which, on being separated and tested, proved to be calcium oxalate. It was evident that the calcium salt in the plant was stable and readily soluble in water. This latter fact was farther demonstrated by evaporating some of the extract to dryness and again taking it up with water. Almost the entire amount of the calcium salt was redissolved, only a small portion of it becoming insoluble and precipitating as the carbonate. This ready solubility demonstrated the fact that the salt was not derived from the incrustation on portions of the plant used, and the same fact excluded from the list of possible compounds, salts of some of the mere common organic acids found in plant juices, which are insoluble. Qualitative chemical tests were, however, made to determine, if possible, whether any of these acids were present with negative results, and it was demonstrated by this means that there was but a single salt present and not a mixture. Search was then made to determine the acid present, and a result obtained which was so unexpected that it was seriously questioned and the work was gone over again. The second result confirmed the the first and the work of ascertaining the correctness of these two results was turned over to Mr. F. E. West, Instructor in Chemistry in Alma College, who had had special training and much practice in organic analysis. His work was done entirely independently, with material gathered at a different season, and by another method of analysis, but his results were identical with my own, and show that calcium exists in the water extract of Chara as calcium succinate. The fact that the succinate is one of the few water soluble calcium salts and that there is a soluble salt of the metal in the cell sap of the plant makes it probable that this is the compound of the metal which the plant accumulates in its cells. It is not possible from actual investigation to explain the method by which the calcium salt is abstracted from the water, where it exists as the acid- or bi-carbonate or the sulphate1 in 'It has been shown that Chara decomposes several calcium salts, the sulphate among others. small per cent., and is concentrated in the cells of the plant as calcium succinate and later deposited upon the outside of the same cells as the normal or monocarbonate in crystalline form in considerable quantities. Some culture experiments which were undertaken by the writer to determine under what conditions of soil, light, and temperature Chara thrives best, incidentally demonstrated that the plant actually gets its lime from the water and not from the soil. One of the soils which was used as a substratum in which to grow plants was pure quartz sea-sand which had been washed with acid to remove any traces of calcium salt which might be present. The plants grew in this medium readily, and on the newer parts developed nearly, if not quite, as many calcium carbonate crystals as plants growing in pure marl. It should be apparent, however, to even the casual observer that the plants cannot take all the lime they precipitate from the soil, or even a considerable part of it, for if they did the marl beds, being made up principally of Chara remains, would never have accumulated, for the material would have been used over and over again and could not increase much in amount, if it increased at all. In the present state of our knowledge of the life processes of aquatic plants, it seems hardly possible to state the probable method of the formation of the calcium succinate, or even the probable use of it to the plant, and no attempt will be made by the writer in the present paper to do so. It does seem probable, however, that this compound accumulates in the cells, until it reaches sufficient density to begin to diffuse through the cell walls by osmosis. Outside the cells, or in its passage through the walls, it is decomposed directly into the carbonate, possibly by oxidation of the succinic acid by free oxygen given off by the plants, possibly by some substance in the cell walls, or, more probably, by the decomposition of the acid by some of the organic compounds in the water, such as the organic ferments, due to bacterial growth in the organic débris at the bottom of the mass of growing Chara. The water extract of Chara rapidly changes on standing, undergoing putrefactive decomposition, becomes exceedingly offensive in odors developed, and calcium carbonate crystallizes out on the bottom and sides of the containing vessel, while the succinic acid disappears, gas, possibly carbon dioxid, being given off more or less abundantly. Whether these changes takes place on the outside of the living plants, in the cell walls, or in the water surrounding the plants has not yet been determined. Sufficient evidence is here presented, however, if the writer's conclusions are correct, to show that the plants under discussion are active agents in the concentration of calcium salts in the fresh water lakes of Michigan, and that they alone have produced a very large part of the marl which has accumulated in these lakes. It seems probable also that the principles developed by these studies are of very wide application in working out problems presented by formations developed under similar conditions elsewhere. ALMA COLLEGE, July 1, 1901. CHARLES A. Davis. PERKNITE (LIME-MAGNESIA ROCKS)1 THERE are sometimes associated with diorites, gabbros and peridotites, dark rocks composed largely, or entirely, of monoclinic amphibole or pyroxene, or both. These rocks differ mineralogically from diorites and gabbros, in containing little or no feldspar, and from peridotites in containing rhombic pyroxine or olivine in relatively small amount, if present at all. Chemically these rocks contain less alumina than diorites and gabbros, and less magnesia than peridotites. They are low in alumina and in the alkalis, moderately rich in lime, magnesia, and the iron oxides. The chief constituents of perknite are monoclinic amphibole and monoclinic pyroxene; the secondary constituents rhombic pyroxene, olivine and feldspar; the accessories biotite, iron ore, etc., but only one of the primary constituents may be present with none of the secondary constituents or accessories. The existence of this group of rocks has long been recognized, but from their occurrence usually in small masses, and from the fact that many of them are of simple composition so that the selfexplanatory names pyroxenite and amphibolite or hornblendite have answered, they have never been grouped together under one name. 2 In the State of New York and in California3 there are rocks containing both monoclinic pyroxene and amphibole as principal constituents, and doubtless this is likewise the case in many other parts of the world. Moreover, in California such rocks form areas of geological importance. There is, therefore, some reason in grouping all of these lime-magnesia rocks under a common name. It is proposed to call the group perknite from folio. Published by permission of the Director of the U. S. Geological Survey. 2 G. H. WILLIAMS: Am. Jour. Sci., Vol. XXXI, 1886, p. 40. 3 TURNER: Am. Jour. Sci., Vol. V, 1898, p. 423. Turner and Ransome. Sonora the Greek word πерvos, meaning dark. lites of the following specific names: Pyroxenite. Hornblendite (Williams). It will include grano Websterite (Diallage and ortho-rhombic pyroxene) (Wil liams). Diallagite. Hornblende-hypersthene rock (Merrill). The group may be graphically represented by the method employed by Hobbs' and his representation of a composite pyroxenite will approximate to that of a typical perknite. The following table of analyses will give the reader a notion of the composition of the rocks which may be properly included in this group. 1. Hornblendite.--Geo. Steiger, analyst. This partial analysis is here published for the first time. The rock is from a dike cutting through the basement complex and overlying Cambrian rocks, 2 km north of Silver Peak village, in Esmeralda county, Nev. It is composed chiefly of green hornblende with some feldspar. The rock grades into a basic diorite. 2. Amphibole-pyroxene rock.-W. F. Hillebrand, analyst. Not before published. Rocks of this type are very abundant in Mariposa county, Cal. Mr. F. M. Anderson, of the University of California, has likewise collected them in northern California. This rock in its typical development is composed of original pyroxene and amphibole in grains of nearly equal size, with a little quartz and pyrrhotite. Scattered through the rock are phenocrysts about one centimeter in diameter, of brown amphibole, which contain in a poikilitic manner, as inclusions, the constituents of the groundmass. 3. Perknite (author's name, peridotite).- Belchertown. Bull. U. S. Geol. Survey, No. 168, p. 30. L. G. Eakins, analyst. The rock is composed of hornblende, pyroxene, biotite, olivine and magnetite. JOUR. GEOL., Vol. VIII, 1900, p. 14. |