated as the inner or ventral, and the opposite one as the outer or dorsal surface. Along the ventral surface are sometimes three, sometimes four, rows of cells, with their ong axes at right angles to the long axis of the sporangium. Passing outward on each side from these rows of transverse cells the other cells of the external layer of the wall become more and more oblique, till on the dorsal surface they correspond in direction with the long axis of the sporangium.

In the three or four rows of transverse cells of the sporangium-wall, usually one row is of shorter cells than those composing the other rows, and the cells of this row are strengthened by rings. The transverse cells of the adjoining rows are marked by both rings and spirals; and the oblique and longitudinal cells are spiral, an annular cell being very rarely found among them (fig. 4). In Equisetum hyemale, however, though the transverse cells are mostly marked with rings, the other cells, without definite arrangement, are some annular and some spiral.

In addition to this outside layer of cells, the sporangiumwall contains two or three other layers of cells, not so conspicuous as the annular and spiral cells just described, but none the less constant. The sporangium-wall has been described by authors as composed of a single layer of cells. In Equisetum arvense and hyemale this is certainly not the case. These inner or lining cells have probably escaped notice because of the difficulty in detecting them by looking down upon or through the sporangium-wall. If sections of the sporangium be examined, the inner layers of cells become clearly visible. In working out this structure, groups of sporangia of Equisetum arvense were carefully imbedded in paraffin, and both longitudinal and transverse sections made on the rocking microtome. On examination, the tissue was found to have been injured in no way by the process of imbedding. Fig. 5 is a portion of a longitudinal section of a sporangium

with a part of the peltate scale and of the stalk: a, portion of the scale-stalk; b, section of the transverse cells of the ventral wall of the sporangium; c, section of the dorsal wall of the sporangium; below the sporangium is the scale in which the fibro-vascular bundle is seen to end. The spiral cells of the dorsal surface are continuous with the epidermal cells of the scale. Occasionally a spiral or annular celi is found in this epidermis. Fig. 6 is a transverse section of a sporangium-wall, midway between base and apex. In three positions-one dorsal and the other two lateral-the wall is strengthened not only by an increase in size of the spiral cells, but also by a greater number of the inner or lining cells. As we approach the region of the ventral transverse cells, the sporangium-wall becomes thinner and thinner by the decrease in number and size of the lining cells. Sometimesas shown in fig. 6 at a—the lining cells can be seen to be continued across the external transverse cells; but here the inner cells are always reduced to a single very thin layer. Usually this layer of lining cells disappears in the ventral region; for it becomes closely appressed to the transverse cells. From the base to the apex of the sporangium, the lining cells are never more than one layer thick in the region of dehiscence, while dorsally and laterally these cells are three layers thick at the base and two layers thick at the

apex.

Sablou found that the length of the moist spiral cell was to that of the same cell when dry as 20 to 14, while the width is imperceptibly lessened.

In alcoholic material the relative length of the cell when moist and when dry is, with slight variation, as 2 to 1; the relative width, as 4 to 3. From the arrangement of the external cells of the wall, it is evident that the sporangium will contract in length much more along the dorsal than along the ventral surface. In fig. 3 the position of the line of dehiscence in the moist sporangium is indicated by an unbroken line. From what we know concerning the arrangement of the external cells and their contraction, we should expect, in drying, one edge of the wall along the line of dehiscence to move to the position indicated in fig. 3 by a dotted line-this line moving, as it passes from the base, more and more from its original position. And this is exactly what happens, as shown by fig. 2, which gives the appear.ance of an open sporangium.

Annales des Science, 7 Series, Tome 2.