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Cornell Mniversity Library

BOUGHT WITH THE INCOME
FROM THE

SAGE ENDOWMENT FUND

THE GIFT OF

Henry W. Sage

1891

| CT OL (4 VT IS...

i © 3777

Cornell University Library

SB 63.B94A3
v.8

TT
3 1924 008 976 874 ol

Cornell University

Library

The original of this book is in
the Cornell University Library.

There are no known copyright restrictions in
the United States on the use of the text.

http://www. archive.org/details/cu31924008976874

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LUTHER BURBANK

HIS METHODS AND DISCOVERIES AND
THEIR PRACTICAL APPLICATION

PREPARED FROM
HIS ORIGINAL FIELD NOTES
COVERING MORE THAN 100,000 EXPERIMENTS
MADE DURING FORTY YEARS DEVOTED
TO PLANT IMPROVEMENT

WITH THE ASSISTANCE OF
The Luther Burbank Society
AND ITS ;
ENTIRE MEMBERSHIP

UNDER THE EDITORIAL DIRECTION OF

John Whitson and Robert John

AND

Henry Smith Williams, M. D., LL. D.

VOLUME VIII

ILLUSTRATED WITH
105 DIRECT COLOR PHOTOGRAPH PRINTS PRODUCED BY A
NEW PROCESS DEVISED AND PERFECTED FOR
USE IN THESE VOLUMES

NEW YORK AND LONDON
LUTHER BURBANK PRESS
MCMXIV

fe

\a00915

Copyright, 1914, by
The Luther Burbank Society
Entered at Stationers’ Hall, London
‘All rights reserved

VIII

\

Volume VIII—By Chapters

a seiaasassiadatieds Page 3
Corn—The King of
America’s Crops
~—Not Only Better Corn, But a 1
Better Stalk—and Why........... gdsinelgensaesuiveaeeees

Getting the Most Out of
the Small Grains
“ers stp uae 45
Manufacturing Food for
the Live Stock

—Some Suggestions on Clover,
Timothy and Alfalfa... ...... isadsceaedeteean 17

A Rich Field for Work in
the Textile Plants

Improving the Fibers of Flax,
Hemp, and Santor, acwirnnsissitiionnenoiibiionaty 107

Plants Which Yield Useful
Chemical Substances

Hloprand Sugar Beet oss cesseeeeeesees ee, 133
Reclaiming the Deserts
With Cactus

—The Methods Used to Produce
a Spineless Cactus... .........cccsceeneecesecennenees 169

Rival of Alfalfa

—The Commercial Possibilities of
Cactus as Cattle Food... ... 1.1... cs scereeeesseccecees 209

Many Useful Substances

in Cactus
—The Richness of Its Chemical 9 AT

Other Useful Plants Which Will
Repay Experiment
~Teertfarmationp eat

Waiting to Be Made... .........cssscccnseccecensces 271

FOREWORD TO VOLUME VIII

Corn, Wheat, Oats, Barley and Hay are crops
which receive attention in this volume, as well as
the textile plants and those which yield useful
substances to commerce and chemistry; also the
complete story of the Cactus, which has often been
hinted at, but never before told, is given here.

All of the work described in this volume is new,
and the public, hitherto, has known but little of
Mr. Burbank’s efforts along these lines.

His work with corn, that already much
improved crop, is in particular noteworthy. In
addition to the many practical pointers on method,
which Mr. Burbank outlines in this volume, there
will also be found scores of suggestions for further
plant improvement—concrete ideas which have
come to Mr. Burbank in his work, but which he
has not yet had time to carry out.

THE EDITORS.

A Section of Rainbow Corn Leaves

This curious and beautiful variation in the foliage of the
familiar maize was brought about by Mr. Burbank through
hybridization and careful selection; the original mutant with which
he worked having been imported from Europe. Mr. Burbank
is now endeavoring to combine these beautiful qualities of
leaf with correspondingly attractive qualities of grain.

valTieteY

CoRN—THE KING OF
AMERICA’S CROPS

Nor ONLy Betrer Corn But A Betrer STaLK—
AnD WuHy

HE potato, tobacco, and Indian corn or
| maize—these are the three great American
contributions to the company of cultivated

plants.

The potato and tobacco and bean have gone
everywhere, but corn is still chiefly raised in the
country of its nativity. It is extensively cultivated,
however, far to the north of its original habitat.
The great corn state now is Iowa, and the original
home of the ancestors of the corn plant was the
region of Southern Mexico and Central America.

In a recent year there were 1,144,500 acres of
land in the United States given over to the cultiva-
tion of tobacco, and the crop raised amounted to
963,000,000 pounds. For potatoes 3,655,000 acres
were utilized, raising a crop of 421,000,000 bushels.
Wheat was raised on 18,663,000 acres, giving a
crop of 330,000,000 bushels.

[VoLumME VIII—Cuapter I]

LUTHER BURBANK

This is an enormous acreage and a colossal
output. Yet it seems almost insignificant in com-
parison with the record of corn. For to that crop
106,884,000 acres were devoted, and the crop
harvested aggregated 3,125,000,000 bushels.

Nothing that could be added would better show
the supremacy of King Corn than this citation of
comparative statistics. A crop that tops the three
billion bushel mark stands by itself among all the
products of the cultivated acres of the world. Not
only is it America’s greatest crop; there is no crop
of any other cereal or any single vegetable product
whatever that equals this record anywhere in the
world.

It is true that the corn crops of other nations
are comparatively insignificant in contrast with
the crops of small grains. But this is merely
because corn demands peculiar conditions, notably
a very hot summer, to bring its product to perfec-
tion. A goodly quantity of corn is exported; and
the beef and pork that corn has produced are sent
everywhere.

Tue ANcEsTOoR oF Kina Corn

Among the most interesting experiments that
I have performed in the development of corn, have
been those that had to do with the primitive plants
that were the progenitors of the present developed
product.

[8]

A Typical Corn Stalk

This picture is shown to make clear the relations of pollen-
bearing and ovule-bearing organs in the mechanism of the corn
plant. The pollen, being borne in the tassel at the top, naturally sifts

down, as carried by the wind, on the “silk’? which constitutes
the stigmas of the seed-bearing flower. It is obvious that
the opposite arrangement of the two types of flow-
ers would not have answered at all,

LUTHER BURBANK

The plant from which Indian corn was unques-
tionably developed, or at all events, a very closely
related form that has not been greatly modified
from the primeval type, is a gigantic grass that
still grows in Mexico and is a valuable forage
plant. It is called Reana luxurians, or Euchleana
Mexicana. Its familiar name is Teosinte.

This is a tall, sturdy plant, resembling corn as
to its stem and stalk, but having a rachis like
wheat or barley or rice that by comparison with
the ear of the cultivated corn is insignificant.

In the wild teosinte each grain shells out readily
like oats, wheat, or barley, and has an exceedingly
hard, polished, chitenous covering, for protection
against marauding birds and animals. The grains
are arranged in two double opposite rows on a
fragile rachis, like that of other grains such as rye,
barley and rice; the cob of the developed corn
being wholly a product of man, and being required
to hold the numerous large, fat, nutritious kernels
which it has been induced to produce through
centuries of cultivation.

Teosinte, when brought under cultivation at
the present time, after a few generations in the
new and more favorable environment, like all
other cultivated plants tends to vary. Like many
of the half wild plants, teosinte has an inveterate
tendency to sucker from the root.

[10]

ON CORN

Anyone who has suckered a field of corn on a
hot June day will appreciate the importance of
eliminating this wild habit of the teosinte, espe-
cially when grown for grain rather than for food.
It must have taken centuries to eradicate this
defect, as it is even yet more or less persistent in
nearly all varieties of corn.

In kernel the teosinte most resembles, though
not by any means very closely, our common varie-
ties of pop corn; but with this great difference:
only a pellicle protects the kernel in all our culti-
vated corn, while the tough, chitenous covering
envelops the kernels of teosinte. But the resem-
blance of the plant itself to the corn plant leaves
no question of their affinity, and the head of grain,
notwithstanding its insignificant size, has individ-
ual kernels that are suggestive of diminutive
kernels of corn.

If any doubt were entertained as to the
relationship of this wild plant to the cultivated
corn, this would be dispelled by hybridizing
experiments, for the two cross readily.

In Mexico it is quite common for the teosinte
to hybridize with the Mexican corn, through the
agency of the wind, and the product is well-known
under the name of “dog corn.”

In my own extensive experiments with teosinte,
no difficulty was experienced in effecting hybridi-

[11]

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ON CORN

zation, after I had succeeded in making the plant
flower at the right season.

Left to itself, the plant in this part of California
does not bloom until after even the latest varieties
of corn are through blooming. It will produce
seed only in the southern part of Florida, except
the new varieties lately sent me from the high
mountains of Mexico, where it necessarily had to
adapt itself to a shorter season. I was able, how-
ever, by starting the teosinte in the greenhouse,
and thus securing fine, large plants to set out in
May, and by placing these in the hottest possible
positions and fertilizing them heavily, to cause the
plant to bloom much earlier. .

This was further facilitated by removing all
side shoots, so that the energies of the plant could
be centered on the production of pollen.

My hybridizing experiments demonstrated
clearly enough the affinity of the teosinte with the
cultivated corn plant. They also convinced me
that this is without question the parent of the
cultivated plant.

TRACING ANCESTRAL ForMS AND HaBits

The experiments that seemed demonstrative as
to this were made partly with the aid of a primitive
form of corn known as the single-husked corn,
Zea lunicata, of which I received specimens from
Mexico. This I believe to be the true primitive

[13]

LUTHER BURBANK

type of corn—that is to say, the first corn after
advancing from the original type of the teosinte.

The seed of the half ear of fine yellow corn of
this primitive type that was received from Mexico
was planted. The plants that grew from this seed
showed the widest variation. Every one knows
that the cultivated corn bears its pollenate flowers
or tassels at the top of the stem, and its pistillate
flowers marked by tufts of so-called corn silk—
and subsequently, of course, producing the ears—
in the axils of the leaves far down on the stalk.

Teosinte bears small tassels at the top of each
stalk, in competition with the diminutive ones all
along down the stalk, But some of the plants of
my single-husked corn bore both tassel and silk
together at the top of the stalk. Others bore silk
and tassel mingled up and down the stalk, like
teosinte.

The ears of corn that developed sometimes
showed clusters of kernels of the size, shape, color,
and general appearance of the Kaffir corn. Others
bore long tassels with numerous kernels.

By selecting among these different types, I have
been able to develop races of corn that, I am con-
fident, represent the primitive type, running back
to the form of teosinte, and thus clearly enough
demonstrating the origin of the plant that occupies
so important a place among the present day farm

[14]

*
R
is

=,

rena

Corn Hybrids

At the right, an ear
of sweet corn; at the
left, ears of Teosinte; in
the middle, hybrids be-
tween the two, Teosinte is
believed to be the original
stock from which the de-
veloped corn sprang. The
ear of Teosinte, however,
suggests the head of wheat
rather than the seed-group
of its developed de-
scendant.

LUTHER BURBANK

crops, even if the abundant evidence had not
already been developed by my own experiments.

In the course of a few generations of selective
breeding, I had a race of descendants of the single-
husked or tunicate corn, three-quarters of the in-
dividuals of which produced kernels only at the
top of the stalk. By farther selections a race could
readily be produced that would bear its kernels
exclusively in this location.

As a rule the plants that thus produce kernels
at the top of the stalk produce no ears in the ordi-
nary location, although a few generations earlier
they had produced the grain about equally in the
two locations.

The chief interest of the experiment lies in the
demonstration that our cultivated corn, which now
shows the anomalous habit of bearing its pollenate
flowers only at the top of the stalk and its fruit on
the main stem below, was originally a grass with
the characteristic habit of bearing its grain at the
top of the stalk, just as other grasses—including
wheat and rye and barley, oats, rice, sugar-cane,
and Kaffir corn—habitually do to this day.

The presumption is that as the corn was
developed under cultivation, and evolved a large
ear which attained inordinate size and weight, it
became expedient to grow this ear on the part of
the stalk that was strong enough to support it.

[16]

ON CORN

Obviously an ear of corn of the modern variety
could not be supported on the slender tip of the
stalk where the tassels grow.

We saw in the case of the potato plant that was
grafted on the stem of the tomato, that the tuber-
bearing buds might put out from the axils of the
leaves under these exceptional circumstances,

Just what the circumstances may have been
that led to the bearing of its fruit buds exclusively
in the leaf axils in the case of the corn, we of
course cannot know. But presumably the anomaly
first appeared as a “sport”, due without doubt to
some altered conditions of nutrition, from being
placed under unusual environment, and some one
had the intelligence to select this sport and breed
from it, with the result of developing a race of
corn bearing grain on the stalk that gradually
supplanted the old form altogether—except, in-
deed, that the wild teosinte maintained the tradi-
tions of its ancestors, unspoiled by cultivation.

I may add that the experiment of running the
tunicate corn back to the primeval wild type by
selective breeding is a much more simple one
than would be the attempt to run it forward within
a few generations to the plane of the good varie-
ties of cultivated corn, but even this is compara-
tively easy of accomplishment,

To stimulate and accelerate degenerative

[17]

A Teosinte-Corn Hybrid, in the Stalk

The home of Teosinte is Mexico, and the plant there takes
on a more or less tropical growth. It retains its tendency to
giganticism when reared in northern climates; and such hybrids as
this frequently attain a height of nineteen feet. The quali-
ties of the wild and the civilized parent are
curtously blended in the offspring.

ON CORN

processes is comparatively easy; to make progress,
as civilized man interprets progress, is far more
difficult.

One reason at least for this is that the qualities
that man prizes in a cultivated vegetable are
usually not those that adapt the plant to make its
way in a state of nature. They are new innova-
tions that to a certain extent run counter to the
hereditary tendencies that have been fortified in
the wild plant through countless generations of
natural selection.

Rainsow Corn

Interesting experiments of another type that I
have carried out in recent years have resulted in
the development of a variety of corn that has the
curious distinction of bearing leaves that are
striped with various and sundry colors of the
rainbow.

The parent form from which this new race was
developed, I secured in 1908 from Germany. It
was called the quadri-colored corn. Among the
plants raised in the first season there were
two stalks, and two only, that justified the name,
their leaves being striped with yellow, white,
crimson, and green.

The other plants of the lot bore green leaves
like those of other corn plants, and the seeds of
even the two best ones reverted.

[19]

LUTHER BURBANK

I surmised that the corn was really a hybrid
between the common green-leaved dwarf corn and
the old Japanese variegated corn, sometimes
spoken of botanically as Zea mais variegata. The
fact that it was a hybrid stock gave the plant addi-
tional interest, however, and I determined to
experiment farther with it.

The ears of corn themselves gave further
evidence of their crossbred origin. Some of them
were red both as to cob and kernel, and others
bore yellow kernels and white cobs. The stalks
varied in height from two and a half to six feet.

The best plant of the lot was selected, and from
the three ears it bore I raised about six hundred
plants.

About one-third of these hybrids of the second
generation resembled their parent plant in having
leaves striped in four colors. The rest reverted
to the form of their Japanese grand-parent; a
plant with variegated leaves that first came from
Japan, and which has been known in this country
for the past thirty years.

From the best of the quadricolor stalks I took
suckers, and developed in this way a good-sized
patch of corn from cuttings, perhaps the first corn-
field ever raised by this method. All of these
suckers being from an original quadricolor plant,
of course reproduced the qualities of the parent

[20]

“Pod” Corn Varia-

tions

Here are a few of

the anomalous types of
corn growing in a sort of
pod, that probably repre-
sent stages of evoluiion of
corn during the process of
its development. These
specimens were of course
raised in Mr. Burbank’s
gardens in a recent year;
but they are reminiscent
of a time when the best
ears of corn in existence

were probably not very

different from these.

LUTHER BURBANK

form, just as we have seen to be the rule with all
other plants reproduced by root division or cutting,
or by grafting of cions.

The method of suckering these plants was to
pull down the suckers from the old plants when
the young were about one foot high. About two-
thirds of the foliage was cut back, leaving the
stalk with shortened leaves about two to three
inches in length. These were placed in pure sand
in a moist place away from the wind for a day or
two, but in the bright sun, and after a week when
they showed signs of making growth they were
transplanted into rows in the field.

Unfortunately, the suckering was not done
early enough in the season to give all the new
plants time to ripen a crop of corn. If they had
been planted even three or four days earlier, all
would have been well. As it was, only about half
or two-thirds of the plants ripened their crop.

Of course the plants had been hand-pollenized
to avoid danger of vitiating the strain with wind-
borne pollen from ordinary corn tassels.

To guard absolutely against the danger of
cross-pollenizing, if there is any other corn in the
neighborhood, it is necessary to cover the tassels
with a paper bag while they are maturing and
before they are pollenized. Pollenizing is effected
by dusting a tassel with its load of pollen against

[22]

Ears of Corn-Teosinte Hybrid

These ears, as will be seen, have departed very radically

from the snake-rattle type of the original Teosinte. On the
other hand they quite as obviously lack a good deal of conforming to

the accepted standards of the developed corn. They have

peculiar interest as representing another stage of the

evolution through which the plant doubtless passed
in the course of its development, under
guidance of the aborigines of
southwestern America.

LUTHER BURBANK

the corn silks; these filamentous threads being of
course the pistils of the corn flower. Each thread
leads to an ovule that becomes a grain of corn in
due course, after the nucleus of the pollen grain
has made its way down the entire thread to unite
with it.

I may add that the corn raised from the suckers
proved fully as good in all respects as that raised
from originally planted seed, when removed early
enough in the season and properly treated, the
weight of grain per acre being fully as great. But
the stalks were much shorter and more compact
than those of the other plants.

The object of suckering, of course, was to
secure a large crop of quadricolor corn in order
that the experiments might be carried out more
extensively in the next generation.

The attempt was altogether successful. Not
only did we secure an abundant supply of the
quadricolor, but I found also two stalks among
many that bore leaves in which the tendency of
striping with varied colors had been greatly
accentuated, producing a variety that might be
called multicolor corn.

In addition to the four colors borne by the
other plants, these had stripes of bronze and choc-
olate, and arranged in far more pleasing manner
than in any of the former plants.

[24]

More Like Wheat
Than Corn

This ts another
corn-teosinte hybrid,
illustrating yet another
stage ofdevelopment.
These heads of grain bear
greater resemblance to
heads of wheat than to ears
of corn; yet their future
possibilities are adum-
brated in the swollen ker-
nels and the tendency to
discard the swaddling-
cloth bracts.

LUTHER BURBANK

It was by selecting seed from these plants that
I grew in the next generation a number of stalks
in which this tendency to multiple striping was
accentuated, thus producing a race of corn with
leaves beautifully striped in six colors, to which
the name Rainbow Corn has been given.

In perfecting the variety, nothing further was
necessary than to select seed from the plants that
showed the most even distribution of the stripes,
and the most vivid display of color, as well as
uniformity of size and early ripening, as this was
a very late maturing variety, even for California.
In earlier generations there had been a marked
tendency to variation, some plants producing only
a single stripe of red, some only a stripe or two of
yellow or white. But by rigid selection through
several years these variants were. eliminated, and
a variety produced that may be depended on to
exhibit rainbow leaves of a pretty uniform type.

My further experiments with this variety con-
sisted of crossing the Rainbow Corn with some of
the sweet corns, in the hope of giving to this hand-
some ornamental plant the capacity to bear sweet
corn of good quality.

These experiments are still under way, but
they give no great promise of immediate success,
as the stripe seems to be recessive.

A rainbow-leaved corn that bears good edible

[26]

ON CORN

ears would constitute a notable addition to the
very small company of habitants of the vegetable
garden that are prized equally for their ornamen-
tal qualities and their food product.

Extra-EaRLY SWEET Corn

My earlier experiments with corn date back to
the Massachusetts period when I was developing
the Burbank potato.

I recall a small success that at the time seemed
to me quite notable, gained through a trick in the
cultivation of sweet corn, that is not without
interest.

I had learned the value of a very early sweet
corn, and I devised a method of forcing the growth
so that I was able to put my corn on the market in .
advance of anyone else in the neighborhood, and
therefore to sell it at a fancy price. Many a time
I was able to take a buggy load of corn from
Lunenberg, where my place was located, to Fitch-
burg, and return with $50 or $60 as the selling
price of what I could load on a common one horse
spring wagon.

I had a complete monopoly of the early sweet
corn market in the manufacturing city for three
or four years, and my early corn brought usually
50 cents per dozen ears, although a week or two
later any amount of corn could be bought for a
fraction of that sum.

[27]

Sida gaale

.
3.

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6bujbuvs spjiqiy ajuis

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juaudojaaaq
fo sa6p}5 sno,

ON CORN

One of the secrets was in germinating the coi
I obtained fresh stable manure in the proper s¢
son, and mixed this with leaf-mould, about hi:
and half. Corn placed in this when it was mo
and warm would germinate rapidly.

When the young roots were from two to six
eight inches in length, and the tops had made
growth of half an inch or so, I would plant the
sprouted grains in ordinary drills, dropping the
in just as corn would be dropped, no attenti
whatever being paid to the way they fall—whett
with roots down or up.

A half inch covering of dirt being put over t
sprouted grain, it was nothing unusual to fi
shoots coming through the soil the next mornin;

And this early start would enable the plants
grow marketable ears at least a week earlier th
they would have done had the seed been planted
the ordinary way. The growth of the plants cot
be further stimulated by placing a small quant
of bone meal, or of a good nitrogenous fertili:
containing a certain amount of phosphorus, in 1
soil about the roots.

Preliminary to this method, I had made «
tremely useful selections of the earliest-ripeni
ears for a number of seasons.

Ear_y HysripizING ExPERIMENTS
My experiments of this early period were 1

[29]

LUTHER BURBANK

confined to methods of germinating and forced
cultivation, but included also hybridizing tests.

My principal work was in crossing the black
Mexican corn, the common sweet corn, and the
New England yellow field corn. There was, of
course, no difficulty in effecting crossing, but I
found it very difficult to fix any good variety.
These were the first experiments in this special
line ever made with corn. They have of course
been duplicated a thousand times since.

The most important experiments that I made
had to do with crossing the yellow field corn with
the Early Minnesota and other varieties of sweet
corn, my intention being to produce a sweet corn
with yellow kernels. There was a demand for
such a variety, and none existed at that time.

I succeeded in producing hybrids that com-
bined the yellow color of the field corn with the
sweetness of the other variety, but had not thor-
oughly fixed the new variety so that it would uni-
formly breed true from seed at the time when I
removed to California, in 1875; and this inter-
rupted the corn experiments.

In the meantime, however, I had gained valu-
able lessons in heredity from observation of the
cross-bred corn.

In the second generation numerous fine pure
yellow ears were obtained without a trace of white,

[30]

VIP =at

A Freak Ear of Corn

This curious seed cluster was developed in the course of
the hybridizing experiments with teosinte and corn. Doubtless
it tells the story—did we only know how to read it—of some ances-
tral strain in which the seeds grow in a rounded cluster, Uttle
suggestive of the long ear that characterizes the modern
product. But the kernels of this freak ear have
after all a good deal of the corn quality.

LUTHER BURBANK

but a part of the kernels were hard and smooth,
and not the wrinkled sweet corn that was desired.
In the following generation, when the corn was
grown in California, I obtained some first-class
ears with almost their entire lot of kernels wrin-
kled, and was confident that in another year I
could have obtained the variety desired; namely,
one that would bear exclusively wrinkled or sweet
corn kernels of a yellow color.

But the pressure of other work led me to aban-
don the experiments at this stage.

There is peculiar interest, in the light of more
recent knowledge, in noting the results of these
early crossbreeding experiments, as just related.
It will be observed that I had no difficulty in ob-
taining crossbred corn with the yellow kernels
of one of the parent forms, but that it was difficult
to secure a complete ear of wrinkled sweet corn
kernels.

STARCH VERSUS SUGAR

To understand the conditions clearly, it should
be explained that the kernel of the sweet corn
differs from that of field corn in that it contains
a large percentage of sugar in solution, and that
the wrinkling of the kernel is the outward sign
of this condition.

The smooth kernel, on the other hand, is one
in which the sugar content has been largely trans-

[32]

Another Evidence of Old Heredity

Here we see a corn plant bearing a complete, although

very primitive, ear in the midst of its pollen-tassel. All the
other familiar cereals except the corn bear their seed bracts in this

way. Corn has developed the habit of bearing only the pollen

tassel at the top, placing the seed-head lower down on

the stalk, where the stalk has strength to support
it. This specimen shows an _ interesting
reversion to the primitive type.

LUTHER BURBANK

formed into starch, and deposited in this insoluble
condition.

More recent experiments have shown that
whiteness versus yellowness of kernel constitutes
a pair of hereditary characters, in which yellow-
ness is dominant. Similarly starchiness versus
sweetness of kernel constitutes another pair of
characters, in which starchiness is dominant. This
being understood, we can predict with some cer-
tainty what will occur when such a cross is made
as that of my early experiments in hybridizing the
field corn and the sweet corn.

The crossbreds of the first generation will have
ears with yellow kernels, that are all starchy like
the field corn kernels, because yellowness and
starchiness are dominant qualities. But the off-
spring of the second generation will show a certain
proportion in which the recessive characters of
whiteness and of sweetness reappear,

Thus in the second generation we shall have
yellow kernels that are starchy, and others that
are sweet, and white kernels also of both kinds.

And the interest of the experiment is enhanced
by the fact that the kernels showing these differ-
ent characteristics are likely to be distributed on
the same ear. In many plant breeding experi-
ments we have no tangible feature to guide us as
to the quality of the fruit. Some of the seeds of

[34]

What to Work for

in Corn

The ear at the left
shows corn well filled
out at the butt. The pic-
ture at the right shows the
same ear well filled at tre
tip. The presence cf weil
filled kernels at both ez-
tremities, proves that this
corn is of good hereditary
strain, and also that it has
been fully pollenized. Ears
of corn used for seed
should always be, carefuily
examined with reference
to this quality of bearing
well filled kernels at either
end. The kernels in the
middle should be well
filled, as a matter
of course.

LUTHER BURBANK

a hybrid blackberry, for example, may bear fac-
tors for thornlessness, while others bear factors
for thorns. But this can be shown only when the
seeds have been planted and have germinated.

In the case of the corn, on the other hand, the
qualitics of the individual kernels are revealed in
the outward appearance of the kernels themselves.
The kernel that bears the factors for yellowness
will be yellow; the kernel that bears the factor
for starchiness will be plump and rounded; and
the kernel that bears the factor for sweetness will
be wrinkled because of its sugary content.

So a glance at the crossbred ear of corn reveals
at once the story of its ancestry.

So striking is the illustration of Mendelian
heredity when yellow field corn and white sweet
corn are crossed, as in my early experiments, that
recent tests, in which actual count of the different
types of kernels has been made, have shown
results of mathematical exactness.

Thus in an experiment recorded by Mr. R. H.
Lock, of Cambridge University, in which a smooth
yellow type of corn was crossed with a wrinkled
white variety, the grains of different colors ob-
tained from a certain number of ears borne by the
plants of the second generation were distributed
almost as evenly as if the work had been done by
hand by a careful human calculator.

[36]

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“Dis

Paatazat uzoa jo sia

yooidfiy aap asayy

yuawuona
-uyq jo samog 2Y J,

LUTHER BURBANK

The precise result was this: (1) Smooth yellow
grains 2,869, or 25.3 per cent.; (2) smooth white
grains 2,933, or 25.7 per cent.; (3) wrinkled yel-
low grains 2,798, or 24.5 per cent; (4) wrinkled
white grains 2,803, or 24.5 per cent.

We have seen that the condition of whiteness
and the wrinkled condition (due to large sugar
content) are recessive traits. Therefore if we
plant the wrinkled white kernels we may expect
sugar corn, the ears of which will be uniformly of
that type. 2

But what we wished to secure, it will be re-
called, was an ear bearing only yellow wrinkled
kernels. There are as many of these as of the
others on the ears of the second-generation hy-
brids. But they will not all breed true, because
yellowness is a dominant factor, and so in a cer-
tain number of the yellow kernels the quality of
whiteness exists as a recessive trait in hiding, that
will reappear in the next generation.

All the progeny of yellow wrinkled kernels will
be wrinkled because the wrinkled condition is re-
cessive; but only about one in four of these ker-
nels will produce yellow progeny with certainty.

And no one can tell from mere inspection which
of the four is the pure dominant and which the
mixed dominant that will have a certain propor-
tion of white offspring.

[38]

Mr. Burbank’s
Extra Early

Sweet Corn

This is a bantam
corn and bears earlier
than any other corn Mr.
Burbank has produced. It
represents the present out-
come of experiments that
were started when he was
a boy in Massachusetts. As
the name indicates, the
corn bears extra early; it
is aiso extra sweet.

LUTHER BURBANK

This, of course, accords perfectly with the
results of my experiments, as just recorded. But
the new tests, which explain the distribution of
kernels of different colors, and enables us to pre-
dict the manner of their distribution, give added
interest to the earlier observations.

I should add, however, that whereas it is usual
for the crossbred kernels to show this mixed dis-
tribution on a single ear, in more recent experi-
ments, in which the Orange sweet corn and a late
white variety were crossed, I have secured a prod-
uct in which there was a pure white ear that
exhibited all the qualities of the orange except
color, and in another case a pure yellow ear was
produced which showed the characteristics of the
late white, including the large number of rows of
kernels.

This is altogether unusual in crossing yellow
and white varieties of corn, and the anomaly is
not easy to explain.

BREEDING FOR VARIED QUALITIES

My other experiments with corn have been
rather numerous, but have largely been concerned
with minor details, such as the development
through selection of a corn that will produce ears
bearing a large number of rows of kernels.

I have been able in three years, working with
Stowell’s Evergreen Corn, to produce a few ears

[40]

ON CORN

with eighteen to twenty-two rows to the ear, mak-
ing it clear that by extending the experiments it
would be possible to fix a variety growing uni-
formly twenty-two rows of kernels.

Other experiments have shown the feasibility
of changing the form of the kernels, making them
long, broad, and of uniform size. Attention has
also been paid to the production of corn that
would fill out all the kernels uniformly, instead
of producing a certain number of nubbins as corn
is prone to do.

The size of the stalk and the number of ears
to the stalk are also matters that are subject to
easy modification through selection. I have re-
ferred in another connection to experiments of
others, in which the location of the ear on the stalk
was lowered or raised at will in a few generations,
and made to droop or stand erect as desired,
through selection.

I myself have developed a race of corn with
gigantic stalks, in which the ears are borne so high
that a man of average height can barely reach
them from the ground. This was done for experi-
mental purposes, and not because a variety of this
kind would have commercial value. I have per-
sonally produced and introduced four distinct new
varieties of corn, including the two unique orna-
mental varieties, and two improved extra early

[41]

*10]8a9UD 9}U]SO2} S}t
0} yovqg burysvy fjuo
s1 uso ayy ‘yzmoi6 6uria
-mo} siy} uo BuyyD} ut ‘11D
aajfy ‘yuauidojaaap Jo sai}
~1]1q1ssod ay} Sujmoys sp
Gurjsaiajui St quauniadxa
ayz nq Syb1y os moi6 ui09
ayy Sulapy uz abpjupapo
yoai6 ou sz aLay} ‘saauD}s
-wno19 « fimpujpio 4apu)
*yaaJ aajzam} aaogp pam spam
pray sy uy syipis ayy Jo
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p buimoi6 ‘pjey-us09
yupqging D $1 a1aH

uso‘)
Plaid FUDD
syupg.mg “Iq

ON CORN

sweet corns, besides several strains that have been
greatly improved by selection and then turned
over to various seedsmen.

Reference has been made also to the experi-
ments through which the kernels of corn were
made to produce more protein or more starch, as
the case might be. These experiments have prac-
tical importance because a corn to be used as
fodder should have a high protein content, whereas
grain to be used for making starch or for purposes
of distillation should have a high starch content.
The oil content can also be similarly increased or
diminished at will.

By selection alone it is possible to modify these
qualities, and they can be accentuated, modified,
combined or separated through the crossing of
different varieties.

All in all, the great American cereal offers in-
terest for the plant developer somewhat commen-
surate with the economic importance of the plant
itself. Much has been done, but there is still ample
opportunity for the improvement of different vari-
eties, and for the development of specialized new
varieties differing as to their sugar content, as to
time of ripening, and the like.

No plant is easier to experiment with for the
amateur, and few plants offer better prospects of
interesting developments.

[43]

*yjiou ay} 0} wwf mas8
yoy} $10}saauD spy jDaym
ay} yoy] s}sabGns ‘1aaamoy
‘styz sD juauniadxa uD
yong “visy Usazjsamyjnos
spm ‘mouy am sp «Df os
qpaym fo auroy }Du16110 ay}
JaX ‘adnjosaduia] 92,91
]SOU]D UD UP ayDUIUW1aB UDI
jvy] Juv} d D fijsno1aqgo st J]
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ssaulpipy ay) $ajD1}]8N]]2
yoy} juauniadxa =up
smoys ainjaid siyt

aay uo bun
“JouuLIaD wauM

GETTING THE Most OUT
OF THE

SMALL GRAINS

IMPROVEMENTS IN WHEAT, Oats, BARLEY

O one needs to be told of the part that the
N small grains take in the scheme of the
world’s agricultural activities.

Their place to-day is what it has been from the
earliest historic periods. Indeed the ethnologists
who probe into the prehistoric period tell us that
the lake dwellers were cultivators of wheat, and
it is known that this plant was under cultivation
in Egypt and Mesopotamia at the very earliest
period of which there is any record.

Then as now the little company of grasses rep-
resented by wheat, barley, rye, and oats occupied
a pre-eminent position in supplying man and his
domesticated animals with suitable foods.

In recent years, to be sure, the American prod-
uct, Indian corn, has gained supremacy over the
small grains as food for domesticated animals,
and has attained a notable place as a supplier of

[Votume VIII—Cwapter IT]

LUTHER BURBANK

food for man himself. But important as this new
cereal is, it by no means takes the place of the
others. Wheat and rye in particular stand un-
challenged as the producers of the chief vegetable
foods of mankind throughout the civilized world.
Oats constitute the most highly prized food for
man’s chief helper, the horse; and barley is raised
in enormous quantities for purposes of fermenta-
tion to produce beverages that retain their popu-
larity generation after generation, whatever may
be said as to their wholesomeness.

The relatively close relationship of these four
grasses is obvious to the most casual observer.
Wheat, rye, and barley in particular are so similar
that only the practiced eye can distinguish be-
tween them with certainty when growing in the
field. They are closely related in the eye of the
botanist as well, and what may be said of one of
them with regard to possibilities of development
applies, with minor modifications, to them all.

They are plants that, having been for ages
under cultivation, have developed many varieties.

But, on the other hand, the varieties that asume
commercial importance are relatively fixed, owing
to the fact that they have always been grown in
mass, thus giving no great opportunity for varia-
tion, and no necessity for cross-fertilization. These
are the good and sufficient reasons why they get

[46]

ON THE SMALL GRAINS

few varieties in the field grains and so many in
corn and singly cultivated garden vegetables, in
which variation is quite evident and varieties are
easily segregated.

It is obviously necessary that a plant grown
from the seed, and for its seed, must reproduce
itself accurately from generation to generation;
otherwise the agriculturist could have no assur-
ance as to what might come forth when he sows
his grain.

In point of fact, the numerous varieties have
become fixed so that each may be sown with a
large measure of assurance that the crop will have
the uniform character of the seed. The differ-
ences among the different varieties have to do with
size of grain, productivity, season of ripening, pro-
tein content, quality of so-called hardness, which
is important in bread-making, color of grain, pe-
culiarities as to beards, chaff, and the like; and—
perhaps most notable of all—condition of suscepti-
bility or immunity to the attacks of the fungus
known as rust, which is the chief enemy of the
wheat, and a perpetual menace to the crop.

A Microscopic Pest

There are always penalties associated with any
specialized development in a cultivated plant or a
domesticated animal.

In the case of the small grains, the penalty of

[47]

LUTHER BURBANK

specialized breeding in which selection has been
made generation after generation with reference
to the quality of the seed has been the gradual loss
on the part of many varieties of the cereals of the
power to ward off the attacks of a fungus pest
that finds their stalks its favorite feeding ground.

This pest is known to the farmer as “rust,”
because in many forms it gives to the stalks of the
plant, once it is fairly lodged and under develop-
ment, a blotched, reddish brown appearance sug-
gestive of the scales of rust that appear on a
metallic surface.

To the botanist the fungus is known as a mem-
ber of the tribe of so-called Euridineial or Cup
Fungi. The most familiar species is known as
Puccinia graminis.

The precise history of this parasite has been
very difficult to trace. It is known, however, that
the germinal matter lodges on the stalks of the
grain in the form of minute spores, and that these
send little rootlets into the substance of the grain
cell and sap its vitality.

It is further known that at one stage of their
career some varieties of rust plant lodge on the
leaves of the common barberry and there develop
another type of spores. This fact has made the
botanist look askance at the barberry, not unnat-
urally. Yet it is known that rust attacks the wheat

[48]

Mr. Burbank
Among His 1914
Wheat Ex-

periments

Mr. Burbank is now
experimenting exten-
sively with hybrid wheats
at Santa Rosa. He has
wild wheat from Palestine,
and cultivated wheats from
all over the world; and he
is blending the strains and.
watching results. The lux-
uriant growth of some of
his pupils is illustrated
in this picture.

LUTHER BURBANK

in Australia where the barberry does not grow;
and experiments have also shown that the rust
may be propagated for an indefinite period with-
out passing through the phase of development in
which the barberry is its best.

So the elimination of the barberry does not
constitute the important agency in fighting the rust
that the botanist once hoped it might.

Nor has any other agency been suggested that
will combat the pest. Once its spores have found
lodgment, it is obvious that there could be no
means of spraying or otherwise giving treatment
for their destruction or removal that could be
applied to a host plant that is grown not individ-
ually or in small clumps, like orchard fruits or
garden vegetables, but in fields that aggregate
millions of acres.

So it has long been recognized that the battle
with the rust plant must be fought out along dif-
ferent lines. There could be no hope of eradicat-
ing the pest except by making the grain plant itself
resistant to the attacks of the enemy.

DESTRUCTION WROUGHT BY THE Rust

Experiments in selective breeding, through
which new races of wheat have been developed by
saving for seeding purposes the grain of plants
that proved individually resistant to the rust, have
long been carried out more or less systematically.

[50]

ON THE SMALL GRAINS

Partly in this way, and partly perhaps through
accidental development in regions where the rust
does not prevail, some varieties of wheat have
been introduced that show a large measure of im-
munity to the disease. But unfortunately these for
the most part have been plants that did not pro-
duce grain of very good quality. In general the
favorite wheats of the world have remained sub-
ject to the attacks of the fungus. Their degree of
immunity in any given season has depended upon
accidental conditions of weather that interfered
with the development or spread of spores of the
rust fungus rather than upon any inherent resist-
ance of the cereal itself.

Thus it is familiar experience everywhere that
the farmer cannot have any full assurance as to
the amount of his grain crop until the grain
approaches the ripening stage; because at any time
the invisible spores of the rust may sweep as a
devastating horde across his fields and, finding
lodgement on the grain stalks, so devitalize them
as greatly to reduce their capacity for seed
formation. '

The attempt has been made many times to esti-
mate the average loss that results to the grain
growers of the world—and hence, of course, ulti-
mately to the consumers in every rank of life—
from the attacks of this microscopic but all-pow-

[51]

*g91)a}1Da mau Jo
Jaqunu fiup jo juaur
-dojaaap fo $a}j121q1ss0od
ay} sjsabins pup ‘sjpaya
pargsso1a2 asay} Guoup
uolNvliva fo abun fisnu
-1plopijxa ayy smoys ain}
-91d ay) yD aoupjh y *yrGE
fo dauruns ay] up uapsvs
Juaurjtadzxa syupqmg “4
uy pajaajjo9 yoaym fo spvay.
Burfiasgva jo aajsnjo
ajdums D 51 SIND

sjuauniad

“xq DIUM FET
jo szjnsay aurog

ON THE SMALL GRAINS

erful enemy. It is conservatively estimated, for
example, that the loss to the wheat growers of
Australia is from ten to fifteen million dollars a
year. Yet Australia is relatively free from the
pest. In an old wheat country like Prussia, where
the rust has gained a more secure foothold, the
losses are enormously greater.

It has been estimated that in a single season
the loss from rust on the various small grains in
Prussia alone was not less than $100,000,000.

In America the losses from rust vary greatly
from year to year; but there is no season when
the destruction wrought by this pest would not be
calculable in millions of dollars. There are ex-
ceptional seasons when in entire regions the wheat
crop is almost totally destroyed and other seasons
in which the losses amount to a high percentage
of the total crop.

All in all, the microscopic uredospore must be
listed among the most important and most menac-
ing encmies of our race.

A pest that perpetually threatens our chief food
product must surely be so considered, notwith-
standing the individual insignificance of its
members.

THE PLANT-DEVELOPER TO THE RESCUE
It is obvious, then, that there is no single task
that the plant developer could undertake that

[53]

LUTHER BURBANK

would give larger promise of benefit to mankind
than the task of rendering the cereals immune to
the attacks of the rust fungus.

But it is also obvious that the task is one that
should be carried out under the auspices of the
government, rather than as an individual effort.
Nevertheless a very notable beginning has been
made in the direction of developing immune races
of wheat through the efforts of an individual ex-
perimenter, who, however, had the backing of a
university position and was therefore not under
necessity to have his experiments attain commer-
cial success.

The experimenter in question is Professor R.
H. Biffen of the Agricultural Department of Cam-
bridge University, England. His experiments with
wheat constitute by far the most satisfactory inves-
tigations in plant development that have been
carried out under the guidance of the new Men-
delian principles of heredity.

The investigation through which Professor
Biffen was enabled to develop an immune race of
wheat in a few. generations promises to he of
immense economic importance. The story of this
development is too important not to be told in
some detail.

In order to understand Professor Biffen’s suc-
cess in developing an immune race of wheat, it is

[54]

Selected Wheat Heads

This bunch of bearded wheat heads was selected by Mr.
Burbank as representative of a certain type of crossbred wheat
with which further experiments are to be made. It is but one of a
large number of selected clusters of quite different types, as the
preceding picture will make readily comprehensible,

LUTHER BURBANK

necessary to review briefly the preliminary studies
through which he familiarized himself with the
hereditary characteristics of the wheat plant.

Professor Biffen had given attention to the
development of the wheat through the ordinary
methods of selection as early as 1900, and before
anything had been heard of the researches of Men-
del, which, as we have elsewhere pointed out, were
quite unknown to anyone after the death of Men-
del himself in 1884 until about the beginning of
our new century. But he had not proceeded far
before three observers, De Vries, Correns, and
Tschermak, independently discovered and made
known the forgotten work of Mendel, and, as Pro-
fessor Biffen himself says, “changed the whole
aspect of his problem.”

It was at once obvious to Professor Biffen that
wheat offers opportunity for hybridizing experi-
ments closely comparable to those that Mendel
had performed with the pea.

Both of these plants are normally self-fertilized,
their stamens and pistils being enclosed in recep-
tacles that are never opened and made accessible
to insects or subject to wind pollenation.

This makes the hand pollenization of the plants
a rather tedious and delicate task.

But once this is effected, the further experi-
ments are greatly facilitated by the fact that there

[56]

ON THE SMALL GRAINS

is no danger of unintended cross-pollenizing—in
other words, the plants of the second and subse-
quent generations will normally inbreed and thus
reveal hereditary potentialities without further
attention from the experimenter; whereas with
most other plants of another habit it is necessary
to guard constantly against cross-fertilization.
MENDELIAN CLUES

The essential facts of Mendelian discovery with
regard to “unit” characters and their grouping
into pairs, in which one character is dominant and
one recessive, have been more than once called to
our attention and have been illustrated again and
again with instances drawn from my own plant
experiments.

The cases of the black and white blackberries,
the thorny and thornless blackberry, and of stone-
bearing and stoneless plums, among others, will
be recalled.

But we have also observed cases in which the
characters of two parents seemed to be blended in
the offspring, there being no clear dominance of
one character over another. Such was the case,
for example, with the Sunberry, the Primus berry,
and the Plumcot.

Now it is peculiarly interesting to note, in the
light of our experiments with various fruits and
flowers of widely different orders, that Professor

[57]

Seven Headed Wheat

Sometimes wheat shows a tendency to develop several
heads on a single main stalk. At one time, Mr. Burbank thought
of developing cereals of this type, improving the stalk to make it able
to bear the increased weight, in the hope of thus increasing the
yield, But he has decided that on the whole it is better
to increase the quality of the individual head rather
than to increase the number of heads.

ON THE SMALL GRAINS

Biffen was able to analyze the diverse qualities of
the various wheats with which he experimented
and to discover that different groups of unit char-
acters operated differently in heredity. Some of
the pairs showed dominance and recessiveness;
others showed an irregular or partial dominance;
while other pairs showed the blending of charac-
ters, so that the offspring was intermediate be-
tween the parents, there being no apparent ten-
dency to dominance or recessiveness.

Yet all of these characters, whether manifesting
the phenomena of dominance in the hybrid of the
first generation or not, showed the same tendency
to segregation in the succeeding generation, and
to segregation along the familiar Mendelian lines;
that is to say, one offspring in four would reveal
the first character only, the second and third off-
spring were mixed as to the pair of characters,
and the fourth would show only the second
character.

It was necessary only to plant the individual
grains of wheat in plots by themselves, and to note
the qualities of the grains of each (that is to say,
the qualities of the offspring of the first filial gen-
eration) to make sure as to the position of each
individual in the Mendelian scale (whether pure
or mixed in its heredity as to its given factor), and
thus to be able to select pure types that would

[59]

LUTHER BURBANK

breed true; and, what is perhaps equally impor-
tant, to eliminate the impure types that would not
breed true.

DOMINANT AND RECESSIVE CHARACTERS

It will be of interest to note a few characters
that Professor Biffen particularly studied and the
groups into which they fall.

As to characters that show the phenomena of
pure dominance and recessiveness, the following
among others were clearly revealed: Beardless
ears of grain are dominant to the bearded ears;
keeled glumes to round glumes; lax ears to com-
pact ears; red chaff to white chaff; red grain to
white grain; thick and hollow stem to thin and
solid stem; rough leaf surface to smooth leaf sur-
face; bristles on the stem to a smooth stem; hard,
translucent endosperm (central grain substance)
to soft opaque endosperm; and, finally, suscepti-
bility to the attacks of yellow rust was dominant
to immunity to yellow rust.

This implies, as the reader is aware, that in
_ each case of those just listed, when two plants rep-
resented by the opposite characters are crossed,
the offspring will show the first-named character
to the exclusion of the other in the first genera-
tion, but the excluded character will reappear in
one fourth of the offspring of the second genera-
tion.

[60]

ON THE SMALL GRAINS

Breeding a wheat with beardless ears and white
grain, for example, with a wheat having bearded
ears and red grain, all the progeny will be beard-
less and red-grained; but bearded ears and white
grain will reappear, in various combinations, in
one fourth of the progeny of the second generation.

It is never safe for the plant developer to draw
exact inferences as to the hereditary tendencies of
one plant from observation of a quite different
plant. - Nevertheless it is of interest to observe cer-
tain analogies between the wheat grains as studied
by Professor Biffen and certain of our plant devel-
opments already cited.

In particular we may note that red grain is
dominant to white grain, suggesting what we have
said as to the dominance of black blackberries
over white blackberries.

Again, the rough leaf surface and bristly stem
of the wheat proved dominant to the smooth leaf
and smooth stem, suggesting the case of our thorny
stemmed briars in which the thorns proved
dominant to smoothness of stem.

But doubtless the most importamt revelation
made by Professor Biffen’s investigation was the
fact that susceptibility to rust was dominant to
immunity to rust.

This means that when a susceptible type of
wheat is crossed with an immune one, all the off-

[61]

LUTHER BURBANK

spring will be susceptible. But it means also that
the recessive quality of immunity will reappear
in one fourth of the offspring of the second
generation.

And thereby hangs the tale of Professor Biffen’s
great achievement, as will appear in a moment.

Cuaracters Tuat Do Not “MENDELIZzE”

Before following this let us glance at the other
groups of unit characters which Professor Biffen
found not subject clearly to the rules of dominance
and recessiveness.

These groups include fewer characters than
those in the dominant list, partly perhaps because
it is obviously more difficult to study characters
that do not show the clear phenomena of dom-
inance and recessiveness. But these groups are
highly interesting none the less. The unit char-
acters that showed what Professor Biffen speaks
of as irregular dominance as studied in this inves-
tigation, were only two, namely: (1) felted glumes
versus glabrous glumes; and (2) gray colored
glumes versus red or white glumes,

The glume, perhaps it should be explained, is
a bract that has no particular interest for anyone
except the botanist, but which may serve admir-
ably in checking the results of experimental breed-
ing. The glumes have practical significance for
the agriculturist, because their character deter-

[62]

A Sheaf of Oats

Mr. Burbank is experimenting with oats as well as with
wheat. Hitherto he has not experimented very extensively with
these or other cereals, except the corn, because he feels that this work
lies rather beyond the resources of a private individual and
should be carried out by the Government Experiment
Stations and Agricultural Bureaus. Nevertheless
he has found time to take a hand in the
work, as this picture suggests.

LUTHER BURBANK

mines to some extent the readiness with which the
grain is shelled out in the thresher.

The interest in the different types of glumes as
to smoothness and of color, in the present connec-
tion, centers about the fact that neither parent
showed dominance in the first generation of the
hybrid, the individual hybrids differing indefi-
nitely. ;

In some cases there would be almost pure
dominance; in others a blend of the characters.
But in the second generation the characters were
segregated just as if they had shown the typical
phenomena of dominance and recessiveness in the
first generation.

The third group of characters, in which there
was uniform blending in the first generation of
hybrids, with no tendency whatever to manifesta-
tion of dominance of one character over the other,
found representation in the following pairs of unit
characters: (1) lax ears versus tense ears; (2)
large glumes versus small glumes; (3) long grains
versus short grains; (4) early habit of ripening
versus late habit of ripening.

As to each of these pairs of characters, the
hybrids of the first generation were intermediate
between the parents. For example, if a wheat
having long grains was crossed with one having
short grains, the hybrid bore wheat neither long

[64]

ON THE SMALL GRAINS

nor short but intermediate; and if a wheat that
ripened early was crossed with one that ripened
late, the hybrid offspring ripened their grain at
an intermediate season, later than their early
parent but earlier than their late one.

Yet here again—and this perhaps is most sig-
nificant of all—-there was segregation of characters
in the second generation along the usual Mende-
lian lines. That is to say, the first generation
hybrids that bore grain of medium length will pro-
duce offspring one fourth of which bear long grain
and one fourth short grain, the other half bearing
intermediate grain; and similarly the first genera-
tion hybrids that ripened their grain at an inter-
mediate season, produce progeny one fourth of
which ripened their grain early and one fourth
late, the other half ripening their grain at the
intermediate season.

The importance of this observation is that it
shows that the Mendelian principle of the segrega-
tion and recombination of unit characters in sec-
ond generation hybrids follows the same rule
whether or not the characters show clear dom-
inance in the first generation.

And if we look a little beneath the surface it
will appear that there are hundreds or perhaps
thousands of unit characters that for one reason
or another do not show the phenomena of dom-

[65]

Wild Oats

The wild oat is provided with a curious ‘‘feeler,” with
which the seed burrows its way into the ground. The ap-
paratus is not provided with the capacity for automatic motion, of
course, but it twists about under the influence of moisture
and varying conditions of heat, and ultimately effects
the purpose of partially burying the seed.

ON THE SMALL GRAINS

inance in the first generation and hence are ex-
ceedingly difficult to trace, and yet which reappear
segregated in new and varied combinations in the
second generation, thus accounting for the extraor-
dinary diversity of second generation hybrids to
which our attention has been called again and
again,

It is interesting to note that Professor Biffen
found such conspicuous conditions as long grain
and short grain to fail to manifest the phenomena
of dominance and recessiveness.

Considering that tallness of vine had shown
itself to be dominant over shortness of vine in
Mendelian peas, it might perhaps have been ex-
pected, reasoning from analogy, that long grains
of wheat would be dominant to short grains.

But I have already suggested that it is unwise
to attempt to predict the hereditary tendencies of
one plant from observation of another; and in
particular it should be said that the stems of
plants, as regards their fixity of hereditary ten-
dency, are likely to be on a different plane from
the flowers or fruit, or any other new characters.

The particular arrangement of floral envelope
that characterizes the plant of to-day is of rela-
tively recent development, and may be expected to
be subject to greater fluctuations, or in other words
to show greater plasticity under the disturbing

[67]

LUTHER BURBANK

influences of hybridization. Professor Biffen even
found that there was a difference in the manifes-
tation of dominance and recessiveness with regard
to certain characteristics between different varie-
ties of wheat.

Thus in the matter of the glumes, where the
parent that bore a felted glume was the variety
known as “rough chaff,” the felted glume proved
dominant over the smooth glume. But where the
felted parent was the variety known as rivet wheat,
the phenomena of dominance were irregularly
manifested, or manifested not at all. So hybrids
of the rivet wheat were listed in the class of irreg-
ular dominants, as above outlined.

PRACTICAL APPLICATION OF THE NEw KNOWLEDGE

Having thus analyzed his wheat plants and
made himself familiar with their hereditary possi-
bilities, Professor Biffen was ready to make appli-
cation of his knowledge to the improvement of
existing varieties of wheat.

In particular he desired to produce a variety
of wheat that would be immune to rust, yet would
at the same time produce a good head of wheat
having the quality described by the miller as
“hardness’—a quality that is essential to the mak-
ing of high grade flour, yet which some otherwise
excellent wheats altogether lack.

Material was at hand for crossing experiments

[68]

ON THE SMALL GRAINS

in that there was a race of wheat known to be
immune to the yellow rust which had not hitherto
been thought of as solving the rust problem be-
cause it bore grain of very poor quality.

To Professor Biffen, armed with his new knowl-
edge, it appeared that it should be possible to com-
bine this immune wheat of poor quality with sus-
ceptible races of wheat bearing a good grain in
such a way as to secure a new race that would
present the good qualities of each parent and
eliminate the bad qualities.

So he crossed a race of wheat that bore a grain
susceptible to rust with the immune variety that
bore the grain of poor quality, and developed a
generation of crossbreds all of which were—quite
as he had expected—susceptible to the attacks of
the rust.

To the untrained plant experimenter it would
have appeared that this experiment should be car-
ried no further. Progress was apparently being
made in the wrong direction; for whereas half the
parents were immune to rust, all of the children
were susceptible.

But Professor Biffen knew, as we have already
seen, that susceptibility and immunity constituted
a Mendelian pair of hereditary factors. So he
knew that in the next generation one fourth of the
hybrid plants would be immune to rust. And this

[69]

LUTHER BURBANK

expectation was justified by results. The second
generation hybrids showed diverse combinations
of various other qualities that were under consid-
eration, and a certain proportion of them revealed
the combination of the desired quality of grain
with the stems immune to the attacks of the rust
fungus.

As immunity to rust is a recessive factor, it
follows that the second generation hybrids that
show such immunity will breed true to that char-
acter. Their offspring will be immune. But as
regards certain other qualities, notably hardness,
it was necessary to continue the experiment
through a third generation, in order to discover
which of the plants that were individually hard
were pure dominants as regards the quality of
hardness,

To ascertain this it was necessary only to plant
the grains showing the desired quality in plots by
themselves.

The individuals that produced only hard-
grained offspring in the next generation were thus
shown to be pure dominants for that quality. They
constituted a fixed race and could be depended
upon to breed absolutely true.

Thus the clear recognition of the qualities of
Mendelian segregation, as applied to the different
pairs of unit characters representing respectively

[70]

An Experiment With Rye

Since he is experimenting with the cereals, Mr. Burbank
of course includes rye among the others. He made interesting
experiments with this plant a good many years ago, and he is now
extending them. The present experiments will include,
probably, hybridization with other cereals.

LUTHER BURBANK

desirable and undesirable qualities of the wheat,
enabled Professor Biffen to produce in the third
generation a fixed race of wheat having the desired
qualities of grain and a plant stem that is immune
to the yellow rust.

The seeds of this new variety being multiplied
as rapidly as possible, a wheat was produced that
promises to be of enormous importance to the
grain growers of England.

It is obvious that a similar line of experiment
should enable the plant developers of other coun-
tries to produce new varieties of wheat that will
be immune to the various rusts, and thus to rid
the agriculturist of one of the pests that of all
others has hitherto rendered his calling precarious.

PossisLe Aip FRoM THE WILD WHEAT

The greatest difficulty, doubtless, will be to
secure varieties of wheat that are immune to the
various rusts to utilize in crossbreeding.

Much further investigation will be needed
before we can make sure as to the material that
is available. But peculiar interest attaches to the
investigations recently made by Mr. O. F. Cook,
the biometrist in charge of crop acclimatization
and adaptation of the U. S. Department of Agricul-
ture, with reference to the wild wheats of Pales-
tine, which were discovered by Mr. Aronson, a
native of Palestine.

[72]

ON THE SMALL GRAINS

Mr. Cook’s researches have shown that there
are races of wheat growing wild in Southwestern
Asia that are prototypes of the cultivated wheat.
The resemblance of northern wild forms to the
cultivated varieties is striking. Yet the differences
are also conspicuous. The wild wheat has a looser,
less compact head, and some varieties have the
peculiarity of shedding the spikelets that hold the
grain individually, each spikelet being provided
with a barbed shaft which serves the purpose of
helping the grain to attach itself or even to bury
itself in the soil. All of which would be expected
in a wild wheat, which is found also in the wild
oats and rye as well as in rice.

The kernels of some wild wheats are not large,
but some of them are of more or less edible
quality.

A chief interest in the plant centers about its
seeming immunity to rust. And the question at
once arises as to whether it may not be possible to
hybridize these wild wheats with the cultivated
ones to secure resistance to disease as well as
unusual variation, vigor, and hardiness.

Tests calculated to discover possibilities in this
direction are now being made, and there is every
reason to hope that they will have valuable results.

It may be added that the wild wheat is not ©
universally self-fertilized. The stamens and pis-

[73]

A Sheaf of Barley

Barley, like the other cereals, offers good opportunities for
the experimenter, notwithstanding the amount of work that has
been done with it. The amateur should understand that experiments
with the cereals may be made on a small seale, and that the results
of such experiments may be of great economic importance. The re-
markable results of Professor Biffin at Cambridge, England, in
developing an immune variety of wheat, for example, were
made on very small plots of land. Interesting re-
sults might doubtless be secured by hybrid-
izing wheat and rye and barley.

ON THE SMALL GRAINS

tils of its flowers sometimes protrude and permit
cross fertilization by the aid of the wind or insects.
This may to some extent facilitate the hybridizing
of the wild wheat with cultivated wheats.

But on the other hand, it will probably be
desirable to eliminate this propensity from the
new varieties after they are fixed for commercial
use. For, as already pointed out, there are
advantages in the self-fertilization of a grain like
wheat, to prevent deterioration of the type by
undesired crossing.

But the entire question of the hybridizing of
the domesticated wheat with the wild type remains
for future investigation. There is perhaps no
single field of plant development that offers greater
possibilities of usefulness. Fortunately several
experimenters are alive to the importance of the
subject, and it may be expected that their investi-
gation will reveal its full possibilities in the near
future.

As I have already pointed out, this work is pre-
eminently one that should go forward under
government auspices. My own experiments in this
line with the wild wheat are necessarily limited,
as I received specimens only last season.

A work that involves matters of such vast
economic significance, having direct connection
with the cost of living as applied to every member

[75]

LUTHER BURBANK

of the community, should not be hampered by any
financial restrictions, and should have the co-
operation of investigators in many parts of the
world; such co-operation as a government bureau
alone can command.

During the past thirty years I have been
experimenting in a desultory way with various
grains and grasses, both of the best cultivated
varieties and numerous wild species. But I have
not as yet carried out serious experiments in
crossing the cereals. I have selected and perfected,
and some definite results are expected from work
now in hand.

The interest already shown by the authorities
of the Department of Agriculture gives sufficient
assurance that the work will be carried forward
energetically and efficiently. That it will lead to
developments of vast importance, having direct
bearing on the improvement of all the small grains,
can scarcely be doubted.

—The little company of grasses,
represented by Wheat, Barley,
Rye and Oats, have, since pre-
historic times, occupied a pre-
eminent position in supplying
man and his domesticated ani-
mals with suitable foods.

MANUFACTURING FOOD FOR
LIVE STOCK

SoME SUGGESTIONS ON CLover, TIMOTHY,
AND ALFALFA

crop of seventy million tons, valued at
something like three-quarters of a billion
dollars.

Such is the record of hay in the United States.

And of course this takes no account of the other
millions of acres that are devoted to pasturage,
the crop of which would be hay if it were not
harvested directly by browsing live stock. Just
how much this would add to the value of the crop
it is difficult to say. But without attempting an
exact computation, it will be clear that the value
of forage crops in America reaches a colossal
figure.

There are many kinds of grass that may be
found first and last in pasture and hay-field, but
the one grass that over-shadows all others because
of its universal popularity is that known as tim-

Pree million acres devoted to it; an annual

[Votume VIUI—Cnaprter IIT]

LUTHER BURBANK

othy in most regions, and in some regions as
herd’s grass.

It may be of interest to recall that each name
is merely borrowed from the name of the man
who was instrumental in introducing this particu-
lar grass; one man being Timothy Hanson or
Hanse, of Maryland, who is said to have brought
the seed from England in 1720; the other being
John Herd, who is alleged to have found the grass
growing wild in a swamp in New Hampshire as
early as 1700.

One of these men distributed the grass through
Virginia and Carolina, the other through New
England and New York.

From these regions it has spread in every
direction, proving adaptable to all climates and
soils, until it assumes pre-eminence in the pasture
and hay-field quite unchallenged except by mem-
bers of the clover family, with which it is com-
monly associated.

The clovers, to be sure, are not grasses in the
technical sense of the word. Nor, indeed, have
they the appearance of grasses even to the eye of
the most casual observer. But they rival the
grasses in their importance as fodder plants. In
certain regards, as for instance in the amount of
protein they bear, they outrival the grasses. Also
in their capacity to produce successive crops in

[78]

Heads of Timothy

Doubtless the most popular of all the forage grasses in
the eastern United States is the Timothy. In connection with
clover, this may be said to be the typical meadow and pasture plant.
Timothy is not so well adapted to the California climate
and conditions, but Mr. Burbank has experimented
with it nevertheless. This picture shows a
bunch of his Timothy proteges.

LUTHER BURBANK

the same season, some of the clovers, notably the
more recently introduced alfalfa, are superior to
the grasses proper.

But in general clover and timothy are mixed to
form the hay-crop, the clover growing densely
near the ground, and the timothy rising above it,
and the two making a blend that is found exceed-
ingly palatable by all herbivorous animals.

The fragrance of new mown hay suggests
palatability to the human senses as well, and even
though the hay-crop furnishes food for man only
at second hand no one would be likely to question
its wholesomeness.

BETTERING THE CLOVERS

There are certain of the clovers, nevertheless,
that have a poisonous principle. Notable among
these is a form of sweet clover not distantly
related to the alfalfa, which grows in some of the
States of the Middle West and produces an enor-
mous crop which would have great value were it
not that unfortunately the tissues of the plant
contain a considerable percentage of a bitter alka-
loid called brucine, which is highly poisonous,
being closely related to the well-known drug
strychnine.

A few years ago I received from Kansas
samples of this plant, with the request that I
develop from it a variety in which the brucine is

[80]

ON LIVE STOCK FOOD

reduced to a minimum, or, if possible, wholly
removed.

The seeds that I received were of various
colors. My first move was to have the seeds sorted,
placing white ones, black ones, and green and
brown by themselves. The seeds were then
planted in separate lots; a fifth lot being reserved
for a mixture of the seeds of uncertain shades.

Thus it was possible at the outset to determine
whether the production of plants having a large
brucine content was associated with any particular
color of seeds. Should such be found to be the
case, the experiment would obviously be short-
ened, as only the plant bearing the minimum
amount of brucine would be used for further
testing. Experiments showed that the plants from
the white seed apparently contained an appreci-
ably less quantity of brucine than the black ones.

As an additional element in the selection, I
chose, as is my custom, the seed plants that started
very early in the Spring. From among these the
next selection was made of the plants that had
broad foliage and continued to make a very strong
growth. Thus several objects were attained
almost from the outset. A second selection along
the same lines showed that some plants have a
much smaller brucine content than others, and
that it will be quite possible to separate these out

[81]

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ON LIVE STOCK FOOD

and thus produce a variety relatively free from
poison.

Some similar experiments in improving peas,
beans, and other plants related to the clovers, gave
assurance that I should be successful in the present
instance, merely by selective breeding, in produc-
ing a plant with relatively low brucine content,
and the experiments even in their initial stages
justify this belief.

Whether it may be necessary to resort to
hybridizing experiments in order to eliminate the
brucine altogether or to reduce it to a negligible
minimum, remains to be seen.

The experiments were begun only in 1910.

It should be explained that the hybridizing of
the plants of this group is relatively difficult,
because the flowers are encased in a closed recep-
tacle, as with the peas and beans, which belong
to the same family with the clovers.

All of these so-called leguminous plants—and
they are outnumbered only by the composite
flowers—bear the stamens and pistils thus guarded,
and are normally self-fertilized.

As already pointed out, this makes the experi-
ment of hand-pollenizing these plants a rather
tedious one. In the case of the clovers, the flowers
being very small, it becomes a somewhat delicate
operation as well. But the later stages of the

[83]

LUTHER BURBANK

experiment are greatly facilitated by the fact that
the flowers are self-fertilized. With these plants,
as with the small grains, this becomes an important
aid in fixing a type, and in maintaining a pure
race once it has been developed.

For the most part, my experiments with the
clovers have been made through selection, and
without resort to hybridization. But in excep-
tional cases I have cross pollenated these plants,
to test the possibilities of work in this line. I
found that the process involves no great difficul-
ties, notwithstanding the small size of the flowers.

In practice I found it better to remove all but
two or three flowers in a clover head.

The remaining ones have the petals and
stamens removed with a small pair of forceps,
after which the application of pollen from another
clover head presents no special difficulties; care
being taken, of course, to see that the pistil is at
the right stage of development.

DEVELOPING NEw CHARACTERISTICS OF STEM

AND LEAF

In the course of these experiments I have grown
in the neighborhood of two hundred species of
clover. Many of these are native species, some of
which invaded my grounds unasked. Others have
been received from far away regions, in particular
from Peru, Bolivia, and Chile.

[84]

A Bed of Four-

Leaved Clover

This interesting col-
ony of four-leaved clo-
ver grows in Mr. Burbank’s
yard. It is an example
among hundreds of experi-
.ments that Mr. Burbank
has conducted for his own
amusement, er for their
scientific interest, with no
thought of commercial re-
sults. All the clovers in
this large bed bear four
leaves, and they illustrate
the possibility of fixing
any given character
by selection.

LUTHER BURBANK

Whereas the white clover in its common native
forms is a relatively small plant, dwarfed beside
the red and crimson clovers, there are South
American species or sub-species that are of rela-
tively gigantic growth. One of these that I
received from South America was a seeming
“sport”—possibly due to an accidental hybridizing
with some other species—that grew several times
as fast as any of the others in a lot of seedlings.

A single plant of this giant variety would
spread from four to six feet, the foliage being
proportionately enlarged, while a neighboring
plant would perhaps grow ten to fifteen inches.

Selection among these rapid growers enabled
me to develop several varieties that had the char-
acteristic of growing to quite uncloverlike size.
But there is no sale for new clovers unless the seed
can be furnished by the ton, and as I had no
opportunity to produce seed on a large scale, the
giant races were ignored, when they had ceased
to interest me from an experimental standpoint.

I worked for a number of years also upon a
clover that, without having exceptional qualities
of stem, produced very large foliage. In this case
also the development was made solely by selection,
the largest leafed individuals of a fraternity being
selected for preservation generation after genera-
tion.

[86]

ON LIVE STOCK FOOD

In the same way I produced a five-leafed strain
of clover from a sport that appeared among plants
of the usual three-leafed type of white Dutch
clover,

The four-leaved clover is of course well-known
as an occasional sport. A five-leafed clover will
appear in a lot of seedlings now and again, and
there will be found a few five-leafed individuals
among the plants grown from seed of this sport.
It would, however, require many repetitions,
seemingly, to fix a five-leafed race, the tendency
to reversion to the familiar three-leafed type being
very pronounced.

Whether the five-leafed condition acts as a
Mendelian unit character, is a matter that might
be of some interest to determine.

Another anomaly consisted of a clover with
leaves beautifully colored—variegated in black,
brown, crimson, scarlet, yellow, white and green,
in different forms and figures, no two plants being
closely similar in the coloring of the leaves. This
plant was introduced as a new variety, but it did
not thrive in the Eastern States and has probably
been allowed to die out altogether. I have
another stock of this which came from chance
seedlings, but in no respect equal to the well-bred
type formerly possessed.

One of the clovers found on my Sebastopol

[87]

The Root of the Alfalfa

A very prominent characteristic of the alfalfa plant is that
it sends down a relatively gigantic root to really astonishing dis-
tances in search of water. This specimen is placed beside a twenty-
four inch ruler. Note the rugged character of the root, and also
the bends in it, which indicate where it was forced to
make its way around a stone or seme other obstacle.

ON LIVE STOCK FOOD

place has the color intensified to a bright, rich
crimson, which has been reproduced exactly from
seed. This is probably a species introduced from
South America. A very marked tendency to varia-
tion is shown by a large number of clovers when
brought to California from distant regions.

THE CoMING OF THE ALFALFA

Doubtless the most important of the clover
importations of recent years is the plant that has
become familiar as the alfalfa.

This is a form of clover, of which there are
several species and almost innumerable varieties,
that is adaptable to relatively arid regions, inas-
much as it sends its roots to a depth of sometimes
ten or even fifteen feet in search of moisture and
nutriment. Such a plant, once it has attained a
fair growth, is almost independent of the rainfall
for months together. Moreover, the vigor of root
of the alfalfa is duplicated by the complementary
growth of its foliage, which develops so rapidly
and so persistently that it may be cut three, four,
and even five times in the season, depending upon
climate.

The enormous productivity of alfalfa, together
with its adaptability to arid regions, led to glowing
predictions as to the importance of this new for-
age crop, when it was first introduced a few years
ago. In the southwestern part of the country the

[89]

LUTHER BURBANK

predictions have been more than justified, but
alfalfa has failed to make its way in the Eastern
and Northern States as rapidly as had been
expected.

The probable reason for this is that our most
common alfalfa was brought from Peru or Bolivia.
Had the plant come from Patagonia or Southern
Chile instead, or from Russia, its original home,
being therefore represented by hardier varieties,
it would probably have spread all over the Eastern
States and have added vastly to the value of the
forage crop everywhere.

But now hardier types of alfalfa are making
their way to the North, and even into Canada, and
possibly selective breeding may develop races
more resistant to frost than any that have hitherto
been imported.

A form known as Turkestan alfalfa has lately
been introduced that is recommended for its hardi-
ness. When grown side by side with the ordinary
alfalfa on my place, it is difficult to distinguish the
two plants. But the Turkestan variety may of
course have qualities of hardiness that are not
revealed in its appearance. There are other strains
being grown that are said to be even more hardy.

The alfalfa has so recently been introduced that
it has not been extensively experimented upon.
There is no plant, however, which can be taken up

[90]

| gee

Alfalfa Serving a
Double Purpose

Alfalfa grown ona
levee along the Sacra-
mento River. Besides one
of its values as a forage
crop, alfalfa in this case is
being used as a binder for
levee. Plants taken from
the seene depicted here
have been found to have
thrown their roots more
than 25 feet through water,
and this mass of root
forms a network which
holds the levee secure. At
the right will be seen a
cherry orchard which
earned a profit of more
than $700 per acre in 1914.
ii will be a surprise to
middle western farmers to
learn that this reclaimed
land along the Sacramento
River is so rich that in
spite of all the extra ez-
pense and in spite of the
fact that twenty dollars
per acre is assessed to keep
up the levees, it still earns
net profits of from $500
to $1,000 per acre.

LUTHER BURBANK

for development to better advantage by the Gov-
ernment than this thrifty and drought-resisting
clover. With this plant, as with the cereals, work
should be carried out on an extensive scale by the
Government, or by some one who has opportunity
to test the plants in a broad and comprehensive
way.

As already noted, it is useless to develop a small
quantity of seed of a new variety, as the practical
stock raiser will not be interested in the seed until
it can be offered by the ton.

SoME OTHER CLOVERS

I have received a large number of alfalfas and
clovers from the mountains and plains of Chile,
and have been struck with the close similarity
between some of these and the clovers that have
invaded my gardens. Others, however, are indi-
vidual in appearance and differ markedly from
any that I have seen elsewhere.

Among the Chilean clovers that I am testing is
one that is a giant in its proportions as to leaves,
foliage, growth, and blossoms.

Another of the Chilean clovers has a _ heart-
shaped brown spot on the leaf. The bloom and
seed of this variety closely resemble the common
burr clover, but the leaves are several times as
large as those of that plant.

The burr clover is of peculiar interest because

[92]

ON LIVE STOCK FOOD

it produces enormous quantities of seed that fall
from the stalks when ripe, and in our dry climate
may remain edible for some months.

The plant was at first thought to be a nuisance,
but its value in a region where there is no rain
for months together soon came to be recognized.
To any one who is not acquainted with the burr
clover it is matter for astonishment to see a herd
of sheep, cattle, or horses, or a drove of hogs
pastured in a field where there is not a vestige
of green herbage; and yet to note that these ani-
mals are well-conditioned and even fat. They
feed on the burr clover seed, the pods of which
sometimes cover the ground half an inch or more
in depth.

The plant itself has withered or disappeared,
but the seed-bearing pods furnish a forage crop
that has no substitute in this region, although it
would probably be of no special value in the East.

The burr clover has a small leaf and small
blossoms. It runs and spreads by long, wiry,
slender stalks, and does not stand upright, so that
it could never be profitably cut for hay, making
only a tangle of tough thread-like stalks. Yet its
peculiar property of producing an abundant crop
of pods makes it in some localities quite as valu-
able a pasture plant as the common red clover is
in the East.

[93]

‘umoys atay

sp ‘siaj0nb asoja Ul
aajiy} 0} ulay) $ajqnua JDY}
abpjupapp up ulay} saai6
sty ‘*SJoOr 42ay} azzU0jOo
yoyy yang buffy fo
pip ayy yn ‘43D ayy wo1f
uaboryu sayy fo uojj10d
Dp aunaas ‘paurpjdra asym
-asja sp ‘pup ‘saumSa] aD
sayojaa ay “yoyaa firrpy
fo yo jo s0b}a ay}

jsabins uorznjabaa jo

sspur pajSuv} sty

piaiq uado
ayy ur yojaa fino

ON LIVE STOCK FOOD

Neither the crimson clover nor the common
red clover is extensively grown on the Pacific
Coast. White clover is cultivated for lawns, mostly
in combination with blue grass. It will often
cover a bare spot under a tree where the blue
grass does not thrive.

The Alsika clover is another form that is
seldom seen in California, partly perhaps because
it does not tend to send its roots deeply into the
soil, and hence is not as well adapted to a dry
climate as are the alfalfas. On the other hand it
thrives on a clay soil, and in regions to which it
is adapted it is a valuable product.

There are numerous other species of clover that
have as yet been almost neglected by the plant
developer, which offer inviting opportunities.

Even without hybridization, plants grown from
a given lot of seed will vary greatly. Selection
among the most familiar races of clovers would
readily result in the development of new varieties
that might be of enormous value. The fact that
the plant thrives more or less under disadvantage-
ous surroundings has partly accounted, no doubt,
for its neglect by the plant developer. But now
that year by year there is a growing recognition
of the need of intensive cultivation of farm crops,
the clovers are sure to come in for a larger share
of attention.

[95]

LUTHER BURBANK

The leguminous plants, including the peas and
beans as well as the clovers, have long been known
to be characterized by the unusual amount of their
protein or nitrogenous content.

Tue Foop VALUE OF CLOVER

This has led the plant physiologist to regard the
clovers as having an exceptionally high food value,
As compared with timothy grass, for example,
clover contains, pound for pound, a very much
larger amount of nitrogen. As nitrogenous foods
are the muscle-builders, the value of this is
obvious,

There has been a tendency in recent years, to
be sure, to question whether the nitrogen content
has quite the significance that was formerly
ascribed to it. It has been pointed out that horses
do not need a very large amount. of protein foods
unless they are exercising actively, and that in
this event they usually. secure an adequate amount
of protein in the grains, chiefly oats, that are fed
them.

Cattle that are being fattened may thrive as
well on foods that are less rich in protein.

Milch cattle, and growing cattle, on the other
hand, need a nitrogenous diet. And, indeed, all
along the line, it is not to be denied that a protein
food has exceptional nutritive value. It is partly
at least with this in mind that the intelligent agri-

[96]

The Familiar Sunflower

This giant representative of an extremely common family

is deservedly popular, because of its hardiness, luxuriant
growth, and the striking appearance of its large flowers. The sun-

flower will grow in almost any soil, yet nevertheless it responds

readily to good treatment, A plant that is thoroughly wa-

tered may grow to twice the dimensions of a com-
panion plant only a few feet away that suf-
fers somewhat from thirst. Try the ex-
periment for yourself next season.

LUTHER BURBANK

culturist mixes clover with the timothy in his
pastures and in his hay-field.

At least a partial explanation of the high nitro-
gen content of the leguminous plants has been
furnished by the discovery that these plants have
the very unusual capacity to extract nitrogen from
the air. Most plants, as we have seen, are quite
powerless to take even the most infinitesimal
quantity of nitrogen from the air, and would starve
to death for lack of nitrogen even while their tis-
sues are perpetually bathed in it—as the tissues
of all aerial plants necessarily are—inasmuch as
the atmosphere contains nitrogen as its most
abundant element.

But the leguminous plants are able to extract
nitrogen from the air directly; not, however, with
the aid of their leaves or stems, but only by way
of the roots, and there only with the aid of the
little tubercles that develop under the influence of
micro-organisms. It is, indeed, the micro-organism
that extracts and fixes nitrogen and makes it
assimilable for the plant.

The tissues of the plant itself have no direct
share in the work, beyond giving hospitable refuge
to the micro-organisms themselves.

The little tubercles that form on the clovers and
the allied plants vary in size and shape with the
species of plant, although the micro-organisms

[98]

A Hybrid Sunflower

This is a very interesting and beautiful hybrid produced
by Mr. Burbank by crossing the Russian sunflower with the
ordinary variety. It will be seen that the specimen has been induced
largely to give up the habit of seed-formation, graceful petals
or petal-like appendages taking the place of seeds.

LUTHER BURBANK

that produce the tubercles and that assist the plant
in securing a supply of nitrogen are closely related.
There are, however, different groups of micro-
organisms that are able to produce the tubercles
and help in nitrogen-fixation.

As micro-organisms are not always present in
any given soil, it has been found sometimes desir-
able to inoculate the soil in which various clovers
are to be grown.

This may be done by scattering over the field’
soil from a field in which tubercle-bearing plants
of the same species have been grown in the
previous year.

It has been clearly demonstrated that such
inoculation of the soil may lead to much freer
growth of tubercles than would otherwise take
place, and to the increased vigor and growth of
the clover crop. The use of artificial cultures of
nitrifying bacilli has also been recommended. It
is necessary, however, to treat the solution in a
particular way in order to insure that the micro-
organisms may maintain vitality. If they are dried
slowly under the usual atmospheric conditions,
the microbes die.

It has been found possible to preserve them by
rapid drying of pieces of cotton dipped in a solu-
tion containing the microbes.

The Department of Agriculture at Washington:

[100]

Stages of Progress

These pictures illustrate the stages of development of Mr.
Burbank’s Russian-American sunflower hybrid. It will be seen
that the petals or rayflowers gradually invaded the seed-head from
circumference toward the center, until finally they completely
won the day. In its final stages, the transformed
flower bears scant resemblance to its parent.

‘LUTHER BURBANK

has experimented with a method of distributing
liquid cultures in glass tubes. Special packages of
minerals, including phosphate of potassium, sul-:
phate of magnesium, and ammonium phosphate,
are sent with the culture tube to make a nutrient
medium in which the culture may be developed.

The clover seeds are moistened with this liquid
culture, dried rapidly, and sown as quickly as
practicable.

Another method is to sprinkle the liquid on a
portion of soil and scatter this over the land.

This inoculation of the soil with the nitrogen-
fixing microbes constitutes a new departure in
agriculture that would have been quite incompre-
hensible to any one before the day of the modern
bacteriologist. But so much has been learned in
recent years about the bacteria and their almost
universal prevalence and share in the vital activi-
ties of animals and plants that the sprinkling of
the soil with bacteria seems almost as common-
place a performance as the sowing of seed.

This method, however, is obviously only an
accessory to the methods of the plant developer.

It has exceptional interest as illustrating the
application of science to the art of agriculture,
but it has no direct association with the work of
the experimenter who Mevelene plants by hybridiz-
ing and selection.

[102]

ON LIVE STOCK FOOD

Just how the leguminous plants came to develop
this anomalous habit of serving as hosts for the
particular types of bacteria that can aid them by
the extraction of nitrogen from the air, it is diffi-
cult to understand. But the fact that they have
developed the habit is of very great importance,
because it enables these plants to enrich the nitro-
gen content of the soil in which they grow, instead
of impoverishing it as do other plants.

By turning the clover under with a plow, the
farmer is enabled to restore to the soil an equiva-
lent of the nitrogen that was taken from it in a
preceding season by other crops.

The importance of this will be obvious to
anyone who is aware that nitrogen is an absolute
essential as a constituent of a soil on which good
crops of any cultivated plant are to be grown, and
who further understands that the available supply
of nitrogenous salts with which a depleted soil may
be restored has until recently been very limited.

Some readers may recall the prediction made
not many years ago by the English chemist, Sir
William Crookes, to the effect that the world
would presently suffer from a nitrogen famine that
would greatly reduce the wheat crop, and perhaps
subject the entire race to danger of starvation. At
that time the chief supply of nitrates came from
the nitrate beds of Chile; and it had been estimated

[103]

Sunflower Seeds

Here are sunflower seeds, white, black, and variegated.

They suggest interesting possibilities for studies of Mendelian
heredity, similar to those that can be made by interbreeding varieties
of corn having kernels of different colors. Mr. Burbank’s recent ex-
periments with the hybrid sunflowers are of no litile interest,

ON LIVE STOCK FOOD

that in less than twenty years these beds would be
exhausted.

No one then could say just how the need of the
agriculturist would subsequently be met.

But the discovery that leguminous plants
extract nitrogen from the air gave partial answer.

And almost simultaneoulsy a more complete
answer was supplied by scientific workers, headed
by the Swedish chemist, Professor Christian Birke-
land, in association with a practical engineer, Mr.
S. Eyde, who discovered that it is possible to con-
vert atmospheric nitrogen into nitric acid with
the aid of electricity.

Another method of fixing atmospheric nitrogen
was soon afterward developed in Italy. Thus the
inexhaustible sources of the atmosphere were
made available. So there is no longer any danger
of a nitrogen famine, and the developer of plants
no less than the consumer of plant-products may
look forward without apprehension, so far as the
danger of the starvation of plants for lack of nitro-
gen is concerned.

But the mechanical processes of nitrogen
fixation are necessarily expensive, and the aid of
the clovers and their allies will no doubt continue
to be sought for a long time to come by the agri-
culturist who wishes to restore nitrogen to his
fields in the most economical manner.

[105]

LUTHER BURBANK

The first crop of clover is usually cut for hay,
and a second crop used to turn under in the fall
to fertilize the soil. Thus this plant occupies a
unique place among farm products. It not only
supplies a valuable forage food, but it also helps
the farmer to keep his land in a condition of
perennial fertility.

—There is nitrogen, worth
millions of dollars, in the air
over every farm in Amer-
ica—and by the simple proc-
ess of raising inoculated
legumes, we can extract
and employ it — not only
without expense, but at
the same time producing
crops of unusual profit.

A RIicH FIELD FOR WORK
IN THE

TEXTILE PLANTS

IMPROVING THE Fibers oF Fiax, Hemp,
AND. COTTON

very striking illustration of the extrava-
gance of our agricultural methods.

Something like two and a quarter million acres
of land are given over to the cultivation of flax,
the harvested product being about twenty-five
million bushels of seed. But the stalks of the
plants covering this vast acreage are for the most
part regarded as waste material, notwithstanding
the fact that the fiber of the flax plant is every-
where recognized as the most aristocratic of
vegetable textile materials.

Flax fiber, the material from which linen is
made, bears somewhat the same relation to cotton
fiber that silk bears to wool. Unfortunately, the
plant that bears good seed does not make good
fiber; although it can be used as a second quality
flax, and has been used as stock for paper.

T HE cultivation of flax in America gives a

[VotumE VII]—Cnapter IV]

LUTHER BURBANK

Flax in America is usually grown for the seed
only, as the high cost of labor makes competition
with the foreign product difficult.

Contrariwise the hemp plant (Cannabis sativa),
a plant belonging to the mulberry family and dis-
tantly related to the hop, which resembles the flax
only in the fact that it produces a tough and
resistant fiber that may be used for textile pur-
poses, is cultivated in this country exclusively for
the fiber, its seed being almost altogether
neglected. Yet the seed of this plant is prized in
other countries for its oil, and its neglect here
illustrates the same principle of wasteful use of
our agricultural resources.

Hemp, however, is not very extensively grown,
being chiefly confined to regions of the bluegrass
country centering about Kentucky and Tennessee.
Its fiber is coarse, and is used chiefly for making
cordage and warp for carpets. At best the culti-
vation of hemp does not constitute an important
industry in the general scale of American agricul-
ture.

Corton For SEED AND FIBER

But when we turn to the third textile plant,
cotton, we have to do with an industry that ranks
second only to the cultivation of Indian corn.

And here there is a story of waste that assumes
more significant proportions. For the cotton plant

[108]

ON TEXTILE PLANTS

also produces seeds as well as fiber; and it is only
in comparatively recent years that these seeds have
been regarded as other than a waste product the
handling of which gave great annoyance,

Fortunately, however, this has been changed
in recent decades, and the cotton grower now
understands that the seed of the plant is a product
quite rivaling in importance the coveted fiber
itself. Not only does the seed contain an oil that
when pressed out makes a very palatable substi-
tute for the oil of the olive, but the residue consti-
tutes cattle food that sells for from fifteen to
twenty dollars a ton—a residue that until recently
was used only as fuel, until its value for starch
was discovered.

So the cotton plant takes high place among
producers of commercial seeds, quite aside from
its significance as a producer of the most beautiful,
useful, and abundant textile fibers.

In the present connection, however, it is the
quality of the cotton as a producer of textiles
rather than as a producer of seeds that chiefly
claims attention.

The importance of the plant as a producer of
fiber is too well-known to require extended com-
ment. Suffice it that America now produces not
far from three-quarters of the world’s total cotton
crop, the land devoted to this crop aggregating

[109]

LUTHER BURBANK

more than twenty-five million acres, and the
annual yield averaging something like twelve
million bales, with a value of much more than half
a billion dollars.

It is obvious that a plant that has such commer-
cial importance is one that beckons the plant
developer. For even slight improvements, when
applied on so magnificent a scale, may have vast
significance.

CULTIVATON AND IMPROVEMENTS

Some very good work has been done in the
improvement of the cotton by selection, without
the aid of hybridizing.

The cotton plant came originally from the
Orient, having been cultivated in India from time
immemorial. It belongs to a large family that
includes the hybiscus, bearing beautiful flowers,
and the vegetable called in the South the Gumbo.

The Egyptian and Peruvian cotton and Sea
Island cotton falls into one group and the Ameri-
can upland cotton and India cotton into another.
It is doubted, however, whether the wild proto-
types of the cultivated species are known.

The newer classifications recognize twenty-four
species or sub-species of cotton, including a num-
ber of American species that have attained great
commercial importance.

The American upland cotton is a perennial

[110]

yea

The Flax Plant

In this country, flax is grown quite extensively, but al-
most exclusively for the seed; the stalks being regarded as waste
material. There is opportunity for some one to develop a variety of
flax in which the seed will retain its present good quali-
ties, and the stalk will have a textile fiber of the
quality so prized in the European plant.

LUTHER BURBANK

plant, now cultivated as an annual, that had its
original home somewhere in the heart of South
America, but which has proved adapted to the
climate of the North American cotton belt, and
is now the chief producer of cotton in America,
and hence in the world.

Sea Island cotton is a species indigenous to the
West Indies. Itis of larger growth than the upland
cotton, attaining a height of three to eight feet, and
the bolls that contain the cotton fiber are sharp-
pointed and characterized by having only three
instead of four or five divisions or locks. Sea
Island cotton yields less fiber per acre and is more
costly to pick and gin than upland cotton. But it
commands a higher price. It is grown chiefly on
islands, and along the coast of South Carolina and
Georgia. It has peculiar value as material for
the making of the foundation for automobile tires.

The India cotton and the Egyptian are not
grown extensively in this country, although varie-
ties have been introduced and grown by the United
States Bureau of Plant Industry for experimental
purposes. It is probable that these species will
prove valuable when the method of hybridization
is applied to the development of new races of
cotton modified to meet special needs.

The cotton has a large, attractive flower, and
cross-fertilization occurs to a considerable extent

[112]

ON TEXTILE PLANTS

through the agency of bees and other insects. There
is no difficulty in hybridizing different species. On
the contrary, it is difficult to prevent cross-pollena-
tion where different kinds of cotton grow in the
same vicinity. There is danger of contamination
of the strain of any particular cotton in this way.
But, on the other hand, there is also the possibility
of the production of new and important varieties
through such crossing.
IMPROVEMENT THROUGH SELECTION.

Until very recently, as already intimated, the
improvement in cotton has taken place almost or
quite exclusively through the selection of seed,
without any conscious effort on the part of the
grower to pre-determine the characters of the seed
by cross-fertilizing the parent plants.

Indeed, until somewhat recently, cotton growers
in common with other agriculturists, have been
more or less oblivious to the need of care in the
selection of seed. And even now, according to so
good an authority as Professor Thomas F. Hunt,
of the New York College of Agriculture, probably
half the cotton seed planted is taken at random
from the public gin. Yet the importance of selec-
tion has come to be understood in recent years
by a good many growers, and the old slipshod
methods have been abandoned by such cotton
raisers as appreciate the advantages of applying

[113]

‘aay

a1qisvaf f]]p101aurUI0D
2q pinom yaya Jo uo}}na}3
-[N2 ay} ‘paanpoid aq jyG}uWI
fijaliva paaorduiy up fi]q1s
-sod jng ‘jo}1ajpur ubias0f
ay} ya §=uojjNaduioa Ul
xoy aanpord 0} a1q}ssodun
ao NIIP Jl SayDur 10qD]
fo ysoo ybiy ay} ‘fiajunoa
sry} Ul ‘appul st y}oja
uaul, yo1ym urod{ jDI4ajDUL
ay} $ajnjljsuod ‘umouy jjJaMm

sr sv ‘xvyf uvadoing

ayy fo saqy aus

qUD]d
xD} upadomy

ON TEXTILE PLANTS

scientific methods to the betterment of their crop.

The method that has produced excellent results
is one that has been illustrated over and over in
connection with one after another of my experi-
ments in plant development.

It consists essentially in selecting for seed the
products of plants that are observed to be more
productive than their fellows, and which at the
same time produce cotton fiber of superior quality.

With the cotton, as with other plants, it does
not at all suffice to select merely the individual
bolls that chance, through some nutritional advant-
age, to grow to large size. It is necessary to con-
sider the plant itself and its total product as well
as the average quality of that product. We have
seen that, under precisely similar conditions, dif-
ferent individual plants of every species show a
more or less wide range of variation as to size and
productivity, resistance to disease, and other
qualities.

This variation is quite as notable among cotton
plants, even of the most fixed varieties, as among
most other cultivated plants.

The practical method employed by the most
intelligent cotton raisers is to send trusted
employes through the fields to select the plants
the product of which is to be saved for seed. The
seed cotton thus obtained is ginned separately, and

[115]

LUTHER BURBANK

the owner who has taken this trouble is sure to be
repaid by the improved average quality of his
crop the ensuing season.

The United States Bureau of Industry has
published details as to a method of selective breed-
ing that has been practiced for several years by
some growers of Sea Island cotton, through which
the staple has been increased from 1.75 to 2.5
inches in length. The method requires four years
of selection to secure enough seed for general
planting.

The first year, five or more plants are selected
as the best in the field. It is urged that it is
important to take the seed of at least five plants,
not merely of one, because an individual plant of
fine appearance may fail to transmit its character-
istics. Yet my own experience with a wide range
of plants would lead me to have much confidence
in the progeny of the one best plant in the field.

However, the practical cotton growers have
thought that they secured better results by select-
ing several plants instead of depending on a single
one.

The second year, five hundred or more seeds
are selected from each plant for the next year’s
planting. The second year’s crop is examined with
great care to see whether the desired qualities are
being strongly transmitted. If such is the case,

[116]

Hemp Plants

Hemp is grown in America chiefly for its coarse
fiber, used in making ropes, cordage, and warp for car-
pet. Its seed is little utilized, although it makes a valuable oil.

LUTHER BURBANK

several of the best plants are again selected to
furnish seed for a new planting. Meantime the
seed of the remainder will suffice to plant a patch
of about five acres in the third year.

The third year five hundred or more plants will
be grown of each of the individual selections, and
as many five-acre seed patches to produce seed for
general planting as there were individuals of the
first year whose progeny was considered worth
propagating.

In the fourth year there will be seed for general
planting from the five-acre seed patches of the
previous year. There will be several five-acre seed
patches from the specially selected individuals of
the second year; and five hundred or more plants
of each of the individual selections.

That is to say, in this fourth year we shall have
a general crop of cotton plants all of which are the -
descendants in the third filial generation of the
five plants or thereabouts selected in the first year.

And inasmuch as each successive year the five
or so best plants have been selected out to start
a new series, the process of betterment will go on
indefinitely. The general crop in each successive
year will represent the progeny, not of the crop of
the preceding year, but a third-generation offshoot
from the best plant of an earlier year. And the
crop of this year will of course supply five best

[118]

ON TEXTILE PLANTS

plants to become the progenitors of the general
crop four years from now.

And this, it will be obvious, is merely the
applying of the familiar rules of selection which
we have seen illustrated in the production of
specialized races of flowers and fruits and vege-
tables of many types. The only difference is the
practical one that, in my experiments, the inferior
members of a fraternity are usually destroyed
when the best’ half dozen have been selected for
preservation, instead of being preserved for
cropping purposes.

This modification obviously in no wise alters
the principle, but it is a practical change that is
clearly necessary to meet the needs of a cultivator
who, while striving to improve his crop, must at
the same time take such crop as can be grown year
by year, without waiting for the best ultimate
product.

Of course there are limits to the amount of
development that is possible through such
selective breeding.

The plants operated with have certain heredi-
tary limitations, and these are pretty surely fixed
by long generations of inbreeding. When these
limits are attained by the practical plant devel-
oper, through the carrying out of such a system of
rotation as that just outlined for a good many

[119]

Indian Hemp

The so-called Indian hemp is not a true hemp, but a plant
of an altogether different genus. It has not hitherto proved
itself of commercial value, but it has qualities that suggest possibili-
lies of development. The experiments in which the plant
is being tested in Mr. Burbank’s gardens may or
may not lead to important results.

ON TEXTILE PLANTS

years, the best pure types of cotton represented in
the strains under investigation will have been
isolated, and the experimenter will find it difficult
or impossible to make further improvement by the
mere process of selection.

Then it will be necessary to introduce the
method of hybridizing, to give new vigor to the
plants and to produce new segregations and com-
binations of characters that will be equivalent to
the production of new varieties. And for this
purpose, as I have already suggested, the mixing
of strains of the American cotton with the Oriental
ones, and also doubtless, the utilization of some
hitherto neglected wild species may be expected,
reasoning from analogy, to prove of value.

A beginning is said to have been made by H.
H. Webber, through combining the fine, long,
strong lint of the Sea Island cotton with the large
bolls and productiveness of the upland cotton.

Insect Fors or Corron

It goes without saying that a highly specialized
plant like the cotton, and in particular a plant
growing in sub-tropical regions, is subject to the
attacks of many insects.

In point of fact, the distinguished entomologist,
Dr. L. O. Howard, enumerates no fewer than 465
species of insects that feed upon the cotton plant.
But among these there are four that are so pre-

[121]

LUTHER BURBANK

eminent in their destructiveness as to make the
ravages of the others scem insignificant. These
are the cut worm (Aletia argillacea), the cotton
worm, the cotton boll-worm (Heliothis armiger),
and the Mexican cotton boll weevil (Anthonomus
grandis).

The cutworms are dangerous to the young
plants as to other seedlings. The cotton worm may
appear in hordes, but has not been especially
destructive in recent years. The cotton boll-worm
is an insect which, notwithstanding its name, pre-
fers other crops, in particular maize, to cotton, so
that the cotton crop may be protected from its
aggression by planting a few rows of maize at
intervals of twenty-five cotton rows throughout the
cotton field,

But the newest and most aggressive of the
pests, the cotton boll weevil, is an enemy that is
not so easily reckoned with.

This little insect has been known a long time
in Mexico as a pest that attacks and destroys the
tender portion of the cotton boll itself. But it is
only in recent decades that this insect has worked
its way northward and into the cotton region of
the United States.

It must now be reckoned as one of the most
destructive enemies of the cotton plants in the
more southerly districts.

[122]

The Jute Plant

The jute is a plant comparatively easy of cultivation, and
producing a fiber that has commercial value. The great diffi-
culty, is to separate the fiber in such a way as to make it usable.
Lack of machinery for doing this effectively has led to the
neglect of this plant in America, although it is sometimes
grown in the Gulf States. Mr. Burbank has the
plant under observation, but it is perhaps
of no great avail to develop it unless
some one will invent a machine
to handle its fiber.

LUTHER BURBANK

Quite recently, however, an enemy of the boll
weevil has been found in Guatemala by Mr. W. F.
Cook, the botanist in charge of investigations in
tropical agriculture of the Bureau of Plant Indus-
try. This enemy of the boll weevil is described as
a large, red-brown, ant-like insect. It is known to
the native of Guatemala as the kelep; entomolo-
gists describe it as the Guatemala ant, Ectatomma
tuberculatum.

This insect is described by Mr. Cook as strik-
ingly adapted by structure and instinct for the
work of protecting the cotton against the weevils.
It has large jaws or mandibles that fit neatly about
the weevil and hold it firmly, and a sting that
penetrates a vulnerable point in the shelly armor
of the weevil. The sting paralyzes the victim,
somewhat as wasps paralyze spiders and caterpil-
lars to supply food for their young.

After paralyzing the weevil with the poison
injected by the sting, the kelep carries its prey
to its subterranean nest, to feed the larvae.

The kelep does not confine its predaceous
attacks to the boll weevil but kills also many other
insects found upon the cotton, including the larvae
of boll worms and leaf worms. It has the curious
habit, Mr. Cook tells us, of storing the dismem-
bered skeletons of captured insects in special
chambers of its subterranean home.

[124]

Cotton in the Field

This picture, un-
like nearly all the oth-
ers in these volumes, was
not taken on Mr. Burbank’s
fields and does not repre-
sent his individual work.
Santa Rosa does not lie
within the cotton belt. Mr.
Burbank’s advice has more
than once been sought,
however, by those who are
cultivating the plant, and
his ideas have been util-
ized in the development of
cotton in distant
regions.

LUTHER BURBANK

Through Mr. Cook’s efforts, this enemy of the
boll weevil has been introduced. It has shown its
ability to breed both in captivity and in the cotton
fields of Texas. The insect forms colonies that
are said to be even more highly developed than
are the colonies of ordinary ants. New colonies
are formed by a sub-division of the older com-
munities, as among the honey bees, not by solitary
females as is usual among ants.

It is expected that the insects will thrive in the
cotton districts, and will serve at least to keep the
boll weevil in check, although it is not to be hoped,
according to Mr. Cook, that it will altogether ban-
ish the pest; inasmuch as the weevils have not
been exterminated in Guatemala, although the
kelep has there imposed a very important check
on their increase.

It is urged, however, that additional protection
from the boll weevil must be sought through such
development of the cotton plant itself as will make
it resistant to the attacks of the insect. The
authorities of the Department of Agriculture have
observed that in the cotton plants of Guatemala,
where the weevil is native, the buds do not always
drop off after being penetrated, and that the young
bolls continue to develop in spite of the attacks of
the weevil.

It was found on examination that such resist-

[126]

ON TEXTILE PLANTS

ance was due to the actual growth of new normal
tissue into the cavity eaten out by the weevil lar-
vae, with the result uniformly fatal to the larvae
itself. It appears that the larvum in its younger
stages subsists entirely on the highly organized
food material to be found in the pollen grains of
the unopened cotton flower. The new tissue
formed by a mere swelling or proliferation from
the central column of the flower is watery and
innutritious, and may starve the larvum to death
even if it does not act as a poison.

Here, then, is a method by which the cotton is
able to offer effective resistance to the weevil.

It is suggested that if a variety of cotton could
be developed in which the tendency to the growth
or proliferation of the new tissue was pronounced,
as it is in certain individuals, the weevil might be
exterminated. It is considered possible that such
a variety may exist at the present time in some
parts of tropical America, and that if such a
resistant variety can be found, it may be possible
to develop the characters in the cultivated plant
through selection.

Inasmuch as individual plants show this power
of resistance, there should be no difficulty in
developing and raising cotton plants in which this
resistant quality is a uniform characteristic. The
problem is obviously identical in principle with

[127]

Cotton Flower and Seed-Head

The function of cotton fiber is, of course, to protect the

seed and to facilitate its distribution. But Nature would
scarcely have carried the elaboration of the protective fiber to sucha

length, had she not been aided by man, who has selected gen-

eration after generation among the cotton plants for the

ones that produced the best quality of fiber, as
gaged by his own needs. The flower is here
shown at earlier and later stages of
development.

ON TEXTILE PLANTS

numberless other problems of plant development
that have been solved in the same way.

And here, also, we may reasonably assume, aid
may be secured through the careful cross-polleniz-
ing of resistant individuals, even if no resistant
species can be found with which to effect hybrid-
ization. It is reported that a tree cotton indigenous
to southern Mexico is partially resistant to the
weevil.

It will be of interest to determine whether the
peculiar characteristic as to growth of new tissue
that makes the individual cotton plants resistant
to the weevil constitutes a unit character that will
be transmitted along Mendelian lines, comparable
therefore to immunity and susceptibility to rust as
revealed in Professor Biffen’s experiments with
the wheat.

Whether or not such is the case, it may be
expected that the cotton plants that show resist-
ance will transmit this propensity to some of their
offspring. It is obvious that an investigation of
the hereditary tendencies of the cotton in this
regard, coupled with experiments looking to the
improvement of the quality of the fiber itself,
should have at once a high degree of interest for
the plant developer and the promise of large
reward to both grower and consumer.

The geographical location of my experiment

[129]

eel

>.
}-
<=

‘yynog ayy jo suo}baa
auios ut jsad D aulazaq
spy yo1ym ‘p1aaea1 1104 ay?
{0 yan}Jo ay} oj JOatqns $1
1104 ay} ‘umoys ailay juaUt
-dojaaap jo abvjs ay} 3D
uayA4 ‘zaqyl uaj}09 ay} bur
-sodzxa ‘uado sjsinq ,,]10Q,,
ay} Ajjuanbasqng “pauado
jai sp jou aapy Joy] sjaD41q
aaljajord wlyyim Buzinjou
$1 Paas ay] ya1ym Jp samoyy
u0}j09 ayy fo Juautdojaaap
{0 abvjs Dv sjuasaidas
110q pajypa-os ay Ll

nog uowyo0y)

ON TEXTILE PLANTS

farms makes it difficult for me to experiment with
so tender a plant.

But I have thought that a somewhat extended
account of the work of others in the selective
breeding of this plant would be of interest, partly
because it suggests such close analogies with
numerous experiments already detailed. I would
urge upon the attention of plant experimenters
who are located within the cotton belt the possi-
bility of applying the principles that we have seen
outlined in many hybridizing experiments to the
improvement of a plant which, despite the excel-
lence of its product, is by no means perfect.

The fundamental principles of plant develop-
ment are everywhere the same, and the methods
that have been employed at Santa Rosa to perfect
flowers and orchard fruits and vegetables may be
applied with full confidence to the improvement
of the cotton plant.

In my own studies, I have come upon a variety
of cotton grown in a far northern climate, that of
Corea, for ages, and as it appears to be very much
hardier than any cotton heretofore known, I have
thought it of peculiar interest. The bolls, though
produced abundantly, are small and have a short
staple, growing on compact, low-bushing shrubs.
This matures at Santa Rosa when other cottons
seldom reach even the blossoming stage.

[131]

LUTHER BURBANK

I have sent seed of this to experimenters better
located; and this unusually hardy dwarf cotton
may yet prove of value for crossbreeding purposes.

—The function of cotton fiber
is, of course, to protect the
seed and to facilitate its dis-
tribution. But Nature would
scarcely have carried the
elaboration of the protective
fiber to such a length, had she
not been aided by man, who
has selected, generation after
generation, among the cotton
plants, the ones that pro-
duced the best quality of fiber
—as gaged by his own needs.

PLANTS WHICH YIELD USEFUL
CHEMICAL SUBSTANCES

OBSERVATIONS ON SuGAR-CANE Hops AND
SuGAR-BEETS

N English physician residing in Trinidad

A made a casual observation that proved

enormously important to the growers of
sugar-cane.

The physician observed that in the cane fields
there were little grass-like plants coming up here
and there. The planters whom he asked about it
said that it was “grass”, and let the matter go at
that. But the physician had a suspicion that each
blade of grass was really. the shoot of a seedling
sugar-cane plant.

As it chanced both the planters and the
physician were right. The little shoots were young
sugar-cane plants; but of course sugar-cane is itself
a giant grass, so there was no mistake.

But the planters had not a suspicion as to what
kind of grass the shoots were; so when the physi-
cian took some of them up and cultivated them,

[Votume VIII—Cuapter VJ

LUTHER BURBANK

and they were seen to develop into stalks of sugar-
cane, everyone except the physician himself was
greatly surprised.

For it had been supposed that the sugar-cane
does not produce seed, and such a thing as a
seedling sugar-cane was hitherto unheard of.

The sugar-cane does, in point of fact, belong
to that comparatively small company of cultivated
plants that have almost totally given up the habit
of seed-production. We have seen that the horse-
radish is another plant that has similarly stopped
producing seeds, and that the common potato has
almost abandoned the habit. Comment has been
made, also, on the rather extraordinary character
of this departure from the most sacred traditions
of plant life.

That an organism, whose sole purpose beyond
the perpetuation of its own individual existence
might be said to be the production of seed, should
continue to grow and thrive and yet should totally
abandon the habit of seed-production seems
altogether anomalous.

The explanation is found, as we have seen, in
the fact that man provides means for the propaga-
tion of horseradish and sugar-cane by division of
roots or by transplantation of cuttings. In the case
of the potato, nature herself has provided tubers
that take the place of seeds in a measure; and we

[134]

Sugar-Cane Tassel

Notwithstanding its elaborate tassel, the sugar cane or-

dinarily does not bear seed. Indeed, until somewhat recently,
it was not known to bear seed at all. By rare exception, however,

seed is occasionally formed; and the discovery that certain little

grass-like plants in a sugar cane field were really seedlings

of the sugar plant led to the development of a new
variety with exceptional qualities. Ordinarily
the sugar cane is propagated by division,

LUTHER BURBANK

have seen that there is a curious reciprocal rela-
tion between the formation of seeds and the forma-
tion of tubers, under certain circumstances.

In certain cases, for example, the growth of the
roots of a plant or even of the plant stem may be
promoted by the removal of the blossoms.

We saw this illustrated in the case of the
huckleberry.

We saw also how the potato that was grafted
on the stem of a tomato might grow aerial tubers
from the axils of the leaves in the position that
would normally be occupied by the flowers—and
ultimately by seeds, had not the potato given up
the habit of seed production.

Another illustration of the affinity between
bulbs and flowers is shown by the onion, which
sometimes grows a bulb at the top of its stalk, to
perform the function of seeds in storing nutrient
matter and at other times divides at the base like
many other similar plants to form off-shoots from
which the new plant will grow in another season.

But in all these cases nature is substituting one
means of reproduction for another, or supplement-
ing one means with another, and the essential
purpose of race preservation is not for a moment
overlooked.

In the case of the sugar-cane, however, it might
almost be said that nature has abandoned the idea

[136]

ON CHEMICAL YIELDING PLANTS

of provision for the multiplication of the species,
and has left the matter entirely to man. For in
giving up the habit of seed-production, the sugar-
cane has developed no complementary habit of
bulb production. It is propagated by cuttings, but
the agency of man is necessary to place those cut-
tings under proper conditions for growth.

Left to its own devices, the cane would be likely
to give an illustration of race suicide.

REJUVENATION THROUGH SEED PRODUCTION

All this, however, seems out of harmony with
the illustrative case with which we began.

For obviously the Trinidad physician could not
have found seedlings of the sugar-cane unless the
sugar-cane produces seed. In point of fact, it does
produce seed on rare occasions, but the habit has
been so nearly abandoned that most cultivators of
the plant supposed that it had been given up alto-
gether. The Trinidad case, however, shows that
Nature has not altogether abandoned the sugar-
cane to the good graces of man. She still on occa-
sion stimulates the plant to a revival of its long-
forgotten custom. And the benefits that result
from such revival will be obvious if we follow a
little farther the story of the grass-like seedlings
that the physician dug up in the cane-fields of
Trinidad.

It appears that one of these seedlings, grown to

[137]

™

ednifig 3u97}99%3
up saypur j1 jung /juaU
-auyas jo a1qiidaosns jou
sp qonpoid $2 pup ‘aupo ID
-6ns ayy Jo asoy} wosf u0}}
-1sodulo9 [DI}UIaYyo Ul aafip
saainf sjy ‘u4109 a7] pajpa
-1]n9 2q fipul pup ‘YION
ay} 0} apf smos6 jp *SajD1S
panug «ayy «fo suolbat
fluput u} Ipiqiums fi1qD12103
s} agupo-1p6ns ay} {o
uisnos Apsoy sit

umnybs0s
fo saija1IDA

ON CHEMICAL YIELDING PLANTS

maturity, was carried subsequently to the Hawai-
ian Islands, and there propagated in the usual way,
so that in due course sufficient plants were grown
from it to be tested as to their qualities of growth
and sugar production. And it was soon discovered
that the progeny of this seedling constituted vir-
tually a new race of sugar-cane; one that would
grow on land so poor that it had been allowed to
remain fallow.

The new variety, indeed, would produce more
sugar on even the poorest land which had been
abandoned, than the ordinary variety produces on
the best land.

Being taught by this experience, the growers of
sugar-cane paid heed to the seedlings in fields
where they appeared, and subsequently raised
from seed, and distributed in all countries, new
varieties of sugar-cane that have probably in-
creased the sugar production of the world by
millions of tons each year:

One could not ask a better object lesson in the
possibility of rejuvenating a static race of plants
through the growing of seedlings.

I first made experiments with seedling sugar-
cane in my own gardens, and when reports of these
were made, I received letters from the various
sugar-growing regions of the world, asking for
further information, and now there are several

[139]

LUTHER BURBANK

well equipped experiment stations engaged in the
work of raising and testing sugar-cane seedlings.
APPLYING THE NEw KNOWLEDGE

The reader will at once recall the case of the
Burbank potato, which is in all respects compar-
able. There, also, a plant that ordinarily does not
produce seed was found by exception to be fertile,
and the plants grown from the seed showed the
widest departure from the form of the parent
plant, and constituted the progenitors of a new
and improved variety.

The obvious explanation is that the seeds owed
their existence to the union of two plant strains,
one represented by the pollenate and the other by
the pistillate flower, that must necessarily be some-
what divergent. The bringing together of the two
racial strains results, as we have seen illustrated
over and over, in the giving of renewed vigor or
vitality to the off-spring, and in the production of
variation through the new assorting and recom-
bination of characters, some of which may have
been latent and unrevealed in one or both parents.

In the case of the sugar-cane, propagation by
cuttings had been the universal custom with the
planters for no one knows how many generations.

As a result, a single cultivated variety of cane
that chanced to be in existence when the practice
of propagation by cutting was established contin-

[140]

oN 46
er

Kaffir Corn

In somewhat recent years this thrifty plant has become
popular in America as a forage plant. It is of comparatively
stunted but rugged growth, and it constitutes a valuable addition to
the not very long list of forage plants. It is not grown
very extensively, however, in the regular corn belt.

LUTHER BURBANK

ued unchanged as to its essential characteristics,
and there was no apparent opportunity for any
modification, except such minor ones as might
result from increased or diminished nutrition due
to the precise character of the soil and climate.

But the chance finding of the seedlings put the
plant on a new basis, and gave the planters new
varieties that enabled them to improve the cane,
and bring it more in line of competition with the
rival sugar-producer that had only recently come
into notice, namely the sugar-beet..

At the time when the custom of propagating
cane by cuttings was established this plant stood in
a class quite by itself as a sugar-producer.

But within the past fifty years the merits of the
sugar-beet have come to be understood. The pos-
sibility of developing a beet with a high sugar
content has been established, and the beet sugar
industry has risen to such proportions that it more
than rivals the cane industry.

Stimulated by this unexpected competition,
which threatened to annihilate the cane sugar
industry, somewhat as the work of the synthetic
chemist has practically annihilated indigo growing
and madder growing, the planters have in recent
years given serious attention to the question of the
possible improvement of the sugar-producing
qualities of the cane.

[142]

ON CHEMICAL YIELDING PLANTS

Several experimenters from different parts of
the world have written me concerning this matter
within the past fifteen years.

And a number of my friends and acquaintances
are now raising sugar-cane from seed in Mexico,
the Hawaiian Islands, and Cuba, with an eye to the
production of improved varieties. Their efforts
should be successful.

Crossbreeding the sugar-cane will give it new
vitality, and careful selection from among the new
varieties that will appear in the second generation
should enable the cultivators to develop new
strains of the sugar-bearing cane that will be far
richer in their sugar content than any of the old
varieties. The cane is at best handicapped in com-
petition with the beet by the fact that it can be
grown only in tropical and sub-tropical climates.

If it is to hold its own, it must be developed to
its full possibilities of productivity.

Doubtless it will be possible to develop races
of sugar-cane having greatly increased size of
stalk, and having also a higher percentage of sugar
in a given quantity of pulp. In attempting such
developments, the experimenters are merely bring-
ing the sugar-cane industry into line with the other
great plant industries, most of which were neg-
lected by the scientific plant developer until very
recent years.

[143]

Broom Corn

Broom corn bears a very close general resemblance to
its distant cousin, the familiar corn plant of field and garden;
but it has the peculiarity of developing an extremely tough fibrous
tassel, furnishing an inimitable material for the making
of brooms, The plant would repay cultivation in
many regions where it is now neglected.

ON CHEMICAL YIELDING PLANTS

My own experiments with the cane have not.
extended beyond the greenhouse, but I have found
that the seed germinates readily there, although
only a few seeds out of a handful may grow; the
contrast in this regard being very striking with the
seed of the allied Pampas-grass, which is as
dimunitive as that of the sugar-cane and not dis-
similar in appearance, but which germinates
promptly almost to the last seed.

ALLIES OF THE SuGAR-CANE

I have experimented more extensively with
certain relatives of the sugar-cane of the tribe of
sorghums.

This includes not only the sorghums that
produce the syrups, but also broom-corn, Kaffir
corn, and a score or so of allied plants, some of
which have great value as fodder plants.

The best known of the sorghums shows its
relationship with the sugar-cane in that it produces
a syrup which, although not of the same chemical
composition as cane sugar, is very sweet and
palatable.

Sorghum differs very radically on the other
hand from sugar-cane, in that it is a hardy annual
plant. It came to us from China but probably
originally from South Africa, and it proved adapt-
able to our soil and climate almost everywhere. It
is grown in practically every state in the Union,

[145]

LUTHER BURBANK

for syrup-making. It is known also as a forage
plant of very great value, and its stalks supply
fodder for the farm animals.

It will be gathered from this that the sorghum
is a much less specialized product than the cane,
and that it retains its full vigor as a seed producer.

Partly as a result of its cultivation in widely
different regions of the globe, and partly no doubt
through conscious and unconscious selection on
the part of its cultivators, the sorghum has devel-
oped many varieties, which are divided into three
quite distinct groups.

One type of sorghum is the syrup-producer to
which we have just referred.

The other type constitutes a very valuable
forage and grain-producing plant, not altogether
unlike Indian corn in general appearance, that is
almost devoid ‘of sugar.

The third type resembles the others in some
respects, but the kernels are smaller and more
primitive in form, the plant being used for the
manufacture of brooms.

My own work with the sorghums has included
a good many different varieties, but has chiefly
concerned the non-saccharine types, and, in par-
ticular, the one known as broom-corn.

This is a variety of sorghum having long, slen-
der panicles of a specialized ‘form, produced by

[146]

Staminate Hop Plant

The flowers of hops are grown on different plants. Only
the pistillate flower has value from the standpoint of the hop
grower; but it is supposed to be advantageous to have the flowers
fertilized, and therefore is customary to grow staminate
plants at regular intervals in the hop field. This pic-
lure, showing the staminate hop plant, may
be contrasted with the succeeding one.

LUTHER BURBANK

long selection for the special purpose of making
brooms and brushes. The product of this plant
is familiar in every household, but the plant itself
has not been very generally grown in the United
States until of late.

There is a vast difference in the different
varieties as well as individual plants of broom-
corn as regards length, strength, and symmetry of
the group of panicle stems, or brush as it is tech-
nically called, and equal diversity as to the quan-
tity produced per acre.

My experimental work with the broom-corn
has been directed toward the development of a
long, and in particular a straight, panicle stem.
Most of the broom-corns have long but crooked
stems—that is, stems with crooks or crinkles near
the base. Moreover, most of the broom-corns
under cultivation vary as to the quality of the
brush, some of them being long, some short, and
there being a corresponding diversity as to color.

I have succeeded, in a few generations of
selective breeding, in greatly increasing the num-
ber of straight stems of the brush, and giving
them a more shapely form. The broom-corn
responds readily to selection and care.

My experiments were made by selecting seed
from the plant or plants in a lot that showed the
best individual characteristics.

[148]

Pistillate Hop Plant

The hop is unique among plants having large economic
importance in that the only part of it that has value is the
flower. The bitter principle, called lupulin, developed in the flower,
has great value from the standpoint of the brewer; and hop-
growing is an important industry wherever beer is manu-
factured extensively. It is suggested that selective
breeding might improve the quality or en-
hance the quantity of the essential lu-
pulin borne by the hop flower.

LUTHER BURBANK

Attention was paid not merely to the brush
itself, but also to the stalks of the plant. There is
obvious advantage in growing a large, long brush
on a dwarfed stalk, that as little plant energy as
possible may be used for the production of the
stalk, the chief supply being reserved for the more
important brush. It was found very difficult, but
not impossible, to improve the plant along both
lines simultaneously, as it seemed to be working
in opposite directions.

I was also able to develop a brush that had
improved qualities of firmness and durability,
combined with pliable texture.

The syrup-producing sorghums are chiefly of
two very closely related types, which are usually
spoken of as Amber and Orange sugar-canes.

Individual plants vary a good deal as to their
sugar content and other characteristics. My ex-
periments with the syrup-producers have shown
that there is a great diversity in the individual
plants as to the amount of saccharine substances
in their tissues; and that it is possible by careful
and systematic selection through successive gen-
erations to increase the sugar content, as has been
done with the sugar-beet, and is being done with
the sugar-cane.

My work, however, has not extended beyond
the experimental stages.

[150]

ON CHEMICAL YIELDING PLANTS

I satisfied myself as to the feasibility of the
project; it should be carried to completion by some
one working under the auspices of the Govern-
ment or an Agricultural Society where abundant
acreage and intelligent help are available.

The work is important, for the syrup-bearing
sorghum is a plant of real value, and there is a
great demand for its product. But the work of
developing the plant does not offer commercial
inducements that make it profitable for the private
investigator to devote a large amount of time to it.

Some Curious CaRBOHYDRATES

The differences bétween the sweets extracted
from the sugar-cane and those taken from the |
sorghum are very obvious and tangible.

One plant supplies a juice that when boiled and
evaporated and refined gives a fine granular
product familiar to everyone as sugar.

The juice of the other plant, somewhat
similarly treated, constitutes a syrup of varying
color, which is exceedingly sweet and palatable,
but which cannot be reduced to a granular condi-
tion in which it could by any chance be mistaken
for cane sugar. Yet the chemist tells us that the
sugar content of the juices of these plants is in
each case a compound made up exclusively of
three elements—carbon, hydrogen, and oxygen—
and that the differences observed are due to modi-

[151]

eerces

A Hop Plant Vista

This view between the rows of hop plants was taken just
before the vines were let down for picking. The vines are
heavily laden with flowers, and it is necessary to pick these by hand,
and just at the right time. Therefore the harvest season is
always a busy time in a hop region. There is no me-
chanical device that gives any assistance to the
hand-picker in gathering this crop.

VII-5p,

ON CHEMICAL YIELDING PLANTS

fications in the proportions in which the different
elements are compouaded.

It appears that sugar of the glucose type, as
represented in the syrup of the sorghum, is a much
more simple compound than cane sugar.

The Glucose has only 6 atoms of carbon while
cane sugar has 18; it has 12 atoms of hydrogen
only, whereas cane sugar has 32; and 6 atoms of
oxygen, in contrast with the 16 atoms of the cane-
sugar molecule.

We have elsewhere seen that starch is a
compound of the same elements; differing, indeed,
from glucose only in that it has 10 hydrogen
atoms instead of 12, and 5 oxygen atoms instead
of 6.

Stated in chemical terms, a molecule of starch
that has had a molecule of water incorporated with
its substance in a chemical union, becomes a mole-
cule of glucose; and, of course, the converse holds
—a dehydrated molecule of glucose becomes a
molecule of starch.

But to build up a molecule of cane sugar from
either starch or glucose requires the introduction
and incorporation of many individual atoms,
although no new kinds of atoms are required. It
is simply that the molecule of cane sugar is a very
much more intricate structure, made of the same
material. The glucose molecule is, if you will, a

[153]

LUTHER BURBANK

simple dwelling; the cane sugar molecule an
elaborate mansion.

But the materials with which they are com-
pounded are precisely the same.

There is a good deal of uncertainty on the part
of the chemists as to the exact way in which the
various molecules of the different sugars and allied
carbohydrate substances are built up.

Some chemists regard a molecule of a substance
called methyl aldehyde, which consists of a single
atom each of carbon and oxygen combined with
two atoms of hydrogen as the basal form of carbon
compound which the chlorophyll in the plant leaf
makes by bringing together an atom of carbon
from the atmosphere and a molecule of water.

From this relatively simple carbon compound
more elaborate compounds are built, through the
introduction of varying numbers of additional
atoms of carbon or hydrogen or oxygen, as the case
may be, and all of the intricate juices and flavors
and sweet and bitter principles of the various
plants are thus compounded in the marvelous
laboratory of the plant cell.

THE Propuct oF THE Hop

Among the multitudes of compounds of the
almost endless series in which carbon, hydrogen,
and oxygen are joined through the agency of the
plant cell, there is one that is of peculiar interest

[154]

A Hop Field

This picture, taken
earlier in the season,
shows the hops before the
vines have attained full
maturity. They are grown
on high poles, with sup-
porting wires or cords, so
that the vines may have
ample opportunity for
growth without interfering
with one another. Hop-
growing involves work, but
the crop is highly
profitable.

LUTHER BURBANK

from the standpoint of the agriculturist, because it
gives value to a plant that otherwise would be at
best a troublesome weed, to be ignored and
despised.

The carbon compound in question is the bitter
principle known as lupulin or humulin, which is
the really important constituent of the flower of
the hop.

This so-called alkaloid, with its exceedingly
bitter taste, would never be suspected by any one
but a chemist of having the remotest relationship
with sugar; yet, in point of fact, it is made of
precisely the same elements that make the sweet
content of the sugar-cane’s delectable juices.

But the three essential elements are differently
assorted, as any one might readily surmise who
contrasts the bitter taste of the hop with the sweet
taste of sugar.

In point of fact, there are 32 atoms of carbon,
and 50 atoms of hydrogen, with only 7 atoms of
oxygen making up the composition of the alkaloid
that gives the hop value. No one knows precisely
what is the share of each element in giving any
particular quality to a plant product.

The chemist at present can only tear down the
molecular structure and tell us of what it is
composed.

In the presence of the elaborate carbon

[156]

Dried Hops by the
Carload

The hop flowers,
picked while green, are
cured in kilns such as
those shown in the front-
ispiece of the present vol-
ume. The dried hops are
then stored away for fu-
ture use or shipped to the
markets. They require ro
treatment beyond
drying.

LUTHER BURBANK.

compounds that are represented by such sub-
stances as sugar and lupulin, he is like a barbarian
standing before a beautiful temple.

The barbarian could tear down the temple, but
he could not rebuild it.

Similarly the chemist can tear the carbohydrate
molecule to pieces, but he cannot put it together
again. He knows how to pull to pieces the mole-
cule of sugar, for example, making it into a simpler
form of sugar, but he cannot build up even the
simplest form of sugar from elementary atoms,
were these ever so freely supplied him.

Carbonic acid is everywhere in the air, and
water may be had for the asking.

The chemist knows just how many molecules
of water he should take to combine with just so
many atoms of the carbon to make a molecule of
sugar or a molecule of lupulin.

But he does not know how to go about the task.

His only resort is to appeal to the agriculturist
in the field, who deals with living laboratories in
which the method of compounding these intricate
substances is understood.

If the chemist would have sugar, he must ‘seek
it in the product of the cane or sorghum, or beet.
If he would have lupulin, he must go to the hop
vine, for this plant alone has learned the secret of
its production.

[158]

ON CHEMICAL YIELDING PLANTS

So it chances that the ancient calling of the
. agriculturist is as essential to-day as it has always
been; and that it is necessary now as always here-
tofore to cultivate different varieties of plants in
order to gain the diverse products that man needs
or desires as focd or as aids in the industries.

The particular product that a hop vine grows,
and in the production of which it has an absolute
monopoly, is used, as everyone is aware, by the
brewer in the process of the manufacture of beer.

He has been able to find no product that makes
a satisfactory substitute for the bitter principle
supplied by the lupulin of the hop.

The particular place in which the hop vine
stores this bitter alkaloid, once it has manufac-
tured it, is the curious cone-like leafy seed-case
or envelope of the pistillate flower. Without doubt
the plant develops this bitter principle and stores
it there to give the seeds protection from the
depredations of animals. But whatever its pur-
pose, the bitter alkaloid provided by the hop was
discovered at an early date to have value for the
purposes of the brewer, and the hop vine continues
to be grown in large quantities solely for the
production of this alkaloid.

The hop vine belongs to that somewhat
numerous tribe of plants that grow the pistillate
and staminate flowers on different vines. It is

[159]

ae =
ree cence

*sdos2 Jo 31qv}yYJo1d
sour ayy fo auo $1 }}
Mou j1juNn ‘Jaaq ay} jo jua}
-u0a «spins ayy Aulspasut
{0 ulajqoad ay} paajos ado
-ing {oO Silapaaiq jun}d ayy
ing ‘saijqjupnb bujfivd ut
$]2aq ay} wouf ww6ns aonp
-oud 0] a]qissodui j1 pai]?
-ap oym ‘abn fiznjuaa v fo
s]slwuayd ay} 0} a]qiparour
ajzinD paulaas aapy pymoat
siy.y ‘fjddus anins s,pjiom
ayy jo aaimmos falyd ayt
sp aupo apGns ay} pazupjd
-dns spy jaaq ay] Ssivafi
quaval figaa UlYTIM

firojaD q
ay} yD sjaag apbng

ON CHEMICAL YIELDING PLANTS

only the pistillate flower that is of value to the hop
grower. But a few staminate flowers are grown
here and there in the field to fertilize the others,
the cultivators feeling that the seed which would
not otherwise be produced has at least the value
of adding weight to the flower heads, and probably
it adds lupulin also.

The hop has been grown from prehistoric
times, and the exact country of its origin is not
known, although it is found growing wild in Colo-
rado and New Mexico in the high mountains where
it cannot have escaped from cultivation. But
comparatively little has been done in the way of
developing it, and there is good opportunity for
work in this field.

It goes without saying that different strains of
hop vines differ in productivity, and in the amount
of lupulin that their flowers secrete, and in the
quality of the product. Certain Bavarian hops
have lupulin of peculiarly fine flavor, but these are
all less productive than the hops grown in America.

Following out the principles of plant develop-
ment repeatedly presented, it may be assumed that
the hop can be improved as to productivity and
alkaloid content and the quality of the latter by
selection. Presumably improvement could be
facilitated by hybridization.

The plant is one that can readily be experi-

[161]

‘aanjaid ay} U} pajd4j
-snjj1 112m $1 dois ay} fo
avuppungy ayL *x1Nq 1)j0}
ay? pljlyj-auo upy} alour
$1 Juajuoa apGns ay} yoy
ui sjaaq fo saav1 dojaaap
0} 2]q1Ssod punoj uaaq spy
yu supaut siy} Aig *syuarpd
jaaq sv past alam juazu0a
upins ybiy vo Bulapy asoyj
fizuo pup ‘sjaaq juasas
-fip fo appur azam sasfijoup
yooiuraya jnfammy *u01j9a7a$
ynjams fiiaza jo suoj}DJa
-uab fig padojaaap usaq
spy }20q sawbns aul

sjaag
un6ng Jo plaid V

ON CHEMICAL YIELDING PLANTS

mented with, and it should attract the attention of
some one living in a region where this plant is
extensively cultivated. It is well to bear in mind
the staminate parent, and to test its strain of
productivity.

THE SuGar-BEET

The possibilities of stimulating a plant to outdo
itself in the production of its characteristic carbon
compounds are well illustrated by the story of the
sugar-beet.

It was not much over a half century ago that
the merits of this vegetable as a producer of sugar
began to be seriously considered.

The fact that sugar-cane grows only in warm
climates, and that here is a hardy plant that may
be grown anywhere within the temperate zone, .
stimulated the older Vilmorin brothers of Paris,
France, who had learned that the beet produces a
sugar chemical identical with that of the sugar-
cane, to make inquiry as to whether it might not
be possible to grow the beet on a commercial scale,
and extract its sugar in competition with the
product of the cane.

For a long time the attempt was not attended
with great success. But it was finally demonstrated
that the sugar-beet, even in its undeveloped form,
could be made available as a supplier of sugar on
a commercial scale, and then the attempt began to

[163]

LUTHER BURBANK

be made to develop varieties of beet having a
larger sugar content.

It is said that the beets at first used contained
only about six per cent of sugar.

But by careful selection through a series of
generations it has proved possible to increase the
sugar content of the beet, just as the length of
fiber of the cotton-boll was increased, merely by
paying heed generation after generation to the
individual plants that showed the best qualities,
and saving the seed of these plants only for the
raising of future crops.

Year by year the sugar content of the best
varieties of beets was increased until from six per
cent it had advanced to twenty per cent, and in
the case of some individual beets even to thirty-
five per cent; and in a few cases as high as thirty-
six per cent has been secured from whole fields of
beets in Colorado. This should be a wonderful
stimulant to plant developers everywhere.

There is perhaps no other case so widely known
or involving such large financial interests in which
a corresponding improvement has been made ina
commercial plant within recent years.

My own share in this work has been, until quite
recently, that of an adviser rather than that of a
direct experimenter. Some twenty years ago I
was asked by the sugar-beet manufacturers of both

[164]

A Sugar Beet Anomaly

This curious development on a sugar beet plant was found
in the field of Mr. W. K. Winterhalter. Its precise character
and significance have not been very clearly determined. Mr. Burbank
has frequently seen a similar phenomenon in connection with
the squash vine, but regards it as very unusual
among beets. Puzzles like this present them-
selves now and again to add zest to
the work of the plant developer.

LUTHER BURBANK

Europe and America to take up the improvement
of the beet. But while I gladly advised in the mat-
ter, and pointed out the lines of development
through which further improvement might be
expected, was unable to give personal attention to
experiments with the beet, owing to the pressure
of almost numberless other lines of investigation.

More recently, however, I have experimented
with varieties of the beet that were already very
greatly improved, working with seeds supplied by
prominent beet raisers who had developed their
product by combining the qualities of ten or more
varieties of Russian, German, French, and English
sugar-beets.

The crossbreeding experiments through which
I was endeavoring to increase still further the
capacity of the beet for sugar were, for reasons
already several times repeated, neglected.

But, so far as they progressed, they fell in line
with almost numberless other series of experi-
ments in plant development, and gave promise of
the production of a beet that would have a higher
sugar content than any beet hitherto under
cultivation.

Just what may be the limit to the percentage
of sugar that the beet can be expected to develop
would be matter of mere conjecture, but that it
will represent a considerable advance upon the

[166]

ON CHEMICAL YIELDING PLANTS

percentage already attained is scarcely open to
doubt. And even as the case stands, the sugar-
beet has attained a position in which it is, as we
have already seen, a dangerous rival for the sugar-
cane,

—The producers of sugar-beets
have been at work while the
producers of sugar-cane were
sleeping; and the results of
their efforts constitute a trium-
phant demonstration of the
value of scientific plant ex-
perimentation as an aid to
the practical agriculturist.

The So-Called Candle Cactus

No explanation is required as to how this cactus re-
ceived its popular name. It is a species oft grown for ornament
in regions suited to it. Mr. Burbank has utilized it, along with many
others, in his experimental work, although not with
directly productive results.

Vini-56

RECLAIMING THE DESERTS
WITH CACTUS

THE METHODS Usep To Propuce A SPINELESS
Cactus

they have known the antelope and the

buffalo to come for many miles to feast on
cactus plants whose spines had been burnt off by
a chance fire.

The spines of the catcus burn like tiny tapers,
leaving the slabs nearly unprotected, and the suc-
culent forage thus made accessible constituted a
treat that was precisely to the liking of the antelope
and the buffalo. Horses and cattle were found to
relish the plant equally under the same circum-
stances.

In the midst of the desert sands, with little else
eatable in sight that was more inviting than the
sagebrush with its dry and dusty foliage, the succu-
lent cactus slabs, held out invitingly, offered juicy
herbage that the animals browsed on with avidity.

Even when the cactus still retained its spines,

Pee tae will tell you that in the old days

[Votume VITJ—CuartTer VI]

LUTHER BURBANK

the antelope would sometimes.try to find a way of
getting at its juicy substance. I have heard plains-
men tell of seeing the antelope holding in its mouth
a slab that had been dislodged, and twisting its
neck this way and that in an effort to find an
unprotected spot at which it could nibble.

Obviously the cactus had need of its spines if
it was to escape the unwelcome attentions of the
browsing animals that found such difficulty in
securing sustenance among the dwarfed herbage
of the plains and deserts.

But by the same token it appears that if a way
could be found to take from the cactus its bristling
array of spines, the plant might be made to supply
forage in regions where other succulents cannot
secure a foothold. So the problem of producing a
spineless cactus was one that had but to be sug-
gested to any one who knew the life of the arid
regions to make instant appeal.

MATERIALS AND RESULTS

It was obvious, however, to anyone having any
clear knowledge of plant development, that the
task of removing the spines from the cactus would
be a very arduous one.

It is true that there are small species of cactus
that are spineless, or nearly so, that have been
familiar for generations. One of the first pets of
my childhood days was a thornless cactus, a beau-

[170]

The Quisco Cactus

This is @ species
from South America
which is so thorny that it
is impossible to touch the
finger to it at any point.
Mr. Burbank has given it
a place in his garden,
along with many others, to
see whether it shows a
tendency to variation, and
thus gives promise of pas-
sible modification. It is
viewed, however, more as
a curiosity than as the
probable progenitor of a
plant of economic
importance.

LUTHER BURBANK

tiful little plant of the genus Ephiphiylum. There
are also members of the Cereus family that are
thornless, showing not a trace of spine on any part
of the plant or fruit.

But the cactus plants that are thus unprovided
with spines were without exception small and
inconspicuous species, and also with a bitter prin-
ciple so disagreeable that cattle generally refused
to eat the plants. So the plants offered no possi-
bilities of direct development through selection,
that could promise the production of varieties that
would have value as forage plants.

Meantime the large varieties, in particular the
members of the genus Opuntia, which have pecu-
liarly attractive qualities of size and succulence,
are thickly studded with spines for the very reason,
doubtless, that were they not thus protected they
could never have maintained existence in regions
inhabited by the jack rabbit, antelope and buffalo.

If the problem of securing:a spineless cactus of
value as a forage plant—to reclaim the deserts and
supply succulent food for herbivorous animals
where now little but sagebrush grows—was to be
solved, it would be necessary, I thought, to hybrid-
ize the already well-known, partially spineless
species of cactus with the large-growing, spiny
ones. There seemed reason to hope that a reas-
sortment of hereditary characters might be

[172]

ON THE SPINELESS CACTUS

brought about, such as we have seen, for example,
in the case of thornless blackberry and sioneless
plum among other plant developments.

Thus the qualities of size and succulence of the
Opuntia might perhaps be combined with the
smooth skin of the small, partially spineless
species.

The hope that it might be possible to effect such
a transformation through hybridization was
abundantly justified. In due time such a new race
was developed, a gigantic cactus, overtopping all
its known ancestors in size, and surpassing them
all in succulence of flesh, producing fruit of unpre-
dicted excellence in almost unbelievable quantity,
and having a surface as smooth as the palm of your
hand. Such a plant was produced as the result of
hybridizing experiments, followed up and supple-
mented by the usual methods of rigid selection.
But the result was not achieved with the small
cacti referred to. Meantime I was carrying on
extensive experiments with all the half-spineless
ones which had been well known for centuries.

A Sovut-Testing EXPERIENCE

But the work through which this result was
achieved constituted in some respects the most
arduous and soul-testing experience that I have
ever undergone.

In carrying out the experiments, from the initial

[173]

LUTHER BURBANK

pollenizing through stages that involved the
handling of seed and the constant handling of seed-
lings, I was obliged to associate intimately with
the cactus plants, and it was impossible to avoid
their spicules, Particularly after the work had
advanced to a stage where the larger spines had
been removed and the remaining spicules were in
little bundles on the older leaves, did it become
impossible to handle them without filling one’s
fingers with the irritating prickles.

For five years or more the cactus blooming
season was a period of torment to me both day and
night, Time and again I have declared from the
bottom of my heart that I wished I had never
touched the cactus to attempt to remove its spines.
Looking back on the experience now, I feel that I
would not have courage to renew the experiments
were it necessary to go through the same ordeal
again.

Not only would the little spicules find lodgment
everywhere in my skin, but my clothing became
filled with them, and the little barbs would gradu-
ally work their way through the cloth and into my
flesh, causing intense irritation.

At first I devoted much time to the endeavor to
remove the very inconspicuous but exceedingly
irritating and pain-producing little spicules with
the aid of a magnifying glass and forceps. ButlI

[174]

viil-58

Vestigial Leaves

Tne spine-like projections here shown on the slab of the
cactus are vestigial leaves. An account of them, with reference
to their evolutionary meaning, is given in Volume I. They are all that
remain of the leaves that the cactus once bore; and these
reminiscent spikes drop off shortly after coming out.

LUTHER BURBANK

learned ultimately that the only satisfactory
expedient was to shave off the spicules with a
sharp razor, or to sandpaper them off, which can
readily be done where a great quantity is to be
dealt with. When thus reduced in size they would
not farther enter the flesh, and gradually the pain
would subside.

But the recollection of the torture in connection
with the development of the spineless cactus will
always remain the most painful one associated
with any of my plant developments.

No other complication comparable to this has
been encountered in connection with the consider-
ably over ten thousand species of plants with
which I have experimented.

But possibly it will appear in the end that no
other series of experiments that I have undertaken
can be compared in importance to the production
of the race of spineless giants which tower to
almost treelike proportions, and grow with such
rapidity as to produce on good agricultural land
from one hundred and fifty to three hundred tons
of new forage to the acre annually by the third
season after planting, besides nearly one-half as
much fruit, yet which are as tender and succulent
as grass, affording forage of fine quality in
unprecedented quantity, and which can send their
roots far into the earth and gain a supply of water

[176]

Giants and Dwarfs

These cactus seedlings show amazing variation. Though
grown from the same lot of seeds, some of them are mere pig-
mies, while others rise to proportions that, by contrast, are colossal.
The child is father to the man; and the big children of this
lot of seedlings will make big mature plants, while
the little ones will always be dwarfs.

LUTHER BURBANK

for their sustenance from subterranean sources in
regions where the surface of the country is that of
the desert; economizing this for long seasons of
drought which may follow.

HEREDITARY TRAITS

These new races of spineless cactus are of many
varieties, in token of their varied ancestry.

In producing them I followed my usual custom
of securing material from every available source.

The main supply came, naturally, from the arid
regions of the Southwest; the original home of the
cactus. But I received also plants from Minnesota,
Montana, Dakota, New England, Missouri, and
Colorado, South America, North and South Africa,
and regions around the Mediterranean. It could
not be known at the outset just what crosses would
be most effective, and so experimented on every
species on which I could lay hands. I pollenized the
giant Tunas with pollen of the little trailing cactus,
and with such inconspicuous cousins of the giant
as the little hardy Opuntia vulgaris,

There were several small more or less spineless
species available, and others that produced a com-
paratively small crop of spines, and of course it
was recognized from the outset that these must be
our main reliance, Just as the little French par-
tially stoneless plum had been the foundation for
building the stoneless plums and prunes of to-day,

[178]

ON THE SPINELESS CACTUS

it was thought that the little cactus that was smooth
skinned might furnish the element of spinelessness
in all the future races of spineless cactus, however
varied the other elements of their heritage.

The most curious feature about the crossing of
the giant Opuntias with the small species, in par-
ticular with the little cactus of the Eastern United
States known as Opuntia vulgaris was that the
hybrid was intermediate between the parents as to
every characteristic but one. In size, stem, and
manner of growth and form of pads, it made a
complete blend of the traits of the two totally
dissimilar parents.

But its blossom was a relatively enormous
flower, very much larger than that of either parent.

As to the blend of traits of this bybrid of giant
and dwarf forms of cactus, the phenomena
observed were obviously comparable to those that
we have seen in sundry other connections. The
Primus Berry, the Sunberry, and the Plumcot, will
be recalled as illustrating the production of new
forms, unlike either parent yet breeding true to the
new type in a single generation.

The hybrid between the giant and dwarf
Opuntias furnishes another illustration of the same
thing. This intermediate type, strikingly dissimi-
lar to either parent yet obviously blending the
characteristics of both, bred true to form, showing

[179],

*smjovd = ssajaunds
ay} fo Juauidojaaap ay}
ul abpjs pw juasaidar fiayy
‘asn sayjin{ ao0f pajaajas
aq yim sauids upy} JayyoI
‘saava}? fiapjuagunpni ay}
moys joy} sauo ayy ulay}
Guoup ulolg ‘Uu01pasrasqo
Guro61apun ‘sadAj juasa{ip
fizaa jo sBuljpaas sn}
-0D9 aUlOs am alaH

uo1zads
-uy 10,] fippay
sbuiypaag snjzop")

ON THE SPINELESS CACTUS

nothing of that tendency to racial variation in the
second generation that marks hybrids in general,
and that, as will appear in a moment, marks the
hybrids of the other cactuses very conspicuously.

But there is an added element of great interest
in the fact that the blossoms of the new hybrid
so markedly differs from the flowers of either par-
ent and so conspicuously excels either of them in
size and beauty.

It would seem that the floral envelope occupies
a position in the hereditary scale somewhat dif-
ferent from that of the main stem of the plant. And
this is perhaps not strange, when we reflect that
the flower is a relatively recent development in
the history of plant life.

We have already noted that flowering plants
are of comparatively recent origin, geologically
speaking.

We have seen evidences here and there of the
relative adaptability of the floral envelope as com-
pared with the stem and leaf structure of the plant.
So this new illustration of that phenomenon need
not surprise us, however much it may interest us.

It would appear, if we may interpret the phe-
nomena just presented, that the giant and dwarf
Opuntias have diverged so widely that they are
practically at the limits of affinity that permit
crossbreeding. The stems and main structures of

[181]

LUTHER BURBANK

the plant, therefore, refuse to conform to the prin-
ciples of Mendelian segregation, and hit upon a
compromise in which the traits of each plant find
representation.

But the flower, somewhat less fixed as to its
characteristics, and indeed somewhat less widely
divergent in the two species, accepts a compro-
mise of a different order, and, under stimulus of
that strange influence which we do not well under-
stand but which we see constantly illustrated, it
takes on a new vigor of growth.

It surpasses the flowers of either one of its
immediate ancestors somewhat as the hybrid
Royal Walnut tree surpasses its parents in growth.

This phenomenon of great vigor or tendency to
excessive growth developed through hybridization,
is, as we have seen, a very common one; its peculi-
arity in the present instance is merely that here it
applies to the flower of the plant alone, whereas
elsewhere we have usually seen it apply to the
entire structure of the plant, including at least in
some cases (for example the Primus Berry, the
Phenomenal Berry, and the Royal Walnut) the
fruit as well.

Let me add that when the Opuntias not quite
so diverse in form as the giants and dwarfs were
hybridized, the progeny showed the tendency to
increased vigor of general growth, not merely to

[182]

Spineless and
Spiny of the
Same Fra-
ternity

These plants were
grown from the seeds
of a single cactus fruit.
Three of them are perfectly
spineless, while one is un-
usually spiny; but all have
the long rounded form of
the parent, which differed
in this particular from
most other plants of
the same variety.

LUTHER BURBANK

increase of the flower, although productivity was
also emphasized.

Indeed, it is to the fact of such stimulus of
growth by hybridization that my success in devel-
oping the gigantic races of spineless cactus is due.

Hysripizinc MATERIALS AND METHODS

The hand pollenizing of the cactus, which was
the foundation of these experiments in the pro-
ducing of the new spineless races, presents no
technical difficulties yet requires to be carried out
in a particular way.

The cactus flowers open only in the very hottest
part of the day, and within fifteen minutes after
the pollen-bearers are exposed there is probability
that the wind or bees will have accomplished self-
fertilization of many of the flowers, It is neces-
sary, therefore, for the experimenter to be on the
spot, to anticipate the opening of the flower.

Our method was to collect pollen in watch crys-
tals, and, if necessary, keep it until the flowers we
wished to pollenize were matured. As the differ-
ent varieties of cactus bloom at different seasons,
it was sometimes necessary to keep the pollen for
a considerable period.

When the plant to be pollenized is ready to
bloom, nothing more is necessary than to remove
its stamens just before they are matured, and to .
dust pollen from watch crystal with a camel’s hair

[184]

Mr. Burbank Selecting Cactus Seedlings

Remember that most of these little fellows are covered
with spicules. Mr. Burbank’s hands are also covered with
spicules; and his clothes are full of them. He asserts that the task
of dealing with these tiny citizens, in the effort to edu-
cate them into spinelessness, was the most
painful one in his experience.

LUTHER BURBANK

brush over the receptive stigma, being careful not
to allow the brush to become smeared with pollen
from the stamen, lest the next pollenizing be
vitiated.

Each blossom thus pollenized is of course
tagged to make permanent record of the cross, in
accordance with the method detailed in an earlier
chapter.

It was customary, wherever possible, to make
the cross reciprocal, although with the Opuntias
as with other plants, it appears to make little if
any difference as to which is the staminate and
which the pistillate parent. Here as elsewhere in
the plant world the factors of heredity appear asa
rule to be distributed impartially between pollen
grains and ovules.

The cactus plants that served as material for
my comprehensive experiments aiming at the
development of a spineless race of economic value
were very numerous as to species and very widely
diversified as to form and habit. More than one
thousand species of cactus are listed by the botan-
ist, and there is the greatest amount of variability,
so that no two botanists are agreed as to the pre-
cise classification of all the forms.

Of course I have not had every species of cactus
at my disposal, but the number with which I have
worked is very large indeed.

[186]

ON THE SPINELESS CACTUS

For years collectors in all parts of the world
have gathered specimens for me, and as knowledge
of my work went abroad, even collectors who
knew me only by reputation have sent specimens
of one kind or another, until my experiment gar-
den may be considered the great gathering place
of the varied clans of the cactus family.

In addition to the specimens received from
private collectors, I received also a collection that
had been gathered at Washington for botanical
classification. Most of these were curious thorny
specimens, and I think none of them was used in
my successful experiments, although all of them
were tested.

Some of the most important acquisitions were
sent by my friend, David C. Fairchild, including
slabs gathered in France and Sicily. I received
also specimens from Mexico, South America, and
Hawaii, as well as almost numberless varieties
from all regions of the United States where any
form of cactus grows. The so-called Smith Cac-
tus, a variety introduced into California by Pro-
fessor Emery E. Smith, about forty years ago,
proved of value as a hybridizing agent.

Many Species, But More NamMes

But it is almost impossible to gain a really
accurate conception of the materials employed,
because of the great confusion of the classifiers,

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ON THE SPINELESS CACTUS

which has led to the ascribing of different names
in many cases to the same species.

For example, the variety which I received
under the name “Anacantha” (meaning “without
spines”) from Fairchild, is identical with speci-
mens received from the Department of Agriculture
bearing only a number, and with others received
from Italy on one hand, and from my collector in
South America on the other, one of the numerous
specimens coming under the name “Gymnocarpa.”

It was often only by careful inspection and
observation under hybridizing experiments that
we could identify the various specimens as being
of the same species, or same variety.

Again the so-called Morada, another species
that proved of value, was first received under the
name Amarillo, meaning yellow, from near Vera
Cruz, Mexico, it having been sent me by the late
Walter Bryant, formerly of Santa Rosa. This I
found to be practically identical with another
specimen that had come from southern Europe,
under the name of Malta.

Another useful variety that came from various
regions under different aliases was the form that
has been grown in Florida and in California for
the last thirty or forty years and which goes by
the common name of White Fruit.

There are marked variations in the color and

[189]

LUTHER BURBANK

quality of the fruit of this cactus, the pulp some-
times being white and again variegated with
yellow.

Specimens from different parts of the world
might at first sight be thought to represent different
species or at least different varieties; but I have
found the various kinds of fruit growing on con-
tiguous branches of the same plant.

The large species of cactus that grows
commonly in the Mediterranean region, known
there as Indian Fig or Barbary Fig, is closely simi-
lar if not identical with the species called Tuna in
Mexico, although the fruit of the Mexican variety
is usually somewhat smaller than that of the Old
World form. The name tuna is applied indiscrim-
inately in Mexico to cultivated and wild species
of the tribe, but the varieties are sometimes recog-
nized by different names, as Tuna Amarillo, Tuna
Colorado, Tuna Blanca, etc.

Another quite common Mexican form known as
Tapuna, appears to be entitled to recognition as
a distinct species of Opuntia.

It produces flat leaves that are generally
circular or heart-shaped. The plant does not grow
as rapidly as others of the large-fruit Opuntias,
and the fruit ripens late in the season. The leaves
have a somewhat white appearance, as if dusted
with flour, which distinguishes them readily from

[190]

Cactus Plants in the Nursery

Here the slabs originally planted have put forth several new
slabs, showing that they have taken root and are thriving. The
plants here are much too close together for permanent growth. At the
end of the first year, the new slabs are used for transplanting
at wider distances for forage or fruiting purposes.

LUTHER BURBANK

the others. The fruit is rarely edible except for
stock.

The Tapuna is also of rather exceptional com-
pactness of growth and has high nutritional value
as a forage plant. Moreover it is a much hardier
species than many others, resisting both cold and
wet better than most of the best Opuntias.

So this species has characteristics of obvious
value from the standpoint of the plant developer.
THE QUESTION OF SPINELESSNESS

But what about the matter of spines?

This, of course, from the standpoint of the
present investigation, is the vital question.

The question might be answered categorically,
with the statement that not a single one of the
Opuntias received from any source was altogether
spineless. Spineless forms of some of the other
genera are familiar, but it was early discovered
that the Opuntias must be looked to for the devel-
opment of a race of cactus that would have
economic value. And, as I said, no form of Opun-
tia was received, among all the hundreds of
specimens from various parts of the world, that
was altogether spineless and spiculeless.

The form already referred to as the Anacantha,
of which specimens were received from Fairchild
and from others, came as near to spinelessness as
any other form of true Opuntia.

[192]

ON THE SPINELESS CACTUS

There is a very small and very tender species
that is allied to the Opuntias, but is generally
classified as a Nopalia, which was received from
various parts of California and Mexico, as well as
from the Hawaiian Islands, the Philippines, and
from Europe, under various names, which is
altogether spineless.

But this species is very sensitive to frost or to
excessive heat, and in general succumbs to any
untoward conditions so readily as to be valueless
for this purpose, besides not being relished by
any stock.

We have already referred to the fact that there
are absolutely spineless forms of the genera
Epiphyllum and Cereus.

These, indeed, have been well known to me for
fifty years, and are familiar to all students of
plant life. But, as just noted, investigations
showed that the genus Opuntia must be depended
on for material with which to build an economic
race of spineless cactus.

My experiment, it will be understood, was,
intensely practical in its aim from the outset.

It was not at all my thought merely to produce
an interesting race of spineless cactus of diversi-
fied forms.

The spineless cactus of my ideal was one that
would have practical value as a forage plant; one,

[193]

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ON THE SPINELESS CACTUS

therefore, that would grow luxuriantly in arid
places, would be reasonably hardy and resistant
to extremes of temperature, and would produce
an abundance of succulent forage as well as a
supply of palatable fruit.

I repeat that I have still to see a form of
Opuntia that is of good size and suitable for forage
and yet that is altogether free from spines and
spicules, except the ones that have been developed
in my experiment gardens, and their progeny; and
no such variety has yet been reported, although
the authorities of the Agricultural Department of
Washington scoured the earth to find such a
variety.

These, indeed, are Opuntias fulfilling every
specification of spineless forage plants of reason-
able hardiness, great adaptability as to soil and
easy culture, and enormous productivity; and they
are wonderful fruit producers as well. But they
are the result of a most arduous series of experi-
ments in plant development, and they constitute
new races, entitled to the rank of new species if
ordinary botanical standards are to be accepted,
that have been developed here, and that, so far as
there is any evidence, had never previously existed
anywhere in the world.

Their descendants have gone forth to begin the
reclamation of the arid places of many lands, and

[195]

LUTHER BURBANK

also to be grown with profit even in the most
expensive agricultural lands, especially for feed-
ing with other forage crops. But in no land will
they come upon a cactus from any other region
that closely resembles them in their combination of
entire spinelessness and inviting forage qualities.
PARTIALLY SPINELESS MATERIAL

Yet it must be understood that the various
specimens of cactus that have been sent me from
all over the world, many of which were utilized
in crossing and hybridizing and selective experi-
ments, were often forwarded under the supposi-
tion that they were specimens of spineless races.

And many of them were relatively spineless.

Some of them showed individual slabs that
were almost free from spines.

But without exception these plants, notwith-
standing their relative smoothness, would be found
to have inconspicuous spicules or bristles, which
constituted an armament almost as offensive as
the larger spines; or else would soon demonstrate
that their spinelessness was an individual peculi-
arity rather than a trait of the race to which they
belonged, by developing spines on new slabs.

Yet the fact that partially thornless Opuntias
exist in many regions demonstrates a tendency on
the part of this plant to give up its spines partially
under some circumstances.

[196]

Spineless Cactus
Showing Two
Months’ Growth

This picture shows

the rapidity of growth
of some of Mr. Burbank’s
improved varieties of
spineless cactus. The cen-
tral slab originally planted
has put forth several off-
shoots, and these of course
have sent out numerous
branches; so. that now,
oniy two months after the
time of planting, the plant
begins to take on the as-
pect of a cactus colony. Of
course rapid growth was
one of the important fac-
tors which Mr. Burbank
had constantly in mind
in making his selections.

LUTHER BURBANK

It shows that in the heredity of the plant there
are strains of spinelessness that might presumably
be utilized by the plant developer in the produc-
tion of a spineless race.

In particular it was learned that there is in the
Hawaiian Islands cactus that develops specimens
that are partially thornless when grown on moun-
tain sides in positions absolutely inaccessible to
browsing animals. -Also in California, Mexico,
Colorado, New Mexico, and Texas, as I learned
from various reports, small patches of half thorn-
less cactus are sometimes found, always in inac-
cessible crevices among the rocks. These all appear
to be species of Nopalia and not Opuntia.

In some of the South Sea Islands where vegeta-
tion is abundant, and where browsing animals
are few, the Opuntias have either reverted to a
spineless condition, or have retained spines that
have become merely hairlike appendages.

This tendency to produce partially spineless
races when the plant is grown under conditions
that make it inaccessible to browsing animals,
seems clearly to demonstrate that there are
obscure factors of thornlessness in its prehistoric
heredity. Our general studies in the effects of
hybridizing give adequate clues as to the way in
which these submerged factors may be brought
to the surface.

[198]

A Thrifty Yearling

Here is a year-old plant of one of Mr. Burbank's improved
varieties of spineless cactus. So thrifty is this youngster that
it will need to be considerably thinned by the removal of numerous
slabs, if it is to attain symmetrical growth. But of course
each discarded slab may serve as the basal slab
of a new plant just like the parent.

LUTHER BURBANK

The open secret, of course, is to blend the
different strains of heredity by hybridizing the
various Opuntias, and to select for propagation
the seedlings that reveal the spineless condition
in combination with other desired qualities.

A SPINELESS RACE ACHIEVED

From the outset I had been making hybridizing
experiments, in which I utilized in particular the
hardiest races of Opuntias that I could find, choos-
ing, of course, at the same time, those that showed
a tendency to produce relatively sparse crops of
spines.

In this way I had developed races of cactus
that though small in size were hardy, and that
ultimately, after nine years’ work, produced speci-
mens that were absolutely free from spines. After
’ the spines were gone, however, there remained
-Spicules, which grow in little clusters of several
hundred here and there over the surface of the
leaf, and which are an even greater annoyance
than the larger spines to the plant experimenter,
although they are sometimes ignored by browsing
beasts. At the present day absolutely smooth ones
have been produced on my grounds, bearing also
smooth, handsome fruit of excellent quality. As
these have come from a stock hardier than any
oak tree, they can probably be grown in Alaska.

The hardy and partially spineless cactuses first

[200]

A Yearling of Dif-
ferent Type

This is another
spineless cactus year-
ling, but one showing a
quite different manner of
growth from the one in the
preceding picture. Here
the slabs are put out sym-
metrically from the edge
of the parent slab, and it
may be predicted that the
plant will grow into 1
compact tree-like form,
and need little at-
tention.

LUTHER BURBANK

produced were hybridized, when my more exten-
sive experiments were under way, with the best
examples of the large Opuntias received from
all parts of the world.

In making these crosses I bore in mind always
the condition of relative spinelessness, but also the
characteristics of the plant as regards size and
fruit-production and quality.

The precise parentage of the hybrids of the first
generation was recorded, as already stated. But
when the seedlings came to be handled by literal
millions, and when the specimens that were util-
ized numbered scores of alleged species, between
which it was often difficult to differentiate, it
finally became impossible to attempt to follow the
exact pedigrees of the selected plants, if my
experiments were to be carried out on the
expansive scale that was contemplated.

The seeds from different crosses were planted
separately, and the character of the seedling would
reveal at an early period the quality of the plant
as regards the tendency to produce spines, but not
at this early stage the quality or quantity of fruit.

When the cactus seedlings first appear above
ground, their cotyledons are spineless. This sug-
gests a period when all cactus plants were without
spines, for it is a familiar doctrine that the devel-
oping embryo reproduces in epitome the stages of

[202]

|

Another Well-Balanced Cactus

This photograph also shows a spineless cactus in its first
season. The manner of growth of.this specimen is almost ideal.

It spreads its slabs in such a way as to get the largest available supply
of light and air for each, without mutual interference. Plants
that take this form may be grown relatively close
together, insuring a large production per acre.

LUTHER BURBANK

its racial history; and the plant at the cotyledon
stage may be regarded as really still an embryo,
inasmuch as it is drawing its nourishment from
the nutritive matter stored in the seed.

The first leaf that puts out just above the
cotyledons may be spiny or hairy, in recognition of
the racial period when spines were worn, even in
my new spineless varieties. But the quality of
these little spicules will enable the experienced
experimenter to determine whether they represent
future spines or only a racial reminiscence.

So it is possible to make first selection among
the seedlings at a very early period, and to weed
out from among the hundreds of thousands all but
a few.

Unfortunately the cactus requires from three
to five years from the seed to come to fruiting time.
So the experimenter who is attempting to develop
an improved spineless race must wait patiently
throughout this long period before he can effect a
second hybridization and thus carry his plant one
stage farther along the road to the coveted goal.

But by carefully selecting the seedlings that
show the most likelihood of a propensity to pro-
duce smooth slabs, yet which at the same time are
strong of growth and resistant to unfavorable con-
ditions, it is possible to note marked progress even
in a single generation. And when the selected

[204]

ON THE SPINELESS CACTUS

plants have come to blossoming time and have
been hybridized with the best among their fellows,
the seedlings of this second generation will show
numerous individuals that are markedly superior
to their parents or their grandparents in regard
to all the desired qualities.

In this second generation (we are not now
speaking of the giants and dwarfs referred to
earlier in the chapter) is manifested the usual
tendency to recombination of the hereditary
factors.

In such companies of seedlings as I developed,
where hundreds of thousands of plants are
grouped together, one is sure to find at least a
few specimens that combine the spineless quality
of one remote ancestor with the tendency to large
growth of another, the fruiting capacity of a third,
and so on. By attentive scrutinizing of the seed-
lings, at an early stage of their development, it
was found possible to select thus the few individ-
uals among the thousands that revealed the best
combinations of qualities.

These are transplanted by themselves, and
given every favorable condition to stimulate their
growth and development, and finally placed in
long rows for field culture, where they are allowed
to stand for three or four years, and in the end, if
one out of three hundred or four hundred is found

[205]

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ON THE SPINELESS CACTUS

sufficiently valuable with which to continue the
work, the experiment may be considered success-
ful thus far.

It is tedious to wait another term of years
before going to the next hybridizing experiment
that will give a still better crop of seedlings from
which to make new selections. But of course
numberless experiments with other plants are
being carried out in the interval, and so the time
does not seem so long while it is passing, as it
seems in retrospect.

Let it suffice that after fifteen years of effort,
involving the collection of materials from all over
the globe, the hybridizing in the aggregate of
thousands of individuals, and successive selections
among literal millions of seedlings, I was at last
rewarded by the production not merely of one but
of numerous varieties of hybrid Opuntias that
grow to enormous size, producing an unbelievable
quantity of succulent forage; the slabs of which
are as free from spines or spicules as a water-
melon; and that produce enormous quantities of
delicious fruit.

Some inkling, perhaps, of the difficulties of the
experiments through which this result was
achieved have been revealed in the preceding
pages.

Something of the economic importance of the

[207]

LUTHER BURBANK

achievement will be suggested in ensuing chapters.
Here let it suffice to repeat that the series of
experiments in which the giant spineless fruiting
Opuntias were developed was in some respects the
most painful, arduous, and difficult of all my long
series of plant developments; and that there is
reason to believe that its results will ultimately vie
with the results of any other single experiment in
economic importance.

—Here is a new species of
spineless giant cactus which
towers to almost tree-like
proportions, and grows with
such rapidity as to produce,
on good agricultural land,
from one hundred and fifty
to three hundred tons of new
forage to the acre annually,
by the third season after
planting, besides nearly
one-half as much fruit.

A RIVAL OF ALFALFA

THE COMMERCIAL POSSIBILITIES OF CACTUS
As CATTLE Foop

first of my spineless cactus productions in
the southern hemisphere was sold to Mr.
John M. Rutland, of Australia.

Mr. Rutland had come to Santa Rosa to observe
my experiments, and desired to take back with
him the Spineless Cactus along with certain other
of my new products, including the first of the
Plumcots.

He very gladly paid one thousand dollars for a
single slab of the most important of the new
Opuntias, named the “Santa Rosa,” and somewhat
smaller sums for slabs of several other varieties,
including the “Sonoma”, “California”, “Fresno”,
and “Chico”. He purchased the privilege also of
introducing the new plants throughout the south-
ern hemisphere.

This was the first financial return for the work

[VotumE VIII—Cuaprter VII]

T HE right of introduction of certain of the

LUTHER BURBANK

on the Opuntias. It practically paid for the build-
ing of my new home, but, of course, fell far short
of the sum expended on the cactus experiments.

A little later a company, formed to control the
introduction of the plant in the northern hemi-
sphere, paid me a large sum for my interest in the
entire stock, including one or two hardy hybrids
that had value for further experimental purposes.
The original sale included individual slabs of the
different varieties just named, and a few others,
The later deliveries included more than fifty tons
of slabs and plant bodies, constituting the tangible
results of the long series of experiments.

My experiment garden, however, still has a
large quantity of Opuntias in various stages of
development, but particularly those that are being
developed for their fruiting qualities. Not less
than five hundred tons of forage—as nearly as can
be estimated—are now standing on less than half
an acre at Santa Rosa.

As forage plants, the spineless Opuntias already
developed have attained a degree of perfection
that leaves little to be desired.

PROPAGATION OF THE SPINELESS OPUNTIAS

It should be understood that the new varieties
of Opuntias, while as a whole they may be
regarded as constituting a new species, are individ-
ually comparable to the different recognized varie-

[210]

The “Gravity” Cactus

This very commendable member. of Mr. Burbank's spine-
less colony has been named the “Gravity.” The name was sug-
gested by the fact that many of the slabs tend to assume a perpendicu-
lar position, as if they were suspended by invisible wires and
under influence of gravity. A plant of this kind grows about
the largest possible number of slabs on a given area.

LUTHER BURBANK

ties of any given orchard fruit, like the best apples,
or pears, or plums.

That is to say, they may be indefinitely propa-
gated by division, and all the plants grown from
the original individual will retain the essential
characteristics of the original. But, like apples,
pears, and plums, they cannot be depended on to
transmit their best characteristics unvaryingly
from the seed.

With the new Opuntias, as with the orchard
fruits and so many cultivated plants, the various
hereditary factors are blended in more or less
unstable combinations, and this unstability will be
revealed in the offspring grown from the seed.

So the recognized method of propagating the
Opuntias is to plant a slab, and to let this serve
as the foundation from which roots and branches
will grow. The slabs that develop on each plant
may of course be similarly cut off and planted, so
that a large territory may be rapidly covered with
cactus plants, all precisely like the original.

Mention was made in the preceding chapter of
certain cases in which an individual cactus slab
that was practically without spines might develop
other slabs that would be spiny. This could only
occur, however, in case the slab in question was
an individual variant which owed its lack of spines
to some local condition of altered nutrition.

[212]

Contrasting Types

of Cactus

At the left, a col-
ony of spineless cactus
called the ‘“Tapuna’; at
the right a quite different
type called the “Tuna.”
Like all Mr. Burbank's
spineless cactuses, these
are crossbred seedlings;
and they are of closely sim-
ilar lineage, notwithstand-
ing their widely different
appearance. Another in-
stance of the segregation
of hereditary char-
acters.

LUTHER BURBANK

A slab growing as a part of a plant that is
spineless throughout will produce only spineless
plants, with the exception of very rare bud sports
which appear on all plants from time to time.

The case of the Opuntias in this regard is
precisely comparable to that of the orchard trees
that are propagated by grafting. In each case the
entire crop of plants, although multiplied until the
offshoots of a single plant may cover hundreds or
thousands of acres, really constitutes essentially
one plant with divided personality, rather than
successive generations of plants.

SPINELESS CACTUS FROM THE SEED

Yet the important question has arisen as to
what will take place when the transplanted Opun-
tias, once they have come to populate the arid
places, produce fruit, and scatter their seeds. The
answer is that no bad results will ensue.

The reason is that the new hybrid Opuntias
have been found to be seedless; or, where the seeds
are not entirely eliminated, they are reduced in
size and have lost vitality. In my experience, then,
when the improved species have ripened and
dropped to the ground, under the most favorable
possible circumstances, no seedlings have been
seen; whereas, when the fruit of the wild ones
drops there are abundant seedlings.

The case is comparable to that of the Shasta

[214]

A Promising Fruit Crop

This cactus is known as the “Opaline.” At the time when
the photograph was taken the fruit was only partially matured.
It is obvious that a good crop is in prospect. The fruit crop per acre
of Mr. Burbank’s best fruiting varieties of spineless cactus is
measured by scores of tons, instead of by mere bushels.

LUTHER BURBANK

daisy, which never spreads from the seed, unlike
its wild prototype. When the Shasta was first
introduced, one of the western states passed a law
forbidding its growth in the state. At the present
time the Shastas are grown by the millions in that
state, as well as in all other regions of the world,
and no one has ever complained.

With care in propagating, and reasonable
protection, the new spineless Opuntias constitute
a race that gives every assurance of permanency.

Yet it should not be forgotten that this race has
been developed under conditions of artificial
selection, and may need man’s protection while it
is establishing itself in any given region.

The new spineless Opuntias represent a race
that has been permitted, through the fostering
influence of artificial selection, to develop, not-
withstanding its loss of the protective spines. Now
that it has been developed, and the spineless con-
dition combined with the traits of prolific growth
and abundant bearing, the race which could never
have made its way under natural conditions may
be sent back to the desert to provide forage for
browsing animals in almost unbelievable quantity.

But even now it will be necessary to protect the
young plants from the herds. It is only after the
Opuntia has attained a fair growth that it could
withstand the attacks of the herbivorous animals,

[216]

Vill 74

The Niagara

Cactus

It is no easy mat-
ter to find appropriate

names for new varieties of
plants, where so many of
them are in evidence as in
Mr. Burbank’s gardens.
Possibly no one recalls just
why the present cactus was
called the “‘Niagara,’’—con-
ceivably because its slabs
tend so to overflow into

space and buffet

one another.

LUTHER BURBANK

which find its succulent slabs altogether to their
liking.

Some uninformed newspaper reporters have
unfortunately given the impression to the pub-
lic that the seed of the improved varieties
could be sown on the desert land like wheat, and
grown without fencing or other protection. Let
us ask, what crop that man values in any country
is not fenced? The more valuable the crop, the
more carefully must it be protected. The very fact
that all herbivorous animals relish these new
creations proves their value and the necessity for
protecting them.

Botu Foop anp Drink

So thoroughly appealing, indecd, is the flesh of
the cactus plant to the palate of the herbivorous
animals that many of them will feed on it even
when the slabs are protected by spines.

There are regions in Mexico and Hawaii where
the cattle feed habitually on wild species of Opun-
tias, even though this involves the habitual inges-
tion of millions of spines and spicules with which
the slabs are protected; resulting quite often in
sickness or death of the animals.

The manager of a ranch in Hawaii, writing to
the editor of the “Butchers’ and Stockgrowers’
Journal,” of California, under date of April 17,
1905, declares that on his ranch there is a paddock

[218]

VIN-15

The “Prolific”

Cactus

It requires but a
glance at the picture to
show that this cactus de-
serves its name. These
young plants, only a few
months old, are already
crowding one another and,
as it were, clamoring for
space. It will be necessary
to transplant them very
quickly, or they wiil con-
stitute an impenetrable
jungle.

LUTHER BURBANK

of 1,200 acres covered very thickly with cactus or
prickly pears, with only a slight growth of Ber-
muda grass. In this paddock, he tells us, are
pastured all the year round 400 head of cattle
and about 700 hogs.

For both cattle and hogs the cactus furnishes
the chief food. The hogs receive only a slight
ration of corn, fed to keep them tame, and for the
rest live exclusively on the young leaves and fruit
of the cactus.

Both cattle and hogs thrive wonderfully. But
when the cattle are killed, it is found that the walls
of their first stomach are filled with myriads of
small spines. The manager adds that he has never
known an animal to die from the effects of these
spines. This is a half dwarf, partially spineless
variety, which is sometimes found in tropical
islands. Yet it is obvious that the spines cannot
add to the health of the creature, and it is hardly
to be doubted that the animals will appreciate the
spineless varieties when they have access to them.

But the most remarkable part of the story
remains to be told.

This is the fact that the cattle have water to
drink only during the rainy season, which usually
includes the months of December and January.
During these two months there is a certain amount
of grass and they have water to drink.

[220]

ON CACTUS AS CATTLE FOOD

But during the other ten months of the year
the cattle subsist exclusively on the fruit and
young leaves of the cactus.

They receive not a drop of water except as they
find it in the succulent cactus slabs.

“Yet,” the narrator continues, “it is a remark-
able fact that during the dry months of the year
we get a higher percentage of fat cattle from that
paddock than from any of the others.” He adds
that he considers the cattle fed in this way on
cactus to make as well-flavored beef as any that
he has tasted in San Francisco and New Zealand.

Another record of the same sort is given by Mr.
Robert Hind, a millionaire sugar planter and
ranchman of Honolulu, who declares that on his
ranch in Hawaii he has horses that “do not know
what water is and will not drink it if it is brought
before them. They have never tasted water.”

“I have good, fat cattle,’ Mr. Hind continues,
“that have never seen water and would not know
how to act if water touched them. I have other
cattle that I have imported from the United States
which have not tasted a drop of water since being
turned out on my cactus and blue grass pastures.
They have lived for years without water, and are
as fat as any grass-fed cattle in the United States.
They make just as good beef as you can get in any
restaurant.”

[221]

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ON CACTUS AS CATTLE FOOD

To any one who knows the prime necessity of
a water supply for cattle and horses under ordi-
nary conditions of grazing, such statements seem
almost incredible. But they are thoroughly
authenticated and, indeed, they need excite no sur-
prise in the mind of any one who appreciates the
succulent quality of the cactus slab.

In point of fact, the entire cactus plant is a
receptacle for holding water.

It was doubtless because the leaves of the
cactus transpired water, as do all leaves, that these
appendages were given up, so that the cactus of
to-day is a leafless plant. A plant that grows in
the desert finds it necessary to conserve water.
So through natural selection the cactus developed
the custom of dropping its leaves when they were
only tiny bracts, at the very earliest stage of its
growth, developing chlorophyll bodies in its slabs
to perform the functions usually performed in the
leaf of the plant.

These present a relatively small surface to the
air in proportion to their bulk, and conserve in
large measure the water that would be transpired
from an ordinary leaf system.

This, combined with the habit of the cactus of
sending its long, slender roots deep into the soil,
accounts for the power of the plant to grow in arid
places.

[223]

LUTHER BURBANK

It is not that the cactus can perform its life
functions without water any better than can
another plant. It is only that the cactus has
learned how to seek a water supply in the depths,
and to conserve it after it has been found.

What the cactus does then, essentially, is to
bring water from the depths of the parched earth,
and to store it in its flat slabs, along with nutritious
matter, so that these constitute both food and drink
for the animal that eats them.

It is obvious that a plant that has such charac-
teristics, now that it has been robbed of the spines
that were hitherto its greatest drawback, and quad-
rupled in productiveness—with a good prospect of
increasing it one thousand per cent—constitutes a
forage plant that is in a class quite by itself.

The importance of this forage plant is already
widely appreciated, but it will be more and more
fully understood as the years go by.

Enormous Propuctivity oF THE NEw OPUNTIAS

Not only is the quality of forage produced by
the new species of Opuntias of a character to
recommend it most highly, but the quantity of
forage produced by a given acreage is altogether
without precedent. Moreover, being available
throughout the year in a succulent form, it -is
peculiarly valuable for feeding milch cows, pro-
ducing a greatly increased flow of milk.

[224]

The “Banana”

Cactus

This variety of
of spineless cactus per-
haps does not bear a very
striking resemblance to
the prototype suggested by
its name; but, names aside,
there is something curious-
ly interesting about the
sprangly form it has taken.
It solves the problem of
eactus architecture by
growing horizontal slabs,
then adjusting vertical
ones along their upper bor-
der,—with a few along the
lower border for good
measure. Carried a few
stages farther, this would
give the plant the appear-
ance of a modern steel
skyscraper in process
of construction.

LUTHER BURBANK

’ The plants grow rapidly from cutting, and only
a few months are required to produce a growth
that begins to present forage possibilities.

Of course it will be better to allow the plants
to grow for two or three years, and thus attain
large size, before slabs are cut away. But after
that the new growth may be removed from time
to time as required, and the plant will be a con-
stant forage producer for a century at least.

The different varieties of new spineless Opun-
tias vary a good deal as to size, but all are plants
that on good land attain a growth of six or ten
feet during a few seasons, and some of them grow
much larger.

There is a good deal of difference also as to
size and weight of the individual pads or slabs.
Many of these weigh eight or nine pounds, al-
though the average is from two to six pounds for
the improved varieties. Some of them weigh as
high as eighteen to twenty-two pounds, but these
are exceptional. But the varieties having largest
slabs do not usually produce by any means the
greatest amount of food. One of the new varieties
of the gigantic Tuna type has produced a slab four
and one-half feet in length. This, of course, is
something quite out of the ordinary; but slabs
from twelve to eighteen inches in length are by
no means unusual.

[226]

=
3
i
A

The “Sugar”

Cactus

Many of Mr. Bur-
bank’s carefully se-
lected spineless varieties
have been chosen for their
fruiting qualities. Here is
one that bears fruit of ex-
ceptional sweetness, as its
name suggests. The speci-
mens in the foreground,
however, had not attained
the fruiting age when
this picture was taken.

LUTHER BURBANK

The growth of the plants is so prolific that the
total weight of the new slabs grown in a single
season, under favorable conditions, has been esti-
mated at almost one hundred tons to the acre.
On the best agricultural grounds, as on my own
grounds at Santa Rosa, the plants have produced
quite five hundred tons per acre in their first four
years of growth. This is from some of the most
highly improved varieties, on the best of land, but
without irrigation or special fertilization.

Of course this growth would not be duplicated
on all soils or under all conditions, but even in
inferior soils the growth of the Opuntias is phe-
nomenal, and the amount of forage produced each
season is greatly in excess of that produced by
any other forage plant, not excepting alfalfa.

When the extraordinary weight of fruit that is
borne by some varieties is further taken into con-
sideration, it becomes evident that the new spine-
less Opuntia is the most productive plant ever cul-
tivated. It is within the possibilities that a field
of Opuntias, under ideal conditions of cultivation,
might yield in new slabs and in fruit an aggregate
edible product approximating five hundred tons
to the acre. This has already been attained in
smaller areas,

As to soil, the Opuntias grow everywhere. They
may be planted on rich level land, or on the steep-

[228]

The “Signal”

Cactus

This variety is
characterized bg hav-
ing peculiarly long slender
spiked slabs. A glance at
almost any of the other
pictures will show the dis-
tinction. This form is not
particularly meritorious;
but the variety has been
preserved for its other good
qualities and for use in
future experiments.

LUTHER BURBANK

est and poorest rocky hillside, along old river-
beds, and among rock piles.

But it must not be inferred from this that the
plant is oblivious to good treatment. The growth
and succulence of the slabs are greatly increased
by good soil. Reasonable cultivation of the soil
is also of benefit, and, under semi-arid conditions,
a very slight irrigation once during the dry season
will be highly beneficial, but not absolutely neces-
sary, as the plants will live where not a drop of
rain falls for many years, if the soil is not too
fiercely sunbaked.

By such treatment, the fruit is greatly increased
in size and improved in quality, and the slabs for
forage are doubled in weight.

In a word, no plant responds more promptly
to good treatment than does the Opuntia.

Yet, on the other hand, the plant retains the
primeval capacity of its ancestors to make its way
under the most unfavorable conditions.

MakING A ForaGE AND Fruit FIELD

Unlike most other plants, the Opuntias root
best during the heat of summer. This is also the
best time to transplant them. In fact they should
not be moved at other seasons. No one who is
familiar with the Opuntias would undertake to
root or transplant them during the cold, damp
weather, such as would be best for other plants.

[230]

The “Hemet” Cactus

Contrast these round, flat, robust slabs with the relatively

slender ones’ shown in the preceding picture. It is obvious that
these will produce a far greater yield per acre. Note that the small
new slabs are dimpled where the embryo leaves have been. They
will be as smooth as their parent slab in due course.

LUTHER BURBANK |

But if transplanted during May, June, July,
August, or September they will thrive under al-
most any treatment. The leaves, blossoms, buds,
half grown fruit, or any part of the plant will take
root and grow under the most discouraging cir-
cumstances. I have seen them develop on the floor
back of a cook stove, in the pocket of a winter
overcoat, lying on a writing desk, and in similar
unlikely places.

The Opuntias differ from nearly all the other
plants in that the cuttings must first be wilted
before they will grow (unless in the dry, heated
part of summer) ; after which, nothing grows more
readily.

When you receive cuttings, place them in some
warm, sunny place, and allow them to remain a
week or more, after which they will readily form
roots and start to grow almost anywhere. They
may best be planted so that about one-third of the
cutting is below the soil. The cutting may be
planted in an upright position, or at any angle—
such details make no difference to the Opuntias.

On fairly good soil, to provide a forage field
for stock feed, the giant Opuntias should be
planted two rows together at intervals of three or
four feet, according to variety, and then a space
of ten or twelve feet left, and another pair of rows
planted in the same way. This has been found to

[232]

The “Melrose”

Cactus

Here, as in the pre-
ceding picture, some of
the slabs show the dimpled
appearance showing where
vestigial leaves recently
grew. But old slabs and
young alike are absolutely
without prickles. You may
rub them against your
face with impunity.

LUTHER BURBANK

be the best way to plant the cactus, as by this
arrangement space is left for general cultivation
and for gathering the crop; otherwise the plants
would too completely cover the ground.

The young plants must have protection from
marauding beasts. Squirrels and rabbits are par-
ticularly fond of the young slabs, and in a country
infested by these creatures it may be necessary to
fence in a young field of cactus until it attains a
considerable growth. Needless to say, it must be
protected from the encroachments of farm ani-
mals, as they would destroy the young plants
utterly.

When the Opuntia attains a reasonable size,
it becomes, as already pointed out, a perennial
source of forage. The plants live to an indefinite
age, and year by year they put out new slabs,
which may be cut at any season for feeding
purposes.

It is best to cut the forage, and not to give the
animals access to the growing plants, as in the
latter case they would waste the feed and seriously
injure or destroy the plants. The central stems
of the old plants, however, attain a woody char-
acter that protects them against extermination by
stock.

In practical feeding, it is desirable, where pos-
sible, to combine the Opuntia slabs with straw,

[234]

The “Quillota”’ Cactus

After inspecting a field like this, one has no hesitancy in
accepting the statement that the new growth of slabs and fruit
on an acre of perfected Opuntias may amount to 150 tons in a season,
It may be questioned whether there is any other type of
vegetation that transforms inorganic into organic
matter at such an astounding rate.

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Afusnt joy) ,,Aouaz
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snjoD')
guajaduro),, ay.

ON CACTUS AS CATTLE FOOD

hay, bran, and other carbonaceous and especially
dry foods, like straw, hay, and the like. The
Opuntia slabs may be fed as an exclusive diet, and
in this case farm animals will have no craving for
water. But in fact the cactus is not a complete
food, and it is always more economical to feed
some dry food with it, alfalfa hay being one of
the best, to complete and round it out as a
nitrogenous diet. ;

Almost without exception, herbivorous animals
are fond of the cactus. Cattle prefer it to almost
any other food, and it makes a superior quality of
beef, and exceedingly rich milk, which is not sur-
prising considering the succulence of the cactus
and the fact that it contains a relatively large per-
centage of the salts of sodium, potassium, and
magnesium.

A very superior quality of pork is produced
from pigs fed on the cactus fruit. The fruit is used
also with success as a poultry food. The plant has
been fed to horses, which, however, are said as a
rule not to relish it until they become accustomed
to it.

But the merits of the cactus as a food for ani-
mals have too long been recognized to require
extended comment. The wild thorny cactus is
frequently prepared for stock feeding by burning
off its spines, and in Australia the leaves and fruit

[237]

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-i1D{ a1D SqDjS ]DNplaip
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-]at ul pajup}d aq alofasay}
fipu 72 pup ‘sioqybiau
sy. jo fisoji1itaj ay} uo
yapoi2ua 0} fijjsuadoid ou
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jo Jauupul huladasuos
-aopds janduroa fijqpyipwat
ay}, osyp fsnjapa ssajaunds
yupqing {fo fijajrpa = sty}
fo sqpjs ay}z jo uisof
ajpj]njods ay} aj0N

snjoD7)
.vadg,, ayy

The “Robusta”’

Cactus

Not an inch of
waste space here. It
would be difficult to mass
the slabs more closely to-
gether had they been ad-
justed by hand. In many
places they overlap one an-
other like shingles on the
roof of a house. Yet the
individual slabs are of
good size and healthy in
-appearance, and the planis
thrive notwithstanding
their scant breathing
space.

LUTHER BURBANK

are boiled to make them available as food for
hogs, especially in long seasons of drought. Such
facts sufficiently attest the value of this plant, as
well as its palatability.

The spines which have hitherto constituted the
one perennial drawback having now been re-
moved, and the plant itself having been made to
reveal new capacity for growth and for the pro-
duction of flesh and fruit of peculiar succulence
and food value, the cactus, as represented by the
new races of spineless Opuntias, must take a lead-
ing place among forage plants in all arid and semi-
arid districts, where the climate is semi-tropical.

—There is no reason why the
cactus should not compete on
something more than equal-
ity with any other forage
crop—not excepting alfalfa—
even in regions admirably
adapted to the growth of
plants of less hardy character.

MANY USEFUL SUBSTANCES
IN CACTUS

THE RICHNESS OF ITs CHEMICAL CONTENT

HE chemical content of the cactus slabs
depends largely on the variety and also
to a certain extent upon the age of the

slabs.

The young shoots in the early period of their
growth have a very high water content, as is the
case with all succulent herbage. The amount of
crude fiber in the leaf at this stage may represent
less than one per cent of the total bulk.

On the other hand, the old slabs and the main
stalk of the plant take on a growing percentage
of woody fiber, which renders them less and less
palatable, but which adds to their value from
another standpoint, as will appear presently.

The slabs during the period of their best devel-
opment, when they would ordinarily be used for
forage, contain, according to chemical analysis,
from 2.71 per cent. to 4.6 per cent. of starch and

(Votume VIII—Cuaprter VIIT]

LUTHER BURBANK

its equivalent, with from .58 per cent. to .72 per
cent. of protein, and .96 per cent. to 1.68 per cent.
of mineral salts. There is also a very small
amount of fat, which like the other nutritious
elements is being increased in quantity in some
of the newer varieties. The varying amount of
these food constituents suggests that the quantity
may be considerably increased by selection.

Of course the same thing is true of the other
constituents. No doubt the protein content, for
example, may be increased by selective breeding,
just as we have seen done in the case of corn. And
in general the constituents of the Opuntia slabs
that give them food value may doubtless be in-
creased by careful combination and selection.

Hitherto the development of the plant has been
carried along the lines of spinelessness and great
size and productivity; although, even as the case
stands, there has been a considerable improve-
ment in the percentage of food constituents.

In particular the variety Chico shows such
advance upon the other varieties, notably the
Santa Rosa, in its percentage of mineral salts as
to suggest still greater possibilities of development
in this direction, although in some respects the
Chico is not an exceptionally good variety. In
general the solid content of the Chico variety is 2
per cent. greater than that of the Santa Rosa. Such

[242]

ON USEFUL SUBSTANCES IN CACTUS

variation is not surprising, but it is sufficient to
show that there are possibilities of selection
through which the Opuntia is given additional
food value.

Even at the present time, however, the slabs of
the Opuntias furnish fodder of highly nutritional
character. That there is also a high water content
is no disadvantage in a plant growing in arid
regions. On the contrary, we have seen that this
is to be regarded as one of the greatest merits of
the plant, inasmuch as it enables animals to secure
their water supply by eating the slabs, thus main-
taining health and growth even when no drinking
water is available for months together.

The qualities of the cactus fruit have been dealt
with in an earlier chapter.

It will be recalled that there are numerous vari-
eties of fruit, differing almost as widely as the
varieties of apples. The essential character of all
the fruits of the improved varieties, however, is
a peculiar juiciness of pulp, combined with indi-
viduality of flavor and in some cases a slight trace
of acid. The fruit of the wild Opuntias has some-
times been characterized as lacking flavor. But
constant attention has been paid to the bettering
of the fruit and the fruit of the new varieties is
popular with all those who are acquainted with it.

On my grounds the choicest varieties of fruits

[243]

The “Titania” Cactus

Here is indeed the Sandow of cactuses, struggling
manfully under the weight of twenty-nine leaves, the season’s
outgrowth of a single slab. The parent slab was set out in the
Spring, and this picture was taken in August, 1912, Such
an infant prodigy deserves its name,

ON USEFUL SUBSTANCES IN CACTUS

of many kinds are grown, but the workmen usually
prefer the fruit of the Opuntias to any other that
is in season at this same time.

The improved fruits are rapidly gaining in
popularity in the markets. When shipped to the
east they bring about the same price as the best
oranges, and the fact that they can be produced
at a fraction of the cost of growing the orange
should give them importance from the standpoint
of the orchardist.

Reference has been made also to the fact that
the fruit has excellent qualities for making pre-
serves and jams and jellies. The scarlet and crim-
son varieties have value in supplying coloring
matter for other fruit preserves, ices, and
confections.

This newer vegetable pigment, with its beau-
tiful shades of color, should largely supplant the
objectionable analine dyes that are now sc gen-
erally used to color ices and confections and non-
alcoholic beverages.

THE Foop VALUE OF THE “LEAVES”

In countries where the cactus grows abun-
dantly, it has long been known that its young slabs
make a palatable form of greens when cooked.

In recent years some scientific experimenters
have made the attempt to test the food value of the
leaves of the partially improved cactus.

[245]

LUTHER BURBANK

The cactus leaves when fried are a substitute
for some of the poorer vegetables. Tender leaves
should be selected, the skin peeled off, and the
plants fried rapidly in butter. Appetizing pre-
serves may be made from the fruit, somewhat
after the manner of apple butter. The fruit itself
may be dried and thus preserved for winter use.
With the production of 100 tons an acre, there is
opportunity to preserve the fruit on a commercial
scale, if a sufficient market for it can be developed.

To me it seems that the cooked fruit lacks the
fine flavor of the raw fruit. In general the fruit
may perhaps be served to best advantage as a
salad. But I have on several occasions had jars
of delicious jams, made from cactus fruit, sent me
from different localities.

The fact that the fruit of the perfected Opun-
tias contains a high sugar content, amounting
sometimes to from 12 to 16 per cent., makes it
obvious that this plant might be used for the pro-
duction of methyl alcohol. The slabs may be used
for the same purpose, and the enormous produc-
tivity of the plant would make amends for the
comparatively low percentage of fermentable
starch in its composition.

As A FAMINE PREVENTER

It has been estimated that the improved Opun-

tias produce foliage and fruit so abundantly that

[246]

A Remarkable
Fruit Colony

Here are forty-
three fruits on a single
slab of a spineless cactus.
It is hardly necessary to
state that this is one of Mr.
Burbank’s highly devel-
oped fruiting varieties. The
slabs do not often quite
duplicate this record, to be
sure; but on occasion they
even exceed it. A hundred
tons to the acre is the pos-
sible yield of fruit
like this.

LUTHER BURBANK

they could be grown advantageously on lana that
cost even one thousand dollars per acre.

Analyses made by the Agricultural Department
of the State University of California have shown
that the new varieties greatly exceed the old ones
in nutritive qualities. Yet even the undeveloped
Opuntias have long been recognized, particularly
by the peoples of the Mediterranean, as having
high food value.

The importance of the new plants as suppliers
of food for human beings, in regions subject to
occasional or habitual shortage, has been recog-
nized by several governments.

The German Government in recent years has
tested the new Opuntias at several places in its
possessions in Africa.

In parts of India where famines threaten and
from time to time destroy millions of people, the
spineless cactus is being planted for the purpose
of tiding the people over in the years of famine,
even if not used as a part of the regular dietary.

The English Government is testing the new
plants in Egypt and India.

The plants have been sent to Australia. They
are also being tested in Argentina and in other
parts of South America.

The new Opuntias differ from almost every
other plant, and may be said in a way to resemble

[248]

ON USEFUL SUBSTANCES IN CACTUS

canned food, in that their food content remains in
perfect condition on the plants year after year
until needed. Nothing more is required than to
plant the Opuntias, and fence them against the
encroachment of animals. It is not necessary to
cultivate them, although it is advantageous during
the first two or three years, nor need any attention
be paid them until their slabs are needed.

They would thus grow enormously and when
the occasion arose they would supply an almost
indefinite quantity of food to meet the needs of a
population that otherwise must die of starvation.

The value of a plant that need not be cultivated
and needs no preparation yet which will perpetu-
ally hold in reserve a colossal quantity of food per
acre, constantly adding to it (the annual increase
being measured in scores or even in hundreds of
tons), offers a refuge to populations that are
threatened with years of drought and failure of
cereal crops that is not duplicated by any other
food produced hitherto under cultivation.

Even if the new spineless Opuntias had no
other function than this, the time and labor
devoted to their production would obviously be
repaid a million fold.

ImporTANT By-Propucts

There is one curious property of the slabs of

the Opuntias that to some extent militates against

[249]

cuapiob s,yuvqing
“Ij” Ul ulosSso}]q Ul SDI}
-undo ssajau1ds padojaaap
ayy fo dnoiB pv uaas a9uo
spy oym auo fiup fiq payoo}
-daao aq oj fifayi] JOU 24D
flay} ng “payxoo)taao fi]yon
-sn ai saijzjpnb Suzramoy
871 yoy? Jinafl fo Jaonpoid
pup }unjd a6p10j v sp ‘sasn
alwaUu0Ia ~juDjlodum yons
soy jJ ‘uapip6 zamoy fiun
mi aonjd v jo fiyjiom s} pus
‘yupjd jyoyuawpuio up sp
ua1jD1apIsuod 0} urID}9 1)T4
spy snjapo ay} jDy} «vad
yl aypur pyrm@ = aanyo}d
siyy jo aounj6 Vy

wi0sso]g
ul y2jDq = snypovZD

ON USEFUL SUBSTANCES IN CACTUS

their popularity as foodstuffs. This is the fact
that the leaves contain a mucilaginous substance,
the quantity of which, however, varies widely with
the different varieties.

The varieties that contain less of the mucilage
are used by the Mexicans for the making of con-
fectionery. Some of the finest confections of
Mexico are candied cactus leaves.

The leaves also make excellent pickles, the only
drawback to which is the presence of the mucilage
in the case of some varieties, Those that lack the
mucilage make pickles as fine in flavor as the best
cucumber pickles.

On the other hand, the mucilage, while unde-
sirable from one standpoint, is not without its
value. It may be extracted by cutting the leaves
in thin slices, and placing them in water. One or
two slabs will make a gallon of good, thick, per-
fectly transparent mucilage. When this substance
dries slowly, it produces a gum that is generally
white or of a pearly color, and not easily dissolved
in water.

The mucilage is often used locally to mix with
whitewash, to which it gives something of the
permanency of a paint. It is also used at times
for stiffening sleazy cotton goods, and for water-
proofing cloth.

Beyond this the economic uses of mucilage

[251]

LUTHER BURBANK

have not been developed. But sooner or later
someone will find use for this by-product of the
cactus, for the dressing on a large scale of fabrics,
or any one of the hundred purposes to which mu-
cilaginous substances are put. I myself have made
tentative experiments to test the qualities of the
mucilage, but these have not been carried far
enough to produce conclusive results.

The Opuntias have possibilities of a quite dif-
ferent character, connected not with their juices
or pulp, but with the woody fiber which makes a
network in the older leaves, and which comes to
form the main substances of the central stalk.

It has been found that this woody network,
when the pulp is removed, makes a clean white
fiber that is in the most beautiful condition for
paper making. The older stems and roots furnish
the fiber in considerable quantities, and even the
roots are available for the purpose. The amount
of paper stock varies much in the different species.
The expert estimate of the fiber as a stock for the
making of the finest paper, including bank note
paper, has been so enthusiastic that it might be
well to devote attention to the breeding of some
of the spineless Opuntias with an eye to the devel-
opment of the fiber, so that this by-product of the
plant may become of value as a source of paper
stock; also for the making of leather board.

[252]

A Cactus Patch in
Fruit

This picture by no
means shows the best
that the spineless cactus
can do in the way of fruit
production. If is selected
as representing a fair aver-
age. Even at that, the ag-
gregate mass of fruit in
this patch of opuntias is
enormous. The fruit itself
still retains some spicules,
—although Mr. Burbank
expects to banish these in.
due course,—but there are
no thorns on the slabs to
interfere with the gath-
ering of the crop.

LUTHER BURBANK

One striking peculiarity of the Opuntias fiber
is that it is bleached without any preparation.
When the pulp is removed, the remaining fiber is
perfectly white, and ready for use without neces-
sitating the usual process of bleaching.

So the Opuntia which develops its enormous
weight or tonnage of forage and its abundant sup-
ply of food for man in the early stages of its
growth, will subsequently, without relinquishing
its original function, produce supplies of fiber that
may be of value. The rapidity and growth of the
plant would insure the production of such quan-
tities of material as to give it a certain importance
even if it could be grown only on arable lands;
but the quantity is at best relatively small.

That it can be grown also on the waste places
is obviously an additional merit of the first grade.
A SumMMaRY OF QUALITIES

Let us, then, in conclusion summarize briefly
the qualities that give the new spineless Opuntias
economic value. In so doing J] may refer to two
or three subordinate uses to which the plants have
been put that have not been specifically mentioned
in the preceding studies. Here is the list:

First: The new spineless Opuntias supply abun-
dant quantities of fresh fruit that is unique in form
and color, of superior flavor, of sure crop, and of
good shipping quality. Delicious jams, jellies, and

[254]

ON USEFUL SUBSTANCES IN CACTUS

syrups may be made from the fruits; and its juices
are used for coloring ices, jellies, and confec-
tionery.

Second: The slabs or so-called leaves of the
plant supply an unprecedented amount of forage
for stock of all kinds and for poultry.

Third: The young slabs make excellent pickles,
and are a good and wholesome food when fried
like the eggplant. They are also boiled and used
as greens, and may be prepared with sugar to
produce a sweetmeat similar to preserved citron.

Fourth: The leaves are extensively used in
Mexico and elsewhere for poultices, and as a sub-
stitute for hot water bags—the thornless kind
being naturally preferred!

Fifth: The abundant plant juices contain a mu-
cilaginous substance that is used to fix pigments,
and which in time will be put to many other
important uses.

Sixth: The thorny varieties are used for hedges
or fences, as well as for ornament, and even to
protect the thornless ones. No animal of any kind
will undertake to pass through one of these thorny
hedges. In regions subject to the drifting of sand
they serve an important purpose as barriers.

Seventh: The fiber of the plant makes an ad-
mirable stock for the manufacture of paper, but
not as yet in large quantities.

[255]

*yywf sdos2

uyouB ayy uaym «Dati
auros Up, UuoRDAIDIS uot
saayjpu ayy aaps ADuL ginal
pup sqvis $s} }OYT qubnoy}
ay} yjyim ‘pipuy ul fijaajsua}
-xa pajupjd 6ujaq §1 St}
-9n09 ssajaulds ay, “pvyps
Dp sp uajpa pup a6pqqva
ay1y dn jna Jo ‘ypajsfaaq
p jo nay ut uaypa puD
pajal aq fipur fay} Joy} fiaua
-js1suoa yans jo amp ‘abpIs
s1y} yo ‘yazyar $Qd]S Tapua}

ym papmois ;uUd] d

fumoi Dp st aaH

yuvid
snjoD7) ,,opDt

-op}q7,, Sunox Y¥

ON USEFUL SUBSTANCES IN CACTUS

Eighth: In general, the adaptability of the new
Opuntias to the arid regions gives assurance that
vast semi-arid regions of the globe will be made
habitable and productive, although hitherto they
have produced scant if any vegetation of economic
value.

Without looking further, it must be clear that
a plant having such qualities may be regarded as
the most neglected of vegetable products. Owing
to its spines, the cactus has been regarded as an
enemy of man. Now that its spines are removed
its good qualities will in due course be ap-
preciated.

Should their present promise be fulfilled, the
giant spineless Opuntias may make vast areas that
hitherto have been relatively sterile among the
productive regions of the world.

They may supply fodder for unlimited num-
bers of cattle, that will give cheaper food to the
masses, and conspicuously decrease the cost of
living.

They may even avert famines in regions that
have hitherto accepted the recurrence of starva-
tion years as an inevitable visitation.

And even should the future benefits that accrue
from the new spineless Opuntias realize but a
fraction of their present promise, these plants
might still be entitled to a foremost place among

[257]

LUTHER BURBANK

the forms of vegetable life that have been intro-
duced, or improved, for the service of man within
the historical period.

THE HEREDITY OF SPINELESSNESS

Before taking leave of the spineless cactus, it
may be of interest to make further inquiry as to
the hereditary bearings of the condition of spine-
lessness.

We have seen that the new spineless opuntias
were developed by a long series of experiments in
hybridizing and selection, in which use was made
of individuals that showed a propensity to depart
from the spine-bearing custom of their race.
Among the seedlings of these plants, some were
found to be much less spiney than others, and it
was ultimately possible, by selecting among literal
millions of specimens, to develop races absolutely
devoid of spines and spicules, as we have seen.

It would not have been unreasonable, perhaps,
to expect that the spineless races thus developed
would breed true to spinelessness; particularly
when we recall that the thornless blackberry, if
inbred, produces only thornless progeny. But if
such an expectation were entertained, it would be
doomed to disappointment, for the spineless cac-
tus does not breed true. In point of fact, there
may be found among the seedlings of a spineless
variety plants that fairly bristle with spines, rival-

[258]

Propagating for
Quick Results

Here three slabs of
the cactus have been
planted together. Each of
them will take root, and
the production of the new
slabs will go ahead with
Fs oe ER te pet : : eee : ERS 2 : . proportionate rapidity.
baa bane See gars sie Se eas Sea e Fe en : With quick-fruiting in
: : ; : ere ee aS view, such an expedient as
Sas this is desirable. The cac-
tus slab takes root equally
well whether it is placed
on the ground on its side
or on the edge, or at either
end. It is a hard vege-
table to discourage.

LUTHER BURBANK

ing in this regard the best-protected of their wild
ancestors.

Obviously, then, the condition of spinelessness
in the cactus has quite different relations in the
scheme of heredity from the conditions that gov-
ern spinelessness in the blackberry. In the latter
case, as we have seen, the spineless condition ap-
pears to be recessive, and the thornless individual
is as free from tendency to produce thorns as if
its entire coterie of ancestors had been perfectly
smooth-stemmed. The individual spineless cac-
tus, on the other hand, retains the factors for
spines in its germ plasm, to make their influence
tangibly felt in a large proportion of the offspring.

Nevertheless, it does not appear that the con-
dition of spininess acts as a simple Mendelian
dominant. On the contrary, it appears that the
hereditary conditions that govern the spiny con-
dition in the cactus are very complex. The best
interpretation would seem to be that there are
multitudes of actors for spicules and spines, vari-
ously blended in the germ plasm of any given
individual. The spiny condition, on the whole,
tends to be dominant to the spineless condition,
because the spines are a relatively late develop-
ment in the history of the evolution of the cactus
tribe.

But doubtless the period in question was an

[260]

ON USEFUL SUBSTANCES IN CACTUS

exceedingly long one, covering many thousands of
cactus generations, during which the plants were
becoming better and better protected; and each
stage of such development may be thought of as
having its hereditary factors in the germ plasm,
capable of acting independently.

Thus it is that in the same fraternity some
seedlings are exceedingly spiny, while others have
a comparatively small number of spines, and a
few may be absolutely spineless. Thus, also, is
explained the fact, to which attention has been
called, that the plants that are altogether spineless
may still be provided with minute spicules. Such
minute spicules were, perhaps, the first defensive
mechanism to be developed in the evolution of the
cactus tribe, and they have back of them such
numberless generations of heredity that they hold
their own with exceptional persistency.

In dealing with the spines and spicules of the
cactus, then, we must consider that we have to do
not with a single hereditary factor or two, but with
a multitude of factors. Now our earlier studies
have taught us that where several or many heredi-
tary factors are in question, the probability that
they will all be combined in any given way in a
single individual decreases at a geometrical ratio.
We found, for example, that where ten hereditary
factors were under consideration, the probability

[261]

‘fqispjndod ur umvh
11m fipupd snjopa yoy}
paj9adxa aq fipur j1 ‘ajqp
-jipap amp ‘sdoia2 paaupy
-ua fijjpar6 way} yjia ‘sai}
-a}i0a Burns mau s,yuvg
-ing ‘4jg jDyy Mou pup
fqupjd sty} wosf suoijaas
-u0d ayDur Of pauiojsnzaD
uaaq Huo] aavy supoixay
ay *SnjovI ay} uloss appul
fipupa snoroijap fijjpal
fo fiviy Dd 81 ala

fipup snjov)

ON USEFUL SUBSTANCES IN CACTUS

of their combination in a predicted manner was
only one in something over a million. In the case
of the cactus the factors for spininess doubtless
number far more than ten; from which it follows
that the probability that any given seedling will
have germ plasm absolutely free from any of the
factors for spininess is much less than one in a
million.

This explains why it was necessary, in our ex-
periments at Santa Rosa, to plant the seeds by lit-
eral millions, and to select persistently among un-
computed multitudes of seedlings.

Fortunately the spiny condition reveals itself
almost from the outset, so that it was possible to
weed out the vast majority of all the seedlings,
retaining only, perhaps, a stray dozen or so from
among the legions.

As the experiment proceeded, however, it was
gratifying to note that in succeeding generations
there was an ever-increasing proportion of spine-
less seedlings. This suggests that some of the fac-
tors for spininess were being dropped out of the
heredity of the selected plants.

Obviously this seems to augur that should the
experiment be carried forward through a suffi-
cient number of generations, the time will prob-
ably come when all factors for spininess will have
been eliminated from the germ plasm of the

[263]

LUTHER BURBANK

selected opuntias; in which case, they will then
breed true to spinelessness from the seed.

This prediction finds further warrant in the
fact that the newest races of spineless opuntias
show a far more pronounced abhorrence—if the
phrase be permitted—of the spiny conditions than
did the earlier ones. It was observed that the first
spineless opuntias to be developed at Santa Rosa,
although remaining perfectly smooth under ordi-
nary conditions of cultivation, had, nevertheless,
a tendency to revert to the spiny condition if
placed under disadvantageous conditions—say in
arid soils, unwatered and uncultivated; a state
comparable to that of the wild spiny progenitors.

This tendency to reversion is in itself highly
interesting from the standpoint of the student of
heredity; being comparable, perhaps, to the ob-
served tendency of some plants, on rare occasions,
to form what are termed bud sports. As a rule,
plants grown from cuttings or roots or buds repro-
duce absolutely the characteristics of the parent
form. We have seen this illustrated over and over
in endless numbers of cases, from orchard fruits
to shasta daisies. This rule holds true of the cac-
tus, as has been pointed out in recent chapters.
You may produce an entire field of spineless opun-
tias of any given type, as offshoots of a single slab.

But of course no plant is free from the power

[264]

A Cactus-Slab Fan

The fibrous portion of this fan represents the fiber of a
cactus leaf from which the pulp has been removed. In the
young slab, these fibers are tender and fragile, but they become tense
and rigid in the old slabs. An excellent paper may be
made from this fiber, and it will doubtless in
time be put to many other economic uses.

LUTHER BURBANK

of environment, and no one needs to be told that
the choicest orchard fruits, for example, will fail
signally to justify expectations based on observa-
tions of their parent forms, unless they are given
proper conditions of soil and cultivation. Cut-
tings or buds of the Baldwin apple, for example,
will produce but perverted replicas of the original
Baldwin if grown in an arid soil, deprived of mois-
ture, and shaded by other trees. Under such con-
ditions, the choicest varieties of apples tend to
revert more or less to the primitive type of the
wild ancestor of very remote generations.

Similarly the spineless opuntia may tend to
revert to the wild form if placed under primeval
conditions. In a stony, arid soil, deprived of mois-
ture, it may not only be stunted in growth, but it
may show a propensity to revert to the spiny con-
dition. Such, at any rate, was the case with the
earliest spineless opuntias that were produced at
Santa Rosa.

As the experiment has gone forward, however,
the condition of spininess has been more and more
subordinated, as just related; the proof being not
only that the individual plants are absolutely free
from spines and spicules, but that more and more
of their seedlings are found to be spineless. And
this elimination of the hereditary factors for spini-
ness is so profound and deep-seated that the newer

[266]

Odd Uses of Cactus
Spines
Here are needles
and a fish-hook made
of cactus spines; and a
piece of leather with a hole
in it put together with cac-
tus needles. It is prob-
able that the aborigines
made constant use of the
eactus spines for such pur-
poses as these; and the
modern Mexicans have not
altogether forgotten the
customs of their primitive
forerunners in this
regard.

LUTHER BURBANK

or more recently developed varieties of spineless
opuntias appear to have lost altogether the capac-
ity to revert to the spiny condition. Even under
the most adverse conditions of soil and climate,
they remain absolutely smooth. One other step
of progress, and, we may confidently predict, the
factors for spininess will be so completely elim-
inated from the germ plasm, that the spineless
opuntias will breed true from the seeds.

Even then, it must not be expected that the seed-
lings in any given case will reproduce all the good
qualities of the parents; any more than the seed-
lings of cultivated varieties of apple or pear or
peach will duplicate the qualities of their parents.
We have seen that the seedlings of the thornless
blackberry are not precisely like the parent form.
But they all are thornless. Such will be the case,
ultimately, with the spineless opuntias.

And it must be obvious that when this condi-
tion is attained, the experiment of developing the
opuntias in any direction will be greatly facili-
tated. With many varieties of spineless opuntias
in hand, each one absolutely free from the ten-
dency to revert to the spiny condition, we shall be
able to carry forward experiments in crossbreed-
ing and selection through which any desired
quality may be accentuated and developed.

At the present time, for example, the spineless

[268]

ON USEFUL SUBSTANCES IN CACTUS

opuntias are somewhat lacking in protein content.
Their forage value is not quite what it would be
if the protein content could be increased. And
there is no reason to doubt that such increase may
be possible, through selective breeding. Already
the developed spineless opuntias exceed all other
plants in their capacity to produce an enormous
quantity of forage. Through selective breeding
their pre-eminence may be still further advanced
in that each individual slab may be given enhanced
food value. And the quantities of other useful
chemical substances in the cactus may similarly
be increased in selective varieties.

—Heretofore the develop-
ment of my cactus has been
along the lines of spineless-
ness, size and productivity;
the future will see a marked
improvement in the percent-
age of its food constituents.

A Bundle of Rice

In recent gears rice has been introduced into northern
California, and is now grown quite extensively in some re-
gions. Not only is it grown in the water, according to the usual cus-
tom, but there are also upland varieties that grow like wheat
or rye on ordinary soil. It is probable that the pro-
duction of rice will become an important
industry along the Pacific Coast.

OTHER USEFUL PLANTS WHICH
WILL REPAY EXPERIMENT

TRANSFORMATIONS AND IMPROVEMENTS WAITING TO
BE MADE

of Japan an important place among plant
developers.

The Mikado, so the story runs, was riding about
the country—as was once the custom—to inspect
the crops, and he espied a bunch of rice which
seemed to be earlier and more productive than
others in the same field.

Evidently aware of one of the fundamental
principles of plant breeding, the Mikado directed
that the seed from this hill of rice should be care-
fully preserved and sown by itself the next season.
From this seed, if we are to believe the legend, a
superior new variety of rice was produced in
Japan.

Whatever the authenticity of the story, the fact

\ STORY is told that, if true, gives a Mikado

[VoLtume VIII—Cwapter IX]

LUTHER BURBANK

that it is told gives evidence that some of the fun-
damental principles of improvement of plants by
selection are widely recognized in the land of the
Mikado.

But this, indeed, is a proposition that scarcely
needs demonstrating, considering the curious vari-
ety of flowers and fruits that have been developed
there. That the revered name of the Mikado
should be associated in popular legend with the
perfecting of the rice, is to be interpreted, I sup-
pose, as an evidence of the importance of this
grain to the people of Japan, rather than in any
literal sense.

Rice is to the Oriental people what wheat is to
the people of the western world, and it is natural
that folk-lore should associate the perfecting of
this most important of foodstuffs with the most
sacred office of the ruler who is regarded as the
Father of his people.

RIcE AND Its IMPROVEMENT

Mention of the perfecting of special varieties
of rice implies the existence of different varieties
of this grain.

In point of fact, rice is a variable plant, and
one that is therefore susceptible of great improve-
ment. There are many varieties of rice grown in
the Orient. There is, for example, a variety that
has a very pleasant aroma when cooked. There

[272]

A Wild Chilean Grass

This is an unnamed species of grass sent Mr. Burbank by
his collector from Chile. Mr. Burbank is experimenting ex-
tensively with all manner of grasses, and this specimen will be used
in hybridizing tests, with an eye to the possible
development of a new forage plant.

LUTHER BURBANK

are varieties that grow on the upland, the culture
of which is similar to that of wheat or barley; not-
withstanding the fact that rice is usually thought
of as a marsh plant. These have recently been
introduced into the cotton regions of the south,
and I am told that in some regions they are sup-
planting the cotton crop, Also an attempt is being
made to grow the upland rice in certain sections
of northern California, and with a large measure
of success.

In point of fact, some botanists have classified
no fewer than six species of rice, and there are
hundreds of varieties, variation seeming to be no
more unusual than with wheat, oats, or barley. It
is only the relative unfamiliarity with rice of the
western world that has led to the supposition that
one kind of rice is like another.

Our estimate of the grain is somewhat anal-
ogous to our estimate of the Oriental peoples.

The casual western observer thinks that all
Japanese and all Chinamen look a good deal
alike; but to the practiced eye there is nearly as
great diversity among them as among European
Taces.

The upland rices show their derivation by re-
quiring somewhat moist soil, and they are not
grown to advantage in California; at least they
have not been extensively cultivated hitherto

[274]

ON SOME UNTRIED EXPERIMENTS

except in the moist retentive soils of the Sacra-
mento Valley, and to a certain extent in the Coa-
chella Valley. In the former region, however, the
reports as to the growth of the upland rice are
exceedingly favorable.

I have tested different kinds of rice here on
several occasions, but the results were not such as
to induce me to continue its culture, the condition
not being favorable.

But the fact that varieties of rice have been
developed that grow on the upland gives assur-
ance that further development may be possible in
the direction of adapting the plant to general cul-
tivation on lands suitable for growing of other
cereals, as already demonstrated in the South.
Doubtless a good deal can be done also to make
rice a hardier plant through selective breeding;
and few attempts at plant development could have
greater importance, for rice is a grain not inferior
to wheat itself in nutritional value, and one that
might be cultivated far more extensively in this
country, to very great advantage.

My own experiments have had in view the pos-
sibility of the development of the American wild
rice of the northern lake regions. This, however,
is not a true rice, being classified as Zizania, while
rice belongs to the genus Oryza. Some twenty
years ago I desired to undertake such an experi-

[275]

“Blue-Eyed Grass”

This pleasing cluster represents another of Mr. Burbank’s
almost numberless proteges of this lowly but interesting tribe.
It has greater claims to beauty as a flowering plant than most of its
congeners; but of course the qualities for which it is
being tested are of a quite different order.

ON SOME UNTRIED EXPERIMENTS

ment, and sent to many places in the United States
to get seed of the best varieties. But although I
secured seed of the wild rice (it is known to the
botanist as Zizania aquatica), my experiment, I
regret to say, never got beyond the preliminary
stages, because the seed would never germinate.

After testing it in successive years I was con-
vinced that the seed of the wild rice must be gath-
ered fresh for planting. For its improvement it
would be necessary for men with boats to watch
individual plants, and gather seed for immediate
planting.

The fact that the plant grows in the water
accounts, no doubt, for this unusual quality of the
seed, as it will not germinate after once being
dried like other grains. It grows always in stand-
ing water, and is generally collected by the In-
dians, who are extremely fond of it. They go out
in canoes when the wild rice is ripe, and bending
the rice over their canoes thresh it from the heads
into the boat. During the last year a well-known
San Francisco grain firm collected some of the
wild rice and kept it moist, and they expect to
make a successful introduction of it in this state.
Conceivably a commercial variety of importance
might be developed that would be hardier and
better adapted to the American climate than the
Oriental rice.

[277]

LUTHER BURBANK

I hope even yet to be able to make the experi-
ment. Failing this, I trust that someone else will
take the matter in hand.

Some NEGLECTED GRASSES

If my work with the rice has been only tenta-
tive, there are almost numberless allied grasses
with which I have experimented on a compre-
hensive scale.

Indeed, I have raised, at one time or another
during the past thirty-five years, almost every
grass that has economic importance, and many
never supposed to have value. Among these sey-
eral fine varieties have been introduced through
Cecil Rhodes of South Africa, which proved enor-
mous croppers in moist, warm regions of this state.
Some of these I have grown extensively year after
year; others only for a single season, for the pur-
pose of obtaining variation in some _ useful
direction.

My work with the familiar giant grasses, Indian
corn, sorghum and teosinte, and with the equally
familiar small grains, has already been detailed.
I refer here to other grasses that are less widely
known to the general public, including some that’
are rarely seen even by the agriculturist.

My experimental work with these various
grasses has been as diverse as the qualities of the
plants themselves.

[278]

A Bed of Land

Cress

The cresses are or-
dinarily grown, as is
well known, for their
aromatic qualities, and to
serve as dainty garnish-
ings, rather than as pur-
veyors of food. Here isa
cress that is distinctly or-
namental; and is doubly
attractive because it grows
on land, instead of in the
water, as is rather the cus-
tom of its tribe. The
cresses are a numerous
family, and Mr. Burbank
has experimented with
mIany of them.

LUTHER BURBANK

In some cases I have selected for increase of
productivity, in others for increase of chemical
constituents, or for beauty of plume, or ability to
resist drought or frost or wind or moisture; or,
again, for compact growing or for ability to spread,
or for length and breadth of leaves, or for striping
of foliage.

The grasses are so numerous and so diversified
that there is opportunity for almost indefinite
choice as to lines of development, and there are
few other groups of plants that offer greater
possibilities.

To casual inspection, to be sure, most of the
grasses seem rather uniform, commonplace, or
unattractive. They lack the beautiful flowers that
so many other plants present, and their forms, if
almost universally graceful, are for the most part
lacking in picturesqueness. Add that the grasses
present great difficulties to the botanical student
because of the minuteness of their flowers and the
vast number of species more or less closely related,
and you may readily understand why this tribe of
plants is so commonly neglected by the amateur.

But when we reflect that the family includes the
most important producers of food for man and
animals; and when we further reflect that there
are doubtless many species still undeveloped that
might be brought into the company of economic

[280]

ON SOME UNTRIED EXPERIMENTS

plants, along with wheat, oats, rye, corn, and rice,
it is evident that the grasses should be second to
no other form of vegetation in their interest for
the plant developer.

Nor will the plants themselves be found to lack
interest when once their acquaintance is made in
the right way.

They vary in size from tiny sprigs of vegetation
to the giant pampas grasses, and to bamboos two
hundred feet in height and six inches in diameter.
We have already seen that their products com-
prise nof merely universal food and forage for
domestic animals, and grains of inestimable value,
but juices (in the case of cane and sorghum) that
are second in importance only to the grains
themselves.

We saw too that there are minor products, such
as the panicle of the broom-corn, that have no
small measure of usefulness. And it is known to
everyone that the stalks and straws of the various
grasses have a wide range of utility in the manu-
facture of numerous articles of everyday use,
including the mats beneath our feet and the hats
on our heads, as well as the food from the tubers
of the nut grass.

Whereas it cannot be said that a family of
plants that is thus comprehensively in the service
of man — having had, indeed, a most important

[281]

Another Unnamed Exotic

This is another of the large group of grasses from Chili,
especially collected for Mr. Burbank, most of which have never
come under the eye of a classifier, and so are quite unprovided with
names. This particular individual grows in a rather compact
bunch, and sends up its seed stalks to good height, sug-
gesting possibilities of the making of a good
forage plant. It is still undergoing educa-
tion in Mr. Burbank’s gardens.

ON SOME UNTRIED EXPERIMENTS

share in the development of civilization—has
failed of recognition, yet it remains true that there
are perhaps thousands of grasses that are almost
surely susceptible of great improvement, from the
human standpoint, to which very little attention
has been given by the plant developer.

These present an inviting field for further
development.

I shall offer in the succeeding pages suggestions
as to a few of them, drawn from my own experi-
ences. To attempt to deal with all the neglected
grasses comprehensively, and to point out every
individual possibility of useful development,
would require volumes rather than paragraphs.

A New Breap-MakinG PossIBILiTy

One of the grasses upon which I worked for
several years was what is known in the catalogues
as “Idaho Brome-grass,” classified as Bromus
inermis, or Bromus gigantius.

I chose this plant on account of its extreme
hardiness. It resists drought remarkably, and is
very productive. My original seed was received
from Montana. I have also grown extensively
other species of the same genus, to the number of
four or five. My main object was to produce a
variety that would yield more forage.

Seeds were sown thinly in boxes in the green-
house, or in plots out of doors. Selection was

[283]

LUTHER BURBANK

made when the plants were about half an inch
high, and before they had put forth their second
leaves. At this stage a fairly correct judgment
can be formed as to which plants will be rapid
growers.

In general, the plant that will ultimately tower
above its fellows is found to show superiority in
its earliest stages.

By selecting the plants that seem to give most
promise, and planting these in rows where the
soil is practically the same throughout, it is not
difficult to discover the most rapid growers and to
weed out the others.

The brome-grasses are much more variable
than is commonly supposed even by those who are
familiar with them. In point of fact, even within
the same species, it is difficult to find two plants
that are precisely alike. Some have broad leaves,
and some narrow, and the leaves may be variously
curled or twisted, as well as variant in color, some
being much darker than others.

Some specimens go to seed without producing
much foliage; others grow abundant foliage but
are tardy of seed-production.

The plants that show this propensity to produce
foliage rather than seed are, other things being
equal, the ones to select, except from the view-
point of the seedsman, who does not appreciate

[284]

A Bunch of Millets

The millets are a very numerous company, it being esti-
mated that there are at least three hundred species, mostly
natives of the tropics. Some of them are cultivated extensively in
Europe, but they are not as popular in this country as many
other grasses. The species here shown has peculiarly
attractive panicles, drooping gracefully
with their burden of seeds.

LUTHER BURBANK

this kind of grass. I have aimed to get a variety
with broad, rich, dark green leaves, and found it
comparatively easy to develop such a variety.
Notwithstanding the great variation shown by the
individual bromes, I found that varieties once spe
cialized tend to come somewhat true to type in the
next generation.

Therefore it is a very easy matter to improve
the different species of bromes.

By far my most interesting experiment with
plants of this genus was made about twenty years
ago with a plant, seemingly of the species known
as Bromus mollis, that was found on the edge of
the Santa Rosa Creek, about one mile east of Santa
Rosa.

This wild grass bore a long head of rather
plump seeds that were without awns, and that sug-
gested to my mind the possibility of the develop-
ment of a commercial grain. The seeds were
planted and carefully cultivated, and the best seed-
lings were selected for propagation, with the result
that in the course of a few years a variety was
secured in which the size of the seed-head was
markedly increased, and in which the individual
grains are very much plumper than the original
one.

The grain seemed so promising that I tested it
by grinding it in a coffee mill. It was found to

[286]

ON SOME UNTRIED EXPERIMENTS

produce an excellent flour with a slight yellow
tinge.

When prepared and baked in the ordinary way,
it made a very good bread.

I was quite sure that a grain of good commer-
cial value could be produced by further selective
breeding from the seed of this brome. But I had
only a small quantity of seed, and as other mat-
ters took my attention I neglected to plant it for
two or three seasons; and when.it finally was
planted it failed to germinate. So the experiment
came to an end in unsatisfactory fashion, yet not
without offering interesting suggestions as to the
possibilities of development of this and other
plants of the tribe.

Unfortunately I was not quite sure as to the
exact species of brome that furnished the material
for this experiment. Moreover, I have not found
another plant that showed the same exceptional
qualities of seed, with which a new line of inves-
tigation might be begun. The one mentioned was
discovered only after careful inspection of more
than twenty-five thousand examples.

But the finding of one sufficiently proves that
there must be others to be found if we search
widely enough, so I record the experience as a
stimulus to farther search and investigation with
a tribe of grasses represented by numerous other

[287]

Another Type of Millet

The upright panicles of this millet are strikingly differ-
ent from the drooping ones shown in the preceding picture.
The wide range of variation among the millets makes them peculiarly
attractive as plants for the experiments of the would-be
developer. Mr. Burbank has various millets among
the almost numberless grasses in his colony.

ON SOME UNTRIED EXPERIMENTS

species that are familiar enough in fields and

waste places, but which at present are regarded as

weeds rather than as friends of the agriculturist.
Some CULTIVATED GRASSES

Some of the most striking results I have ever
seen in the way of development of grasses were
obtained with the perennial known as the Sweet
Vernal Grass (Anthox anthum).

This grass is exceedingly variable. A few
years ago I raised about fifty thousand plants in
boxes. From the seedlings I selected the largest
and the smallest; the broad leafed and the nar-
row; the dark green and the light green; and those
showing any other striking peculiarity.

By planting the individuals that presented
these diversified traits in plots by themselves, and
carefully selecting their seed, races of perennial
sweet vernal grass were obtained presenting the
widest range of characteristics.

Thus varieties were produced that would bear
almost no seed, and others that bore seed abun-
dantly; some which increased from the roots with
great rapidity, and others that increased very
slowly.

From among the thousands of plants that were
raised and scrutinized, I found two or three that
would grow more than one hundred times as fast
as the smaller ones. Not only was this startling

[289]

LUTHER BURBANK

quality of the fruit of this cactus, the pulp some-
times being white and again variegated with
yellow.

Specimens from different parts of the world
might at first sight be thought to represent different
species or at least different varieties; but I have
found the various kinds of fruit growing on con-
tiguous branches of the same plant.

The large species of cactus that grows
commonly in the Mediterranean region, known
there as Indian Fig or Barbary Fig, is closely simi-
lar if not identical with the species called Tuna in
Mexico, although the fruit of the Mexican variety
is usually somewhat smaller than that of the Old
World form. The name tuna is applied indiscrim-
inately in Mexico to cultivated and wild species
of the tribe, but the varieties are sometimes recog-
nized by different names, as Tuna Amarillo, Tuna
Colorado, Tuna Blanca, etc.

Another quite common Mexican form known as
Tapuna, appears to be entitled to recognition as
a distinct species of Opuntia.

It produces flat leaves that are generally
circular or heart-shaped. The plant does not grow
as rapidly as others of the large-fruit Opuntias,
and the fruit ripens late in the season. The leaves
have a somewhat white appearance, as if dusted
with flour, which distinguishes them readily from

[190]

Cactus Plants in the Nursery

Here the slabs originally planted have put forth several new
slabs, showing that they have taken root and are thriving. The
plants here are much too close together for permanent growth. At the
end of the first year, the new slabs are used for transplanting
at wider distances for forage or fruiting purposes.

Japan Grass

Here is a grass of a still different type, imported by Mr.
Burbank from the Orient. The grass experiments are still
under way in Mr. Burbank’s gardens; but it may confidently be
predicted that when the strains of different species from
Europe, South America, and Japan are blended, the
results will be interesting and notable.

ON SOME UNTRIED EXPERIMENTS

worthy of further attention. In a few more sea-
sons, according to present indications, it will be so
fixed as to produce regularly from seed a type of
orchard grass that would nearly or often double
the growth of the ordinary variety.

Another variable grass that I have cultivated
extensively in recent years, for observational pur-
poses rather than commercial varieties, and from
which new varieties are being developed, is the
species known as Acrostis fontanesi, recently
introduced from Algeria. From the same plant
have been produced seedlings with broad spread-
ing panicles, others with compact spikes, and yet
others with beautiful spreading spikes. On sow-
ing seed from different panicles, it was found that
the tendency to compactness or looseness of head
was transmitted or accentuated, so that widely
differing varieties were developed in the second
generation from seed of a single plant,

I have obtained some similar results with the
Bermuda grass (Capriola), with which I have
experimented from time to time during the past
twenty years, more particularly in the effort to
produce a lawn grass which would fulfil the func-
tion in arid regions that the bluegrass fulfils in
moist climates.

I have found that this grass varies even more
than most others do from seed, and by selection

[293]

\

LUTHER BURBANK

was able to produce dwarfed varieties, or, on the
other hand, the tallest and largest-growing ones;
also varieties with broad leaves and others with
narrow leaves.

There were plants that came up thickly and
made a compact sod, not having the wild running
habit of the original variety. And there were
others that sent out runners and spread so rapidly
that in a single season one plant would cover the
ground for ten feet in all directions.

These extraordinary diversities were shown
among plants selected from the same lot of seeds.
In all there were at least twenty quite distinct
varieties developed, each marked by one or more
obvious and striking peculiarities.

But as the Bermuda grass is commonly
regarded as a weed, none of these were introduced.
ORNAMENTAL AND USEFUL GRASSES

I have at various times taken great interest in
the ornamental grass, commonly known as pam-
pas-grass, the plumes of which were at one time
in great demand.

The form of pampas-grass that is most grown
in California is that known technically as Corta-
deria argentea. The plume-like panicles of this
grass are familiar ornaments everywhere, and
were, in the time of their greatest popularity,
articles of some commercial importance.

[294]

Australian Rattlesnake Grass

No one who has seen a rattlesnake will need to be told

how this grass from Australia received its name. But as the
rattlesnake is an American product, it is a question whether the grass

bears the same name in its native country. Be that as it may,

the seed heads of this curious grass give one the rather

disagreeable impression of objects cut from the ex-
tremity of a rattlesnake, instead of what
they really are. The plant itself is
grown as a curiosity raiher than
for its economic value,

LUTHER BURBANK

The plumes to be preserved in the best way
should not be allowed to come out of the sheath
before drying. The long stems, with several leaves
attached, are cut just as the tip of the plume
begins to show. The leaves are stripped off, and
the stalk is placed in the bright sunshine, prefer-
ably standing, but more commonly spread on
boards or on the ground. Prepared in this way,
the panicles do not shake to pieces. They assume
the aspect of silky plumes, which are given a
peculiar fluffiness and brought to perfection by
being placed in a hot oven for a few moments.

I have raised perhaps a hundred thousand
seedlings of various pampas-grasses, and have
crossed them extensively.

There is no difficulty in effecting cross-fertiliza-
tion, provided, of course, the two species bloom at
the same time. Pollen from the ripe male plant is
simply dusted over the pistillate flower. The
female plant is the one that is useful for ornament,
the male plant having a smaller and coarser
plume, which is never silky or fluffy, and which
readily falls to pieces under treatment.

There are pampas-grasses, however, that have
hoth staminate and pistillate flowers in the same
blossom, and, of course, these cannot be cross-
fertilized with such facility.

My most interesting experiments have had to

[296]

ON SOME UNTRIED EXPERIMENTS

do with the crossing of a pink variety of pampas-
grass that bears both staminate and pistillate
flowers, with some of our finest large white varie-
ties. These plants crossed readily and I raised
many thousand seedlings. A large proportion of
the seedlings were plants bearing both stamens
and pistils like the pink parent. Very few were
female plants, and therefore bearers of good
plumes,

Even when the plumes were produced, they
were usually not as large as those of the white
parent, and many of them were smaller even than
the small plume of the pink parent. This is easily
accounted for by the fact that the great white
plume has been produced through artificial selec-
tion, and therefore its characters were not as well
fixed as in the wild type.

An interesting feature of this experiment was
that the pink color seemed to appear oftenest on
the staminate plants and not on those that bore
both stamens and pistils.

This gives a suggestion of the element of sex
selection in heredity, which is seldom observed
in plants, although common enough among ani-
mals. A further evidence of this was seen in the
fact that I was never able to fix the color so
thoroughly on the female plants as on the male.

The pampas-grass is multiplied by division, so

[297]

Water Grass in Bloom

As the number of plants of pleasing appearance that
thrive in the water is not very large, this artistic grass with its
very attractive clusters of flowers and its sprangly foliage might be
thought an acquisition. It has distinctly greater claims
to beauty than most members of its tribe.

ON SOME UNTRIED EXPERIMENTS

that there is no difficulty about the multiplication
of a new variety. The new varieties do not usually
come true from seed. But this is of no importance,
inasmuch as a single plant may be so multiplied
by division as to produce probably fifty thousand
marketable plants, on good soil, in the course of
two or three years.
SoME MISCELLANEOUS IMPROVEMENTS

From among a great variety of experiments
looking to the improvement of farm and forage
crops, I will select only three or four additional
ones as offering further suggestions,

An interesting anomaly with which I have
experimented is a hybrid form of the wild oat.

A field of the second generation of these hybrid
oats furnishes one of the most interesting studies
of variation that has come under my observation.
Inspecting a field of these oats, sown quite thinly,
one finds on the same day some that are thor-
oughly ripe, while others are not yet in bloom.
There is corresponding diversity as to the appear-
ance of the plants, some having broad leaves and
some narrow ones.

Some of the plants are very tall, and others
short and stocky. The panicles are of all forms
and sizes. In a word, the hybrids vary in almost
every way in which they could vary, and still be
recognized as oats.

[299]

LUTHER BURBANK

It is obvious that such a variant type of oats
gives opportunity for selection and development
of new varieties.

The tendency to vary as to time of ripening
has peculiar interest, as suggesting the possibility
of adapting oats—and doubtless also the other
cereals—to different climates, or even of the
production of different varieties in the same
locality, which, by ripening at different seasons,
would enable the farmer to avoid the excessive
rush of work that attends the harvest season.

Several years ago I worked quite extensively
on buckwheat. My work consisted largely of
selecting the larger, plumper, and lighter-colored
kernels. I worked with both the common buck-
wheat and the Japanese species. A certain amount
of crossing was done, but in general the plants
were found to be so variable that nothing more
was necessary than to select among the different
forms that appeared spontaneously.

Considerable, though relatively slow progress
was made in the production of a better quality of
grain. The experiments were discontinued before
I began the extensive hybridization of the two
species that had been contemplated. They could
without doubt be crossed to advantage.

Among textile plants, and plants of use in the
textile industries, my most interesting recent

[300]

ON SOME UNTRIED EXPERIMENTS

experiments have had to do with the wild teazel
and with the Chilean hemp, that give promise of
the production of a valuable fiber.

The teazel, as is well known, has been an
important plant, inasmuch as its long hooked burrs
are used for producing the nap on cloth, more
especially the woolens, and no mechanical device
has ever been invented as a thoroughly satisfac-
tory substitute. There are several distinct varie-
ties of the plant, and one of them is a weed that
grows along neglected roadsides in California.
Among any lot of wild teazels one may find a
number of types, and it is not unusually difficult
to fix these types by selective breeding.

If it were necessary or desirable for any
particular use to make the hooks several times the
usual length, or the burrs themselves several times
as large, this could easily be accomplished.

My work had to do with some of the peculiar
forms rather by way of experiment than with
any practical idea. The forms worked with were
those with vertical rows of hooks, instead of the
spiral ones, and with varieties having extra large
hooks at the base and double heads. I carried
the experiments forward for several years for my
own information and education, and these experi-
ments demonstrated that different kinds of teazel
burrs could be developed and fixed if desired.

[301]

‘umy} fiuy uo u0lj9UuIF
-sip jo aan]d v fo fy}s0ar
$2 1] ‘10dojspqag jo unmDs
s,.yupqging ‘IpfZ uo uaas aq
us fipur yoy] 42]sn]2 D $i
asay ‘fijim0jndod jo fippfiay
ayy poy fay} uaym alam
fiay) upy} jnj1jnvaq ssa] Ow
aap fiay} nq ‘obp sipafi maf
D azam fiay? so mou spin
-dod sv jou aap sassviB sod
-upd ayy ‘“uo}JIa]a3 puD
uolpzpisgiy fig ‘satjaiiva
6uijsazazuy auros Huidojaa
-ap ‘sspi6 spdurod jo sadfi}
sno1isva yum Ajaarsuaz
-xa fidaa pajuautiiadza
spy yunqing “IW

sspin) spdurng

ON SOME UNTRIED EXPERIMENTS

Possibly some modified form of teazel may be
of use in a future industry. Hitherto it has not
been known that modified forms were available.

My experiments with the hemp were con-
ducted largely with an improved Chilean variety,
but included also the use of seed from Japan,
Russia, and France, as well as from various parts
of the United States. The experiments have
grown out of a suggestion that I made a number
of years ago to a large Boston paper manufac-
turer, to the effect that it seemed possible that the
fiber of the hemp might be used as a substitute
for wood pulp in the manufacture of paper.

The experimental work is only at its begin-
nings, but it seems to be of considerable promise,
especially as to improved size of plant, as a
hybridized variety has been secured which out-
grows all other hemps. The hemp, as is well
known, is a dioecious plant, and it may be well to
mention the simple but uncommon method of
making crosses. All the varieties are first planted
separately; and only a few of the largest and
tallest male and female plants of each variety are
left to bloom. When the heads blossom, the tallest
of each variety obtained from different sources
are crossed with pollen of the tallest male plants.

After two seasons of this selection and crossing
of different strains from different countries, the

[303]

LUTHER BURBANK

varieties were combined by crossing, as before,
by selecting the largest and tallest plants, out of
which a new race was produced of giant hemp.

I found that a hemp received from China and
one from Chile were at first the two tallest and
most rapid growers, but they were very shy seed
producers in this climate, especially the Chinese
one. The variety which I produced from Russia
was the most slender, and also the most dwarfed,
so this had little to do with the giant hemp which
was produced.

Paper made from the fiber of the hemp is
found to be of good quality, and although not
generally used heretofore must certainly be more
prized as other paper pulps become scarce.

I mention this line of investigation here merely
to suggest the wide range of opportunities that will
open up for the plant developer when he has
learned to cooperate with workers in the various
industries,

Hitherto we have been prone to take it for
granted that all the valuable textile plants have
been investigated and perfected. The newer
studies suggest that there is still almost boundless
opportunity for progress, not only through the
improvement of the plants that have been utilized,
but also through the introduction of species that
have been ignored or neglected.

[ENp oF VoLumE VIII]

LIST OF
DIRECT COLOR PHOTOGRAPH PRINTS
IN VOLUME VIII

Alfalf:
alta Page
The Root of the Alfalfa...... SAE Ae MORIN oera beacause oo 88
Alfalfa Serving a Double Purpose..............2. aiaieasierscaeai'a . 981
Barley
A Sheaf of Barley........... ce eee ee een eneee Shajareseie/eotaiacaveseye 74
Beans
Soy Beans for Fodder............. Bdiciatsieie Bissereteites janees Saeed: 182)
Beets
Sugar Beets at the Factory.......... ioe ewes se Sa ave 160
A Field of Sugar Beets....... ee Cee veewere 162
A Sugar Beet Anomaly,......cecerseecccecrecereseeeseens 165
Cactus
The So-called Candle Cactus......... istkaatdaranesaie Wass andy evoreveusise: LOS
The Quisco Cactus.......... as +. 171
Vestigial Leaves... 175
Giants and Dwarf: -. 177
Cactus Seedlings Ready for Inspection............eeceecaee 180
Spineless and Spiny of the Same Fraternity.....seeceeeeers 183
Mr. Burbank Selecting Cactus Seedlings..........eesseeeeee 185
How Cactus Plants are Propagated............. ie ice sa anereaces 188
Cactus Plants in the Nursery..........cceesceseeee
Spineless Cactus Slabs Ready for Shipment casdh Reeah Beare: csghaxencie
Spineless Cactus Showing Two Months’ Growth......

A Thrifty. Year ng ices ccc consow nessa dtnesenveawannensce 199
A Yearling of Different Type............0e00. scaserisy 22

Another Well-balanced Cactus.. 5
A Promising Colony..sscsessscscscsacvsveeeececvacavnencs 206

LIST OF ILLUSTRATIONS (Continued)

Contrasting Types of Cactus. .
A Promising Fruit Crop..

The “Prolific” Cactus... csscscccesccerocccctenveccssesse alg

Young “Royal” Cactus Plants........scccssessvcveceecs aie 222

The “Banana” Cactus.........+++ o/Guicheile enor dycvetia sco SoXe ones stdin to. 16 225

The: Sudan? Cactus oo :cces eis savasacarscese: s shapece isan siacacat ave: stove eratevncec’

The “Signal” Cactiis sc cc vaseccaaivnveae’s (MAGN eeauR eRe ee

The “Hemet” Cactus.......... ' P

The “Melrose” Cactus.......

The “Quillota’ Cactus.....

The “Competent” Cactus....

DHE S*Special?”’ CaACtus ss <.os.<.c:5:s:005: scojogere-d.2is tans sicierere bvera.cuwieomienarecs

The “Robusta” Cactus..... Wiig sins F eeustatatalnia seem eaaeN ne 239

The “Titania” Cactus......eerre

A Remarkable Fruit Colony.......

Cactus Patch in Blossom........+.... sieieiiep a aieresea ene eralsvetare 250

A Cactus Patch in Fruit............ 3

A Young “Eldorado” Cactus Plant

Propagating for Quick Results.......

Cactus Candy ..ccskscatnncaanvnraens peaeeneeeeneeencense 26

A. Cactis Slab Pativcss cs casaeseuns dadaveei. cone iewccwus «. 265

Odd Uses of Cactus Spines. sida ovacshs secetaai ile Buetoke end: ate tereehavers wee 267
Clover

A Bed of Four Leaved Clover....... petieexniiutwneeenases 85
Corn

A Section of Rainbow Corn Leaves..........sceceeeseceee « §&

A Typical Corn. Stalks vcs ss cece isris 44 yrsatinscas ea seweewreee 9

Primitive Types of Corn........ 02. cece cece creas ener eece «. 12

COCR TAY DEI GS ose sec sr sgew, 8 BA Tse dieid reyes Sighs tees h Ena e-o Sienere See e 15

A Teosinte Corn Hybrid in the ae Wet ara ehaxeca &:iinetaeealeces . 18

“Pod” Corn Variations......... - 21

Ears of Corn Teosinte Hybrid. . so 23

More Like Wheat than Corts sosssis sets sence es ee enaeenes o. 25

Various Stages of Development..........ccceccee ee ceence . 28

A Freak Ear: Of Gorn. <5. o ccs sescig- ese 8 0 bosidisrece te niw eeu reiaeen . 31

Another Evidence of Old Heredity..............ceeceeeeeee 33

What to Work fordn Cort.cccccsesscrsasecsasacsveaccrece 88

The Power of Environment............ccceeeeneeeeneeeees 37

Mr. Burbank’s Extra Early Sweet Corn... 39

Mr. Burbank’s Giant Field Corn.......... ~. 42

HAY COT 6255544858 e ds ine eke tees ee eT ee ee +. 141

Broom Corn........2.... a: byate saleriejwie ss’ stacduaneierecereiere 16.00 fauwinvararate's 144
Cotton

Cotton in the Field...........45 eT ee eee ere eee 125

Cotton Flower and Seed Head....... -. 128

Cotton Boll....... WSS eee sei cee ESS poeta eens 1380

LIST OF ILLUSTRATIONS (Continued)

Cress —
A Bed of Land Cres8............ccceeeeeeeee Lasienaiay a8
Flax
Grasses
A. Wild Chilean: Grass. .....:. ccc scisisieniscesnin sie eieicaeiee ee 273
“Blue-eyed” GrasS......cseeceeee RcAtere R Ga TAR Ras Sie sete . 276
Another Unnamed Exotic... ». 282
Japan Grass.......e.eeee +. 292
Australian Rattlesnake Grass. .. 295
Water Grass in Bloom..........0.ee0e. gee in anehaehelareceveiace «ie wee 298
Pampas GIass........6.. eee c cece e ee tect eee cere eee enees 302
Hemp
Hemp Plants......... tia tie Pa cea WAG) su etaverariar suas: Seapee arerietawielecaanen dd
Indian Hemp..........csecssceceee ighaiaie ioiai trefecaterha@ieiete a Rereie. LAO)
Hops
In the Hop Country.............eeeeeee Pee ere Frontispiece
Staminate Hop Plant.......... 0. ccc cece een eee enee 9 masa sa 147
Pistillate Hop Plant...........--- 2: eee e cece e ee eee eee eees 149
A: Hop ‘Plant: Vistas. siscocew cass atieralon sean astewrelneceie wey we 152
As HOD) Piel Gh ais icy aie sstisiece ee ioe Gorge igaihel eine arenas wegeewee BG
Dried Hops by the Carload............... a biscsaaeis seas Loe
Jute
The Jute Plant....... duatatetasscetemavenes fiteTeidatncweneaseeen 12D
Millets
A Bunch Of (Millets)... see ccc esse erssssvereseincopernie ecaneceiecedel ieee acesace 285
Another Type of Millet.......cccceceeecccceeeneensaes sees 288
Oats
A Sheaf of Oats.....0002ceese00 ial Siahshalad exe tesa erarsieneaexeregecaisaebsrite 63
WATE) LOBES 5 oes caiccstesundunsete78.seslaverteciniieye iasevansdacsessanerd}e torenorlnas.orasdvaravasnnens: 66
Rice
A Bundle of Rice........ OOO LOCO CC Re” LA
Rye

An Experiment with Ry€......ceseeeeeeseeenee oratetweavem aay dd

LIST OF ILLUSTRATIONS (Continued)
Sorghum

Page

Varieties of Sorghum........... ccc ce cece eee eeeeceeces wee 238
Sugar Cane

Sugar Cane Tasse]..... cc cee ccecccctwenscccccccscccenence 135
Sunflower

The Familiar Sunflower............ $b e DL LATING Boos Buel er sidee 97

A Hybrid Sunflower.............0. sige W 6 ele lorwtelniene se ote Se see 99

Stages of Progress....-cecscrsecerseceesrerscceseseencsess 101

Sunflower Seeds...... Catacashs 89 (an Sieretal Byerar's BS Terr ere rere 104
Timothy

Heads of Timothy iiccsiiscvcvcaswewae vasceswnein sevaee wa 3D

Vetch
Hairy Vetch in the Open Fields..........cecceceeccsccccce 94

Wheat

Wheat Germinating om Ice.............cc ee eeees enreswecna 4
Mr. Burbank among His 1914 Wheat Experiments sasepansuai ~. 49
Some Results of 1914 Wheat Experiments 52
Selected Wheat Heads...........00csceeenes aia 55
Seven-headed Wheatscfiictru scat cenainscenene caate 58