The vascular cryptogams are especially characterized by their mineral composition.16 The ash is extraordinarily rich in silicic acid and alumina.

Equisetum 17silicic acid60per cent.
Aspidium"13"
Asplenium"35"
Osmunda"53"
Lycopodium 18"14"
"alumina26 to 27"
"manganese2 to 2.5"

These various plants contain acids and compounds peculiar to themselves.

As we ascend in the plant scale, we reach the phanerogams. These plants are characterized by the production of true seeds, and many chemical compounds not found in lower plants.

It will be convenient in speaking of these higher groups to follow M. Heckel's19 scheme of plant evolution. All these plants are grouped under three main divisions: apetalous, monocotyledonous, and dicotyledonous; and these main divisions are further subdivided.

It will be observed that these three main parallel columns are divided into three general horizontal planes.

On plane 1 are all plants of simplicity of floral elements, or parts; for example, the black walnut, with the simple flower contained in a catkin.

On plane 2 plants which have a multiplicity of floral elements, as the many petals and stamens of the rose; and finally, the higher plants, the orchids among the monocotyledons and the composite among the dicotyledonous plants, come under the third division of condensation of floral elements.

It will be impossible to take up in order for chemical consideration all these groups, and I shall restrict myself to pointing out the occurrence of certain constituents.

I desire now to call attention to chemical groups under the apetalous plants having simplicity of floral elements.

Cassuarina equisetifolia20 possibly contains tannin, since it is used for curing hides. The bark contains a dye. It is said to resemble Equisetum21 in appearance, and in this latter plant a yellow dye is found.

The Myrica22 contains ethereal oil, wax, resin, balsam, in all parts of the plant. The root contains in addition fats, tannin, and starch, also myricinic acid.

In the willow and poplar,23 a crystalline, bitter substance, salicin or populin, is found. This may be considered as the first appearance of a real glucoside, if tannin be excluded from the list.

The oak, walnut, beech, alder, and birch contain tannin in large quantities; in the case of the oak, ten to twelve per cent. Oak galls yield as much as seventy per cent.24 The numerous genera of pine and fir trees are remarkable for ethereal oil, resin, and camphor.

The plane25 trees contain caoutchouc and gum; peppers,26 ethereal oils, alkaloids, piperin, white resin, and malic acid. Datisca cannabina27 contains a coloring matter and another substance peculiar to itself, datiscin, a kind of starch, or allied to the glucosides.

Upon the same evolutionary plane among the monocotyledons, the dates and palms28 contain in large quantities special starches, and this is in harmony with the principles of the theory. Alkaloids and glucosides have not yet been discovered in them.

Other monocotyledonous groups with simplicity of floral elements, such as the typhaceae, contain large quantities of starch; in the case of Typha latifolia29 12.5 per cent., and 1.5 per cent. gum. In the pollen of this same plant, 2.08 per cent. starch has been found.

Under the dicotyledonous groups, there are no plants with simplicity of floral elements.

Returning, now, to apetalous plants of multiplicity and simplification of floral elements, we find that the urticaceae30 contain free formic acid; the hemp31 contains alkaloids; the hop,32 ethereal oil and resin; the rhubarb,33 crysophonic acid; and the begonias,34 chicarin and lapacho dyes. The highest apetalous plants contain camphors and oils; the highest of the monocotyledons contain a mucilage and oils; and the highest dicotyledons contain oils and special acids.

The trees yielding common camphor and borneol are from genera of the lauraceae family; also sassafras camphor is from the same family. Small quantities of stereoptenes are widely distributed through the plant kingdom.

The gramineae, or grasses, are especially characterized by the large quantities of sugar and silica they contain. The ash of the rice hull, for example, contains ninety eight per cent. silica.

The ranunculaceae contain many plants which yield alkaloids, as Hydrastia canadensis, or Indian hemp, Helleborus, Delphinum, Aconitum, and the alkaloid berberine has been obtained from genera of this family.

The alkaloid35 furnishing families belong, with few exceptions, to the dicotyledons. The colchiceae, from which is obtained veratrine, form an exception among the monocotyledons. The alkaloids of the fungus have already been noted.

36Among the greater number of plant families, no alkaloids have been found. In the labiatae none has been discovered, nor in the compositae among the highest plants.

One alkaloid is found in many genera of the loganiaceae; berberine in genera of the berberidaceae, ranunculaceae, menispermaceae, rutaceae, papaveraceae, anonaceae.

Waxes are widely distributed in plants. They occur in quantities in some closely related families.

Ethereal oils occur in many families, in the bark, root, wood, leaf, flower, and fruit; particularly in myrtaceae, laurineae, cyperaceae, crucifereae, aurantiaceae, labiatae, and umbelliferae.

Resins are found in most of the higher plants. Tropical plants are richer in resins than those of cold climates.

Chemical resemblance between groups, as indicating morphological relations, has been well shown. For example: the similarity37 of the viscid juices, and a like taste and smell, among cactaceae and portulaceae, indicate a closer relationship between these two orders than botanical classification would perhaps allow. This fact was corroborated by the discovery of irritable stamens in Portulaca and Opuntia, and other genera of cactaceae.

Darwin38 states that in the compositae the ray florets are more poisonous than the disk florets, in the ratio of about 3 to 2.

Comparing the cycadeae and palmae, the former are differently placed by different botanists, but the general resemblance is remarkable, and they both yield sago.

Chemical constituents of plants are found in varying quantities during stated periods of the year. Certain compounds present at one stage of growth are absent at another. Many facts could be brought forward to show the different chemical composition of plants in different stages of growth. The Thuja occidentalis39 in the juvenescent and adult form, offers an example where morphological and chemical differences go hand in hand. Analyses of this plant under both conditions show a striking difference.

Different parts of plants may contain distinct chemical compounds, and the comparative chemical study of plant orders comprises the analysis of all parts of plants of different species.

For example; four portions of the Yucca angustifolia40 were examined chemically; the bark and wood of the root and the base and blades of the leaves. Fixed oils were separated from each part. These were not identical; two were fluid at ordinary temperature, and two were solid. Their melting and solidifying points were not the same.

This difference in the physical character and chemical reaction of these fixed oils may be due to the presence of free fatty acid and glycerides in varying proportions in the four parts of the plants. It is of interest to note that, in the subterranean part of the Yucca, the oil extracted from the bark is solid at the ordinary temperature; from the wood it was of a less solid consistency; while the yellow base of the leaf contained an oil quite soft, and in the green leaf the oil is almost fluid.

Two new resins were extracted from the yellow and green parts of the leaf. It was proposed to name them yuccal and pyrophaeal An examination of the contents of each extract showed a different quantitative and qualitative result.

Saponin was found in all parts of the plant.

Many of the above facts have been collected from the investigations of others. I have introduced these statements, selected from a mass of material, as evidences in favor of the view stated at the beginning of this paper.41 My own study has been directed toward the discovery of saponin in those plants where it was presumably to be found. The practical use of this theory in plant analysis will lead the chemists at once to a search for those compounds which morphology shows are probably present.

I have discovered saponin in all parts of the Yucca angustifolia, in the Y. filimentosa and Y. gloriosa, in several species of agavae, and in plants belonging to the leguminosae family.

The list42 of plants in which saponin has been discovered is given in the note. All these plants are contained in the middle plane of Heckel's scheme. No plants containing saponin have been found among apetalous groups. No plants have been found containing saponin among the lower monocotyledons.

The plane of saponin passes from the liliaceae and allied groups to the rosales and higher dicotyledons.

Saponin belongs to a class of substances called glucosides. Under the action of dilute acids, it is split up into two substances, glucose and sopogenin. The chemical nature of this substance is not thoroughly understood. The commercial43 product is probably a mixture of several substances.

This complexity of chemical composition of saponin is admirably adapted for the nutrition of the plant, and it is associated with the corresponding complexity of the morphological elements of the plant's organs. According to M. Perrey,44 it seems that the power of a plant to direct the distribution of its carbon, hydrogen, and oxygen to form complex glucosides is indicative of its higher functions and developments.

The solvent action of saponin on resins has been already discussed. Saponin likewise acts as a solvent upon barium45 sulphate and calcium46 oxalate, and as a solvent of insoluble or slightly soluble salts would assist the plant in obtaining food, otherwise difficult of access.

Saponin is found in endogens and exogens. The line dividing these two groups is not always clearly defined. Statements pointing to this are found in the works of Haeckel, Bentham, and others.

Smilax belongs to a transition class, partaking somewhat of the nature of endogen and of exogen. It is worthy of note that this intermediate group of the sarsaparillas should contain saponin.

It is a significant fact that all the groups above named containing saponin belong to Heckel's middle division.

It may be suggested that saponin is thus a constructive element in developing the plant from the multiplicity of floral elements to the cephalization of those organs.

It has been observed that the composite occurs where the materials for growth are supplied in greatest abundance, and the more simple forms arise where sources of nutrition are remote. We may gather from this fact that the simpler organs of plants low in the evolutionary scale contain simpler non-nitrogenous chemical compounds for their nutrition.

The presence of saponin seems essential to the life of the plant where it is found, and it is an indispensable principle in the progression of certain lines of plants, passing from their lower to their higher stages.

Saponin is invariably absent where the floral elements are simple; it is invariably absent where the floral elements are condensed to their greatest extent. Its position is plainly that of a factor in the great middle realm of vegetable life, where the elements of the individual are striving to condense, and thus increase their physiological action and the economy of parts.

It may be suggested as a line of research to study what are the conditions which control the synthesis and gradual formation of saponin in plants. The simpler compounds of which this complex substance is built up, if located as compounds of lower plants, would indicate the lines of progression from the lower to the saponin groups.

In my paper47 read in Buffalo at the last meeting of the American Association for the Advancement of Science, various suggestions were offered why chemical compounds should be used as a means of botanical classification.

The botanical classifications based upon morphology are so frequently unsatisfactory, that efforts in some directions have been made to introduce other methods.48

There has been comparatively little study of the chemical principles of plants from a purely botanical view. It promises to become a new field of research.

The leguminosae are conspicuous as furnishing us with important dyes, e.g., indigo, logwood, catechin. The former is obtained principally from different species of the genus Indigofera, and logwood from the Haematoxylon and Saraca indica.

The discovery49 of haematoxylin in the Saraca indica illustrates very well how this plant in its chemical, as well as botanical, character is related to the Haematoxylon campechianum; also, I found a substance like catechin in the Saraca. This compound is found in the acacias, to which class Saraca is related by its chemical position, as well as botanically. Saponin is found in both of these plants, as well as in many other plants of the leguminosae. The leguminosae come under the middle plane or multiplicity of floral elements, and the presence of saponin in these plants was to be expected.

From many of the facts above stated, it may be inferred that the chemical compounds of plants do not occur at random. Each stage of growth and development has its own particular chemistry.

It is said that many of the constituents found in plants are the result of destructive metabolism, and are of no further use in the plant's economy. This subject is by no means settled, and even should we be forced to accept that ground, it is a significant fact that certain cells, tissues, or organs peculiar to a plant secrete or excrete chemical compounds peculiar to them, which are to be found in one family, or in species closely allied to it.

It is a fact that the chemical compounds are there, no matter why or whence they came. They will serve our purposes of study and classification.

The result of experiment shows that the presence of certain compounds is essential to the vigor and development of all plants and particular compounds to the development of certain plants. Plant chemistry and morphology are related. Future investigations will demonstrate this relation.

In general terms, we may say that amides and carbohydrates are utilized in the manufacture of proteids. Organic acids cause a turgescence of cells. Glucosides may be a form of reserve food material.

Resins and waxes may serve only as protection to the surfaces of plants; coloring matters, as screens to shut off or admit certain of the sun's rays; but we are still far from penetrating the mystery of life.

A simple plant does what animals more highly endowed cannot do. From simplest substances they manufacture the most complex. We owe our existence to plants, as they do theirs to the air and soil.

The elements carbon, oxygen, hydrogen, and nitrogen pass through a cycle of changes from simple inorganic substances to the complex compounds of the living cell. Upon the decomposition of these bodies the elements return to their original state. During this transition those properties of protoplasm which were mentioned at the beginning, in turn, follow their path. From germination to death this course appears like a crescent, the other half of the circle closed from view. Where chemistry begins and ends it is difficult to say. - Jour. Fr. Inst.

[1]

A lecture delivered before the Franklin Institute, January 24, 1887.

[2]

Studien uber das Protoplasm, 1881.

[3]

Vines, p. 1. Rostafinski: Mem. de la Soc. des Sc. Nat. de Cherbourg, 1875. Strasburger: Zeitschr., xii, 1878.

[4]

Botany: Prantl and Vines. London, 1886, p. 110.

[5]

For the literature of starch, see p. 115, Die Pflanzenstoffe, von Hilger and Husemann.

[6]

Kutzing: Arch. Pharm., xli, 38. Kraus and Millardet: Bul. Soc. Sciences Nat., Strasbourg, 1868, 22. Sorby: Jour. Lin. Soc., xv, 34. J. Reinke: Jahrb. Wissenscht. Botan., x, B. 399. Phipson: Phar. Jour. Trans., clxii, 479.

[7]

Prantl and Vines, p. 111.

[8]

L. Crie: Compt. Rend., lxxxviii, 759 and 985. J. De Seynes, 820, 1043.

[9]

Page 279.

[10]

M. Nencki and F. Schaffer. N. Sieher: Jour. Pract. Chem., 23, 412.

[11]

E. Klein: Quar. Jour. Micros. Science, 1875, 381. O. Helm: Arch. Pharm., 1875, 19-24. G. Gugini: Gaz. Chem., 7, 4. W. Thorner: Bul. Ber, xi, 533.

[12]

Handbook of Dyeing. By W. Crookes, London, 1874. p. 367. Schunck: Ann. Chem. Pharm., 41, 157; 54, 261; 61, 72; 61, 64; 61, 78. Rochelder and Heldt, ibid., 48, 2; 48, 9. Stenhouse, ibid., 68, 57; 68, 72; 68, 97, 104; 125, 353. See also researches of Strecker, O. Hesse, Reymann, Liebermann, Lamparter, Knop, and Schnedermann.

[13]

Stahlschmidt.

[14]

E. Treffner: Inaugur. Diss. Dorpat, 1880.

[15]

W. Pfeffer: Flora, 1874.

[16]

Die Pflanzenstoffe, p. 323 W. Lange: Bul. Ber., xi, 822.

[17]

Ann. Chim. Phys., 41, 62, 208; Ann. Chim. Pharm., 77, 295.

[18]

Fluckiger: Pharmakognosie. Kamp: Ann. Chim. Pharm., 100, 300.

[19]

Revue Scientifiqe, 13 Mars, 1886.

[20]

Dictionary of Economic Plants. By J. Smith. London, 1882, p. 294.

[21]

Ibid., p. 160. Pharmakognosie des Pflanzenreichs, Wittstein, p. 736. Ann. Chem. Pharm., 77, 295.

[22]

Rabenhorst: Repert. Pharm., lx, 214. Moore: Chem. Centralbl., 1862, 779, Dana.

[23]

Johansen: Arch. Pharm., 3, ix, 210. Ibid., 3, ix 103. Bente: Berl. Ber., viii, 476. Braconnot: Ann. Chim. Phys., 2, 44, 296.

[24]

Wittstein; Pharm. des Pflanzenreichs, p. 249.

[25]

John; Ibid., p. 651.

[26]

Dulong. Oersted, Lucas, Pontet; Ibid., p. 640.

[27]

Braconnot: Ann. Chim. Phys., 2, 3. 277. Stenhouse: Ann. Chim. Phann., 198, 166

[28]

3 Pflanzenstoffe, p. 412.

[29]

Lecocq: Braconnot: Pharmacog. Pflan, p. 693.

[30]

Gorup-Besanez.

[31]

Siebold and Brodbury: Phar. Jour. Trans., 3, 590, 1881, 326.

[32]

Wagner: Jour. Prakt. Chem., 58, 352. B. Peters, v. Gohren: Jahresb. Agric., viii, 114; ix, 105; v. 58. Ann. Jour. Pharm., 4, 49.

[33]

Dragendorff: Pharm. Zeitschr. Russ., xvii, 65-97.

[34]

Bonssingault: Ann. Chim. Phys., 2, 27, 315. Erdmann: Jour. Pract. Chem., 71, 198.

[35]

Die Pflanzenstoffe, p. 21.

[36]

Ibid.

[37]

Meehan: Proc. Acad. Nat. Sciences.

[38]

Different forms of flowers on plants of the same species. Introduction.

[39]

Meehan: Proc. Acad. Nat. Sciences.

[40]

H.C. De S. Abbott: Trans. Amer. Philos. Soc., 1886.

[41]

For further facts confirming this theory, see "Comparative Chemistry of Higher and Lower Plants." By H.C. De S. Abbott. Amer. Naturalist, August, 1887.

[42]

Different genera and species of the following: Ranunculaceae, Berberidaceae, Carophyllaceae, Polygalaceae, Bromeliaceae, Liliaceae, Smilaceae, Yuccas, Amaryllideae, Leguminosae, Primulaceae, Rosaceae, Sapindaceae, Sapotaceae

[43]

Kobert: Chem Ztg.

[44]

Compt. Rend., xciv, p. 1124.

[45]

Bul. de la Soc. Chim.

[46]

"Yucca angus." Trans. Am. Philos. Soc., Dec., 1885.

[47]

Botanical Gazette, October, 1886.

[48]

Borodin: Pharm. Jour. Trans., xvi, 369. Pax. Firemy: Ann. Sci. Nat., xiii.

[49]

H.C. De S. Abbott, Proc. Acad. Nat. Sciences, Nov. 30, 1886.