The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1897-12-04
CAUSE OF PLANT COLORS
PROF. j. NJ. COULTER ExPOUNDs
SOME REVOLUTIONARY VIEWS.
Relation of Red and the Generation
of Heat-CIOse of the Boz
tanical Series.

course at the First Baptist Church with
lecture on the facts and causes of varia-
ton of plant species. Ee first reviewed
briefly the lecture on color and its signifi-
canoe in nature. An outline of this entirely
new and almost revolutionary view of the
uses of color in plant life is as follows
1.-The recent work OF Stahl in the great
tropical laboratory at Butenzorg Java,
has brought to light many important sug
gestions concerning the significance of
color. Heretofore we have only sought to
explain the green color most largely dis
played in leaves, and the various colors
shown by flowers. The former we have rec
ognized as being intimately concerned with
an important piece of plant work namely,
carbon assimilation the later we have been
IN the habit of regarding as a device for
the purpose of attracting insects TO do the
work or pollination The green color was
thus associated with work, and the flower
colors not with work, but with passive
attraction, making Them appear merely in
the light of a glaring advertisement
The first shock received by our belief
IN the attractive purpose of the color of
MOWERS was the discovery by Stahl that
many of the insects that are known as pol
iinatorS are color blind. This, of course,
was fiat contradiction of the idea that the
cOlorS of f1oWerS are essentially attractive.
The thought is suggested therefore, that
there is some deeper significance in these
cOlorS than attraction, although they may
possibly serve that purpose incidentally
If the display of color by the whole plant
Kingdom be regarded it will be seen that
the presence of which the idea of attract
Ing insects to flowers sinks into insignif-
cance. In addition 10 the green so common
among plaits, We find display of other
colors, as follows: Among leaves, such as
those of the beet, coleus and other so-called
foliage plants; spring buds, which usually
flush up with some tinge of red autumn
leaves, fruits and great groups of plants,
such the red and brown seaWeeds in
which the whole body is colored. Such an
extended display apart from flowers indi-
Gates that these colOrs must have a boos-
ical significance far deeper than the attrac-
ton of insects.
CAUSE OF GREEN AND RED.
"The clew should have been furnished by
| what was known concerning the work of
the green celebration. Nothing is better
known than that the green color is for the
| purpose of manipulating the light and that
by means of this manipulation certain of
the light rays are converted into other
] forms of energy by the use of which the
| protoplasm of the plant is able to assm-
| ilate carhcn-dioxide. This association Of
| color with plant work in relation to light
| would have suggested the possibility that
| other colors may have light relations IN
| connection with plant work. StahlS inVes-
teatio ms We're directed towards discovering
| the possible significance of some of the
most common colors, and his most sug-
| Best1Ve results were in connection with red
| coloration. He observed that wherever red
| coloration occurs temperature rises. This
| has indicated that some of the light rays
| passing through the red celebration were
| converted into heat. He suggests simple
experiment to demonstrate this.
variegated coleus leaf is selected on
which there are splotches OF red.
| cred with film of cocoa butter such
| as Will melt at low temperature, and then
exposed TO light, it will be found that the
| him over the red Splotches will be melted
| sooner than over the rest of the leaf sur
face. In seeking to apply this suggestion
| that red coloration is associated with in
| crease in heat, the result becomes quite
| striking. The red flush of early spring buds
| seem to suggest the need for greater heat
| at that season. The reds of autumn leaves
| which come just when. the living substance
| OF the leaf is ceasing its work
and retiring into the stem, and
a heat protection. The red algae, submerged
| deeper than any other form of marine vege-
| tatlon, need greater heat, both because of
| the chilling water and on account of the
diminished intensity of the light passing
| through the water The reds OF fruits may
| also be associated with the greater devei-
| opment of heat, which may assist in those
chemical changes which occur in the pro-
| cess known as ripening. In this way it
| seems possible to associate all the reds
| with the work of the plant in its need Of
greater heat.
I'm reference to the yellow and other
colors. hardly any suggestion has as vet
been made. 1t is reasonable to suppose
however, in view of the phase just men
toned, that they also are connected with
the plant activities. This certainly presents
a far broader conception of the significance
of color in plants, and it is certainly true
! that we must hereafter associate color with
| work, and of course with light related
work Naturally this applies only to coIors
that are associated with living parts of
plants. COlorS such as exist in 'heartWood
in roots etc, certainly hold no light reIa-
ton and must be explained in some other
way.
Professor Coulter opened the discussion
,F ~. I,r.4
by stating that twenty years ago, when the
study of botany was confined to the analy-
sis of plants, many specimens were found
which did not agree with the book and to
identify those, students just took the aver
age of arguments. We'll" he said, that
is just what scientists are doing now" A
species" only agrees in certain average
| characters with it's fellows The natural
lists who have created the most species are
| the ones who think least of species.
VARIATION OF SPECIES.
The hand of man can make species by
| cultivation; he change not only the
| parts, but the whole But plants do not
| vary under cultivation alone; they vary in
nature. Variations are notorious in wild
| plants This was illustrated by the varia-
| tons of the European wild rose, of which
| seventy species were made by as many
| different botanists. Really it is the COM
| mon dog rose" varied by geographical
| location and climatic conditions. Also, in
| England Bentham said there were only five
brambles; Babbington said forty-fiVe one
found fifteen willows and the other thirty
| one, so very marked are the variations
| DIR. Asa Gray studied the asters of North
| America for thirty years. He then told
Professor Coulter that when he began he
| thought he knew much about the species
| Of asters, but after this long study he did
| not believe there was any such thing as
| species OF aSterS;" they grade into each
other inSenSibly. Groups like asters and
Sedges are made up OF many variations
| These groups have taught great truths of
! evolution. The rare Species standing by
| themselves, are of least use, but are the
| ones which have given the base to the idea
of species.
! The lecturer showed that in wild species
| the per cent. of variation runs from Is to
! % per cent. and affects from 10 to Is per
| cent. of the individuals of a species The
| things which favor variation are, first re-
production by pollen and ovuie; indeed
! sexual reproduction has been the riddle of
| biology 1T is now believed that this form
! nature to bring about variation. and hence
| progress and adaptation. by bringing two
| great and different streams of ancestry to
| work together Besides this there is en-
| vironment, including the great fact of nu-
| triton cause of variation and finally
| what we call in the blindness of our ignor-
| ance a 'deep-seated tendency in nature
| toward variation.
This has proved the most successful
| course of university extension lectures yet
given in this city. The attendance has been
from 250 to 800, including MANY physicia M