By HELEN C. DE S. ABBOTT.
The succession of plants from the lower to the higher forms will be
reviewed superficially, and chemical compounds noted where they
appear.
When the germinating spores of the fungi, _myxomycetes_, rupture their
walls and become masses of naked protoplasm, they are known as
plasmodia. The plasmodium _Æthalium septicum_ occurs in moist places,
on heaps of tan or decaying barks. It is a soft, gelatinous mass of
yellowish color, sometimes measuring several inches in length.
The plasmodium[2] has been chemically analyzed, though not in a state
of absolute purity. The table of Reinke and Rodewold gives an idea of
its proximate constitution.
Many of the constituents given are always present in the living cells
of higher plants. It cannot be too emphatically stated that where
"biotic" force is manifested, these colloidal or albuminous compounds
are found.
The simplest form of plant life is an undifferentiated individual, all
of its functions being performed indifferently by all parts of its
protoplasm.
The chemical basis of plasmodium is almost entirely composed of
complex albuminous substances, and correlated with this structureless
body are other compounds derived from them. Aside from the chemical
substances which are always present in living matter, and are
essential properties of protoplasm, we find no other compounds. In the
higher organisms, where these functions are not performed
indifferently, specialization of tissues is accompanied by many other
kinds of bodies.
The algæ are a stage higher in the evolutionary scale than the
undifferentiated noncellular plasmodium. The simple _Alga
protococcus_[3] may be regarded as a simple cell. All higher plants
are masses of cells, varying in form, function, and chemical
composition.
A typical living cell may be described as composed of a cell wall and
contents. The cell wall is a firm, elastic membrane closed on all
sides, and consists mainly of cellulose, water, and inorganic
constituents. The contents consist of a semi-fluid colloidal
substance, lying in contact with the inner surface of the membrane,
and, like it, closed on all sides. This always is composed of
albuminous substances. In the higher plants, at least, a nucleus
occurs embedded in it; a watery liquid holding salts and saccharine
substances in solution fills the space called the vacuole, inclosed by
the protoplasm.
These simple plants may be seen as actively moving cells or as
non-motile cells. The former consist of a minute mass of protoplasm,
granular and mostly colored green, but clear and colorless at the more
pointed end, and where it is prolonged into two delicate filaments
called cilia. After moving actively for a time they come to rest,
acquire a spherical form, and invest themselves with a firm membrane
of cellulose. This firm, outer membrane of the _Protococcus_
accompanies a higher differentiation of tissue and localization of
function than is found in the plasmodium.
_Hæatococcus_ and plasmodium come under the classes algæ and fungi of
the Thallothyta group. The division[4] of this group into two classes
is based upon the presence of chlorophyl in algæ and its absence in
fungi. Gelatinous starch is found in the algæ; the fungi contain a
starchy substance called glycogen, which also occurs in the liver and
muscles of animals. Structureless bodies, as _æthalium_, contain no
true sugar. Stratified starch[5] first appears in the phanerogams.
Alkaloids have been found in fungi, and owe their presence doubtless
to the richness of these plants in nitrogenous bodies.
In addition to the green coloring matter in algæ are found other
coloring matters.[6] The nature[7] of these coloring matters is
usually the same through whole families, which also resemble each
other in their modes of reproduction.
In form, the algæ differ greatly from filaments or masses of cells;
they live in the water and cover damp surfaces of rocks and wood. In
these they are remarkable for their ramifications and colors and grow
to a gigantic size.
The physiological functions of algæ and fungi depend upon their
chemical differences.
These facts have been offered, simple as they are, as striking
examples of chemical and structural opposition.
The fungi include very simple organisms, as well as others of
tolerably high development, of most varied form, from the simple
bacillus and yeast to the truffle, lichens, and mushrooms.
The cell membrane of this class contains no pure cellulose, but a
modification called fungus cellulose. The membrane also contains an
amyloid substance, amylomycin.[8] Many of the chemical constituents
found in the entire class are given in _Die Pflanzenstoffe_.[9]
Under the _Schizomycetes_ to which the _Micrococcus_ and
_Bacterium_[10] belong are found minute organisms differing much in
form and in the coloring[11] matters they produce, as that causing the
red color of mouldy bread.
The class of lichens[12] contains a number of different coloring
substances, whose chemical composition has been examined. These
substances are found separately in individuals differing in form. In
the _Polyporus_[13] an acid has been found peculiar to it, as in many
plants special compounds are found. In the agariceæ the different
kinds of vellum distinguish between species, and the color of the
conidia is also of differential importance. In all cases of distinct
characteristic habits of reproduction and form, one or more different
chemical compounds is found.
In the next group of the musiceæ, or mosses, is an absence of some
chemical compounds that were characteristic of the classes just
described. Many of the albuminous substances are present. Starch[14]
is found often in large quantities, and also oily fats, which are
contained in the oil bodies of the liverworts; wax,[15] organic acids,
including aconitic acid, and tannin, which is found for the first time
at this evolutionary stage of the plant kingdom.
The vascular cryptogams are especially characterized by their mineral
composition.[16] The ash is extraordinarily rich in silicic acid and
alumina.
Equisetum[17]..........silicic acid 60 per cent.
Aspidium............... " " 13
Asplenium.............. " " 35
Osmunda................ " " 53
Lycopodium[18]......... " " 14
" ........ alumina 26 to 27
" ........ manganese 2 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's[19] 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 equisetifolia_[20] possibly contains tannin, since it is
used for curing hides. The bark contains a dye. It is said to resemble
_Equisetum_[21] in appearance, and in this latter plant a yellow dye
is found.
The _Myrica_[22] 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 plane[25] trees contain caoutchouc and gum; peppers,[26] ethereal
oils, alkaloids, piperin, white resin, and malic acid. _Datisca
cannabina_[27] 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 palms[28] 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 typhaceæ, contain large quantities of starch; in the case of
_Typha latifolia_[29] 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 urticaceæ[30] contain free formic
acid; the hemp[31] 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
lauraceæ family; also sassafras camphor is from the same family. Small
quantities of stereoptenes are widely distributed through the plant
kingdom.
The gramineæ, 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 ranunculaceæ 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 alkaloid[35] furnishing families belong, with few exceptions, to
the dicotyledons. The colchiceæ, from which is obtained veratrine,
form an exception among the monocotyledons. The alkaloids of the
fungus have already been noted.
[36]Among the greater number of plant families, no alkaloids have been
found. In the labiatæ none has been discovered, nor in the compositæ
among the highest plants.
One alkaloid is found in many genera of the loganiaceæ; berberine in
genera of the berberidaceæ, ranunculaceæ, menispermaceæ, rutaceæ,
papaveraceæ, anonaceæ.
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 myrtaceæ, laurineæ, cyperaceæ,
crucifereæ, aurantiaceæ, labiatæ, and umbelliferæ.
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 similarity[37] of the
viscid juices, and a like taste and smell, among cactaceæ and
portulaceæ, 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 cactaceæ.
Darwin[38] states that in the compositæ the ray florets are more
poisonous than the disk florets, in the ratio of about 3 to 2.
Comparing the cycadeæ and palmæ, 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 occidentalis_[39] 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 angustifolia_[40] 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 _pyrophæal_ 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 agavæ,
and in plants belonging to the leguminosæ family.
The list[42] 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 liliaceæ 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 commercial[43] 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 barium[45] sulphate and
calcium[46] oxalate, and as a solvent of insoluble or slightly soluble
salts would assist the plant in obtaining food, otherwise difficult of
access.
The botanical classifications based upon morphology are so frequently
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 paper[47] 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 leguminosæ 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
_Hæmatoxylon_ and _Saraca indica_.
The discovery[49] of hæmatoxylin in the _Saraca indica_ illustrates
very well how this plant in its chemical, as well as botanical,
character is related to the _Hæmatoxylon 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 leguminosæ. The
leguminosæ 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._
[Footnote 1: A lecture delivered before the Franklin Institute,
January 24, 1887.]
[Footnote 2: Studien uber das Protoplasm, 1881.]
[Footnote 3: Vines, p. 1. Rostafinski: Mem. de la Soc. des Sc.
Nat. de Cherbourg, 1875. Strasburger: Zeitschr., xii, 1878.]
[Footnote 4: Botany: Prantl and Vines. London, 1886, p. 110.]
[Footnote 5: For the literature of starch, see p. 115, Die
Pflanzenstoffe, von Hilger and Husemann.]
[Footnote 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.]
[Footnote 7: Prantl and Vines, p. 111.]
[Footnote 8: L. Crie: Compt. Rend., lxxxviii, 759 and 985. J. De
Seynes, 820, 1043.]
[Footnote 9: Page 279.]
[Footnote 10: M. Nencki and F. Schaffer. N. Sieher: Jour. Pract.
Chem., 23, 412.]
[Footnote 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.]
[Footnote 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.]
[Footnote 13: Stahlschmidt.]
[Footnote 14: E. Treffner: Inaugur. Diss. Dorpat, 1880.]
[Footnote 15: W. Pfeffer: Flora, 1874.]
[Footnote 16: Die Pflanzenstoffe, p. 323 W. Lange: Bul. Ber., xi,
822.]
[Footnote 17: Ann. Chim. Phys., 41, 62, 208; Ann. Chim. Pharm.,
77, 295.]
[Footnote 18: Fluckiger: Pharmakognosie. Kamp: Ann. Chim. Pharm.,
100, 300.]
[Footnote 19: Revue Scientifiqe, 13 Mars, 1886.]
[Footnote 20: Dictionary of Economic Plants. By J. Smith. London,
1882, p. 294.]
[Footnote 21: Ibid., p. 160. Pharmakognosie des Pflanzenreichs,
Wittstein, p. 736. Ann. Chem. Pharm., 77, 295.]
[Footnote 22: Rabenhorst: Repert. Pharm., lx, 214. Moore: Chem.
Centralbl., 1862, 779, Dana.]
[Footnote 23: Johansen: Arch. Pharm., 3, ix, 210. Ibid., 3, ix
103. Bente: Berl. Ber., viii, 476. Braconnot: Ann. Chim. Phys., 2,
44, 296.]
[Footnote 24: Wittstein; Pharm. des Pflanzenreichs, p. 249.]
[Footnote 25: John; Ibid., p. 651.]
[Footnote 26: Dulong. Oersted, Lucas, Pontet; Ibid., p. 640.]
[Footnote 27: Braconnot: Ann. Chim. Phys., 2, 3. 277. Stenhouse:
Ann. Chim. Phann., 198, 166].
[Footnote 28: 3 Pflanzenstoffe, p. 412.]
[Footnote 29: Lecocq: Braconnot: Pharmacog. Pflan, p. 693.]
[Footnote 30: Gorup-Besanez.]
[Footnote 31: Siebold and Brodbury: Phar. Jour. Trans., 3, 590,
1881, 326.]
[Footnote 32: Wagner: Jour. Prakt. Chem., 58, 352. B. Peters, v.
Gohren: Jahresb. Agric., viii, 114; ix, 105; v. 58. Ann. Jour.
Pharm., 4, 49.]
[Footnote 33: Dragendorff: Pharm. Zeitschr. Russ., xvii, 65-97.]
[Footnote 34: Bonssingault: Ann. Chim. Phys., 2, 27, 315. Erdmann:
Jour. Pract. Chem., 71, 198.]
[Footnote 35: Die Pflanzenstoffe, p. 21.]
[Footnote 36: Ibid.]
[Footnote 37: Meehan: Proc. Acad. Nat. Sciences.]
[Footnote 38: Different forms of flowers on plants of the same
species. Introduction.]
[Footnote 39: Meehan: Proc. Acad. Nat. Sciences.]
[Footnote 40: H.C. De S. Abbott: Trans. Amer. Philos. Soc., 1886.]
[Footnote 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.]
[Footnote 42: Different genera and species of the following:
Ranunculaceæ, Berberidaceæ, Carophyllaceæ, Polygalaceæ,
Bromeliaceæ, Liliaceæ, Smilaceæ, Yuccas, Amaryllideæ, Leguminosæ,
Primulaceæ, Rosaceæ, Sapindaceæ, Sapotaceæ]
[Footnote 43: Kobert: Chem Ztg.]
[Footnote 44: Compt. Rend., xciv, p. 1124.]
[Footnote 45: Bul. de la Soc. Chim.]
[Footnote 46: "Yucca angus." Trans. Am. Philos. Soc., Dec., 1885.]
[Footnote 47: Botanical Gazette, October, 1886.]
[Footnote 48: Borodin: Pharm. Jour. Trans., xvi, 369. Pax. Firemy:
Ann. Sci. Nat., xiii.]
[Footnote 49: H.C. De S. Abbott, Proc. Acad. Nat. Sciences, Nov.
30, 1886.]
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