The mulberry silk-worm : being a manual of instructions in silk culture

Historic, archived document

Do not assume content reflects current
scientific knowledge, policies, or practices.

wv. 5. DEPARTMENT OF AGRICULTURE.
. DIVISION OF ENTOMOLOGY,

| BULLETIN No. 9.

fe os E

MULBERRY SILK-WORM,

BEING A

MANUAL OF INSTRUCTIONS

IN

Pee CULTURE.

BY

C. V. RILEY, M. A., Pu. D.

SEVENTH, REVISED EDITION.
WITH ILLUSTRATIONS.

WASHINGTON:
GOVERNMENT PRINTING OFFICE.

‘ 1888.
: 16136—No. 9

7

TABLE OF CONTENTS.

Page.
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Growing interest in silk-culture, 5—Profits of prodaatg cocoons, 6—Approx-

imate cost of reeling, 6—Periods of buoyancy and depression, 6—Produc-
tion of eggs for the market, 7—Silk-raising on an extensive or on a mod-
erate scale, 7—Advice to beginners, 8—Co-operation of silk-raisers, 8—
Appropriation by Congress, 8—Its expenditure for experiments in silk-
reeling, 8—Benefit of silk-raising upon small farms, 9—Explanations of
technical terms, 10—Acknowledgment of assistance, 10.

CHAPTER I.

PHYSIOLOGY AND LIFE HISTORY OF THE. SULK-WORM ..« <-<0ccecne oocucccccsaded
Sericaria mori, 11— Results of domestication, 11—Different Bois! or stages

of the Silk-worm, 11—The egg, 1 die ription of the egg, 11—The micro-
pyle, 11—Development of the larva in the egg, 12—Hatching of the egg,
12—Number of eggs in an ounce, 12—Color of albuminous fluid of egg
corresponding with color of cocoon, 12—The larva, or worm, 12—Number
of molts, 12—Time between the molts, 12—Color of the worm at different
stages, 13—Description of a molt, 13—Color of abdominal prolegs corre-
sponding with the color of the silk, 13—Preparations of the worm for
spinning, 13—Elaboration of the silk, 13—Length of time in constructing
cocoon, 14—The cocoon, 14—Description of the cocoon, 14—The chrysalis,
14—Description of the chrysalis, 14d—The moth, 14—Method of leaving
cocoon, 14—Description of moth, 15—Differences between the sexes, 15—
Mating, 15—Varieties, or races, 15—Varieties produced by domestica-
tion, 15—Annuals, 15—Bivoltins, 15—Trevoltins, 15—Quadrivoltins, 15—
Dacey, 15—Classification of commercial cocoons, 15—Lost identity of the
old varieties, 16.

CHAPTER II.

Pema Ase tek VOHING THE! EGGS 2. 22% 1. 232 4 cack 2. eae oe dc oo ee Senequeene
Chemical change of the contents Be eggs after oviposition, 17—Necessity for

circulation of air, 17—Method of wintering eggs by the Department, 17—
Suitable moisture of the air, 17—Changes in the different kinds of egg
during wintering, 17—Lengthening the period of hibernation, 13—Tem-
perature for Se eggs, 1s—Wintering small lots of eggs, 18S—Pro-
tection against enemies, 1; taaceianes of uniform hatching, 13—Hatch-
ing of the eggs, 18—Incubators, 19—Tinware incubator, 19—Basket-ware

incubator, 19,
Itt

11

17

Y
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IV

CHAPTER III.

IMPLEMENTS THAT FACILITATE THE RAISING OF STEK «2. c00 cocq/s-ce eo. cclec owas
Arrangement of the room, 20—Best exposure, 20—A modern magnanerie, 20—

Vertical distance between two shelves, 20—Shelf made of canes, 21—Con-
struction of the cane shelf, 21—Wire-work shelf, 21—Frame covered with
slats, 22—Standard for holding shelves, 22—Transfer of worms, 23—
Stretched netting for transferring worms, 23—Perforated paper for trans-
ferring worms, 23—Lattice-work transfer tray, 24—Transfer drawer, 24—
Bag for gathering Mulberry leaves, 24—Davril’s cocooning ladder, 24.

CHAPTER IV.

eH oREARING OF ASlLK-WORMS ; -< 22. nm soca seem tome e sien ela eee ee
Chief conditions of success, 26—Use of good eggs, 26—Proper care of the

worms, 26—Cleaning room and implements, 26—Handling of the young
worms, 26—Hashed leaves versus whole leaves, 26—Number of meals, 26—
Definite rules of little avail, 26—Experience the only guide, 27—Impor-
tance of dry leaves, 27—Food during a molt, 27—Irregularity of molt, 27—
Importance of keeping each batch together, 28—Food after a molt, 28—
Attention during fourth molt, 28—Change of color of the worm with suc-
cessive molts, 28—Temperature and circulation of rearing-room, 28—
Amount of food consumed by worms, 29—Space occupied by worms, 29—
Necessity of cleanliness, 29—Summary, 29—Preparations for spinning, 29—
Arches for the spinning of cocoons, 29—Method of constructing arches,
30—Temperature of room, 30—Necessity of separating worms, 30—Pre-
vention of double cocoons, 30—Gathering the cocoons, 30—Removal of
stained cocoons, 30—Separation of the pods from the floss silk, 31—Loss
in weight by evaporation, 31.

CHAPTER V.

ENEMIES AND DISEASES.OF THE SILK-WORM 22. .25)..2--0 + pees ceeseuejeas wanoeeee
Insect parasite, ‘‘ uji,” 32—Number of diseases, 32—History of the diseases,32—

Muscardine, 32—Symptoms, 33—Botrytis bassiana cause or effect of this dis-
ease, 33—Views of different authori ties, 33—No absolute remedies known,
33—Rational means of preventing spread of disease, 33—Pébrine, 34A—Ex-
ternal symptoms, 34—Description of spots, 34—Internal symptoms, 35—
Description of corpuscles, 35—M. Guérin-Méneville’s theory, 35—Pasteur’s
demonstration of the source of the disease, 35—Transmittal of corpuscles
from mother to egg, 36—Vittadini’s system of selection, 36—Pasteur’s sys-
tem of selection, 36—Fiaccidity (flacherie), 36—External symptoms, 36—
Appearance of diseased worm, 36—Description of disease, 37—Internal
symptoms, 37—Microscopic appearance of intestines, 37—Chain ferment,
38—Foul cocoons, 38—Predisposition to the disease hereditary, 39—M.
Pasteur’s theory, 39—Verson’s and Vlacovich’s theory, 39—Causes of dis-
ease, 39—No satisfactory remedies, 39—Grasserie, 40—Desciption of dis-
ease, 40—Conclusions, 40.

CHAPTER VI.

IRE PRODUCTION -<comeinc <2 dose aie es een ae eign ee ae ete
Former process of egg production, 41—Pasteur’s system of microscopical selec-

tion, 41—Examination of the worms for flaccidity,41—Examination of the
chrysalis, 41—Directions for extracting stomach from chrysalis, 42—Ap-

26

32

41

REPRODUCTION—Continued.

pearance of ferment in flaccid chrysalids, 42—Examination of the worms
for pébrine corpuscles, 42—Isolation and examination of the moth, 42—
Hastening development of moth, 43—Method employed by M. Maillot, 43—
Selection of cocoons for breeding purposes, 43—Forming chains of cocoons,
44—Bags for egg-laying, 44—Cells used by the Department, 45—Method
of clamping shells, 45—Cell used in the Pasteur system of egg-laying, 45—
Time at which moths emerge from cocoon, 46—Separation of mating
couples, 46—Removal of females to cells, 46—Microscopical examination
of moths after laying eggs, 46.

CHAPTER VII.

ES ESO ot ee So Se ee ae Re a =
Different methods of choking the chrysalis, 47—Drying cocoons, 47—Warning
against ‘‘ museum pests,” 47.

CHAPTER VIII.

Ep Rien Si SS ee a ee ae ee a aS eee pe
Spun, reeled, and thrown silk, 49—The process of silk-reeling, 49—Sorting the
cocoons, 49—Process of reeling cocoons, 50—‘‘ Cooking,” ‘‘ brushing,” and
cleansing,” 50—Elements of the mechanism of all modern silk-reels, 50—
Chambon system, 51—Tavellette system, 51—Fineness of the cocoon fila-
ment, 51—‘‘ Lancing” of the filaments, 51—Mechanical devices for lancing,
52—Temperature of water while reeling, 52—Importance of cleanliness,
52—Composition of fresh cocoons by weight, 52—Percentage of silk in
cocoons, 52.

CHAPTER Ix

ch ehOPeRtTiks OF REELED SILK... 220. is. so. cc-~ ence cece nscenscoenccns
“Dramming” of silk, 53—Principles of the serigraph, 53—Serimeter, 54—
Elasticity or ductility of silk, 54—Tenacity of silk, 55—Composition of
the silk in the cocoon, 55—Hygrometric property of silk, 55.

CHAPTER X.

SN EE ler alee ren a ein Sal a en Sone onile = Sob in eo eee sec we eee
Indigenous species of Mulberry, 56—Imported species of Mulberry, 56—The
Moretti, 56—Russian Mulberry, 56—Paper Mulberry, 56n—Propagation
by cuttings, 56—Growing standard high trees, 57—Amount of water of
vegetation in Mulberry leaves, 57—Amount of mineral matter in Mul-
berry leaves, 57—Osage Orange, 58—The secret of successful rearing of
Silk-worms on this plant, 58—Selection of Maclura leaves for food, 58—
Lettuce leaves, 59.

G LOSSARY OF TERMS USED......... .
EXPLANATION TO PLATES ...... 2222 .-2--0

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LETTER OF SUBMITTAL.

U.S. DEPARTMENT OF AGRICULTURE,
DIVISION OF ENTOMOLOGY,

: : Washington, D. C., March 20, 1888.
rR: The sixth edition of Bulletin No. 9 of this Division, on the Silk-
rm, having been exhausted, I have the honor to present for publica-
n a seventh edition, which is little more than a reprint of the sixth,
1 such slight changes as late experience has suggested.
Respectfully,

C. V. RILEY,

. Entomologist.
Jon. NorMAN J. COLMAN,

Commissioner of Agriculture.

Pr we

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.

PREFACE TO THE SECOND EDITION-

That there exists just now a very general and widespread interest in
the subject of silk-culture in the United States is manifest from the
recent large increase in the correspondence of the Entomological Divis-
ion in relation thereto, and from the demand made for this Manual.
To avoid the disappointment that is sure to follow exaggerated and
visionary notions on the subject, it may be well here to emphasize the
facts that the elements of successful silk-culture on a large scale are at
the present time entireiy wanting in this country; that the profits of
silk-culture are always so small that extensive operations by organized
bodies must prove unprofitable where capital finds so many more luera-
tive fields for employment; that extensive silk-raising is fraught with
dangers that do not beset less ambitious operations; that silk-culture,
in short, as shown in this Manual, is to be recommended only as a light
and pleasant employment for those members of the farmer’s household
who either can not do or are not engaged in otherwise remunerative
work.

The want of experience is a serious obstacle to silk-culture in this
country ; for while, as is shown in the following pages, the mere feed-
ing of a certain number of worms and the preparation of the cocoons
for market are simple enough operations, requiring neither physical
Strength nor special mental qualities, yet skill and experience count for
much, and the best results can not be attained without them. In Europe
and Asia this experience is traditional and inherited, varying in different
sections both as to methods and races of worm employed. With the
great variety of soil, climate, and conditions prevailing in this country,
pxperience in the same lines will also vary, but the general principles
indicated in this Manual should govern.

_ The greater value of labor here as compared with labor in the older
silk-growing countries has been in the past a most serious obstacle to
silk-culture in the United States, but conditions exist to-day that render
this obstacle by no means insuperable. In the first place, compara-
tive prices, as so often quoted, are misleading. The girl who makes
mly twenty or thirty cents a day in France or Italy does as well, because
: This preface was written in 1882, and some passages are omitted which had only
temporary interest and which might be misleading to-day.

— 16136—No. 9 1 1
a

of the relatively lower prices of all other commodities there, as she who
earns three or four fold as muchhere. Again, the conditions of life are
such in those countries thatevery woman among the agricultural classes
not absolutely necessary in the household, finds a profitable avenue for
her labor in field or factory, so that the time given to silk raising must
be deducted from other profitable work in which she may be employed. —
With us, on the contrary, there are thousands—aye, hundreds of thou-
sands—of women who, from our very condition of life, are unable to-
jabor in the field or factory, and have, in short, no means, outside of —
household duties, of converting labor into capital. The time that such ©
might give to silk-culture would, therefore, be pure gain, and in this ©
sense the cheap-labor argument loses nearly all its force. This holds
more particularly true in the larger portion of the South and West, that ~
are least adapted to the production of merchantable dairy products or ~
where bee-keeping and poultry-raising are usually confined to the im- ~
mediate wants of the household. 5

The want of a ready market for the cocoons is now, as it always has ~
been, the most serious obstacle to be overcome, and the one to which ~
all interested in establishing silk-culture should first direct their atten-—
tion. Ignore this, and efforts to establish the industry are bound to~
fail, as they have failed in the past. A permanent market once estab_
lished, and the other obstacles indicated will slowly, but surely, vanish -
as snow before the coming spring. Owing to the prevalence of disease ©
in Europe, there grew up a considerable demand for silk-worm eggs in
this country, so that several persons found the production of these:
eggs quite profitable. Large quantities are yet shipped across the con- —
tinent from Japan each winter; buf this demand is, in its nature, tran-
sient and limited, and, with the improved Pasteur method of selection
and prevention of disease, silk-raisers are again producing their own
eggs in Europe. Silk-culture must depend for its growth, therefore, on —
the produetion of cocoons, and these will find no remunerative sale ex-—
cept where the silk can be reeled. I find no reason tochange the views —
expressed relative to the part this Department might take in succoring
silk-culture through Congressional aid; for, however just and desir-
able direct protection to the industry may be by the imposition of an
import duty on reeled silk, no such protection has yet been given by —
Congress, and silk filatures can not be full y and profitably established ~
without some fostering at the start. Under a heavy protective tariff
our silk manufactures have rapidly grown in importance and wealth,
until, during the year 1881 (according to the reports of W. C. Wyckeff, —
secretary of the Silk Association of Americ a), raw silk to the value of —
$11,936,865 and waste silk and cocoons to the value of $769,186 were
imported at the ports of New York and San Francisco, while our man-—
ufactured guods reached in value between $35,000,000 and $49,000,000. —
Now, the so-called raw silk thus imported to the value of nearly
$12,060,000 is just as much a manufactured article as the woven goods,

moval of the duty would be on the woven goods. The aid that Con gress,
- through this Department, should, in my judgment, give to silk-reeling,
and thereby to silk-production, may be supplied by private and beney-
- olent means.

* %* * * ¥* # e
The obstacles which I have set forth are none of them permanent or
- insuperable, while we have some advantages not possessed by other
countries. One of infinite importauce is the inexhaustible supply of
Osage Orange (Maclura aurantiaca) which our thousands of miles of
_ hedges furnish ; another is the greater average intelligence and inge-
nuity of our people, who will not be content to tread merely in the ways
of the Old World, but will be quick to improve on their methods ; still
another may be found in the more spacious and commodious nature of
the barns and outhouses of our average farmers. [Every year’s experi-
ence with the Maclura confirms all that I have said of its value as silk-
worm food. Silk which I have had reeled from a race of worms fed on
it, now for eleven consecutive years, is of the very best quality, while
the tests made at the recent silk fair at Philadelphia showed that in
some instances a less weight of cocoons spun by Jlaclura-fed worms
was required for a pound of reeled silk than of cocoons from mulberry-

fed worms.
CO. Ve
WASHINGTON, D. C., February 20, 1882.

ak
~

PREFACE TO THE SIXTH EDITION.

The growing interest shown in the culture of silk, in the United States,
is attested by the demands upon this Department for copies of this man-
ual, which has hitherto been published as Special Report No. 11. Origi-
nally prepared as a brief mannal, based on my own experience of the
industry in America, the present demands of silk-growers, or rather of
those desirous of becoming such, call for some farther details, and in
elaborating the work it has been thought best to include it among the
bulletins of the Division. I have also divided the matter into chapters,
and those on the implements which are necessary to, or facilitate, the
work; those on diseases, reproduction, reeling, and the physical prop-
erties of raw silk embrace essentially new material, parts of Chapters
V and VI being from my current annual report not yet distributed.

In Chapter VIII, in speaking of machinery I have omitted the de-
tailed descriptions of special machines given in former editions and ex-
plained rather the mechanical principles that should be involved in all.
A description of the Serrell Reel would have been very appropriate, but
the inventor has been promised by the Commissioner that such should
not be made public until all patents are secured. I shall hope to elab-
orate this chapter in some future edition.

It must not be forgotten that the original manual was never intended
as an extended treatise on silk-raising or reeling, but was prepared to
give,in a simple and most condensed way, information to those inter-
ested, and in a form applicable to the United States. It is gratifying
to know that a number of other pamphlets on the Silk-worm have of
late years been published, and that this manual has been quite freely
used in their preparation, In one instance, in fact, an almost verbatim
copy has been published and sold privately. I have found little or no
occasion to alter opinions expressed in the manual, but in the present
edition have revised the estimates of profits given in the Introduction
to the original edition, leaving out those on egg production, because of
the changed conditions since 1879, which have rendered such work, as
a profitable business, obsolete in this country, and the production of
sound and reliable eggs much more difficult and expensive.

Though particular pains were taken to impress upon readers the faet
that the estimates of profits in silk-raising were based on definite mar-
ket prices at that time, and that prices and profits must needs, as in all
trades, vary from year to year, and though I especially omitted the

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cost of food, eggs, special buildings, etc., because the manual was ad- q
dressed to those who would not have to incur these expenses (and I —
would not now recommend any one to embark in the industry who did
not have these necessaries at command), yet these estimates have been
criticised because silk-raisers have been unable to realize, in 1885, the
profits which I considered attainable in 1879. For, though sharing the
opinion of those directly connected with the silk trade, I then believed
that the prices of raw silk and cocoons had reached as low a figure as
they ever would, the belief proved subsequently unfounded, for fresh
cocoons which in Europe sold in 1879 for 47 cents could be purchased,
in 1885, for 35 cents per pound. Again, any estimates must needs be
approximate only, as they will vary with the race.

This great alteration in the value of silk products has necessarily im-
paired the accuracy of the estimates given by me in the first edition of
this pamphlet. I have therefore prepared another series of figures
which are more nearly accurate to-day than the former ones, and are
based on the French yellow race.

PROFITS OF PRODUCING COCOONS: ESTIMATES FOR TWO ADULTS, OR MAN AND WIFE.

Average number of eggs per standard ounce of 25 grams, in ordinary yellow races,
37,500.

Number of fresh cocoons per pound, 300 to 400.

Average reduction in weight for choked cocoons, 66 per cent.

Maximum amount of fresh cocoons from 1 ounce of eggs, 93 to 125 pounds.

Allowing for deaths in rearing—26 per cent. being a large estimate—we thus get as
the product of an ounce of eggs 69 to 92 pounds of fresh, or 23 to 31 pounds of choked,
cocoons.

Two adults can take charge of the issue of from 1 to 3, say 2, ounces of eggs, which
will produce 138 to 184 pounds of fresh, or 46 to 62 pounds of choked cocoons.

Price per pound of fresh cocoons (1885), 35 cents (300 cocoons per pound)?

184 pounds of fresh cocoons, at 35 cents, $64.40.

Price per pound of fresh cocoons (1885), 25 cents (400 cocoons per pound).

138 pounds of fresh cocoons, at 25 cents, $34.50.

‘Price per pound of choked cocoons (1885), 80 cents to $1.15.

Value of above products, choked, $36.80 to $71.30.

APPROXIMATE COST OF REELING.

Estimated product of 6 non-automatic steam reels for the 300 working days
of the year—1,200 pounds of reeled silk, and 300 pounds of waste silk.
Cost of production of 1,200 pounds of reeled silk, based on the Government
experiments at New Orleans, in 1885:

Value of plant:

DUK MEGS. Sco ata are tele ce sete elias tes eee eee ee $500. 00
One ‘steam! engine .i225. 2. ee ee Se eee 600. 00
shafting, and miscellameouse 24 t = S382 See Uae 400. 00
1, 500. 00
Interest and derreciation on plant, 20 per cent. perannum........ ......- $300. 00
Raw material:
5,076 pounds, of choked ‘cocoons; atl sss eo oe eee 5, 076. 00
Labor (as shown at New Orleans), $1.123 per pound of silk.-.. 2... 1, 350. 00
uel oil, ete 2. fos aves oe aed St De ee esa ee 150. 00

—

Boy ali cain tae ted a Ne Deg las Sy ARs ie Bleek ere ee 6, 876. 00

q
Value of the above product:
ma DOMES TEGO Alin BU GO.U- . 5 ase ganceien's vip din aan as eters incece $6, 600, 00
300 pounds waste silk, at 9 ea Bate AE AOR ps 300. 00
2 CON ES sth OTe ppt 5S Se Oe at ee ee. Se 6, 900, 00

In studying these estimates the reader must, as I have said, bear in
mind that the silk industry, like all industries. will have its ups and
_downs—its periods of buoyancy and depression. Tor the past few years
it has been going through one of the latter. But late last fall an up-
ward tendency was shown in prices for raw silk, which, if they remain
firm, can not but influence for the better the value of cocoons.

In the preface to the second edition I mentioned the advantages to be
- gained by raising Silk-worm eggs, though I called attention to the fact
that the market for them was in its nature limited and transient, and
that European merchants were again producing their own seed by the
aid of the improved Pasteur system of selection. Notwithstanding the
facts there stated as to the limited nature of the egg market, silk-raisers
_ have been disappointed, after having produced large quantities of eggs,
in not finding a ready sale for them. But though the egg market is
important in its place, it will readily be seen that it can be, when ina
healthy state, no more extensive than is necessary to supply each season
the wants of silk growers. In 1884, in France, about 24 per cent. of
q the total crop was employed in the production ofeggs. These figures,
from a country where silk culture is established, furnish a foundation
upon which to estimate. Every pound of cocoons which is sold at the
filature puts money into the pockets of the silk-raising class; while
every pound used in the production of eggs in excess of the amount
actually required robs it of the money that it would otherwise receive.
~The only way to build up the industry, then, is, as I have so often in-
sisted, to create, by the establishment of filatures, a durable and profit-
able market for cocoons. The production of eggs is simply an incident
_ of comparatively little importance.
— Ihave shown in said preface that silk-raising on an extensive seale
is fraught with so many dangers that it is inadvisable to invest capital
‘in such an enterprise. This is partly due to the fact that a large crop
- Inust necessarily be raised with the aid of hired labor, and a consequent
investment of cash capital. A large rearing requires a large and (for
success) a specially constructed building, Which must necessarily lie
dle for the greater part of the year. It has been found, too, that the
average production of cocoons, per ounce of eggs, is much less for large
than for smaller crops. Thus one ounce of eggs of good race will pro-
duce one hundred pounds of fresh cocoons; while for every additional
ounce the percentage is reduced if the worms are all raised together,
until for twenty ounces the average may not exceed 25 pounds of co-
—coons per ounce. Such is the general experience throughout France,
according to Guérin-Méneville, and it shows the importance of keeping
the worm in small broods, or of rearing on a moderate scale. As a re-

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sult we see the great magnaneries disappearing from France and Italy,
where in some establishments as many as 60 ounces were at one time |
annually raised. We find this statement confirmed by looking at the
French official statistics for 1884, where it is stated that the cocoons |
produced in France during that year were raised by over one hundred —
and forty thousand families, who utilized therefor about two hundred
and eighty thousand ounces of eggs, or an average of about two ounces —
per family. 3

To beginuers I would repeat the advice so often given from this Office, ©
to hatch the first season but a small quantity of eggs; not more than |
an eighth of an ounce. Experience counts in this as in other industries, ©
and it will be found that, where only a small quantity of worms are |
being fed, there will be much more time to study their habits and wants.
With a year’s experience there will be a better chance of profit the |
second year. |

It will not be safe for individuals to rely on reeling their own silk.
The art of reeling in modern filatures and with steam appliances has ©
been brought to such perfection that none but skilled reelers can hope ©
to produce a first-class article. Skill comes only after full apprentice- |
ship and practice. The only way in which silk-reeling can be managed
profitably at present is where a colony of silk-raisers combine to put up —
and operate a common filature. Though there is a ready market in the-
United States for large lots of good silk, it will not be found so easy to ~
dispose of small lots of poorer quality. 4

Two years ago Congress appropriated $15,000 for the encouragement
of silk-culture, and the appropriation was repeated for the present fiscal —
year. The appropriation was general in its nature, and the method of ©
encouragement left with the Commissioner of Agriculture. In my An-— |
nual Reports for 1884 and 1885 details are given as to the work done -
by the Department under this appropriation, and various questions dis- —
cussed and conclusions reached as to the outcome of the two years’ ex-
perience. These need not be repeated here. |

Owing to the conviction that the establishment of filatures and their
successful operation was the sine qua non in putting the industry on au
firm basis, a large portion of the money thus appropriated has been de-_
voted to experiments in silk reeling. These experiments have shown ©
that the quality of cocoons produced by American silk-raisers is not yet ©
such as to enable this country to compete with others in the production
of raw silk. The quality of a cocoon is most conclusively shown by the |
quantity of silk which may be unwound from it. A good average re-
sult, after the experience of European filatures, is the production of a
pound of raw siik from 3.80 pounds of dry cocoons. The Government
experiments at New Orleans showed a production of but 1 pound of silk |
from 4.23 pounds of dry cocoons. The cost of producing silk from a
poorer quality of cocoons is proportionately much greater than where the
cocoons are of better quality, and the difference is much greater than —

—

7)

would be thought possible by one unacquainted with the industry. We
have, therefore, much to accomplish from this point of view before we
can hope to make the industry a profitable one in the United States.
The cocoons which have been received at the Government stations dur-
ing the past year have been, to a large extent, raised by persons who
were inexperienced, and who were thus unable to produce a first-class
cocoon. There is an inclination among these very persons to blame the
industry if they do not receive, the first season, what they consider an
adequate compensation for the time which they have expended upon
the work. And yet these same individuals would not expect to be suc-
cessful in any other enterprise until they had made themselves thor-
oughly acquainted, by practical experience, with the special work in-
volved. It is not, therefore, surprising that with such a quality of raw
material it has been impossible to produce silk without financial loss.
Such a loss, in fact, as shown in my annual report as entomologist, for
1885, was incurred as the result of the experiments. We, however, per-
formed these experiments with non-automatic machinery, and that even
of an unimproved type. ‘The loss was, however, so small that we have
reason to believe that it can be more than counterbalanced by the use
_ of improved plant. Automatic silk-reels are now being placed upon
the market, which not‘only effect a slight saving in the quantity of raw
material employed, but also a very large saving in labor, the cost of
which in this country is the principal cause of our inability to compete
_with Hurope and Asia. These new reels are also capable of producing,
with comparatively unskilled labor, as good a grade of silk as can be
made by the expert workwomen of France.

It will be seen by the estimates given above that silk-culture is not
(and it never has been) an exceedingly profitable business, but if adds
vast wealth to the nations engaged in it, for the simple reason that it
can be pursued by the humblest and poorest, and requires so little out-
lay. The question ofits establishment in the United States is, as I have
elsewhere said, “a question of adding to our own productive resources.
There are hundreds of thousands of families in the United States to-day
who would be most willing to add a few dollars to their annual income
by giving light and easy employment for a few months each year to the
more aged, to the young, and especially to the women of the family, who
may have no other means of profitably employing their time.

“This holds especially true of the people of the Southern States,
most of which are pre-eminently adapted to silk-culture. The girls of
the farm, who devote a little time each year to the raising of cocoons,
may not earn as much as their brothers in the field, but they may earn
something, and that something represents an increase of income, be-
cause it provides labor to those members of society who at present too
often have none that is remunerative. Further, the raising of a few
pounds of cocoons each year does not and need not materially interfere
with the household and other duties that now engage their time, and it

/
10

is by each household raising a few pounds of cocoons that silk-eulture
must, in the end, be carried on in this as it has always been in other
countries.”

The reader is reminded that the few quotations not otherwise credited
are from the author’s Fourth Report on the Insects of Missouri (1871).
A number of foreign (more particularly French) terms are unavoidable
in treating of silk-culture, as they have no actual equivalents in our
language. These and the few technical terms used in the manual are
made clear in the glossary.

Tinally, I take pleasure in acknowledging the assistance given me in
the preparation of this new edition by Mr. Philip Walker, who has acted
as the chief agent of the division in the sericultural work during the
past two years.

CC.

WASHINGTON, D. C., May, 1886.

CHAPTER I.

Y PHYSIOLOGY AND LIFE-HISTORY OF THE SILK-WORM.

: The Silk-worm proper, or that which supplies the ordinary silk of
commerce, is the larva of a small moth known to scientific men as Seri-
cariamort. Itis often popularly characterized as the Mulberry Silk-
worm. Its place among insects is with the Lepidoptera, or scaly-winged
insects, family Bombycida, or spinners. There are several closely allied
species, which spin silk of different qualities, none of which, however,
unite strength and fineness in the same admirable proportions as does
that of the mulberry species. The latter has, moreover, acquired many
useful peculiarities during the long centuries of cultivation it has un-
dergone. It has in fact become a true domesticated animal. The qual-
ity which man has endeavored to select in breeding this insect is, of
course, that of silk producing, and hence we find that, when we com-
pare it with its wild relations, the cocoon is vastly disproportionate to
the size of the worm which makes it or the moth that issues from it.
_ Other peculiarities have incidentally appeared, and the great number
of varieties or races of the Silk-worm almost equals those of the domes-
tic dog. The white color of the species, its seeming want of all desire
_ to escape as long as it is kept supplied with leaves, and the loss of the
power of flight on the part of the moth, are all undoubtedly results of
domestication. From these facts, and particularly from that of the
_ great variation within specific limits to which the insect is subject, it
_ will be evident to all that the following remarks upon the nature of the
_ Silk-worm must necessarily be very general in their character.

The Silk-worm exists in four states—egg, larva, chrysalis, and adult
or imago—which we will briefly describe.

revs

:.
cd
¥
c
2
‘
.

DIFFERENT STATES OR STAGES OF THE SILK-WORM,

THE Eac.—The egg of the Silk-worm moth is called by silk-raisers
the “seed.” It is nearly round, slightly flattened, and in size resem-
bles a turnip seed. Its color when first deposited is yellow, and this
color it retains if unimpregnated. If impregnated, however, it soon
— acquires a gray, slate, lilac, violet, or even dark green hue, according

to variety or breed. It also becomes indented. When diseased it as-
sumes a still darker and dull tint.
_ Near one end a small spot may be observed. This is the micropyle,
and is the opening through which the fecundating liquid is injected

11

12

just before the egg is deposited by the female. After fecundation and
before deposition the egg of some varieties is covered with a gummy
varnish which closes the micropyle and serves to stick the egg to the
object upon which it is laid. Other varieties, however, among which —
may be mentioned the Adrianople whites and the yellows from Nouka,
in the Caucasus, have not this natural gum. As the hatching point —
approaches the egg becomes lighter in color, which is due to the fact
that its fluid contents become concentrated, as it were, into the central —
forming worm, leaving an intervening space between it and the shell,
which is semi-transparent. Just before hatching, the worm within be-—
coming more active, a slight clicking sound is frequently heard, which |
sound is, however, common to the eggs of many other insects. The 7
shell becomes quite white after the worm has made its exit by gnawing ~
a hole through it, which it does at the micropyle. Each female pro-
duces on an average from three to four hundred eggs. Inthe standard
ounce of 25 grams* there are about 50,000 eggs of the small Japanese —
races, 37,500 of the ordinary yellow annual varieties, and from 30,000 —
to 35,000 in the races with large cocoons. The specific gravity of the
eggs is Slightly greater than water, Haberlandt having placed it at 1.08, —

It has been noticed that the color of the albuminous fluid of the egg —
corresponds to that of the cocoon, so that when the fluid is white the
cocoon produced is also white, and when yellow the cocoon again cor-—
responds.

Tor LARVA OR WormM.—The worm goes through from three to four

molts or sicknesses, the latter being the normal number. The periods:
between these different molts are called “ages,” there being five of these
ages, the first extending from the time of hatching to the end of the
first molt, and the last from the end of the fourth molt to the transfor-
mation of the insect into a chrysalis. |

The time between each of these molts is usually divided as follows:
The first period occupies from five to six days, the second but four or
five, the third about five, the fourth from five to six, and the fifth from
eight to ten. These periods are not exact, but simply proportionate.
The time from the hatching to the spinning of the cocoons may, and does,
vary all the way from twenty-five to forty days, depending upon the
race of the worm, the quality of food, mode of feeding, temperature,

*281 crams = 1 ounco avoirdupois.

13

etc.; but the same relative proportion of time between molts usually
holds true.

— The color of the newly-hatched worm is black or dark gray, and it is
- covered with long, stiff hairs, which, upon close examination, will be
found to spring from pale colored tubercles. Different shades of dark
— gray will, however, be found among worms hatching from the same
_ batch of eggs. After the first molt, and as the worm increases in size,
_ these hairs and tubercles become less noticeable, and the worm gradu-
ally gets lighter and lighter, until, in the last stage, it is of a cream-
white color. When full grown it presents the appearance of Fig. 1.
It never becomes entirely smooth, however, as there are short hairs
along the sides, and very minute ones, not noticeable with the unaided
eye, all over the body.

_ The preparation for each molt requires from two to three days of
fasting and rest, during which time the worm attaches itself firmly
_ by the abdominal prolegs (the 8 non-articulated legs under the 6th,
7th, 8th, and 9th segments of the body, called prolegs in contradistine-
- tion to the 6 articuiated true legs under the Ist, 2d, and 5d segments),
and holds up the forepart of the body, and sometimes the tail. In front
of the first joint a dark, triangular spot is at this time noticeable, indi-
cating the growth of the new head; and when the term of “sickness”
is over, the worm casts its old integument, rests a short time to recover
_ strength, and then, freshened, supple, and hungry, goes to work feeding
voraciously to compensate for lost time. This so-called “sickness”
which preceded the molt was, inits turn, preceded by a most voracious
appetite, which served to stretch the skin. In the operation of molting
the new head is first disengaged from the old skin, which is then gradu-
ally worked back from segment to segment until entirely cast off. Ifthe
- worm is feeble or has met with avy misfortune, the shriveled skin may
remain on the end of the body, being held by the anal horn; in whieh
ease the individual usually perishes in the course of time. It has been
usually estimated that the worm in its growth consumes its own weight
: of leaves every day it feeds; but this is only an approximation. Yet
“ it is certain that during the last few days before commencing to spin it
‘ consumes more than during the whole of its previous worm existence.

ras

it is a curious fact, first noted by Quatrefages, that the color of the ab-
dominal prolegs at this time corresponds with the color of the silk
which will form the cocoons.
: Having attained full growth, the worm is ready tospinup. It shrinks
_ somewhat in size, voids most of the excrement remaining in the aliment-
Fs ary canal; acquires a clear, translucent, often pinkish or amber-colored
Z hue; becomes restless, ceases to feed, and throws out silken threads.
‘The silk is elaborated in a fluid condition in two long, slender, conyo-
-Inted vessels, one upon each side of the alimentary canal. As these
vessels approach the head they become less convoluted and more slen-
er, and finally unite within the spinneret, from which the silk issues in

14

a glutinous state and apparently in a single thread. The glutinous
liquid which combines the two, and which hardens immediately on ex-
posure to the air, may, however, be softened in warm water. The worm
usually consumes from three to five days in the construction of the co-
coon and then passes in three days more, by a final molt, into the chrys-
alis state.

THE Cocoon.—The cocoon (Figs. 2 and 3) consists of an outer lining

Tic. 2,—Constricted cocoon, with fine Fic. 3.—Non-constricted cocoon, with
texture (original). coarse texture (original).

of loose silk known as ‘ floss,” which is used for carding, and is spun
by the worm in first getting its bearings. The amount of this loose silk
varies in different breeds. The inner cocoon is tough, strong, and com-
pact, composed of a firm, continuous thread, which is, however, not
wound in concentric circles, as might be supposed, but irregularly, in
short figure-of-8 loops, first in one place and then in another, so that, in
reeling, several yards of silk may be taken off without the cocoon turn-
ing around. In form the cocoon is usually oval, and in color yellowish,
but in both these features it varies greatly, being either pure silvery-
white, cream, or carneous, green, or even roseate.

THE CHRYSALIS.—The chrysalis is a brown, oval body, considerably
less in size than the full-grown worm. In the external integument may
be traced folds corresponding with the abdominal rings, the wings folded
over the breast, the antenne, and the eyes of the inclosed insect—the
future moth. At the posterior end of the chrysalis, pushed closely up
to the wall of the cocoon, is the last larval skin, compressed into a dry
wad of wrinkled integument. The chrysalis state continues for from
two to three weeks, when the skin bursts and the moth emerges.

THE Motru.—With no jaws, and confined within the narrow space of
the cocoon, the moth finds some difficulty in escaping. Lor this pur-
pose it is provided, in two glands near the obsolete mouth, with a
strongly alkaline liquid secretion, with which it moistens the end of the

15

cocoon and dissolves the hard, gummy lining. Then, by a forward and
backward motion, the prisoner, with crimped and damp wings, gradu-
| ally forces its way out; and the exit once effected, the wings soon ex-
pand and dry. The silken threads are
simply pushed aside, but enough of them
get broken in the process to render the
cocoons from which the moths escape
comparatively useless for reeling.

The moth is of a cream color, with more
or less distinet brownish markings across
the wings, as in Fig. 4. The males have
broader antenn or feelers than the fe- oy ga. comm aot ister
males, and may be, by this feature, at
once distinguished. Neither sex flies, but the male is more active than
the female, and may be easily recognized by a constant fluttering motion
of the wings, as well as the feature mentioned above. They couple soon
after issuing, remaining coupled during several hours, and in a short time
after separation the female begins depositing her eggs, whether they
have been impregnated or not. Very rarely the unimpregnated eggs
have been observed to develop.

4
!

VARIETIES OR RACES.

_ As before stated, domestication has had the effect of producing nu-
merous varieties of the Silk-worm, every different climate into which it
has been carried having produced either some changes in the quality
of the silk, or the shape or color of the cocoons, or else altered the
habits of the worm.
| Some varieties produce but one brood in a year; such are known as
| Annuals. Others, known as Bivoltins, hatch twice in the course of the
‘year; the first time, as with the Annuals, in the early spring, and the
}second, eight or ten days after the eggs are laid by the first brood.
/ With Bivoltins the eggs of the second brood only are kept for the next
‘year’s crop, as those of the first brood always either hatch or die soon
after being laid. The Trevoltins produce three annual generations,
‘There are also Quadrivoltins, and in Bengal a variety known as Dacey,
which is said to produce eight generations in the course of a year.
Some varieties molt but three times instead of four, especially in warm
ouutries and with Trevoltins. Experiments, taking into considera-
tion the size of the cocoon, quality of silk, time occupied, hardiness,
‘quantity of leaves required, ete., have proved the Annuals to be more
profitable than any of the Polyvoltins. The principle difficulties en-
countered in raising other than the annual races arise from the excess-
ive heat of midsummer, which causes disease, and the deteriorated
quality of the leaves as explained in Chapter X. Silk-growers are
therefore earnestly advised to attempt but one brood per annum ex-

16

cept where, as in some parts of the Pacific coast, the summers are pro-—
longed and equable.

Commercially cocoons are classed as yellow, white, and green, but
through the intermingling of races these colors have become merged
one into the other, and it is often difficult to define the line of demarka-
tion. The same trouble exists in classifying varieties by the different
countries or provinces from which they have originally come. Prior to
the Silk-worm plague of twenty years ago in Europe there was a cer-
tain degree of exactness in the lines drawn between such races. Then,
however, the indigenous races were to a large extent blotted out, and
the egg merchants went first to Turkey, then to Asia Minor and Syria,
and finally to China and Japan, in search of eggs that should be free
from ‘‘the malady.” Thus it was that. there were brought into France
and Italy a large number of races foreign to those countries. These
were crossed together, and after the researches of Pasteur had made
the resuscitation of the native races possible, they were crossed with
these as well. Thus the identity of the old varieties was, in many cases,
lost, or they obtained different names.

CHAPTER IT.

WINTERING AND HATCHING THE EGGS.

As has been said in the last chapter, the egg of the Silk- worm changes
color soon after oviposition. During this operation the contents undergo
a chemical change, absorbing oxygen and giving off carbonic acid. This
absorption of oxygen is very active during the first six days, after which
it rapidly declines and continues at a very low rate during the months
which precede hatching. The eggs should, therefore, be wintered in
such manner that they have plenty of air; otherwise their development
will be seriously interfered with. They must not be packed in thick
layers, but should be spread out thinly. For these reasons the eggs at
this Department are kept through the winter in boxes of perforated
tin, the bottoms of which have a surface of 65 square inches, each box
containing not more than one quarter of an ounce of eggs.

The atmosphere in which the eggs are kept should neither be too dry
nor toohumid. M. Beauvais found a saturation of 50 per cent. to be the
most suitable condition of the air, as when it is below that point the
liquids of the eggs evaporate so rapidly as to require a highly saturated
atmosphere for theirincubation. Excessive moisture, on the other hand,
will assist the formation of mold, which will quickly injure the contents
of theege. The eggs should be frequently inspected, aud whenever such
mold is discovered it should be quickly brushed off and the eggs re-
moved to a drier locality.

Under natural conditions the egg undergoes a partial development as
soon as laid, as shown by its changing color. After oviposition, and un-
til subjected to cold, the eggs of the annual races are not capable of
hatching out. This is the rule, although we often find in a batch of an-
nual eggs a few accidental bivoltins that hatch some fifteen days after
they are laid. The number, however, is very slight, and it has been
determined that the temperature to which they are submitted in no way
alters the result. During this period, which we call prehibernal, the
eggs may be kept at any ordinary temperature, however warm, but once
they are submitted to the cold of winter a certain change takes place in
them, the nature of which has not yet been determined, and their sub-
Sequent warming may then result in hatehing. As in our climate warm
days are quite frequent in late winter, it is very necessary that the eggs
be kept below the hatching temperature until the foliage on which the
worms are to feed is developing and all danger from late frosts is at an
end. The period of hibernation may be lengthened by keeping the eggs
ina cool, dry cellar, wtth a northerly exposure, and in general this will
a, 16136—No, 9——2 17

ss

18

suffice. Butin such a case the temperature is more or less variable, and
the embryo may be started in its development only to be checked by re
newed cold. When kept at a uniform low temperature, after having
once been cooled, development is imperceptible, and when afterward
exposed to the proper hatching conditions, the resultant worms will
prove more vigorous. If possible the temperature should never be 2
lowed to rise above 40° F., but may be allowed to sink below fecuie
point without injury.

When small lots of eggs are to be wintered, they may be placed in
ordinary boxes in the cellar, care being taken to isiseie the precautions
noted above as to ventilation, humidity, and temperature. They should
also be protected from rats, mice, ants, and other vermin. But where
great quantities are to be stored, it will be well worth while to construct
special hibernating boxes, where the requisite conditions may be regu-
lated with nicety and precision.

A great object should be to have them hatch uniformly, and this is
best attained by keeping together those laid at one and the same time,
and by wintering them, as already recommended, in cellars or hiber-

nating boxes that are cool enough to prevent any embryonic develop-
ment. They should then, as soon as the leaves of their food-plant have
commenced to put forth,* be placed in trays and brought into a well-aired
room where the temperature averages about 75° I. If they have been
wintered adhering to the cloth on which ee were laid, all that it is
necessary to do is to spread this same cloth over the bottom of the tray.
If, on the contrary, they have been wintered in the loose condition, they
must be uniformly sifted or spread over sheets of cloth or paper. The
temperature should be kept uniform, and a small stove in the hatching-
room will prove very valuable in providing this uniformity. The heat
of the room may be increased about 2° each day, and if the eggs have
been well kept back during the winter, they will begin to hatch under
such treatment on the fifth or sixth day. By no means must the eggs
be exposed to the sun’s rays, which would kill them ina very short
time. As the time of hatching approaches, the eggs grow lighter in
color, and then, if the weather be dry, the atmosphere must be kept
moist artificially by sprinkling the floor or otherwise, in order to enable
the worms to eat through the egg-shell more easily. They also appear
fresher and more vigorous with due amount of moisture.

It will be found that eggs which have been subjected to great cold
during the winter will require a longer time in their incubation than
those which have been kept at a higher temperature, and it is also true,
as has been intimated above, that when the atmosphere in which the
egos have been retained has been exccssively dry it will require ¢ con-

*Too much stress can not be laid on the importance: of beginning the rearing x of
worms as early as possible, so that the excessive heat of summer may be avoided.
Beginners are very apt to delay sending for eggs until after the leaves have put out,
and there is not only more danger of the hatching of the eggs in transit, but the
worms will be maturing during very warm weather.

hr 48 ot

19

siderable humidity to cause them to hatch. Such matters must be
largely regulated by the experience of the individual raiser.

The desired conditions can be better regulated in specially constructed
incubators than in an openroom. A simple form of incubator is shown
in fig. 5. It consists of a tin cylinder with a perforated shelf avd a

Fic. 5.—Incubator made of tin-ware (after Roman).

movable cover. Under the shelf is placed upon a tripod a small vesse}
of water, beneath which burns a small night-lamp.. This apparatus may
be made about eight times the size of the drawing. <A similar and sim-
ple form of basket-ware incubator is shown in Fig. 6. This possesses

FVIII. LLLLLILRIZZIO >

Fic. 6.—Incubator made of basket-ware (after Roman).

the advantage of being permeable to the air and of thus insuring a more
complete ventilation for the eggs. Many modifications of these designs
will suggest themselves to individuals; amongst others the surround-
ing of the cylinder of the ineubator first described with a jacket, in
Which hot water may be placed, by means of which the temperature of
the interior may be regulated with a considerable degree of nicety.

CHAPTER IT.

IMPLEMENTS THAT FACILITATE THE RAISING OF SILK.

The room in which the rearing is to be done should be so arranged
that it can be thoroughly and easily ventilated and warmed if desirable.
A northeast exposure is the best, and buildings erected for the express
purpose should combine these requisites. If but few worms are to be
reared, all the operations can be performed in trays upon tables, butin
large establishments the room should be arranged with deep and nu-
merous shelves, ranging one above the other from floor to ceiling, as
shown in Fig. 7. The width of these shelves should not exceed 5 feet,

SN

ZS SE
=\\I\) ——
\ yt

= Hs
—

\
ZZ
——

EZ,
O.HLIDEMAN. 3G

Fic. 7.—A modern magnanerie (after Gobin).

as those in charge must be able to reach from either side to the middle
of each table. Bearing this in mind, the dimensions of these tables may
be made to suit the room in which the worms are reared. The vertical
distance between two shelves should not be less than 20 inches, but if
this space is greatly increased it will be found inconvenient to obtain
brush of sufficient length to form the arches upon which the cocoons are
to be spun. :
20

21

The form in which the tables are constructed is also immaterial, and
should depend upon the resources of the owner. Where canes are
abundant, as upon the Mississippi bottom, such a shelf as is shown in

Fic. 8.—Shelf made of canes (after Roman).

Fig. 8 will be found inexpensive and satisfactory. To construct a sheif
in this manner, say 5 by 8 feet, there should be selected for cross-pieces
four stout canes about one inch through at the small end and 5 feet 4
incheslong. Having procured a quantity of smaller canes, 5 feet long, lay
out the four cross-pieces some eighteen inches apart, and, placing a cane
across them, lash the whole together with stout cord. This is done by
having an end of cord attached to each cross-piece, which, after if is
carried over the smaller cane, is brought around the cross-piece and
fastened by a slip knot, as will be better understood by reference to

So Ss ees

= =
eee 2 aa ogee SE

Fic. 9.—Constraction of the exne shelf (after Roman).

Fig. 9. The second cane should be placed tip to butt with the first, and
so on alternately. Fig. 10 shows a shelf formed with wire-work, which

PEEEEEEE EEE herr seen Cees Caxaeoeae
EVSURSERERS RAPA EREEE BRBEEEe
BL UBER E REE ACCC anBaR nnn
EVGSERSRERS TE Perry ‘ERERRERE
Boa BEna PECL ZEEEE
ti AL CEE CLL SeESESEES

Fie 10. Wire-work shelf age Roman).

22

makes a strong and light article. The form shown in Fig. 11 is essen-
tially the same, being covered with wooden slats. Placing these diag-
onally increases the stiffness and diminishes liability to break.

Fic. 11.—Frame covered with slats (original).

Where ié is desired to have a neat and convenient standard, upon
which a small quantity of worms may be reared, it may be constructed
after the manner of that shown in Fig. 12, the shelves being made as

Fic. 12,—Standard for holding shelves (original).

shown in either of Figs. 10 or 11. The principal requisites in tne con-
struction of all the above articles are lightness and strength, and the
shelves should be so constructed as to permit the free circulation of the
air. All wood should be well seasoned, as green wood seems to be inju-
rious to the health of the worms. Theshelves above described must be
covered with strong brown paper before being used, and it will be found
to be more convenient in removing the litter if sheets of the same size
as the table are employed.

23

In rearing Silk-worms great care should be observed in not handling
them more than is absolutely necessary, and as, in clearing up the litter
made by the larve, it is necessary to transport them from one table to
another, several schemes have been adopted to accomplish this object.
The first transfer made upon the birth of the worms is usually performed
with the aid of ordinary mosquito netting, which is lightly laid ever the
hatching eggs. Upon this can beevenly spread freshly-plucked leaves
or buds. The worms willrise through the meshes of the net, and cluster
upon the leaves, when the whole net can be easily removed.

This netting has the disadvantage of sagging in the middle and
lumping the worms. Netting of a coarser mesh may be used later in
rearing, but it should be stretched on light frames. This method
of transfer is such a great convenience and time-saver that in France,
for many years, paper, stamped by machinery with holes of different
sizes, suited to the different ages of the worms, has been used. The
material employed is a stout manila paper, and the perforations vary
in size, aS Shown in Fig. 13. I have experienced some difficulty in the

STE ES SiO BS a a

CPOE) OO: Ore) © ©
OC) GG) GC) Ge
SND AONE) 5 BBS Meese,

ria. 13.—Perforated paper, showing the sizes of the perforations in the first and last ages (original)

use of this paper during the fifth age, the worms being so large that
when the holes are partially obstructed by twigs or leafstems they
must force themselves through the restricted space, often cutting them.
selves on the sharp edges of the paper. This may be avoided by the

24

use, during that age, of a lattice-work tray, such as is shown in —
Fig. 14. 7 3

To prevent this tray from pressing upon the worms beneath, it should |
be propped up by small blocks placed under the corners. j

When large pieces of perfor- —
ated paper are used they should
be handled by two persons. By
cutting them into smaller pieces
and using a transfer tray (Fig.
15) one person can perform the
necessary work with ease. Such
a tray is most.conveniently made
about 13 by 19 inches inside.
When the paper, which should
be made about one inch smaller
| hi each way, has been covered with

Vic, 14.—Lattice-work transfer tray (original). leaves, and the worms have

| come through the perforations in

search of their food, the whole may easily be slipped into the transfer

tray, and as easily taken from it in depositing the worms on another table.

In gathering leaves for the worms

it will be found convenient to eim-

ploy a bag (Fig. 16), so arranged

that it may be attached around the

waistlikeanapron. Twosuch sacks

may be made from an ordinary meal
bag.

The worms should be made to spin their cocoons on brush so arranged
as to form arches between the shelves, as is shown in Fig. 19.

For the same object the co-
cooning ladder shown in Fig.
17 was devised in 1842 by M.
Davril. It consists of two cen-
tral supports, across each side
of which (Fig. 18) are nailed
small strips ofabout one-quarter
by one-half inch section, 14
inches apart. The strips on
one side are placed opposite
the spaces between the strips on the other side. The ladder may be
made about 30 by 15 inches, and the central supports about five-eighths
inch thick. When in use the ladder is placed slantingly between the
tables, with the central supports horizontal.

A thermometer is a very useful adjunct to the appliances above de-
scribed.

Fic. 15.—Transfer drawer (after Roman).

25

Fic. 17.—The Davril cocooning ladder.

Fic, 18.—Partial end view of the Davril cocooning ladder (full size).

CHAPTER Ly.

THE REARING OF SILK-WORMS.

The chief conditions of success in silk raising are (1) the use of good
. eggs; (2) proper care of the worms.

The means of obtaining pure eggs will be described in the next chap-
ter, and we will here consider the second of the conditions.

Unless new, and especially where the worms raised with them the
preceding season have suffered from any disease, all the implements
and furniture used should be cleansed and purified by carefully serub-
bing in soap and water. The walls of the room may, where convenient,
be submitted to the same operation, and covered with a strong coat of
whitewash. The room should then be tightly closed and thoroughly
fumigated with burning brimstone during an entire day and night. It
nay then, after being well aired, be used for the rearing of Silk-worms.

The eggs when about to hatch, whether brought to this condition. by
the systematic processes described in Chapter IJ, or by ruder methods,
should be spread out on clean paper in as thin layers as possible. Over
them should be lightly laid small pieces of ordinary mosquito-netting.
When the worms begin to appear there should be sparsely scattered
over this netting a few buds or finely-cut leaves. The newly born
larvee will at once pass through its meshes in searcli of food, and the
whole can then be easily removed to the table upon which they are to
pass their first age.

It is recommended by many to feed the worms while in this age, and,
consequently, weak and tender, leaves that have been cut up or hashed,
in order to give them more edges to eat upon and to make less work for
them. This, however, is hardly necessary with annuals, although it is
quite generally practised in France. With the second brood of Bivol-
tins it might be advisable, inasmuch as the leaves at the season of the
year when they appear have attained their fuli growth and are alittle
tough for the newly-hatched individuals. In the spring, however, tiie
leaves are small and tender, and nature has provided the young worms
with sufficiently strong jaws to cut them.

Many rules have been laid down as to regularity of feeding, and much
stress has been put upon it by some writers, most advising four meals
a day at regular intervals, while a given number of meals between molts
has also been urged; but such definite rules are of but little avail, as
so much depends upon circumstances and conditions. The food should,

26

27

in fact, be renewed whenever the leaves have been devoured, or when-
ever they have become in the least dry, which, of course, takes place

much quicker when young and tender than when mature. This also is

an objection to the use of the hashed leaves, as, of course, they dry
very quickly. The worms eat most freely early in the morning and late
at night, and it would be well to renew the leaves abundantly between
5 and 6 a. m., and between 10 and 11 p.m. Additional meals should
be given during the day, according as the worms may seem to need
them. Itis only by experience that one can learn just what amount of
food should be given to the worms. It may prove dangerous to feed
them too copiously, as in the first ages the worms may become buried
and lost in the litter, whiie later the massing of food in an attempt to
satisfy their ravenous appetites may cause it to ferment and become
productive of disease.

Great care should be taken to pick the leaves for the early morning
meal the evening before, as when picked and fed with the dew upon
them they are more apt to induce disease. Indeed, the rule should be
laid down, never to feed wet or damp leaves to your worms. In case
the leaves are picked during a rain they should be thoroughly dried
before being fed; and on the approach of a storm it is always well to
lay in a stock, whick should be keptfrom heating by occasional stirring.
Care should also be taken to spread the leaves evenly, so that all may
feed alike. During this first and most delicate age the worm requires
much care and watching.

As the fifth or sixth day approaches, signs of the first molt begin to
be noticed. The worm begins to lose appetite, grows more shiny, and
soon the dark spet already described appears above the head. ‘The
larva at this time generally wanders to an unencumbered spot where it
may shed its skin in quiet and often gets hidden and buried under the
superimposed leaves. When the first worms show these signs of molt-
ing, food should be given more sparingly and the meals should cease
altogether as soon as the most forward worms awaken. When the time
for the molt is near, say during the fourth day, it will be well to clear
away the litter so that the worms may pass the crisis on a clean bed.

Some will undoubtedly undergo the shedding of the skin much more
easily and quickly than others, but no food should be given to these
forward individuals until nearly all have completed the molt. This
serves to keep the batch together, and the first ones will wait one or
even two days without injury from want of food. It is, however, un-
necessary to wait for all, as there will always be some few which remain
sick after the great majority have cast their skins. These should either
be set aside and kept separate, or destroyed, as they are usually the
most feeble and most inclined to disease; otherwise the batch will grow
more and more irregular in their moltings and the diseased worms will
contaminate the healthy ones. It is really doubtful whether the silk
raised from these weak individuals will pay for the trouble of rearing

28

them separately, and it will be better perhaps to destroy them. The
importance of keeping each batch together, and of causing the worms
to molt simultaneously, can not be too much insisted upon as a means
of saving time.

As soon as the great majority have molted they should be copiously
fed, and, as they grow very rapidly after each molt, and as they must
always be allowed plenty of room, it will probably become necessary to
divide the bateh, and this is readily done at any meal by removing the
net or tray when about half of the worms have risen and replacing it
by an additional one. The space allotted to each batch should, of
course, be increased proportionately with the growth of the worms.
The same precautions should be observed in the three succeeding molts
as in this first one.

The second and third castings of the skin take place with but little
more difficulty than the first, but the fourth is more laborious, and the
worms not only take more time in undergoing it, but more often perish
in the act. At this molt it is perhaps better to give the more forward
individuals a light feed as soon as they have completed the change, in-
asmuch as it is the last molt and but little is to be gained by the retard-
ation, whereas it is important to feed them all that they will eat, since
much of the nutriment given during the last age goes to the elabora-
tion of the silk.

It would, too, be found inconvenient if all the worms were to arrive
at the spinning period together, as extra assistance would be required
to place the brush on which they spin their cocoons.

At each successive molt the color of the worm has been gradually
whitening, until now it is of a decided cream color. Some breeds,
however, remain dark, and occasionally there is an individual with
zebra-like markings.

As regards the temperature of the rearing-room, great care should be
taken to avoid all sudden changes from warm to cold, or vice versa. A
mean temperature of 75° or 80° I’. will usually bring the worms to the
spinning-point in the course of 35 days after hatching, but the rapidity
of development depends upon a variety of other causes, such as quality
of leaf, race of worm, ete. If it can be prevented the temperature
should not be permitted to rise very much above 50°, and it is for this
reason that a room with a northern or northeastern exposure was recom-
mended as preferable to any other. The air should be kept pure all of
the time, and arrangements should be made to secure a good circulation.
Great care should be taken to guard against the incursions of ants and
other predaceous insects, which would make sad havoc among the worms
were they allowed an entrance, and all through the existence of the in-
sect, from the egg to the noth, rats and mice are on the waten for a
chance to get at them, and are to be feared almost as much as any other
enemy the Silk-worm has.

So much depends upon the conditions of development mentioned

29

above that it is impossible to state the exact quantity of food con-
sumed by the Silk-worm during its life. It will not be far from the
truth, however, to place the amount consumed by the issue of an ounce
of healthy eggs, which matures in 35 days, at 65 pounds during the
first age, 20 pounds during the second, 65 pounds during the third, 200
pounds during the fourth, and during the fifth and last age 1,250 pounds.
This makes a total of between 1,500 and 1,600 pounds. It need hardly
be said that the food mentioned must be of the best quality. Were it
poor, it would be impossibie to give any figures at all.

Too much can not be said in favor of giving the larvze plenty of room.
Every worm should be free to move easily without incommoding its fel-
lows. We should therefore aliow the issue of an ounce of eggs during
the first age, from 10 square feet at the beginning to 39 square feet at
the end of the age, daily extending the space occupied by them by spread-
ing their food over a greater table surface. In the second age, they
should spread in the same manner so as to cover from 50 to 75 square
feet, in the third from 100 to 160 square feet, and in the fourth from 200
to 320 square feet. KEntering the last age, spread over 450 square feet
of surface, they should gradually be extended until they occupy, at the
spinning period, 640 square feet. It need hardly be said that when the
worms have been decimated by disease the surface occupied by them
need not be so extensive. |

The litter of the worms should be cleared away by the use of netting
or perforated paper, before and after each molt, and once at about the
middle of the third age. While small, the frass, dung, and detritus
dry rapidly, and may (though they should not) be left for several days
in a tray with impunity; but he who allows his trays to go uncleaned
for more than a day during the two last ages will suffer in the disease
wud mortality of bis worms just as they are reaching the spinning
point.

Summed up, the requisites to successful Silk-worm raising are; Ist.
Uniformity of age in the individuals of the same tray, so as to insure
their molting simultaneously. 2d. No intermission in the supply of
fresh food, except during the molting periods. 3d. Pienty of room, so
that the worms may not too closely crowd each other. 4th. Fresh air
and as uniform temperature as possible, Sth. Cleanliness. The last
three are particularly necessary during the fourth and fifth ages.

PREPARATIONS FOR SPINNING.

With eight or ten days of busy feeding, after the last molt, the worms,
as we have learned before, will begin to lose appetite, shrink in size,
become restless, and throw out silk, and the arches for the spinning of
the cocoons must now be prepared. These can be made of twigs of
different trees, two or three feet long, set up upon the shelves over the

30

worms, and made to interlock in the form of an arch above them.
Interlace these twigs with broom-corn, hemlock, or other well-dried

Fic. 19.—Method of constructing arches upon which the cocoons are spun (after Roman).

brush. The*feet of each arch should be only about a foot apart. The
Davril cocooning ladder, described in Chapter IIT, may be used with
advantage in the place of the brush arches.

The temperature of the room should now be kept above 80°, as the
silk does not flow so freely in acool atmosphere. The worms will imme-
diately mount into the branches and commence to spin their cocoons.
They will not all, however, mount at the same time, and those which
are more tardy should be fed often, but in small quantities at a time, in
order to economize the leaves, as almost every moment some few will
quit and mount. There will always be a few which altogether fail to
mount, and prefer to spin in their trays. It is best, therefore, after the
bulk have mounted, to remove the trays and lay brush carefully over
them. The fact that the worms already mounted make a final discharge
of soft and semi-fluid excrement before beginning to spin makes this
separation necessary, as otherwise the cocoons of the lower ones would
be badly soiled.

As the worms begin to spin they sbould be carefully watched, to guard
against two or three of them making what is called a double or treble
cocoon, which would be unfit for reeling purposes. Whenever one
worm is about to spin up too near another, it should be carefully re-
moved to another part of the arch. In two or three days the spinning
will have been completed, and in six or seven the chrysalis will be
formed.

GATHERING THE COCOONS.

Hight days from the time the spinning commenced, it will be time to
gather the cocoons. The arches should be carefully taken apart, and
the spotted or stained cocoons first removed aud laid aside. Care should

*,

31

be taken not to stain the clean ones with the black fluids of sneh worms
as may have died and become putrid, for there are always a few of
these in every cocoonery. The outer cocoons of loose or floss silk are
then removed from the inner cocoons or pods, and the latter sorted ae-
cording to color, weight, and firmness of texture; those which best re-
sist pressure indicating that the worm has best accomplished its work.
Too much care can not be taken to remove the soft or imperfect cocoons,
as,if mixed with the firm ones, they would be crushed and soil the others
with their contents. The very best of the firm cocoons are now to be
chosen as provision for eggs for the next year, unless the raiser prefers
buying his eggs to the trouble of caring for the moths and keeping the
eggs through the winter. Eggs bought from large estabiishments are,
however, apt to be untrustworthy, and it is well for all silk-raisers to
provide their own seed. The precautions to be taken in choosing
cocoons for reproduction are set forth in Chapter VI.

Kept at a temperature of about 70° F., new silk cocoons lose, through
the giving off of humidity by the chrysalides, a material proportion of
their weight. According to Dandolo the loss in 100 pounds during the
first ten days amounts to about 74 per cent.* Theamount of humidity
in the atmosphere naturally affects this result. The loss continues until
the cocoons are thoroughly dry, when it will be found that they have
lost two-thirds of their original weight.

* Dandolo states that 100 pounds of cocoons will suffer the losses indicated by the
following table:

Pounds.
Weight when taken from the brush and after the floss has been removed. .-..--. 100. 0
es i OR AE RR na oS ah wal on en pew tpn ee eee ae 99. 1
enn WP TOMU OEE UENS Moe 2h foci tee cial oon > a sein ne Se cinta Soon Boe 93. 2
A I a a pA SP go er ape 97.5
UNMET SRGGEY Ch hia acest ee Sk. sce a ed pee oo we ee so oe ee 97.0
et CRM ME AMEE) 06 Whe ote an Sette <a se ances Ue eon d JAb Wu. 2 LU Ve 96.6
enrrrerina attr 15.20 os ae ol a deans dh enw cite bd hn 2 we 96. 0
EE a a OC a ee RS 95. 2
eI OL EROS 2 eS on Sh we on ee inne an Sy web eae dacs eee 94.3
TRIER TU MEARGRIEI A094 oa SOIC Sache cc Cui ain Pans We'd eee van bs 05 < wae eee 93.4
I MRE Sd) yet Waco a wont aptheds ce hes cane ands scan case gaeeme 92.5

CHAPTER V.

ENEMIES AND DISEASES OF THE SILK-WORM.

As regards the enemies of the Silk-worm but little need be said. It
has been generally supposed that no true parasite will attack it, but in
China and Japan great numbers of the worms are killed by a disease
known as “uji.” This is produced by a Tachinid called by Rondani
Ujimyia sericaria, and the life history of which has been carefully worked
up by Prof. C. Sasaki of Japan (Journal Science College, Imp. Un.,
Tokio, Japan, 1886, Vol. I, part I).

There are, however, several forms of disease against which it is nee-
essary to guard and of which it is therefore necessary that silk-raisers
should have an intimate knowledge. Through the multitude of local
names given to these diseases abroad, one would suppose that there
were as many diseases.to which the Silk-worm is subject. But Pastenr,
after studying the subject very carefully, concluded that all may be con-
sidered as varieties of four principal diseases, viz: the muscardine, péb-
rine, flacherie, and grasserie.*

The gattine, one of these varieties, is considered by Pasteur as a mild
form of the pébrine,t but Maillot, in a later work,t considers it as a
species of the flacherie.

These diseases are found to some extent intercurrent, though at all
times one (at least one of the first three) has been more prevalent than
the others, generally amounting to a plague. So in 1849 we find M.
Guérin-Méneville studying, on the part of the French Academy, the
then prevalent disease, the muscardine. This was soon followed, in the
fifties, by a veritable scourge in which the pébrine was the leading feat-
ure, with flaccidity (flacherie) quite frequently found. The same learned
body appointed Pasteur to study the causes of these diseases, and after
two years of patient research he devised a means, which will hereafter
be described, of successfully preventing the return of the pébrine. This
made way for flaccidity, which is to-day the dread of silk-raisers, for
although it does not reach the importance of a plague, its effects are |
distinctly visible upon the national crops of cocoons in France and Italy,
and I have never known it to be absent from worms reared by me al-
most every year for nearly two decades in this country. The grasserie
has never attained any such importance. but occurs in rare instances
only.

* Pasteur, ‘ Htudes sur la maladie des vers & soie,” Vol. 1, p. 225.
t Pasteur, ‘‘ Htudes,” etc., Vol. I, p. 12. |
t Maillot, ‘‘ Legons sur le vers a soie du murier,” p. 109,

3d

MUSCARDINE.

The first of these, the muscardine, has been more or less destructive
in Europe for many years. Itisof precisely the same nature as the fun-
gus (Hmpusa musce), which so frequently kills the common house-fly,
and which sheds a halo of spores, readily seen upon the window-pane,
around its victim.

A worm about to die of this disease becomes languid, and the pul-
sations of the dorsal vessel or heart become insensible. It suddenly
dies, and in a few hours becomes stiff, rigid, and discolored ; and finally
in about a day, a white powder or efflorescence manifests itself, and
soon entirely covers the body, developing most rapidly in a warm, hu-
mid atmosphere. No outward signs indicate the first stage of the dis-
ease, and though it attacks worms of all ages, it is by far the most fatal
in the fifth or last age or stage, just before the transformation.

‘‘This disease was proved by Bassi to be due to the development of
a fungus (Botrytis bassiana) in the body of the worm. It is certainly
infectious, the spores, when they come in contact with the body of the
worm, germinating and sending forth filaments which penetrate the
skin, and, upon reaching the internal parts, give off minute floating
corpuscles which eventually spore in the efflorescent manner described.
Yet, most silk-worm raisers, including such good authorities as F. E.
Guérin-Méneville and Eugene Robert,* who at first implicitly believed
in the fungus origin of this disease, now consider that the Botrytis is
only the ultimate symptom—the termination of it. At the same time
they freely admit that the disease may be contracted by the Botrytis
spores coming in contact with worms predisposed by unfavorable con-
ditions to their influence. Such a view implies the contradictory belief
that the disease may or may not be the result of the fungus, and those
who consider the fungus as the sole cause certainly have the advantage
of consistency. Dr. W. BL. Carpenter, an eminent microscopist, believes
in the fungus origin of the disease, and thinks it entirely caused by
floating spores being carried in at the spiracles or breathing orifices of
the worm, and germinating in the interior of the body.

Whichever view be held, it appears very clear that no remedies are
known, but that care in procuring good eggs, care in rearing the worms,
good leaves, pure, even-temperatured atmosphere, and cleanliness are
checks to the disease.

As the sole means of disseminating the disease are the spores which
only appear several hours after the death of the worm, the most ra-
tional means of preventing the spread of muscardine is by carefully
taking from the tables all dead worms as soon as they are discovered,
and if the disease seems to have gained a foothold in the magnanerie
it will be well to remove the litter oftener and give the worms more

*Guide ad Véleveur de versa soie.

16136—No, 9——3

o4

space. The spores retain their power ot communicating disease for at
least three years; hence the importance of cleansing and fumigating as
described in the last chapter.

PEBRINE.

External symptoms.— The disease, pébrine, shows itself outwardly by
the dwindling away of the worms and their inequality of size; eating
little, they do not grow as large as when in their normal state. At the
end of a few days black spots frequently make their appearance on
the skin, resembling punctures or burns; the anal horn, the prolegs,
the soft parts between the rings, are especially subject to these
spots.”*

Fic. 20.—Silk-worms spotted with pébrine, twice natural size (after Pa teur).

Fig. 20 “represents, at twice the natural size, the anterior part of the
body of sick worms covered with such spots. In one of the worms, a,
they are just becoming visible, and the eye should be aided by a magnify-
ing glass to render them distinct; the other, b, shows them farther ad-
vanced, easily recognizable with the naked eye, if the worm be examined
with a little attention. Finally, Fig. 21 shows one ring spotted with pé-
brine, magnified to six diameters. For this cut
was chosen a worm bearing two kinds of marks,
one with clear-cut edges, the others surrounded
with a halo. The first are wounds, the others
the true spots belonging to the disease and serv-
ing as an indication of its existence, if not al-
ways, at least under many circumstances. The
halos in question have generally a yellowish
tint. They must be observed through a mag-

; nifying glass to be well seen.” f

Fie. 21.—Joint of a Silk-worm 4 5 jl

showing wounds and spots These spots disappear with the shedding of

of pébrine, six times natural : :

size (after Pasteur). the skin at each molt only to reappear again
within a few days. Worms bearing them are figured in plate I, A, B,
C, and D. In addition to these symptoms it is noticed that the prolegs
do not seem to attach themselves easily to objects. In the chrysalis
the abdomen is very much swollen and the rings stretched. In a
highly-diseased moth the wings are wrinkled as when they emerge

* Maillot, Legons, etc., p. 96, + Pasteur, Etudes, ete., p. 15,

35

from the cocoon, and are often covered with bloody pimples, which be-
come black on drying. Part of the body and the wings have a leaden
color; but this must not be confounded with a certain natural brown-
ness which some healthy moths exhibit, and which extends over the
whole body; but it is only with highly diseased subjects that these
exterior signs become visible, and to find the symptoms of the disease
we are often obliged to resort to a microscopical examination of the
interior of the insect.

Internal symptoms.—“ In the interior of the body microscopic observa-
tion reveals the presence of innumerable corpuscles of an ovoid shape
(Plate II), filling the cells of the walls of the stomach, those of the silk
glands, the muscles, the fatty tissues, the skin, the nerves—in a word,
all the portions of the body. There are often so many of them that the
cells of the silk glands become swollen and white, and appear to the
naked eye to be sprinkled over with chalky spots; the silky liquid al-
ways remains exempt from this parasite, but it is much less abundant
than when the worm is in a healthy state.”*

In 1849, M. Guérin-Méneville first noticed these floating corpuscles in
the bodies of the diseased worms. ‘They were supposed by him to be
endowed with independent life; but their motion was afterwards shown
by Filippi to depend on what is known as the Brownian motion, and
they are now included in the class Sporozoa of the Protozoa, and re-
ferred by Balbiani to the order Microsporidie.

These corpuscles are found in the Silk-worm in all its stages—in the
egg, larva, chrysalis, and moth. It was for a long time a mooted ques-
tion as to whether they were the true cause or the mere result of the
disease; but the praiseworthy researches of Pasteur have demonstrated
that pébrine is entirely dependent upon the presence and multiplication |
of these corpuscles. The disease is both contagious and infectious, be-
cause the corpuscles which have been passed with the excrement or
with other secretions of diseased worms may be taken into the alimen-
tary canal of healthy ones when they devour leaves soiled by them, and
because it may be inoculated by wounds inflicted by the claws of other
worms. The malady may be carried to a distance with the corpuseu-
lous dust coming from infected magnaneries, and such dust holds the
power of communicating disease from one season to another.

When the “seed” is thus diseased it hatches irregularly and incom-
pletely, and the larve often perish before or during the first molt. When
the corpuscles are taken into the intestines, as above described, the
malady usually becomes apparent, through some of the external symp-
toms mentioned, at the end of four or five days. M. Pasteur determined
that if the worm partook of the soiled food after the fourth molt it
would make its cocoon, but that corpuscles would be found in profusion
in the chrysalis and moth. If, on the other hand, the worm is thus ex-

* Maillot, Legons, etc., pp. 96, 97,

36

posed to contagion just before spinning, the chrysalis will show the par-
asites only during its last days, while they will be abundant in the moth.

From the mother moth the corpuscles pass into the egg and give rise
to the diseased ‘‘seed” already remarked upon. Disease in the male
will not, however, affect its progeny. The egg is formed while the in-
sect is still in the chrysalis state, and it has been ascertained that
where the corpuscles become abundant only during the last days of this
stage they enter into the seed to a very small degree only, if at all.
Tor this reason eggs are sometimes found to be entirely pure, though the
issue ofa highly pébrinous parent. The development and multiplication
of these corpuscles, though ordinarily very rapid, is insignificant in the
egg until the formation of the larva begins. It will be easily understood
that, though the parasite may exist in the vitellus of the egg, its detec-
tion may be extremely difficult. But when the development of the em-
bryo has commenced, the number of corpuscles grows also, so that just
before, or, better still, just after the time of hatching they may be found
by hundreds upon a casual observation. Upon a microscopical exam-
ination at this time, Vittadini, in 1859, founded his system of selection,
examining samples of eggs just at the time of hatching and rejecting
those lots which showed the corpuscular disease.

At that epoch it was believed that the corpuscles existed even in the
healthy moth when well advanced towards its natural death. But Pas-
teur showed this theory to be fallacious, proving, as we have said above,
that the corpuscle is only present when the moth is diseased. He
showed that, where the moth is free from the parasite, the egg, too,
would be exempt, and that, as a rule, where the corpuscles exist in the
moth, then its issue will probably be corpusculous also. There is, to be
sure, even then a chance of its purity, as mentioned above—that is,
where the corpuscles become abundant in the chrysalis only after the
formation of the egg. But here, too, it is highly probable that the
malady will have so affected the general health of the parent as to make
her issue more apt to succumb to disease, as in the case of flaccidity.
Therefore it is laid down as a rule, and upon this rule the Pasteur sys-
tem of selection rests, that if, upon microscopical examination of the
mother moth, the corpuscles of pébrine are found, then her eggs and
issue will also be pébrineus, and should be destroyed.

The details of the Pasteur system of selection will be given in the

next chapter. 3
FLACCIDITY (flacherie).

Heternal symptoms.—When, after the worms have passed their fourth
molt, and are eating well and regularly, they have all the appearance
of perfect health and vigor, and the silk-raiser feels full confidence in
the success of his crop, some will often be seen to crawl to the edges
of the trays, and lie there languid and without motion. But for the
loss of their wonted activity and the cessation of their naturally vora-

37

cious appetite, one would still think the worms in perfect health, for
they yet retain all the outward perfection of form that we have re-
marked above (Plate I, ig. G). In color they have, perhaps, become
somewhat more rosy, especially if the disease is in a violent form. On
touching them, however, we find them soft, and even in this seemingly
live condition they are often dead. Had the worms been carefully ob-
served at this time, it would have been seen that the beating of the
dorsal vessel was gradually becoming slower, and thatit finally stopped
altogether. A green drop appears at the mouth and the worm secretes
a dirty liquid, which soils the anal orifice and gradually closes it.

Before many hours are passed the skin begins to shrivel and draw in
around the fourth and fifth joints of the body, viz: those two lying be-
tween the set bearing the legs
proper and the set bearing the
prolegs (Plate I, Fig. F). Later,
at this restricted point, the body
begins to turn brown (Plate I,
Fig. E), then black, and the whole
worm is soon in an advanced state
of putrefaction. Then, and even
before the death of the worm, a
sour odor is perceptible in the
magnanerie, due to the fatty vol-
atile acids exuded by the victims
to the disease. Should the malady |i
strike the insects at a later period, \\
when they are ready to spin their
cocoons, the same languishing air
will be observed; they will show a
reluctance to crawl up into the
arches, and will be seen to gather
around their bases, seeking some
place which it requires no exertion
to attain to spin their cocoons.
Many of those which reach the
branches stretch themselves out i |
motionless on the twigs and die hh |
there. They are to be seen later wil, { |
hanging by their prolegs in differ e < §
ent states of putrefaction (Fig. 22): Fig. 22.—Silk-worms at the spinning period, after
When these symptoms are ob- death by flaccidity (after Pasteur).
served we may be sure that the worms are attacked by ftlaceidity
(flacherie).

Internal symptoms.—A microscopic examination of the intestines of
the sick worm will show masses of undigested food, and the coats of the
intestines will be found to be opaque. Here, too, the microscope re-

38

veals the parasites ordinarily attending putrefaction, chief among
which is a bacillus, seen sometimes with and sometimes without a bright
nucleus. There also exists a special form of ferment, not unlike that
which accompanies the formation of vinegar (Mycoderma aceti Pasteur),
which is found in short chains, the links of which are almost spherical

Fic. 23.—Chain ferment, taken from the stomach of a flaccid chrysalis. Magnified 400 times (after
-asteur).

in form (Fig. 23).* These two parasites are sometimes found together
and sometimes separately. When the bacillus is abundant death quickly
follows its appearance, and the disease, spreading rapidly, will some-
times destroy a whole school in a single day. At times this bacillus
appears so short a time before the spinning of the cocoon that the
worms are able to mount into the branches, and even make their cocoons
and become chrysalides. Then, however, the disease overcomes them,
and their putrefaction produces foul cocoons. This case is, however,
more rare, and in general the bacillus is not often found in the chrysalis.
When the ferment alone appears the disease progresses differently.
The worms then show the same languor on the approach of the spinning
period, and the same indisposition to make their cocoons; but even
then they mount the branches, perform their work of spinning, are
transformed into chrysalides, and these into moths which may have a
fine appearance. The silk crop may even be exceptionally good; but
where this state has existed, when the worm has been without its usual

_* The distance from center to center of the links of these chains is about
1 uw (=0,001™™—0,00004 inch).

39 a

agility at the spinning time, where it has shown this apparent laziness,
then, though the cocoons be of the firmest and the moths the finest,
there will exist a weakness, a constitutional debility, that will show
itself in the next generation. This is the only way in which flaccidity
is hereditary, in this predisposition of the worm to succumb to disease
on account of the affection which weakened but which did not kill the
parent. :

Such are the symptoms attending flaccidity in Silk-worms, and from
them M. Pasteur evolved the theory that the disease was caused by the
fermentation of the food in the intestinal tube of the larva, which was
followed by diarrhea and the closing of the anal orifice, as already men-
tioned. Confirming this theory of food fermentation is the fact that the
same parasite (Fig. 23) which is found in the intestines of flaccid larve
also exists in a fermented broth of mulberry leaves. Digestion thus
arrested, the worm ceases to eat and becomes languid. The gases
evolved by the processes described burst the walls of the intestines and
cause the death of the victim. Such is the Pasteur theory, followed, as
a rule, by the French scientists.

Italians, on the contrary, believe with Verson and Vlacovich, who
claim to have observed ‘that in the flaccid worm the micro-organisms
are not at times to be found; that it has been proved that in the begin-
ning there occurs a tumefaction of the membrane of the intestines,
and that this membrane, as the disease advances, disappears here and
there, and finally altogether. According to them flaccidity consists
primarily of a lesion of the membranous walls of the intestines, which
would generally be followed by the development and multiplication of
the micro-organisms which Pasteur considered the primitive cause of
the disease. It is a fact, nevertheless, that all acknowledge, that in
most cases flaccidity is accompanied by bacilli and ferments in great
numbers in the intestinal tube.”*

Flaccidity generally appears after some sudden change in the weather
or temperature, as, for instance, a thunder shower, or a hot, heavy day.
It is apt, too, to follow the feeding of wet or fermented food. If the
shelves go too long without cleaning and begin to mildew; if the worms
are too crowded on the table and their natural respiration interfered
with, flaccid subjects will soon appear in the school. These, by their
unhealthy excrement, soil the food of their neighbors, who quickly fol-
low them in the path of disease. It is thus that flaecidity becomes
highly infectious.

No very satisfactory means have been proposed for combating this
malady when once it appears. It would be well, on the discovery of
the first victims, to take the worms remaining healthy into another
apartment and give them more space and plenty of air. Attentive care
may then save the crop, though by no means with certainty.

*Perroncito, J Parassili, p. 35.

. 40

To avoid the disease one should carefully follow the fundamental rules
already laid down (Chapter IV), though even then circumstances may
be against the silk-raiser and the crop be lost through no apparent
fault of his.

GRASSERIE.

This disease is of little importance, and has therefore received but
little attention from scientists. It is thus described by Maillot :*

‘‘In the middle of a school of worms in good condition it is not rare,
as a molt approaches or just before the spinning begins, to find here
and there some worms which crawl slowly, and have a shining, stretched,
thin skin; the body is of a bright yellow in the yellow, and of a milky
white in the white races; a troubled liquid transudes through the skin ;
soiling the food and the worms over which the diseased subjects pass.
* * * A moist, cold, stagnant air seems to favor the occurrence of
grasserie. The disease is not contagious, * * * nor does it appear
that it can be transmitted by heredity. From this point of view there
is nothing to be feared, unless a great number die of the malady, in
which case it will be imprudent to use the stock for reproduction.”

Victims of this disease should be removed as soon as discovered, as
they are apt to crawl into the branches and soil the cocoons spun by
other worms.

Prefacing the next chapter we may draw the following conclusions
from what has been said: Grasserie is never hereditary, as the victim
never dies later than in the chrysalis state, and the disease can never
originate in the moth. This is equally true of muscardine, provided
the moths be not mingled with worms covered with the spores of the
Botrytis. In such a ease the moth might also catch the disease and its
general debility decrease the vigor of its progeny. Flaccidity is hered-
itary in an indirect manner, a debility springing from the affection of
the parent rendering its issue more apt to succumb to disease. And
finally, pébrine is hereditary in its true sense, the corpuscles passing
from the mother through the egg to the next generation. In the pro-
duction of eggs, then, we need look for flaccidity and the pébrine only,
the other diseases not entering into the consideration.

* Legons, etc., p. 111.

CHAPTER VI.

REPRODUCTION.

It has been said in Chapter IV that the first condition of success in
raising Silk-worms is to “‘ procure good eggs.” The object of the present
chapter is to describe the most approved processes of producing such
eggs.

Were it not for the diseases to which the Silk-worm is subject, the
old, simple processes of egg production might still be followed, and
even now, unless the egg producer is able and ready to undertake
the microscopical examination required by the Pasteur system, it is
needless to observe the more complex rules for the isolation and ex-
amination of the moths.

The simple process formerly employed in all sericultural countries
consisted in stringing the cocoons and letting the moths couple, as in
the modern process. A sheet was then hung up with the lower edge so
turned as to form a trough into which any badly gummed eggs might
fall. After uncoupling, the females were placed upon the sheet and per-
mitted to lay their eggs promiscuously. The only precaution taken
against disease was in the selection for reproduction of lots of cocoons
whose larve had shown no signs of any malady, and which were
themselves of first quality. From what has been said it will at once be
seen that pébrine contracted after the fourth molt and the slow form of
flaccidity due to the presence of chain-ferment are not thus guarded
against. The modern system has a deeper, more scientific basis, and
aims to guard against these.

The Pasteur system of microscopical selection. As we have seen, pébrine
and flaccidity are the only diseases which it is necessary to guard against
jn selecting eggs. If pébrine or flaccidity have appeared in a positive
form in the larve, either through the external or internal symptoms de-
scribed in the last chapter, no further examination need be resorted to,
as the stock will evidently be unfit for reproduction. The most im-
portant and positive sign of the latter disease to be looked for is languor
at the spinning time. If a greater degree of certainty is desired, or if
the egg-producer has not had the opportunity of observing the rearing
of the worms, a miscroscopical examination of the chrysalis may be re-
sorted to. In flaccidity this examination should be confined to the
stomach, where the chain-ferment to be sought for is more easil y found.
M. Pasteur gives the following directions for extracting this organ:

41

42

“ Cut away the walls of the thorax of the chrysalis with fine SCISSOFS,
after the manner shown in Fig. 24, so as to reveal the stomach s. Draw
this out with a pair of tweezers. The re-
stricted part of the digestive tube, whic’.
unites the stomach with the urinal sack
u, Should then be cut. The anterior part
of the digestive tube now alone holds the
stomach in place, and this easily gives
way. Lay the small ball thus withdrawn
on a glass slide and scratch away the
very soft, fatty envelope which covers the
Fi¢.24.—Anatomy of thechrysalis, show. J4terior. Of this interior substance take

eee Lea ges the stomach a, piece as big as the head of a pin, wash

it with a drop of distilled water, and,

placing it upon a slide with a cover glass over it, examine it with a

microscope magnifying about four hundred diameters. With a little ex-

perience this work may be done very rapidly. It would be well to take

out at the same time the stomachs of, say, twenty chrysalides, and lay
them on as many glass slides. * * *

‘The first few days after the formation of the chrysalis the contents
of the stomach are generally very liquid, which makes their extraction
inconvenient. It is better to make these observations seven or eight
days after the spinning begins, when the matter will be found to have
more consistence. * * * Fig. 23, page 38, shows the appearance of
the ferment found in flaccid chrysalides under a magnifying power of
400 diameters. It is associated with the débris of leaves, morsels of the
trachea, and chlorophyl cells. These matters ordinarily accompany the
little ferment in the stomach of the chrysalis, because of the incomplete
digestion of the leaf whenever it is submitted to fermentation.” *

No parasite indicative of flaccidity has been discovered other than
this ferment, which is not found in the adult insect; and if the trans-
formation into the moth is permitted, all opportunity will be lost for
detecting the disease.

In pébrine, on the contrary, the corpuscle is found in the moth as
well as in the chrysalis. We might, therefore, wait for a final exami-
nation of the moth to be made after oviposition. But, in case disease
is then found, it will be too late to stifle the cocoons, and the emergence
of the moths will have ruined them for certain commercial purposes.
For this reason it is important to detect the disease, if it exists, at as
early a stage of the work as possible. If the larve have shown no ex-
ternal signs of the pébrine, it would be well to microscopically examine
a few of the last worms to spin. The corpuscles will be found in these
laggards, if anywhere.

Isolation and examination of the moths.—If left to themselves the in-
sects remain in the chrysalis state for from two to three weeks in our ordi-

“Pasteur, Etudes, ete., Vol. I, p. 233.

43

nary summer weather. Their development may, however, be hastened
or retarded by increasing or lowering the temperature. This fact is
taken advantage of to obtain a few adult insects which may be micro-
scopically examined before the whole lot becomes fully developed.

I was very much pleased with the method employed by M. Maillot,
which J had an opportunity of examining at Montpelier, in 1884, and I
here give a description of it in his own words:

“Three or four days before the cocoons are taken from the branches
we take, here and there, from the early spinners as well as the late,
several hundred cocoons; as, for example, five hundred from a lot of 90
pounds. This sample should be placed in an oven or warm room, where
it will be kept day and night at a temperature of from 100° to 110° Fah.,
and a high degree of humidity. In this way the formation of the moth
is hastened. As during this time the cocoons of the lot itself remain at
a temperature of from 75° to 90°, and often during the night at even
lower temperatures, we shall still have time to stifle them if the lot is
discarded, or to string them into chains if, on the contrary, it proves
healthy.

‘““Hvery two days we take ten chrysalides from the sample and ex-
amine them microscopically for corpuscles. If we find them in the first
eight or ten days, no matter in how small quantities, we can be sure
that the proportion of pebrinous moths will be considerable. When the
chrysalides are mature, which is easily seen by their eyes becoming
black and the eggs harder to break under the pestie, and also by some
of them turning into moths, we proceed to the definite examination,
We crush one by one the moths which have come out and the chrysa-
lides which remain and search for corpuscles; the per cent. which is
thus found will not differ materially from that which exists in the whole
lot.”*

The examination of the chrysalides here mentioned may be made in
the manner already described when searching for the ferment of flaccid-
ity and at the same time. But if we are looking for the pébrine only
we need simply crush the whole chrysalis in the manner hereafter de-
scribed for the moth.

Proceeding now with stock of which the purity has been ascertained
by one or more of the different methods of observation above described,
200 cocoons should be selected for each ounce of eggs that it is desired
to produce. In making this selection great care should be exercised in
taking only cocoons that are fine in texture and firmly made. This fine-
ness is one of the prerequisites of a first-class cocoon. What is meant
by this difference in texture will be seen by an examination of Figs. 2
and 3, page 14, the former being fine and the latter coarse. The firm-
ness of the cocoon, depending as it does on the amount of silk whieh it
contains, is an indication of the vigor of the worm, and another item to
be considered in selecting stock for reproduction. Rules hav e been

*Maillot, Legons, etc., p. 250,

AA

given for the determination of the sex of the inclosed insect, and among
them, perhaps the most common, is the assertion that those that are con-—
stricted in the middle (Fig. 2) contain males, while those not constricted
(Fig. 3) contain females. This, however, may be regarded as an indi-
cation rather than a fixed rule, and there are races in which the cocoon
is almost uniformly constricted and others where the reverse is true.
But this careful selection for sex is comparatively unimportant, and we
consider it wiser to choose the cocoons in relation to their firmness and
texture, and trust to chance to bring as many male moths as female.
Double cocoons, where two worms have spun together, should never be
used in egg-making.

The proper cocoons having thus been selected, they should be strung
upon stout threads about 3 feet long. Care should be taken not to
prick the chrysalides with the needle while passing it through the end
of the cocoon in making the chains. These chains should then be hung
in a cool, darkened room while waiting for the moths to emerge. They
should not be placed near any object which would be soiled by the se-
cretions emitted by the moths on their emergence from their cocoons.

Previous to this emergence there should be prepared for each ounce
of eggs to be produced about one hundred small bags of fine muslin
(cheese cloth makes a good material), made in the following manner:
Cut the cloth in pieces 3 by 6 inches, then fold one end over so as to
leave a single edge of about three-quarters of an inch, as shown in Fig.

Fic. 25.—Cell used in the Pasteur system of egg-laying (after Roman).

25. This should be sewn up into a bag with the upper end open, and
then turned inside out so that the seams will cause the sides to bulge.
Thus completed they are called “cells.” The cells should be strung —

45

on a cord stretched across the room. Some trouble having been expe-
rienced in keeping the moth from crawling out of the cell at either side
‘of the pin, which is the method of closing it shown in the cut, the
scheme shown in Fig. 26 was adopted last year in the Department.

Fic. 26.—Method of clamping cells (original).

This consists in clamping the bags in fours between two sticks of wood,
rough sawn, about one-half by one-quarter inch through and 14 inches
long. They are bound together by rubber bands and may be laid
across parallel wires stretched across the room at about 13 inches apart.
M. Pasteur suggests that asimple piece of cloth about four inches square
be used instead of the sack. The moth lays her eggs on this and is then
retained by being fastened to the cloth, the corner of which is turned
up over her and a pin passed through it and over her wings (Fig. 27).

é

iia usiy | sty

Epes

iii

1}

HA i isiguulilli ili

Fic. 27.—Cell used in the Pasteur system of egg-laying (after Pasteur).

Some trouble has been experienced by this process, as the eggs, if not

properly gummed to the cloth, will sometimes fall off and be lost, and

the moths, not being confined as in the sacks, will wander to other

cloths and get their eggs mixed with those of other moths, which would

be detrimental to the microscopical selection to be hereafter described:

It has the advantage, however, of enabling the microseopist to avoid
_ the labor of turning the sacks.

46

The moths emerge from the cocoons, as a rule, from 5 to 8 o’clock in a
themorning. Atthe latter hour many of them will be found coupled and
clinging to the chains. These should be carefully taken by the wings
and placed upon a table by themselves, the single moths being piaced
upon another table where they will couple if the sexes are evenly divided.
They should then be transferred to the first table as the fluttering of
the male moths is apt to disturb the couples. These should be left
together until 4 or 5 o’clock in the afternoon, when they may be sepa-
rated by drawing them gently apart by the wings. The females should
then be placed in the cells or upon the cloths already described, where
they will at once commence their egg-laying, completing it in about
thirty-six hours. Most of the males may then be thrown away, though
it may be wise to keep a few of the more active ones to compensate for
any Superabundance of females in the issue of the following day. But
little difficulty will be encountered in distinguishing the sexes, themales
being noticeable by their smaller abdomens, more robust antenne, and _
by their greater activity. 3

When the eggs have been laid, the microscopical examination of the
moths should be made with a view to ascertaining whether or no they
are afflicted with pébrine. The entire moth should.be ground up with
a few drops of distilled water* ia a small glass mortar (1 ounce is a con-
venient size). A drop of this water is then taken with a medicine drop-
per and placed upon a glass slide with a cover glass over it. It is then
microscopically examined with a power greater than three hundred
diameters. Plate II shows a field very highly charged with the cor-
puscles of pébrine. When the moths are not examined until some time
has elapsed after their death, they will be found to contain other germs
peculiar to putrefaction. These do not indicate any disease that would
affect the egg or its issue; nor does their presence imply any lack of
vigor in the parents. They are simply post-mortem parasites. Great
care should be taken in cleansing the mortar, pestle, and other imple-
ments before making an examination, by washing them in an abund-
ance of water and rinsing them thoroughly with distilled water. In
making the above examination only the corpuscles of pébrine need be
looked for. The bacilli and the ferments of flaccidity are rarely found
in the moth. ;

$$

* The amount remaining in the mortar after rinsing is sufficient.

CHAPTER VII.

CHOKING THE CHRYSALIS.

In most silk-producing countries the parties who raise the cocoons sell
them to the reeling establishments before suffocation is necessary, as
these establishments have better facilities for this work than are to
be found in private families. If, however, the reeling is done by the
raiser, or some time must elapse before the cocoons can be sent to a
reeling establishment, some means must be used to kill the contained
chrysalis before the cocoon is injured for reeling purposes by the egress
of the moth. This can be done by stifling them with steam or choking
them by dry heat. Steaming is the surest, quickest, and best method,
if the facilities are at hand; it can be done at any steam mill. The co-
coons are laid upon shelves in a tightly-sealed box and the steam is
turned in. Twenty minutes will suffice to do the required work, and
the cocoons are then dried in the sun.

The following apparatus has been used by Mr. Walker at the De-
partment:

It consists of a tin reservoir, about
one-third filled with water. Slightly
above the surface of the water is a
movable perforated partition, B, in-
tended to prevent spattering during
ebullition. The upper portion con-
tains a perforated pan for holding the
cocoons, while all is tightly closed by
a cover. Cocoons may be thoroughly
stifled by exposure in this apparatus,
over boiling water, for twenty minutes.
Tt will be seen, too, that much the
Same apparatus may be contrived by
the use of a deep kettle, into which is
set an ordinary colander full of eo-
coons. It is well to avoid, however,
So filling the kettle with water that it
will splash upon the cocoons in boiling,
as they should only be subjected to

: Fic. 28.—Simple stifling apparatus.

the action of steam. The apparatus is 12 inches in diameter and 13
Inches deep, and will stifle from 3 to 4 pounds of cocoons at a time.

‘ 47

-

A8

The dry-heat method occupies a much longer time. The cocoons are
placed in shallow baskets and slipped on iron drawers into an oven
which is kept heated to a temperature of about 200° F. This should
not be increased for fear of burning the silk. This operation lasts from
two to twenty-four hours. <A certain humming noise continues so long
as there is any life, and its cessation is an indication that the chrysa-
lides are all dead. Where the choking is well done there is little loss,
only about 1 per cent. of the cocoons bursting at the ends. After
choking in this manner, the cocoons should be strewn upon long
wooden shelves in the shade, with plenty of air, and, for the first few
days, frequently stirred. After remaining on these shelves for about
two months, with occasional stirring, the chrysalides become quite dry,
and the cocoons will preserve indefinitely. They are, however, still
subject to the attacks of rats and mice, and the little beetles known as
“museum pests,” belonging to the genera Dermestes and Anthrenus, are
attracted by the dead chrysalis within and will penetrate the cocoon,
injuring it for reeling purposes. In the warm Southern States the
dry-heat choking can be accomplished by simple exposure to the sun.
Two or three days of such exposure are sufficient. Buf, as strong wind
may annihilate the effect of the sun’s warmth, it is good to have for that
purpose long boxes, 4 feet wide, sides 6 inches high, to be covered with
glass frames. This will increase the heat, and, by absorbing the air of
the box, stifle the chrysalis most surely. The glass cover should be
slightly raised to permit the escape of the excessive moisture which
evaporates from the cocoons, and care should be had to keep out the
ants.

A” ee ae

es
—_— ee

CHAPTER VIII.

SILK-REELING.

Spun, reeled, and thrown Silk.—From the cocoon the silk is by different
processes transformed into spun or reeled silk. The former is generally
made from pierced cocoons or silk waste, and serves in the manufacture
of inferior classes of tissues. The method of manufacture consists in
cleaning and macerating the raw material, after which it is carded and
made into thread somewhat after the manner of cotton. The process
of producing reeled silk, which will be hereafter treated at length, con-
sists, in general, of softening the gluten of the cocoons in hot water and
then taking the ends of the constituent threads of several of them to-
gether and winding these threads from the cocoons upon a reel.

By virtue of the next process of manufacture to which this material
is Submitted it becomes thrown silk. Thrown silk is classified as organ-
zine and tram. It is made either from spun or reeled silk, Tram con-
sists of two or three threads of reeled (or spun) silk twisted together at
about 75 to 100 turns per running meter (67.5 to 90 per yard). If is
used in making the warp in weaving. Organzine, used in the woof, is
produced by twisting two threads together at about 500 to 600 turns
per running meter, and then taking two of the threads thus made and
twisting them together in the opposite direction at about 400 to 500
turns. It is, in the language of the trade expression, ‘ cable laid.”

It is the object of this work to deal only with one of these classes;
that is to say, reeled, or, as it is commonly called, raw silk. Although
the former name indicates more exactly than the latter the processes to
which the raw material has been previously submitted, yet the term
“raw silk” has acquired a special meaning by trade usage and applies
only to reeled silk.

The process of Silk-reeling.—The cocoons should have been roughly
sorted before they were spread out in the cocoonery, the double and
feeble specimens having been laid aside. They should now be sorted
so that cocoons of the same color and shade may be reeled together, for
the use even of cocoons of the same color but of different shades will
give astreaked skein of silk. They should, too, be sorted as to their text-
ure. Those of fine texture, among ordinary cocoons, are considered
first choice and are used to produce the finest qualities of raw silk.
They are more easily unwound than those of coarser texture which are

16136—No. 9——4 49.

50

called satiny cocoons. This satinage appears to be due to the fact that
the successive layers of the cocoon are insufficiently gummed together.
As a result the water penetrates quickly into its center while itis being
reeled and causes it to sink to the bottom of the basin, which interferes
with the process of unwinding. Towards the end a satiny cocoon comes
off in flocks, making a dirty silk.

A comparison of the cocoons shown in the cuts on page 14 may convey
an idea of the difference of texture mentioned, Fig. 2 being fine, and
Fig. 3 of coarse grain. In addition to the above features some regard
must be paid to the reeling of cocoons of the same size together. An
extended experience is needed to make a rapid cocoon-sorter, and it is
work that should be followed without intermission, that the knack neces-
sary to quickness may not be lost.

The process of reeling cocoons, while extremely simple, is still one
that requires an amount of skill to acquire which the experience of sev-
eral months is necessary. The cocoons are first plunged into boiling
water, whereby their gluten is softened in such a manner as to render
the unwinding of the filaments an easy matter. This done, they are
brushed with a small broom, to the straws of which their fibers become
attached. The bundle of filaments is then taken and they are unwound.
until each cocoon shows but one clean thread. These three operations
are called “cooking,” ‘‘ brushing,” and ‘‘cleansing.” All of these oper-
ations can be accomplished mechanically.

The elements of the mechanism of all modern silk-reels are essentially’
the same. They are shown in Fig. 29, and consist, in general, of a basin,

c
©. :
i] N
1 \ y
i eg

Xs

1 Vv
i {
| {
{ i]
j 'M
1
i
ran
| rs IN
ans
ap

Fic. 29.—Elements of the mechanism of a modern silk reel (original).

A, in which is a perforated steam-pipe, P, by means of which the water
in the basin may be heated. A few inches above the surface of the
water is placed a perforated agate, B. The cocoons having undergone
the three operations mentioned, the ends of the filaments of four or more

22k BONS ile AFG ares See Oar cxtet ot s 4 eS ie a a

51

of them are twisted together into a thread, which is passed through the
hole in the agate. From this it runs through the “croisure” M, which
will be hereafter explained, and over the guide H to the reel at F. Be-
tween EH and F' the thread passes a guide, G, moving to and fro (in a
line perpendicular to the plane of the paper), which distributes it in a
broad band over the surface of the reel. This facilitates the drying of the
silk, without which the gluten would bind together the threads of the
skein as it does those of the cocoons, and thus ruin its commercial value.
In winter it is often necessary to use supplementary means to effect this
drying. Perhaps one of the best is by passing a large steam-pipe near
the reel, as at Q. The shaft of the reel carries at one end a friction-
wheel, H, which rests on the large friction-wheel J that constantly re-
volves on the shaft V, and thus motion is imparted tothe reel. In order
to stop the reel it is only necessary to raise the wheel H from its bear-
ings by means of the lever L. This movement presses the wheel against
the brake-shoe A, and its motion is at once arrested.

As has been said above, the thread is passed between the agate and
the reel through the croisure. The making of the croisure consists in
twisting the thread around itself or another thread so as to consolidate
its constituent filaments and wring the water from it and thus aid in its
drying. The mode of the formation of this croisure forms the principal
distinguishing mark between the French and Italian systems of reeling.
The former is called the ‘Chambon system.” Each reeler manages two
threads. These are passed through separate agates, and after being
brought together and twisted twenty or thirty times around each other
are again separated and passed through guiding eyes to the reel. The
other system, called ‘“tavellette,”* consists in passing the thread up
over asmall pulley C, down over another D, and then twisting it around
itself, as shown at JJ, in Fig. 29, and thence to the reel.

The cococn filament is somewhat finer in the floss or beginning, thick-
ens at the point of forming the more compact pod, and then very gradu-
ally diminishes in diameter until it becomes so fine as to be incapable of
standing the strain of reeling. Therefore a thread which is made up of
five new filaments becomes so small when the cocoons from which it is
drawn are half unwound as to require an addition. This addition might
_ also be made necessary by the rupture of one of the constituent filaments.
Itis here that the skill of the operator is called into play. When her
experience tells her that the thread needs nourishing from either of
these causes she takes the end of the filament of one of the cocoons
which lie prepared in her basin, and, giving it a slight snap or whiplash
movement with the index finger, causes it to wind around or adhere to
the running thread of which it from this moment becomes a constituent
part. This lancing, as it is called, of the end of the filament, although
in hand reeling performed in the manner described, is also accomplished
mechanically, several devices having been invented for this purpose.

*The trade name of the small pulley mentioned,

52

They consist, in general, of a mechanism which causes a small hook to
revolve in a horizontal plane about the running thread, and to twist
around it any end of the filament that may be placed in the path of the
hook. The reeler, seeing that a new filament is needed, holds the end
of one in the way of the attaching device and it is automatically caught.

The temperature of the water used while reeling the cocoons varies
from 140° to 175° F. The more cocoons have been cooked the lower
will be the temperature required. It is customary, however, to work
in the neighborhood of the maximum limit. Whenever the silk rises in
locks the temperature of the water is known to be too hot, and when it
unwinds with difficulty the temperature is, on the contrary, too low.
The operator is supplied with a skimmer with which to remove all chrys-
alides and refuse silk; also, with a basin of cold water, in which to cool
her fingers, which are being constantly dipped in the hot basin.

It is highly important that the silk be kept as clean as possible. It
lacks cleanness when the filament ends are badly attached in lancing,
when the figure 8 loops, of which the cocoon is composed, come off one
or more at a time instead of unwinding continuously, or when the thread
after breaking is not neatly knotted. All these faults show in weaving
and injure the value of the silk.

According to Dandolo the fresh cocoons consist, by weight, of:

Per cent.
CP Gil eee Meee sberces Heed encasy eae aes BRE eee be besos se. 84. 20
AUB NUE i ie See ale o, ows ase Ve heres pra ee © wr ee ota ot ee I Sim eee ee 0. 45
rlleennpORS os: 2 .'. Ses ate eet Tee ee San See 2a aac ene ane 15. 35

It is from this 15.35 per cent. that the reeler draws her silken thread.
But a large proportion of even this is lost, so that there is recovered
but 8, 9, or rarely 10 per cent. of the original weight of the cocoons.
From this it will be seen that it takes from 10 to 124 pounds of fresh
cocoons, or 34 to 41 pounds of dry ones to make a pound of silk. A
more usual working average, with good stock, is in the neighborhood
of 33 pounds of dry cocoons per pound of silk. If cocoons are of poorer
quality they necessarily produce less siik and their commercial yalue
fails off in far greater proportion than their power of silk production.

CHAPTER IX.
PHYSICAL PROPERTIES OF REELED SILK.

Certain physical properties are of great importance in determining
the commercial value of reeled silk. They are its cleanliness, already
mentioned ; ifs mean size; the irregularities in its size; its ductility, or,
as it is wrongfully but universally called, its elasticity ; its tenacity, and
the amount of soluble gum which it contains.

The mean size of a skein is determined in the following manner:
One thousand yards of the thread is wound off on a reel, supplied with
a counter called an éprouvette, and made into a little skein termed an
échevette. This échevette is then weighed and the number of sixty-
fourths of a dram which it is found to equal becomes the size number
of the thread. This process is called the sizing, or, colloquially, the
“dramming” of silk.

In Europe the same system is employed, but the units are a length
of 476 meters (400 old French ells) and a small weight called the denier.
One dram silk in America is equivalent to a thread of 174 deniers in
France.

Until recently there has been no means of determining the irregular-
ities in size existing in a silken thread, but manufacturers were content
to approximate it by weighing four échevettes per sample skein. The
difficulty in making this determination is owing to the fact that the
thread is not round, but flattened, being, in fact, in its simple state, two
filaments joined into one, and when several of these naturally com-
pound filaments are combined to make a commercial thread the matter
becomes still more difficult. Mr. E. W. Serrell, jr., of New York, has,
however, overcome these obstacles by relying on another property of a
silk filament, which is, that the distance which a given length will
stretch under a given tension is inversely proportionate to the mean
cross-section of this length. This is the underlying principle of his
serigraph, which will now be described. The mode of testing with this
machine is as follows: The end of the thread is brought from the reel
or bobbin on which it is wound, around a drum (Fig. 30 A), thence over

Fic, 30.—The principle of the Serigraph (original),

54

a pulley, C, and back around another drum, B, mounted on the same
axis as A. From the drum Bit is wound on areel. The drum B is
larger than A, so that the former winds on the thread somewhat faster
than it is paid off by the latter. In thus stretching the thread we
apply a force to the pulley C tending to draw it from its normal posi-
tion. This pulley is attached to the base of a pendulum, D, which,
under the action of the force mentioned, is drawn from the perpendicu-
lar. The weight of this pendulum overcoming this applied force to an
extent inversely proportional to the mean section of the length of thread
submitted to the test, the position of equilibrium taken by the pendu-
lum depends upon that mean section. This length of thread is the
piece between the two drums A and B, and as, through the constant
action of the machine, successive lengths of thread occupy the position
indicated, the pendulum oscillates through a course which depends upon
the irregularities of the thread. These irregularities are graphically re-
corded by a pencil, H, attached to the pendulum, upon a band of paper,
F, constantly moving under its point. In the commercial form of the
machine the mechanism for driving the reel is so constructed as to stop
automatically when a standard échevette has been wound upon it, and
this échevette may then be sized in the manner above described.

The elasticity and the tenacity of raw silk are determined by the use
of the serimeter. This machine is composed of a dynamometer above,
a graduated circle indicating the tension corresponding to the point at
which the index stops. On the lower extremity of this dynamometer is
a knob to which the thread to be tested may be attached. At 50 cen-
timeters below this knob, in the same vertical line, is another knob
attached to a counterweight which is on the inside of the case of the
instrument and which also bears a pointer moving along a graduated
scale on the outside of the case. This weight is held in place by a
detent which is terminated on the outside of the case by a faller, on
which it is only necessary to press lightly to cause the detent to let go
the counterweight and permit its index to slide along the scale; these
stopinstantly, on the other hand, when the faller is released and retakes
its initial position.

The silk thread attached to the two knobs mentioned passes over this
faller, and, as it tends to pull it from its normal position, the detent
lets go the counterweight and the thread stretches until rupture takes
place, when the descent of the counterweight is automatically stopped.
It is then only necessary to read the indication of the dynamometer to
ascertain the weight which caused the rupture. By doubling the dis-
tance passed over by the sliding index, we have the stretch per meter
or per cent. of elasticity.

The elasticity or ductility of silk is about 15 to 20 per cent., being
nearly four times superior to that of cotton. Itis about the same as
brass and slightly greater thaniron; hair has only half the ductility of |
silk,

55

“The tenacity of silk thread is well known; a thread of raw silk of
10 deniers easily supports a weight of 50 grams* without breaking.
Direct relations exist between the tenacity of silk, the country in which
it originates, its hygrometric state, the processes by which it was reeled,
ete. Relations not less interesting may be found between the elasticity
and the ductility.” t

In the silk which constitutes the cocoon as made by the worm we find
three classes of material. They consist of a waxy substance soluble in
boiling water, of a gluten soluble in certain acids and alkalies, and es-
pecially in a solution of soap, and of the fibrine which constitutes the
base of the thread. In the yellow silks there is also a slight quantity
of coloring matter. Robinet found from 4 to 5 per cent. of the waxy
substance, which, being soluble in boiling water, disappears in the proc-
ess of reeling. We therefore find in reeled silk the gluten, or, as it is
technically called, grés, and the fibrine. Before this silk can be prop-
erly dyed it is essential that a certain portion of this gluten be re-
moved. This operation is usually performed by boiling it in a solution
of soap. At the Conditioning Works at Lyons, France, this boiling off,
as it is called, consists of two operations. The silk is first submitted
for thirty minutes to ebullition in a solution containing an amount of
soap equal in weight to about 25 per cent. of the weight of the silk
boiled off. This silk is then wrung, in order to free it from the soap and
the dissolved gluten, and then resubmitted to the same operation of
boiling. Asa result of these tests, it is found that white French silks
contain 19.68 per cent. of gluten and the yellow silks 22.84 per cent.
Silks coming from Italian filatures contain an amount of gluten slightly
in excess of these figures, while the Chinese silks exceed them by more
than 2 per cent.

The silk thread is highly hygrometric, containing under ordinary con-
ditions 10 to 12 per cent. of water, while a thread oferaw silk is capa-
ble of absorbing 21 to 26 per cent. Humidity augments the ductility
of silk and slightly diminishes its tenacity.

* 100,000 times the weight of a piece 50 centimeters long.
t Adrien Perret, “Monographie de la Condition des Soies de Lyon.”

CHAPTER X.
FOOD-PLANTS.

The traditional food-plant of the Silk-worm is the Mulberry (botani-
cal genus Morus). There are two species of Mulberry indigenous to
the United States, namely, the Red Mulberry (Morus rubra) and the
Small-leaved Mulberry (Morus parvifolia), neither of which is suitable
Silk-worm food. I have tried in vain to rear the worms upon rubra,
but they either refuse its leaves entirely or dwindle and soon die upon
it. The imported kinds which are most used are the Black (JM. nigra)
and the different varieties of the White (I. alba). The first is inferior
to the others as Silk-worm food.

The Moretti, a variety of the White Mulberry, is profitably grown in
the form of a hedge, and the large size of its leaves makes it avery de-
sirable variety.

The rosea, japonica, and the multicaulis, varieties of the same species,
are also used with excellent success.

A species of Mulberry new to this country has lately been introduced
into the Western States by the Mennonites. This is the Russian Mul-
berry (W. tartarica). Itis very hardy and its leaves make excellent
Silk-worm food.*

The Mulberry grows readily, being easily propagated by cuttings or
layers or from the seed. ‘The white Mulberry, in particular, grows well

« F

*A tree of a genus allied to the Morus is the Broussonetia papyrifera, commonly
called the Paper Mulberry. It is found quite generally throughout the South, but
its foliage is not suitable for Silk-worm food. The Paper Mulberry is usually a some
what larger tree than the Mulberry and its leaves are subject to a considerable di-
versity of form, being mainly ovate and toothed on the margin; frequently with
lobes on one or both sides of the leaf. They are quite rough to the touch on the up-
per surface, much more so than the Mulberry, and on the under surface they are
softly hairy. The trees are of two kinds, male and female. The male tree, early in
the spring before its leaves are developed, has tassels something like those of the
willow. They soon drop off after shedding pollen. The female flowers then go on
developing during the summer until they make small round balls from which, when
ripe, the seeds stand out. These seeds are covered with a gummy substance and are
very small, being about the size of those of the raspberry. The female trees are
little known in this country, as only the male trees have been introduced into the
United States.

I refer to this tree because of the frequency with which inquiries are made by
Southern correspondents as to whether the Paper Mulberry can be used as Silk-worm
food. The tree is very generally used for shade and ornament in Southern cities,
where it attracts attention by the gnarled and knotted character of its trunk.

56

ee ee ee

aii rk
es.

57

from cuttings, and this is perhaps the readiest and most economical
method of planting to secure a stock.

The cuttings should be started in rows, 3 or 4 inches apart, in ground
prepared by deep plowing and harrowing. They should be about 6
inches long, and should be cut just before an eye in every case. They
should be almost entirely buried. The quickest way to get a supply of
leaves is t grow dwarfs. Set out the young trees from the nursery in
rows 10 to15 feet apart and 6 to 8 feet between the rows, and form the
crown of the tree by cutting down to a foot or so from the ground. The
height of the tree and its form are easily regulated by pruning, and
upon this process depend not only the vigorous growth of the tree, but
also the ease with which the leaves may be gathered when desired.
The pruning may be done in February or March, either every year or
every other year.* All dead twigs and dried bark should be removed
and the limbs kept as smooth as possible, as this greatly facilitates
picking. The best time for planting is in the fall, from frost until De-
cember, and in the spring, from March until May.

For growing standard high trees, a practical raiser gives the follow-
ing directions: The cutting should remain two years in the nursery
without pruning. The third year it is cut close to the ground and trans-
planted. The finest shoot is then allowed to grow, and in good land it
will reach a height of 8 or 10 feet in one season. The fourth year it is
cut back to 6 feet or thereabouts. ‘Then, the three or four terminal buds
only being allowed to grow, all others are removed as often as they ap-
pear by passing the hand along the stem.

It must not be forgotten that 1n the propagation of plants only true
species can be reproduced from the seed. The varieties of the White
Mulberry mentioned above can only be obtained from cuttings or layers.

The fresh mulberry leaf contains a large amount of water of vegeta-
tion, and of certain mineral and organic matters. Of water, it is only
necessary that there should be sufficient to enable the worm to easily
digest its food, and all that is in excess of this quantity is apt to be in-
jurious and productive of disease. In order to avoid this difficulty,
food-trees should be planted in alight loam, and especial care taken to
prevent excessive irrigation. It has been found, too, to be important
that the tree should be so planted as to receive as much sunlight as
possible, experiments having shown that, other conditions being equal,
the leaves of such a tree contained but 55 per cent. of water, while in
the case of one lighted by the sun until 1 o’clock only there was 64 per
cent., and in one which received only diffused light, 73 per cent.

* The better plan is to have two sets of trees, using each set but once in two years,
When pruned a tree is then allowed to grow for one year without touching its leaves,
which are only picked for the second season. The life of the tree will thus be ma-
terially prolonged, and the crop of leaves be more abundant than with annual pieck-
ings.

58

Of the mineral matter contained in the leaf, only certain portions are
appropriated by the worm; these are phosphoric and sulphuric acid,
potash, and magnesia. Its silica and sulphate and carbonate of lime
are not useful in nutrition. In studying the leaf of the Mulberry at dif-
ferent seasons it is found that early in the spring certain varieties pos-
sess these nutritive mineral substances to a greater extent than others,
but that as the season advances they become less abundant while the
proportion of silica and lime increases. It is important, then, if from
this point of view only, that we should rear our Silk-worms as early in
he season as possible. A great many experimenters have occupied
themselves with the value of the different varieties of Mulberry with a
view to ascertaining which would give the best alimentary results un-
der ordinary conditions. As a result, it is generally advised that the
seedling White Mulberry be fed at the beginning of an education and
the rosea during the later ages. The multicaulis possesses many of the
advantages of these varieties, though less rich in nutritive elements
than either of them.

OSAGE ORANGE.—The cultivation of the Osage Orange (Maclura
aurantiaca) is so well understood in this country that there is no need
of giving detailed instructions on the subject. Very generally used as
a hedge-plant in those sections of the country which are particularly
adapted to silk cultere, its leaves may at once be obtained without any
Special investment of capital. Indeed, as the hedges need trimming,
the cutting off of the new year’s growth, as the leaves may be wanted
for feeding purposes, is a saving rather than an expenditure. Those
who use this plant as Silk-worm food must, however, bear in mind that
the shoots from a hedgerow become very vigorous and succulent by the
time the worms are in the last age. These more milky and succulent
terminal leaves should be thrown aside ard not used, as they are apt
to induce flaccidity and other diseases.

In avoiding these more tender leaves and using only the older and
firmer ones, especially when the worms are large, consists the whole
secret of the successful rearing of Silk-worms on this plant; and if care
be had in this respect, and the same judgment used in selecting from
trees or hedges well exposed to sunlight, as suggested for Mulberry,
there will be no appreciable difference in the silk crop from Osage
Orange as compared with that from Mulberry.

The thorns of this plant make it somewhat more. difficult to pick its
leaves than those of the Mulberry, and I should not advise its cultiva-
tion merely as Silk-worm food.

What is said of the Osage Orange is based upon a very extended ex:
perience, and I would not only emphasize the fact of the value of this
plant, but also of the necessity of the careful selection of Maclura leaves,
especially during the last two ages of the worm. I have found that
after the third age time is saved by using the twigs, first taking care to
clip off the spines, which is rapidly done by means ofa pair of scissors, In

59

using twigs instead of leaves, the tender tips of the current year’s growth
should be cut off with the spines. I have found this method of feeding
to have decided advantages (though contrary to all custom in Europe,
where the twigs and branches of the Mulberry are too valuable to be
constantly pruned), for it not only allows more air to circulate as the
food accumulates, buf it gives the worms, as they grow in size, an op-
portunityeof clambering about, which they do not have to the same ex-
tent where leaves alone are used. In adding the new meal there is,
also, where twigs are used, less danger of the transfer paper pressing
injuriously upon the worms beneath.

Should the worms, from whatever cause, hatch before either Mulberry
or Osage Orange leaves can be obtained, they may be quite successfully
fed, for a few days, upon well-dried lettuce leaves. It will, however, be
worse than a waste of time to attempt to feed them entirely on these
leaves, or, in fact, on any other plants than the two here recommended.

ir

GLOSSARY OF TERMS USED.

Age: The interval between hatching and first molt, between any two molts, or between the last larval
molt and spinning.

Alimentary canal: The food canal; a straight, simple tube, running from one end of the body to the
other, and which it is impossible to subdivide into gullet, stomach, and intestine.

Alkaline: Having the opposite reactions to an acid.

Anal horn: The horn upon the posterior end of the body of the worm.

Annuals: Those races which produce but one brood in a year.

Antenne: The feathery feelers upon the head of the moth.

Bacillus: A microscopical vegetable organism, often causing disease.

Bivoltins: Those races producing two broods in one year.

Bombycide: The family of moths, commonly known as ‘‘spinners,” to which the Silk-worm moth be-
longs.

Botrytis bassiana: The fungus causing muscardine.

Brin: The French term for a single thread from the cocoon.

Carneous: F lesh-colored. °

Choked cocoons: A term applied to those cocoons in which the chrysaiis has been killed.

Chlorophyl: The green coloring matter of leaves.

Chrysalis: The third or restful state of tho insect, or that between the worm and the moth, inclosed
in the cocoon.

Cocoon: The silken covering with which the worm surrounds itself before passing into the chrysalis
state.

Cocoonery : The name applied to a room or building where cocoons are dried after being choked.

Corpuscle: A microscopic parasitic organism causing the disease, pébrine.

Croisure: The twist to which the silk thread is submitted in reeling.

Dacey: A Bengalese race of worms producing eight broods each year.

Detent: A stop which locks and unlocks the wheels in clock-work.

Dorsal vessel: The heart, extending from one end of the body to the other, just under the skin of the
back.

Echevette: A small skein of silk of a determined length, the weight of which determines its size
number.

Epizootic: A term having the same significance with lower animals as epidemic with man.

Eprouvette: A reel supplied with a counter upon which échevettes are measured.

Faller: A smalllever, over which a thread runs, and which, upon the breaking of the thread, falls,
thus stopping the mechanism through the action of a detent to which it is attached,

Fil: The French term for the combined threads as they come from the reel.

Ferment: Micro-organism causing fermentation.

Fibrine: An organic compound forming the base of the silk filament.

Filature: The French name for reeling establishment.

Flaccidity : A Silk-worm disease characterized in the text, Chapter V.

Flacherie: The French name for flaccidity.

Floss silk: Silk made from the loose material of the outer cocoon and from pierced cocoons, etc. It is
carded and spun like cotton or wool.

Fresh cocoons: Cocoons that have not been choked.

Gattine: An old name for a mild phase of the disease known as pébrine. Maillot thinks that it is a
form of flaccidity.

Grasserie: A Silk-worm disease allied to jaundice. It is described in Chapter V.

Greencocoons: A name frequently applied to fresh or unchoked cocoons. Should be avoided, except
where it has reference to cocoons of a green color.

Greens: A name applied to those races making cocoons of a greenish tint.

Integument: Skin or outer covering.

Japonica: A variety of the White Mulberry.

Labium: The under lip, upon which is situated the spinneret.

Larva: The second or worm state of the insect.

Lepidoptera : Name of the order to which the Silk-worm belongs.

Lusettes: A name applied to the worms which die from being unable to molt.

Magnanerie: The name applied to the room or building used for the rearing of worms.

Micropyle: The opening in the egg of the Silk-worm moth through which the fecundating liquid
enters.

Moretti: A variety of the White Mulberry discovered in 1815 by Professor Moretti, of Pavia.

Mori: The scientific specific name for the Silk-worm.

Morus: The botanical generic name of the Mulberry.

Multicaulis: A variety of the White Mulberry.

Muscardine; A Silk-worm disease of a fungus nature, characterized in the text, Chapter V.

61

_ Spinneret: A tube projecting from the lower lip, and through which the silk issues.

Organzine: Highly twisted thrown silk used in the woof in weaving.

Ovipositing : Laying the eggs.

Pébrine: A Silk-worm disease characterized in the text, Chapter V.

Pod: The compact portion of the cocoon, which is used for reeling purposes.

Polyvoltins: A term applied indiscriminately to all races which produce mors than one brood ina
year.

Pro-legs : The ten non-jointed legs under the sixth, seventh, eighth, ninth, and last joints of the bod
of the worm. :
Psorospermie : Scientific name for the floating corpuscles in the bodies of worms affected by pébrine.
Quadrivoltins : Those races which produce four broods in one year.

Raw silk: Silk reeled from the cocoons before being thrown and woven.

Rosea: A variety of the White Mulberry.

Seed: The eggs in bulk.

Sericaria : A generic name proposed by Latreille, and to which the Silk-worm is referred by modern
writers.

Sickness : The period of molting.

Spiracles : The breathing-holes of the insect; one row of nine down each side of the body.

Spores: The germinating seed of fungi.

Tavellette: A small pulley used in the Italian system of reeling.

Thrown silk: Silk which has been submitted to the operations following spinning or reeling. It is
classed as tram and organzine.

Trachea: The breathing-tube of an insect.

Tram: Slightly twisted thrown silk used in the warp in weaving.

Transformation : The change from one state to another, as from worm to chrysalis or from chrysalis to
moth.

Trevoltins : Those races of Silk-worms of which there are three broods in one year.

Vitellus: The yolk of an egg.

Whites: Those varieties having white cocoons.

Yellows: Those varieties having yellow cocoons.

EXPLANATION TO-PLATES.
PEATE.
SILK-WORMS AFFECTED BY PEBRINE AND FLACCIDITY (AFTER PASTEUR).

A, B, C, D, Silk-worms affected with pébrine, showing the spots of the disease. On
the eighth joint of the worm A will be seen a wound which is distinguishable by its
clear-cut edges.

E, F, G, worms, after death from flaccidity. G shows the worm just after death,
still retaining all of its outward perfection of form. At F the worm has begun to
shrivel, while at E the blackening caused by putrefaction is shown.

PLATE II.

PEBRINE CORPUSCLES OF SILK-WORM MOTIL HIGHLY MAGNIFIED (AFTER PASTEUR).
(The white ovoid bodies are these corpuscles. )

62

BULLETIN 9, DIVISION OF ENTOMOLOGY, DEPT. AGR. Plate TL.

Db

A.Hoen & Go tath, Ratomore

SILKWORMS AFFECTED BY PEBRINE AND FLACCIDITY.

= fatter PASTEUR)

BULLETIN 9, DIVISION OF ENTOMOLOGY, DEPT. AGR.

PEBRINE CORPUSCULES OF SILKWORM MOTH.

highly magqnified

(after PASTEUR )

Advice to beginners in silk-culture, 8 |
Alteration in value of silk products, 6
Anthrenus injuring cocoons, 47
Ants as enemies of the worms, 28
injuring cocoons, 48 /
Arches for spinuing of cocoons, 29
Atmosphere in which wintering eggs should be |
kept, 17
Automatic reels, 9
Bag for gathering mulberry leaves, 24
Black Mulberry tree, 56
Botrytis bassiana, 33
Broussonetia papyrifera, 57
Canes for constructing shelves, 21
Cells used for egg-laying, 44
Chain ferment in flaccid clrysalis, 38
Chambon system of reeling, 51
Cleanliness in rearing worms, 26
Choking the chrysalis, 47
Chrysalis of Silk-worm, 14
Description of, 14
Examining, for flaccidity and pébrine, 42, 43
Methods of choking, 47
Cocoon of Silk-worm, 14
Description of, 14
~ Constricted, 14
Non-constricted, 14
Cocooning ladder, 24
Cocoons:
Assorting, 31, 49
Cooking, brushing, and purging, 50
Double, 30
Form of, indicating sex of moth, 44
Gathering, 30
Loss of weight in drying. 31
Profits of producing, 6
Sale of, in the United States, 3
Selecting for reproduction, 43
Treatment of, before emergence of moth, 44
Weight of fresh, 52
Congressional aid to silk-culture experiments, 8
Constituents of silk in the cocoon, 55
Constricted cocoons, 14
Cost of reeling, 6
Davril cocooning ladder, 25
Dermestes injuring cocoons, 47
Diseases of the Silk-worm, 32
Flaccidity, 36
_ Flacherie, 36
Gattine, 32
Grasserie, 40
Muscardine, 33
Pébrine, 34

INDEX.

Double cocoons, 30

| Egg of Silk-worm, 11

Development of, 11
Egg-laying of the moth, 44
Eggs, Market for, 7
Microscopic examination of, 36, 46
Number of, laid by a single moth, 12
Wintering and hatching of, 17
Elasticity and tenacity of raw silk, 54
Empusa musce, 33
Enemies of Silk-worms, 28, 33
Ants, rats, mice, 28
Insect parasite, 32
Flaccidity, a disease of Silk-worms, 36
Causes favorable to its appearance aud spread,
39
External symptoms, 36
Internal symptoms, 37
It is contagious and indirectly hereditary, 40
Microscopical examination of chrysalis, 42
Theories of its cause, 39
Flacherie, see Flaccidity
Filature station at New Orleans, 8
Filatures, establishment of, in the United Studer 8
Food-plants of the Silk-worm, 56
Constituents of the Mulberry leaf, 57
Directions for planting Mulberry trees, 56
Lettuce leaves for young worms, 59
Native and imported Mulberry trees, 56
Osage Orange, 3, 58
Paper Mulberry, 57
Varieties of White Mulberry, 57
Food-supply in rearing worms, 26
Fresh air in rearing rooms, 28
Gathering the cocoons, 30
Gattine, a disease of Silk-worms, 32
Glossary of terms used, 60
Gluten, amount of, in reeled silk, 55
Government aid to silk-culture in the United
States, 8
Grasserie, a disease of Silk-worms, 40
Maillot’s description of the disease, 40
Hatching the eggs, 18
Hibernating the eggs, 18
Hygrometric properties of silk thread, 55
Implements that facilitate the raising of silk, 20
Bag for gathering leaves, 24
Cocooning ladder, 24
Perforated paper for transferring worms, 23
Room for rearing worms, 20
Shelves, 20 .
Standard for holding shelves, 22
Transfer tray, M

Importation of raw silk in the United States, 2
Import duty on raw silk recommended, 2
Incubators for hatching eggs, 19
Ladder, Cocooning, 24
Larva of Silk-moth, see Silk-worm
Lettuce leaves as food for young worms, 59
Maclura aurantiaca, 3, 58
Maillot’s method of examining the chrysalis, 43
Market for cocoons, necessity of establishing, 2
Mean size of a skein, determination of, 53
Micropyle of egg, 11
Molting of the worms, 12, 27
Morus alba, 56
japonica, 56
moretti, 56
multicaulis, 56
nigra, 56
parvifolia, 56
rosea, 56
rubra, 56
tartarica, 56
Moch of the Silk-worm, 14
Copulation, 46
Description of, 15
Distinguishing the sexes, 46
Examining for pébrine, 46
Mode of issuing from the cocoon, 14
Mulberry leaves, Constituents of, 57
Bag for gathering, 24
Mulberry Silk-worm superior to other siikworms,
TAL
Mulberry tree, 56
Black, 56
Paper, 57
Red, 56
Russian, 57
Small-leaved, 56
White, 56
Muscardine, a disease of silk-worms, 33
A fungus its cause, 33
Means of preventing its spread, 33
_Symptoms, 33
Muslin bags used as cells for egg-laying, 44
Mycoderma aceti, 38
Obstacles to silk-culture in the United States, 1
Organzine, 49
Osage Orange as food for Silk-worms, 3, 58
Paper Mulberry tree, 57
Pasteur’s investigations of pébrine, 35
method of examining the stomach of
chrysalids, 42
system of microscopical selection, 41
Pébrine, a disease of the Silk-worm, 34
Examination of the chrysalis, 42
moth, 36, 42, 46
External symptoms, 34
Internal symptoms, 35
It is contagious and hereditary, 35, 40
Maillot’s method of examining the chrysalids,
43
Nature of the disease, 35
Pasteur’s investigations, 35, 41, 42
Perforated paper for transferring worms, 238
Profits of produeing cocoons, 6
Preface to second edition of manual, 1
sixth edition of manual, 5

64 ;

Physical properties of reeled silk, 53
Constituents of silk in the cocoon, 55
Determining the elasticity and tenacity of —

raw silk, 54
mean size of a skein, 53

Serimeter, 54
Serrell’s serigraph, 53
Races or varieties of the Silk-worm, 15
Raw silk, 2, 49, 54
Definition of, 49
Elasticity and tenacity of, 54
Import duty recommended, 2
Rearing of Silk-worms, 26
Allowance of plenty of room, 28
Arches for spinning of cocoons, 29
Assorting cocoons, 31
Cleanliness, 26, 29
Food-supply, 26
Fresh air in the rearing room, 28
Gathering the cocoons, 30
Guarding against double cocoons, 30
enemies, 28
Importance of simultaneous molting, 27
Preparations for spinning, 29
Temperature in the rearing room, 28, 30
Red Mulberry, 56
Reel, 9, 50
Automatic, 9
Elements of mechanism of, 50
Serrell’s reel, 5
Reeled silk, 49
Physical properties of, 53
Reeling, 6, 49
Approximate cost of, 6
Process of reeling, 49
Silk reel, 9, 50
Spun, reeled, and thrown silk, 49
Reproduction, 41
Cells for egg-laying, 44
Copulation, 46
Examination of the eggs, 46
mother muths, 42
Old process of obtaining good eggs, 41
Pasteur’s system of microscopical selection, 41
Selection of pure stock, 43
Russian Mulberry tree, 56
Seed, see Egg
Sericaria mori, 11
Serigraph, 53
Serimeter, 54
Serrell’s reel, 5
serigraph, 53
Shelves for rearing worms, 20 1
Silk-culture in the United States, Government
aid to, 8
Obstacles to, 1
on au extensive scale, dangers in, 7
Silk products, alteration in value of, 6
Silk-worm, color of, 13
Development of, 12
Directions for rearing of, 26 :
Diseases of, 32
Enemies of, 28, 32
Molting of, 12, 13, 27
Physiology and life-history of, 11
Spinning of, 13 3

65

Silk-worm moth, see Moth of the Silk-worm Transfer tray, 24
Simultaneous molting, importance of, 27 | Transferring worms, 23
Small-leaved Mulberry, 56 Uji, parasite of silk-worms, 32
Spun silk, 49 White Mulberry tree, 56
Standard for holding shelves, 22 Wintering and hatching the eggs, 17
Temperature at which hibernating eggs should be Atmosphere in which they should be kept, 17
kept, 17 Incubators, 19 j
of rearing rooms, 28, 30 Method of hatching theeggs, 18
Thrown silk, 49 Temperature at which they should be kept, 17
Tram siik, 49 Worm, see Silk-worm

16136—No, 9——5

aOR