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Full text of "The American lobster; a study of its habits and development"

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FOT: 1R«5. Pnjrps I to -jy:. Plates A lo .1 ami 1 In 54.1 



THE AMERICAN LOBSTER 



A STUDY OF ITS HABITS AND DEVELOPMENT. 



BY 



FRANCIS HOBART HERRICK, Ph. D., 

PROFESSOR OF BIOLOGY IN ADELBERT COLLEGE OF WESTERN EESERVK UNIVERSITY 



WASHINGTON: 

G O V E R N M E N T P R INTING O F F I C E . 

18 9 5. 

9 



17 



THE AMERICAN LOBSTER 

A STUDY OF ITS HABITS AND DEVELOPMENT. 



BY 



FRANCIS HOBART HERRICK, Ph. D., 

Professor of Biology in Adelbert College of Western Reserve University, 



J'. C. li. 1895—1 



Invertebrate 
\ zoology 

Crustacea 



""ISe xa\av jtovpi'Saov, i'Se naudpwi', i'Se <pi\a. 
QDddai /.iav doi ipvSpai rivri hai Asiorpixi&>dai." 

" Behold the dainty courides, ray friend, 
And see these lobsters ; see how red they are, 
How smooth and glossy are their hair and coats." 
Sophron, quoted by Athenceus. 



"La Nature a toujours de quoi payer les soins de 
ceux qui l'examinent; il n'est point de si petit cote oil 
elle ne soit inepuisable." 

Reaumur. 



" Wir finden zwar bey alien Scribenten der natiir- 
lichen Historie eine Beschreibuug des Fluskrebses, 
wenn man aber alles was sie von selbigem gesaget 
zueammnimmt, so kommt so wenig heraus, dass auch 
hier das Sprichwort, (Juotidiana vilescunt, was wir 
taglich vor Augen haben, achten wir nicht, allerdings 
einzutreffen scheinet." 

Soesel von Rosenhof. 



CONTENTS. 



Page. 

Introduction 5-13 

Chapter r. Habits and Environment 14-32 

Distribution of the Lobster 14-10 

Cbaracter of the Environment 17 

Intelligence of the Lobster 17-18 

The Lobster's Powers of Movement 18-20 

Periodical Migrations and their Relation to 

Changes in the Environment 20-27 

Sensibility to Light 27 

Digging and Burrowing Habits 27-29 

The Food of tho Lobster and how it is procured . 29-32 

Chapter II. Rep roductiou 33-74 

The Reproductive Organs 33-34 

Pairing of the Lobster and of other Crustacea.. 35-39 

The Laying of Eggs 39-40 

Summer Eggs in Vineyard Sound 41-43 

Summer Eggs on the Coast of Maine 43-44 

Fall and "Winter Eggs at Woods Hole 44-15 

Fall and Winter Eggs iu other places 46-47 

Laying of the Eggs and Absorption of Ovar- 
ian Ova 47^9 

Number of Eggs Laid and Law of Production. . 50-55 
Period of Incubation at Woods Hole and Rate of 

Development 55-57 

The Hatching of the Eggs 57 

Time of Hatching of Lobsters at "Woods 

Hole - 57-58 

Dispersal of the Young 58-60 

Variations in the Time of Hatching 60-61 

Destruction of the Egg-Lobster and its Spawn . . 62-64 

Period of Sexual Maturity 65-70 

Freq uency of Spawning 70-73 

Relative Abundance of the Sexes 73-74 

Chapter HI. Molting and Growth 75-99 

Earlier Observations 75-77 

Structure and Growth of the Shell 77-78 

The Shedding of the Shell in the Lobster 79 

Molting Period 79-81 

Molting Process 81-82 

Habita of Molting Lobsters 82-83 

Casting of the Shell 83-86 

Withdrawal of the Large Claws 86-87 

Cast-off Shell 87-88 

The Gastroliths 88 

Gastroliths in the Lobster; Their Structure 

and Development 88-91 

History of the Gastroliths ; Their Probable 

Function 91-93 

Chemical Analysis of the Shell and Gastro- 
liths 94 

Hardening of the New Shell 94-95 

Rate of Growth 96-99 



Page. 
Chapter IV. Defensive Mutilation and Regenera- 
tion of Lost Farts 100-108 

Autotomy iu the Young and Adult 100-103 

Regeneration of Appendages 103-104 

Regeneration of the Large Chelipeds 104-105 

Regeneration of the Antenna 1 , and Other Ap- 
pendages - - - 105-107 

Internal Changes in Regeneration 107-108 

Chapter V. Large Lobsters 109-120 

The Greatest Size Attained by the Lobster ... . 109-117 

The Relation of Weight to Length of Body 118-120 

Chapter VI. Enemies of the Lobster 120-124 

Animals which prey upon theLobster - 120-122 

Parasites, Messmates, and Diseases 122-124 

Chapter VII. The Tegumental Glands, and their 

lielation In Sense Organs 125-133 

General Structure of the Tegumental Gland 125-126 

The. Cement Glands 126 

Immediately before Ovulation 126 

Immediately after Ovulation 126-127 

Historical Sketch of the Cement Gland 127-128 

Tegumental Glands in other Parts of the 

Body 128-129 

Experiments upon the Sensory Areas of the 

Body and Appendages 129-133 

Chapter VIII. Variations in Color 134-14S 

Normal Coloration 134-135 

Variations in Color 135-137 

Color of the Eggs 137 

Blue Lobsters 137-138 

Red Lobsters 138-139 

Cream-colored Lobsters 139-1 40 

Variations in Color Patterns 140 

Spotted Lobsters 140 

Parti-colored Lobsters 141-142 

Chapter IX. Variations in Structure 143-149 

Normal Variations in the Large Claws 143 

Abnormal Variations in the Claws 143 

Similar Claws developed on Both Sides of the 

Body 143-144 

Division and Repetition of Appendages 144-148 

Variations in Other. Organs 149 

Rostrum 149 

Ovary 149 

Hermaphroditism 149 

Chapter X. Structure and Devdoyntcnt of the Re- 
productive Organs 150-160 

The Female Reproductive Organs 150 

The Ovary 150 

The Ripe Ovary 150-151 

The Ovary after Ovulation 151-152 

3 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Chapter X. Structure and Development of the He- 
productive Organs — Continued. 
The Female Reproductive Organs — Continued. 
The Structure of the Ovary at the Time of 

Hatching of External Eggs 152-153 

Origin of the Ova 153 

The Metamorphosis of the Germinal Vesicle. . J . 153-154 
Movements of the Nucleolus through the Action 

of Gravity 154-155 

The Ripe Ovum 155 

Development of the Reproductive Organs 156 

General Development 156 

Ovary 156 

Oviduct 157 

Seminal Receptacle 157 

Development of the Seminal Receptacle 158 

The Male Reproductive Organs 158 

Testis 158 

Vas deferens 158-159 

Spermatophores 159-160 

Sperm Cells 160 

Chapter XI. Habits of the Lobster from time of 

Matching until the period of Maturity . . . 161-166 
Chapter XTL History of the Larval and early Ado- 
lescent Periods 167-201 

Historical Notes 167-168 

Methods of Studying the Young 168-169 

The Embryo in Late Stages of Development 169-170 

The Hatching of the Larva 170 

The First Stage 171-172 

The Second Stage 172-173 

The Third Stage 173-174 

The Fourth Stage 174-176 

The Fifth Stage 176-177 

The Sixth Stage 177-178 

The Seventh Stage 178 

Description of Small Lobsters (Nos. 1-6, table 

35; No.l,table33) 179-182 

Molting of the Embryo and Larva 182-184 

Color Variations in the Young Lobster 184 



Page. 
Chapter XII. History of the Larval and early Ado- 
lescen t Periods — Continued. 

The Death-feigning Habit , 184-186 

The Food of the Larva 186-187 

Heliotropism of Larval Lobsters 187-189 

Mortality of Larvae 190 

Effect of increased Temperature upon the Rate 

of Development of Larva? 190-19] 

Development and Morphology of the Body and 

Appendages 191 

The Body 191-193 

The Visual Organs and Appendages 193-197 

Development of the First Pair of Pleopods . . 197-200 
The Metamorphosis of the European lobster, 

LTomarus ga.mmarus 200 

The Shortening of the Metamorphosis of the 

Lobster 200-201 

Chapter XIII. Embryology of the Lobster 202-217 

Normal Development 202 

The Maturation and Segmentation of the 

Egg 202-203 

External Phenomena of Segmentation 203-205 

Internal Changes in Segmentation 205-206 

The Invagination Stage 206-209 

Later Stages in Embryonic Development . . - 209-210 

History of Yolk-Cells 210-211 

Degeneration of Cells 211-213 

Abnormal Development 213 

Segmentation of the Egg 213-214 

Invagination and Egg-Xauplius Stages 214-216 

Double Monsters in Ovum and Larva 216-217 

Note on the Development of Cambarns 217-218 

Chapter XIV. Summary of Observations 219-225 

Appendix I. Preparation of the Eggs 226-227 

Appendix H. Composition of the Shell and Gastro- 
liths of the Lobster. By Professor Al- 
bert W. Smith 227-228 

Appendix III. Bibliography 229-237 

Appendix IV. Description of Plates 238-252 



I 1 \y 

•nr 



1 -THE AMERICAN LOBSTER: A STUDY OF ITS HABITS AND DEVELOPMENT. 



By FRANCIS HOBART HERRICK, 
Prof " of Biology in Adelbert College of Western Reserve University. 



INTRODUCTION. 
I. 

While working on the embryology of Alpheus several years ago, I decided to study 
the development of the lobster for the purpose of comparison. An opportunity was 
offered in the summer of 1889, which I spent at the laboratory of the United States 
Fish Commission at Woods Hole, Massachusetts. In the spring of that year I had also 
received, through the kindness of Dr. G. H. Parker, a considerable quantity of embryo- 
logical material of the lobster, representing particttlarly its later stages of development. 

In the spring of 1890 I was invited by Hon. Marshall McDonald, United States 
Commissioner of Fisheries, to prepare as complete a work as possible upon the habits 
and development or general biology of the lobster. Accordingly during the past five 
years I have devoted all the time which could be spared from professional duties to 
this research. For a part of each summer, from June to the latter part of August I 
have enjoyed the excellent facilities for study which the laboratory of the Fish Com- 
mission at Woods Hole affords, and in the autumn of 1893 I was enabled to carry my 
observations into the field by a journey along the coasts of Massachusetts and Maine 
and into the Province of New Brunswick. 

The materials, therefore, upon which this work is based have been gathered from 
a large number of different points, although the most systematic and prolonged 
observations have been made at Woods Hole. In this pleasant task I have been aided 
by the friendly efforts of many who have made collections, particularly of eggs, at 
widely separated parts of the coast and at different times of the year. These I have 
gratefully acknowledged in the pages of this work. 

To everyone at the Woods Hole station I am indebted for many kindnesses, but 
particularly to Hon. Marshall McDonald, whose aid and encouragement I have con- 
stantly received, and to Mr. Eichard Eathbun, of the United States Fish Commission, 
who has forwarded my plans in every possible way. 

II. 

During the course of this study I have published several papers embodying the 
results of my researches (91-93, 96-101), 1 but these should not be consulted without 
reference to this final revision of my work. Whatever errors this may contain I must 
leave for other naturalists to rectify. 

1 Italic figures in parentheses refer to the numbers of publications in the Bibliography at the end 
of this paper. 

5 



6 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

The lobster, though it may be rightfully called the King of the Crustacea, in 
consider ation of both its size aud strength, its abundance and economic value, had, 
until recently, been singularly neglected by naturalists. Even its breeding habits 
were not understood, and so little was our knowledge of many phases of its general 
biology that I determined from the first to devote ample time to this important subject. 

Eathbun, who brought together what was known concerning the habits of the 
lobster in a contribution to the Natural History of Useful Aquatic Animals, published 
in 1887 (155), spoke as follows: 

Although the lobster is one of the most important of our food invertebrates, careful observa- 
tions regarding its natural history, aud especially its breeding habits, rate of growth, etc., have been 
strangely neglected. This fact is greatly to be deplored, considering that the lobster has recently 
become the subject of important legislation by the several States which it inhabits and that its culti- 
vation by artificial means has been frequently attempted. * The success attending the artificial 
breeding of several of our food-fishes has inspired the hope that similar methods might succeed with 
regard to the lobster, aud many persons are now awaiting with interest the results of experiment in that 
direction. It is very certain, however, that the breeding of lobsters can never be successfully carried 
on until we have become acquainted with at least the main features of their natural history. The 
artificial cultivation of animals can only progress through the fulfillment of natural laws, which 
must be thoroughly understood before they can be properly applied. As it is, however, the would-be 
experimenters in the matter of lobster breeding must still follow a very uncertain pathway, meeting 
with numerous failures which previous studies might have arrested (p. 781). 

Many facts relating more particularly to the larval development and reproduction 
have important economic bearings, and for the benefit of those who have neither the 
time nor inclination to read the details of this paper I have added a careful summary 
of the principal observations and conclusions at the end (Chapter xiv). 

Under the subjects discussed in the various chapters I have given all the impor- 
tant historical references, and have added a full bibliography. There has grown up 
around every well-known animal like the lobster a considerable mass of popular 
pseudo-scientific literature, which is of no value either as literature or science, and 
may well be ignored. 

III. 

The lobster is singularly free from common names, in this country at least. It is 
rarely confused with any other animal unless it be with the Palinurus of the Pacific 
Coast aud the West Indies, and with some of the larger species of crayfish, all of which, 
however, are very distinct, the latter being inhabitants of fresh water. 

Patrick Brown tells us in his " History of Jamaica," published in 1789, that the 
Palinurus was then commonly called the " horned lobster or great crayfish." The terms 
rock lobster and spiny lobster are still applied to it in this country and in Europe, 
but the entire lack of large claws — one of the most striking characteristics of the 
lobster — its spines, brilliant coloring, and enormous antennae, should prevent the 
most inobservant person from confusing it with so distinct a form. 

The lobster, as I have explained in Chapters n and in (pp. 55, 82), has acquired 
numerous epithets while carrying eggs or passing through the various phases of 
the molt. 

The old generic name Astacus (anray.o- or oaraxoc) was used by Aristotle and 
the older naturalists down to the present century to embrace the crayfishes and the 
lobsters proper. Aristotle thus speaks in the fourth book of his History of Animals 



THE AMERICAN LOBSTER. 7 

of "the small astaci, which are bred in the rivers"' showing that the reference is 
undoubtedly to the crayfish. 

Athemeus frequently mentions the Astacus in the third book of The Deipnosoph- 
ists, where, as in the passage quoted below, lie undoubtedly had in mind the lobster. 
This is from a famous poem of Archeslratus, wherein, as Athemeus remarks, he never 
once mentions the crab by the name of xa/>a/3»<r, yet does speak of the aWa*.*?. 

But passiug our trifles, buy an astacus, 
Which has long- hands and heavy, too, but feet 
Of delicate smallness, and which slowly walks 
Over the earth's face. A goodly troop there are 
Of such, and those of finest flavor where 
The isles of Lipara do gem the ocean : 
And many lie deep in the broad Hellespont. 

(The Deipnosophists ; Bk. in, tr. by C. D. Yonge, 1854.) 

Athemeus then quotes from another author, Epicharm us, to show that the «W«x«? 
mentioned by Archestratus is the same as the xdpa^oq: 

There are astaci and colybd;en;e, both equipped 
With little feet and long hands, both coining' under 
The name of Kapafiog. 

The English word lobster is from the old English lopystre, 2 which is probably a 
corruption of the Latin locusta — English, locust — a name used by Pliny in speaking of 
the lobster in his Natural History. Thus, in the ninth book, he says: "The lobsters, 
being of that kind which want blood, are protected by a weak shell." s In the next 
section of the same chapter there is a sentence, 4 in which the astaci are mentioned as 
one of the genera of crabs. It is possible that lobsters are here referred to, but the 
meaning is doubtful. 

Gesner, whose remarkable History of Animals was published at Ziirich between 
1551 and 15S7, speaks of the lobster under the Aristotlean name of Astacus, and adds 
a very interesting synonymy. He says : 

The English call the Astacus a creuyse of the sea," for the lopstar of the English is the locust, not 
the astacus; although Eliot in different places has translated astacus, locust, and leo as a lopster. 15 

1 7Vc iiaraKolg /UKpolg, ol yiyvovrai aal kv rolg iroraixol^. A. H. 4. 4. 

- Longusta or langusta, la langouste of the Freuch, the Palinurus, probably has the same origin. 
This was corrupted to ''long oyster" in the West Indies. (See The Natural History of Jamaica, by 
Hans Sloane, vol. II, p. 271.) 

:! Locusta? crusta fragile muniuntur in eo genere quod caret sanguine. Latent men3ibus quinis, 
similiter cancri qui eodeui tempore occultantnr, et ambo veris principio senectutem anguiuin more 
exuernnt renovatione tergoruin. Lib. ix, Cap. xxx, sec. 50. 

4 Cancrorum genera carabi, astaci maeae, paguri, heracleotici, leones et alia ignobiliora. Ibid., 
sec. 51. 

B Creuyse according to Skeat, is probably a variation in the spelling of the Middle English for 

crayfish (crayf-ish), crevis, creves, crevise, or creveys; Old French, crevisse, or eserevisse ; Modern 

French, ecrerisse ; Old High German, crebez ; Middle High German, Tcrebez ; German, Krebs, allied to 
Krabbc. 

,: Anglis astacus est a creuyse of the sea, nam lopstar Anglorum, locusta est, non astacus; qnam- 
quam Eliota diversis locis astacum locustam et leonem interpretatus a Lopster (75, De Astaco. pp. 
113-121). [Eliota is Sir Thomas Elyot, who published a Latin-English dictionary in 1538.] 



8 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Some light is thrown upon this passage by the German translation of Gesner's 
Historia Animalium, published at Frankfort in 1598, where the lobster is spoken of 
as Humer oder grossen Meerlcrebs. The Latin name Astacus is also given to it. A 
paragraph, which I did not find in the original, is as follows : 

These sea-crabs mentioned above, are called by Pliny sea-elephants, on account of their size and 
strength. They are also regarded by some as sea-lions, and by such names are commonly known at 
Montpelier. 1 

The lobster was also called by the Greeks xdiJ.iJ.apoc;, Latin gammarus, probably from 
its arched back, from which Spanish, camaron, and the Italian gambaro are derived. 
Gesner tells us that the crayfish, was often called simply gambaro, to distinguish it 
from the lobster gambaro di mari; that to the French and Normans the lobster was 
known as Homar; to the Germans as Humer. In Norway, Sweden, Denmark, and 
Germany it is now called Hummer. 2 This in French became Homar d (Homar, Latin- 
ized form Homar ns). It has been suggested by Boeck that the name may possibly 
have come from the Norse verb homa, meaning to go backward. 

Gesner adds that the lobster was called by the Venetians astase vecari audio; by 
the Illyrians, larantola (or caranthola), and by the Swiss, langroit or escreviee de mer. 
The Dutch call the lobster Zeelcruft or sea-crayfish, while it is known to the Turks of 
Constantinople as liczuda or Uehuda. 

According to Boeck there are numerous poetical allusions to the lobster in the 
Eddas and Sagas. Thus the sea is described as "the path of the lobster" in Olaf der 
Heilige's Saga, and in Olaf Tryggvason's Saga it is said that " the wave-horses run 
over the fields of the lobster," meaning the ships that sail on the waves. "To be at 
the bottom with the lobster" is to drown, as in the song of Snigly Holle. "In the 
Selkolle Songs of Binar Gilson, in Bishop Gudmund's Saga, the term " the light of 
the lobster," equivalent to the fire of the sea or gold, is used. In the same place the 
expression, "the horse of the lobster mountain," meaning the ship, is used. Finally 
there is found in the poem Liknar-braut, the expression "land lobster," meaning a 
serpent or dragon. (20, p. 224.) 

IV. 

Excluding from our consideration the Palinurus or langouste and the Norwegian 

lobster, Nephrops norvegieus, two species belonging to this genus are now known, 

namely : 

Homarus, Milne Edwards. 

(1) Homarus gammarus (Linn.); —Cancer gammarus (Linn.); 

= Homarus vulgaris (M. Edw.) European Lobster. 

(2) Homarus americanus (M. Edw.) American Lobster. 

A third form, H. eapensis, has been imperfectly described from the Cape of Good 
Hope, but it is doubtful if it belongs in this genus. (See 102, p. 754, note 4.) 

1 Diese obgenandte Meerkrebsz nennet Plinius Meerhelffant von wegen irer grtisse und stiircke 
werden sonst auch von etlichen Meerlowen geachtet sind mit solchem Nameu von menniglichen zu 

Mompelier genennt worden Fischbuoh; translated from the original of Conrad Gesner into 

German by Conrad Forer; p. 125; Franckfurt, 1598. 

The animal described and figured on the next page of this work and called the Small Lobster or 
Small Sea-crab — Astacus marinus parvus — is probably a species of Galatea. Palinurus is described as 
the Meerstoffel. Synonyms are: A Species of Lobster; A Kind of Large Sea-crab ; Locusta; Carabus. 

2 The old Norwegian and Danish writers, Pantoppidans (1752, 152), Strom (1762), Bomares (1767), 
and Leems (1767) speak of the lobster as Hummer, while by Olafssens and Povelsens (1772) it is called 
Hiimar, according to Fabricins. These dates refer to works. For bibliography see Otlio and J. C. 
Fabricius (63-64). 



THE AMERICAN LOBSTER. 9 

1 will now add a fuller synonymy of the technical names which have been applied 
to the European and American lobsters. 

EUROPEAN" STECIES. 

AsiacitH 1551. Rondelet (tn: ). Cancer gammarus 1761. Linnd {123) 

Astacus vent* 1618. Aldrovandus i 

Astacus marinus communis. 1657. Jonston (107 ). 

Astacus marinus 1553. Belon {15). 

1758. Seba (179). 



177ii. Miiller i 139). 

1795. Herbst (88) [2d ed.]. 

1829. Latreille(i/5)[2ded. | 

Astacus europeus 1837. Couch (45 i. 

1762. Baster (5). Homarus vulgaris 1837. Milne Edwards (58). 

1777. Pennant (151). 1853. Bell (14). 

1863. Heller (87). 

Homarus marinus 1868. Bate (10). 

dstacns gammarus 1819. Leach (117). 

1857. White (203). 
1893. Stebbing (186). 



1792. Fabricius (64) 
1811. Olivier (143). 
1838. Lamarck (113) 
[3d ed.]. 

1825. Desmarest (52). 

1826. Risso (166'). 
1842. Ratlike (160). 



AMERICAN SPECIES. 



Astacus marinus america- 

nus 1758. Seba (179). 

Astacus marinus 1817. Latreille (115) 

[1st ed.]. 
1817. Say (177). 



Horn ar u s americanus . .1837 '. Milne Edwards (58) 

.iiid most subsequent 
writers. 

Astacus americanus . ..1893. .Stebbing (1S6). 



Latreille, 1 in 1810, designated as the type of the old genus Astacus the species 
A. fluviatilis Fabricius ( = Cancer astacus Linne), which is the European crayfish. In 
1815 Leach began to dismember this genus by giving to the Norwegian lobster the 
name Nephrons. Later, in 1819 (117), 2 he proposed the generic term Potamobius to 
embrace the true crayfishes, leaving the lobsters alone in possession of the Aristotelian 
name. This division would transfer the type species of Astacus (A. fluviatilis) to the 
genus Potamobius, which is contrary to the rules of zoological nomenclature, and can 
not be accepted. In 1837 the lobsters were placed by Milne Edwards in a distinct 
genus, Homarus, while the elder name was retained for the crayfishes. Spence Bate 
was in favor of uniting the generic name of Milne Edwards to the specific name of 
Fabricius, calling the European species Homarus marinus (Fabr.). The proposal of 
Leach "to use Astacus for the lobsters and to give a new generic name (Potamobius) 
to the fresh-water crayfishes," would, in the opinion of Huxley, " have had the ad van 
tage of retaining the primitive signification of aarar.oq. But Potamobius had already 
been used in another sense, and the change introduced by Milne Edwards is so gen- 
erally adopted that it would be confusing to attempt any further alteration " (102). 
Previous to 1819 the name Potamobie had been used by Leach 3 in a list of the known 
genera of Crustacea. It was, however, a nomen nudum, which would have permitted 
the use of the name Potamobius for the crayfishes had the genus been correctly formed. 
Stebbing (186), apparently unaware of Latreille's restriction, proposed to restore the 
old terminology of Leach. 

According to Milne Edwards's classification, which I have adopted, the common 
European crayfish should be called Astacus astacus (Linn.), the European lobster 
Homarus gammarus (Linu.),and the American lobster Homarus americanus (M. Edw.). 

1 Considerations Gene'rales sur VOrdre Naturel dcs Animaux composant les Classes des CrustacSs, des 
Arachnides, et des Insectes, p. 422. Paris, 1810. 

2 George Samouelle 's Entomologist's Useful Compendium, p. 95. London, 1819. 

3 Dictionnaire des Sciences Xaturelles, XII, p. 75. 1818. 

For the preceding references I am indebted to the kindness of Dr. "Walter Faxon and Miss Mary J. 
Rathbun, and I desire to acknowledge the aid I have received from them on the nomenclature discussed 
in the last two paragraphs of this page. 



10 BULLETIN OF. THE UNITED STATES FISH COMMISSION. 

V. 

Although the lobster has a place in the literature of the Old World, it is seldom 
mentioned by American writers. Eathbun, who was the first to give a history of the 
American lobster fisheries, says that the great abundance and rare flavor of the 
lobster "are not infrequently mentioned in the early annals of New England, and it 
probably formed an important element in the food-supply of the seacoast inhabitants 
of colonial times. As a separate industry, however, the lobster fishery does not date 
back much, if any, beyond the beginning of the present century, and it appears to 
have been first developed on the Massachusetts coast, in the region of Cape Cod and 
Boston, although some fishing was done as early as 1810 among the Elizabeth Islands 
and on the coast of Connecticut. Strangely enough this industry was not extended 
to the coast of Maine, where it subsequently attained its greatest proportions, until 
about 1840." (156.) 

In an account of marketing in Boston in 1740, among various kinds of meats and 
game, "oysters and lobsters" are mentioned "in course, the latter in large size at 
3 half-pence each." (200, vol. n, p. 540.) 

Kalm, the Swedish traveler, writing in 1771, thus speaks of the abundance of sea 
food on the shores of Long Island: 

The soil of the southern part of the island is very poor; hut this deficiency is made up hy a vast 
quantity of oysters, lobsters, eral>s, several kinds of fish, and numbers of water fowl, all of which are 
there far more abundant than on the northern chores of tbe island. Therefore the Indians formerly 
chose the southern part to live in, because they subsisted on oysters and other productions of the sea. 
(IDS, vol. 2, pp. 226-227.) 

The older writers had little to say of the sea and its products in New England, 
yet many interesting facts could probably be gathered by a, careful examination of all 
available sources. 

VI. 

Lobsters are caught in pots or traps made of laths, nailed to a wooden frame, 
with a funnel-shaped opening at each end. The traps are commonly 4 feet long, ti feet 
wide, and 18 inches high. The funnels are usually netted out of manila twine. The 
pots are weighted with stones or bricks, and set either in single warps or in trawls of 
from 8 to 40 pots each. Each pot has a buoy line to which a wooden spindle-shaped 
buoy is attached. The latter bears the owner's mark or stamp, and shows the position 
of the trap. The traps are baited with fish, such as herrings, sculpins, or flounders, 
and the lobster, when once induced to come inside the pot, seldom escapes, unless small 
enough to crawl between the slats. It has been estimated that half a million lobster 
traps have been in use in the Maritime Provinces during a single year. 

The old-fashioned hoop nets formerly in use consisted of a single iron ring or hoop 
to which a net with cord was attached. When baited they had to be closely watched 
and pulled up from time to time, in order to secure the lobster before he could get out 
of the net. 

The lobster fishery is conducted chiefly in the spring and summer months. The 
pots are tended from small boats, and the catch is kept in floating cars moored in 
some protected spot near the shore. Welled fishing smacks, or more rarely welled 
steamers, gather up the lobsters from the fishermen and cany them to the canneries 
and to the markets in the large distributing centers, such as Portland, Boston, and 
New York. Lobsters are shipped alive in barrels, with ice in summer, to many parts of 



THE AMERICAN LOBSTER. 11 

the country. The winter shipment is also very considerable. Large numbers are 
immediately boiled for home consumption, while many are kept, alive in floating cars 
at the market until required. The impounding of lobsters, or placing them in large 
inclosures of salt water, called pounds, where they can be kept during the winter, 
is now successfully practiced on a large scale. 

VII. 

We have witnessed in the lobster fishery for many years past the anomaly of a 
declining industry with a yearly increasing yield, but with the gradual diminution in 
the size of the lobsters caught and an undue increase in the number of traps and 
fishermen. "How much longer," writes the inspector of fisheries of New Brunswick, 
"an increased catch can be made out of a diminishing supply is a problem of some 
interest to those who have watched the rise, progress, and decay of this industry.'" ' 

In 1886 fully 90,000,000 lobsters were captured in Canada, 2 principally in Nova 
Scotia, New Brunswick, Prince Edward Island, and Quebec. Out of this vast number 
nearly 34,000,000 were taken in New Brunswick alone, and 22,000,000 in Prince 
Edward Island. These numbers are extraordinary, when we consider, as in the last 
instance, the small extent of the coast and the narrow limits of the fishing season. 

In regard to the catch of lobsters in New Brunswick for 188G, the inspector of 
fisheries says in his report 3 that the average size is diminishing, and "to fill a pound 
can now requires rather more than an average of six lobsters — about 2} ounces of 
meat per fish. The returns show 4,661,812 cans preserved, and 4,290 tons of fresh 
lobsters. In order to fill these cans, 28,000,000 lobsters were killed. If to these we 
add the number exported fresh, allowing li- pounds to each, which is a large average, 
the number killed during the season will be 33,720,000." 4 

In 1887 about 70,000,000 lobsters were taken in Canada, and in 1S92 upward of 
68,000,000 lobsters (estimated as above) were captured, valued at nearly $2,000,000. 5 

In 1884 the catch of lobsters in New Brunswick amounted to 5,662,072 cans and 
1,709 tons, valued at $900,580, the number of traps in use being 105,984. In 1892 the 
number of traps had increased to 172,022, an increase of over 60 per cent, while the 
product had decreased by nearly the same amount, being 3,204,320 cans and 1,132 
tons, valued at only $493,S04. 6 

The average annual yield of the Norwegian lobster fishery from 1879 to 1884 is 
estimated to have been 1,175,000 lobsters, valued at $107,468, the greater number 



1 W. H. Venning, inspector of fisheries of New Brunswick. (Annual Report of the Department of 
Fisheries, Dominion of Canada, 1886, p. 146.) 

-This estimate is based upon the official statistical return of the lobster fishery, allowing five 
lobsters to a pound can of meat, and a trifle over 2 pounds in weight to each lobster. The yield in 
1892 was 16,434,431 pounds in cans, and 8,662 tons of fresh lobsters, valued at $2,638,394. (Report on 
the Lobster Industry of Canada for 1892. Supplement to the Twenty-fifth Annual Report of the 
Department of Marine and Fisheries, No. 10<7, Ottawa, 1893.) 

■' Annual Report of the Department of Fisheries of the Dominion of Canada, 1886. 

* Ibid. 

6 It should be remembered that these estimates, large as they seem, are based upon statistics 
which are generally reliable, and probably fall far below the number of animals annually killed ; for 
they do not include the number of undersized lobsters illegally used for canning, nor those used 
as food by fishermen and their families. Then there is. besides, the vast number of lobsters which 
annually fall a prey to other enemies than man. 

,; Report, on the Lobster Industry of Canada, 1892. Supplement to the Twenty-fifth Annual 
Report of the Department of Marine and Fisheries, No. 1(W, Ottawa, 1893. 



12 



BULLETIN OF THE UNITED STATES FISH COMMISSION 



being shipped to England. 1 About 3,000,000 lobsters are said to be taken in the 
British Isles in a year, while the total number captured on the North Atlantic coast 
of America has undoubtedly in some years reached close to 100,000,000. 

The total quantity of lobsters taken in the United States in 1880 was 20,238,683 
pounds, valued at $488,432; of this quantity, 19,946,733 pounds, worth $477,484, were 
taken in the New England States, and 291,950 pounds, valued at $10,948, in the 
Middle Atlantic States. In 1887 the United States lobster catch was 28,882,180 
pounds, with a market value of $799,717, of which 28,627,600 pounds, worth $784,238, 
were caught in New England and 254,580 pounds, valued at $15,479, in the Middle 
Atlantic region. The output of the New England lobster fishery in 1889 was 
30,449,603 pounds, valued at $833,736; of this catch, 25,001,351 pounds, worth 
$574,165, were taken in Maine. 

The division of the United States Fish Commission concerned with statistics and 
methods of fisheries took a complete census of the lobster fishery of New York, New 
Jersey, and Delaware in 1892, 2 and in 1893 canvassed the lobster fishery of the New 
England States. Through the courtesy of Dr. H. M. Smith, the assistant in charge of 
the division, I am able to present in the following table the results of these inquiries. 

The total number of persons engaged in the lobster fishery of the United States 
in 1892 was 3,766; of these, 2,628 were in Maine and 616 in Massachusetts. The 
vessels employed in lobster fishing numbered 58, valued at nearly $75,000. The 
number of boats used was 3,976, having a value of $325,000. Over 200,000 traps, 
worth $221,000, were operated. The total investment in the fishery, including the 
value of live cars ($25,835), was $648,065, distributed among the different States as 
shown in the table. The quantity of lobsters taken and sold by United States 
fishermen in 1892 was 23,724,525 pounds, for which $1,062,392 was received. Of this 
output, 17,642,677 pounds, valued at $663,043. were caught in Maine and 3,182,270 
pounds, worth $205,638, in Massachusetts. 



Table showing the 


exteiil 


of the lobster fisher}! of the United States 


in 1892. 




1 

States. 


Number 
of fisher- 
men em- 


Vessels, boats, and traps used. 


Lobsters taken. 


Vessels. 


Boats. Traps or pots. 


ployed. 


No. 


Value. 


No. 


Value. No. 


Value. 


Pounds. 


Value. 


Maine 

New Hampshire 


2,628 

26 

616 


7 


$7, 050 


2.888 

29 

739 

86 

183 

34 

16 

1 


$242. 629 

594 

47, 162 

15, 320 

17, 585 

1,140 

1,062 

40 


153. 043 

1,393 

26, 192 

6,341 

10, 105 

2. 240 

678 

21 


$143. 709 

2,786 

38, 479 

10,090 

22, 178 

3,469 

1,099 

53 


17, 642, 677 

196,350 

3, 182, 270 

774, 100 

1, 614, 530 

165, 093 

143, 905 

5,600 


$663, 043 

11, 790 

205, 638 

53, 762 

101, 358 

15, 655 

10, 861 

285 


2 


1.710 
8,455 
46, 265 
9,880 
1,475 


Rhode Island 

Connecticut 


145 1 12 

258 34 

55 2 




36 
2 


1 




Total 






3,766 


58 


74, 835 


3,976 


325, 532 


200, 013 


221, 863 


23, 724, 525 


1, 062, 392 



Between 1887 and 1892 the decline in the lobster fishery of the United States was 
over 5,000,000 pounds, although the value of the catch was more than $260,000 greater 
in the latter year. When the yield and value of the fishery in the New England 
States in 1892 are compared with the results of the fishery in 1889, we find a falling 



1 Bulletin of the United States Fish Commission, vol. vi; also Report of the United States Fish 
Commissioner for 1889. 

- See a Statistical Eeport on the Fisheries of the Middle Atlantic States, by Hugh M. Smith, m. d., 
Bulletin of the United States Fish Commission for 1894, page 455. 



THE AMERICAN LOBSTER 13 

off of more than 7,000,000 pounds, or over 2;> per cent, but an increase in the market 
value of the output of over $200,000, or nearly 25 per cent. These figures illustrate 
very forcibly the decline which, unless speedily cheeked, threatens to destroy this 
valuable fishery. 

Five attempts to transport lobsters alive across the continent and plant them in 
the Pacific Ocean have been made by the United States Fish Commission (157), in 
1875-1889, and all but the first have proved successful. No evidence bas, however, 
yet appeared to show that the lobster has multiplied and thriven in its new environ- 
ment. More recently attempts have been made, with some degree of success, to ship 
lobsters across the Atlantic, and deliver them alive in the markets of London and 
Paris. 

England, France, and Germany are the principal markets for the export trade 
outside of the United States, but, like other preserved meats, the canned lobster is 
shipped to all parts of the world. 

VIII. 

Civilized man is sweeping off the face of the earth, one after auother some of its 
most interesting and valuable animals, by a lack of foresight and selfish zeal unworthy 
of the savage. If man had as ready access to the submarine fields as to the forests 
and plains, it is easy to imagine how mucb havoc he would spread. The ocean indeed 
seems to be as inexhaustible in its animal life as it is apparently limitless in extent 
and fathomless in depth, but we are apt to forget that marine animals may be as 
restricted in their distribution as terrestrial forms, and as nicely adjusted to their 
environment. Thus, as we shall see, the American lobster occupies only a narrow 
strip along a part of the North Atlantic coast, and while it is probably not possible 
to exterminate such an animal, it is possible to so reduce its numbers that its fishing 
becomes unprofitable, as has already been done in many places. 

The only ways open to secure an increase in the lobster are to protect the spawn- 
lobsters, or to protect the immature until they are able to reproduce, or to take the 
eggs from the lobsters themselves and hatch them artificially. The latter is the 
method which has been adopted and is now in use in the British Maritime Provinces, 
and less extensively in the United States. 

In an earlier paper, published in the United States Fish Commission Bulletin for 
1893 (pp. 75-86), I have discussed the question of the artificial propagation of the 
lobster, and have called attention to what seem to me the weakest points in the 
present method and what the most promising field for future experiments. 

Adelbert College, Cleveland, Ohio, 

June, 1895. 



Chapter I.— HABITS AND ENVIRONMENT. 

DISTRIBUTION OF THE LOBSTER. 

The American lobster inhabits the coastal waters of the Atlantic Ocean from 
Labrador to Delaware, and occurs in depths of from less tban 1 to more than 100 
fathoms. It is thus confined to a strip of the Atlantic Ocean about 1,300 miles long, 
and at some points (as on the coast of Maine, where there is an extensive fishery in the 
outward islands) from 30 to upward of 50 miles wide. Its geographical range covers 
about 20 degrees of north latitude, from the thirty-fifth to the fifty-second parallel; 
but owing to the extreme irregularity of the coast the actual area of distribution is 
much greater. At present the lobster is most abundant and attaius the largest size 
in the northern half of its range, that is upon the coasts of Maine and the British 
Maritime Provinces. 

The lobster was recorded from Labrador by Packard in 1863. ~" The rocky shores," 
he says, " exposed to surf from the gnlf, did not seem to harbor any animal life, but a 
narrow, interrupted belt of sand and mudflats in Salmon Bay" (near Caribou Island) 
supports a feeble assemblage of littoral forms {144). Under the rocks and seaweed the 
lobster was occasionally seen. At Henley Harbor, a little above the Straits of Belle 
Isle, it is mentioned as "rare." This seems to be the northern limit of the lobster. 
At Hopedale, 200 miles above this point, he showed a picture of the lobster to one of 
the native Eskimos, who signified that it was not found there {148). 

The lobster was common at Anticosti and Mingan islands {145), where collections 
were made by Veirill, Hyatt, and Shaler in 1861. Stearns {185), who asserts that 
"lobsters were found everywhere along the coast of Labrador," is doubtless in error. 
He probably had in mind the "Gulf coast," or "Inner Labrador," as the territory of 
the Province of Quebec which stretches southwesterly from the Straits of Belle Isle 
is often erroneously called. 

In speaking of the habits of lobsters in "Labrador," Stearns says: 

Very often the beach is covered with rocks, large and small, interspersed with holes and pits 
tilled with water at low tide. The seaweed grows over these places, thus affording capital hiding- 
places. One can often procure 100 lobsters in an afternoon from a strip of the beach hardly as many 
yards long. The small boys hunt them with long poles on the ends of which are tied large cod hooks. 
With these the boys reach in and feel about in the holes and under the rocks until they feel the shell 
of a lobster, when a smart or careful haul, as the ease may require, generally brings the animal out of 
its snug quarters. [These lobsters] are seldom very large, while the very young ones appear not to 
come inshore among the rocks to any great extent (185). 

Dr. W. Wakeham, to whose kindness I am indebted for much interesting infor- 
mation on the northerly range of the lobster, writes as follows: 

My own experience of the Labrador coast does not go beyond Chateau Bay at the northeastern 
entrance to the straits of Belle Isle. From this point west along the Labrador and north shore of 
Quebec, I have found the lobster everywhere fairly abundant up to Manicouagan in the river St. 
14 



THE AMERICAN LOBSTER. 15 

Lawrence. I have inquired of Gaspe" whalers who arc in the habif of going aa far as Cape Harrison, 
on the eoasl of Labrador, but they all toll me thai, they have never taken a lobster below St. Charles — 
thai is, a few miles north of Chateau Bay. West of Chateau Bay, as I have said, they are found all 
along the coast, bul not in paying quantities. Several attempts have been made to operate canneries on 
this coast, but they have one after another been abandoned. The lobsters seem to give out suddenly. 
The\ are all caught up when the traps are first set. Of course the water is too deep for any general 
fishery, and it is only in shoal bays and harbors that traps can be used. 

Iii reply to a letter of inquiry from Dr. Wakeharu, Mr. P. M. McKenzie, one of 
the chid' factors of the Hudson Bay Company, says that he lias been on the Labrador 
coast and entrance of Hudson Straits tor fourteen years, and has "never seen a 
lobster or heard of any being caught between Grady Harbor (longitude W. 50° 25', 
latitude 53° 46') and Cape Chudleigh." He says farther, that he does not think they 
occur between Grady Harbor and the straits of Belle Isle, but "all along the Gulf 
from Seven Islands to St. Augustine there are a great many at certain points." 

Mr. W. H. Whitely, overseer of .fisheries at the straits, writes to the same effect: 

Lobsters are not found below [i. e., east of] the narrows of the straits of Belle Isle [the lowest 
point, a place called Brodore Bay]. Some are found on the southern or Newfoundland side of the 
straits. They are uot plenty at any place within 100 miles west of the north side of the straits of 
Belle Isle, but a few are found in places sheltered from rough water and drifting ice. I have never 
heard of any lobsters being seen at any point on the Labrador east of the straits. 

From the character and abundance of this testimony we may safely conclude that 
the lobster is not found on the coast of Labrador very far beyond the straits of Belle 
Isle, or not many miles north of Henley Harbor (about 52° north latitude). From the 
straits northward the temperature is said to fall rapidly, owing to the arctic current 
which flows south, and the presence of ice, which is carried along with it close to the 
land. We should not, therefore, expect to meet with the lobster, except as a very rare 
straggler, north of the straits. 

It is interesting to find, on the other hand, that Fabricius (63) iucludes the lobster 
( Cancer gammarus L.) in his Fauna Grumlandica. He is particular to state, however, 
that he does so upon the authority of others, as he had never seen the lobster in 
Greenland himself. He says that the lobster is found under the name of Pekkuk in 
the Greenlandish dictionary. He had heard the natives distinguish the smaller 
Squillas by the name of Pekkungoit, from a much larger form (Cancris), called Pek- 
kuit or Pekkurksoit, and very similar to the "Gammari." This name may have been 
derived from the Esquimaux of the southern Labrador coast or from Iceland, where, 
according to Molar's "Islandske Naturhistorie," the European lobster "has been found 
by Dr. Poulsen in Grondevig, but it does not extend to Greenlaud or Spitsbergen" (20). 

De Kay, writing in 1844, remarks that while the lobster was taken in compara- 
tively small quantities on the New Jersey coast, "two years after building the break- 
water in Delaware Bay, lobsters made their appearance there in great quantities." 
He also says that in about the year 1814 General Pinckney "caused a car full of 
lobsters to be emptied into the harbor of Charleston, South Carolina. A few of their 
survivors, or their descendants, were captured about ten years since, but, as I am 
informed, they were the last." (51, p. 25.) 

The stonework of Delaware" Breakwater, says Bathbun (155), may be considered 
the southern bouiuhiry of the lobster, although he has recorded several instances of 
its occurrence south of this point. Thus it has been said that lobsters have been seen 
along the beach in the surf near Indian Biver Inlet, Delaware. Two or three have 



16 BULLETIN OF THE UNITED STATES PISH COMMISSION. 

been recorded at Johnstown, in the northeastern corner of Virginia, "and in October 
1884, the United States Fish Commission steamer Albatross obtained a single specimen 
of good size off Cape Hatteras, North Carolina, from a depth of about 30 fathoms, by 
means of the beam trawl" (155). Coues (49) also records the capture of a single lobster 
at Beaufort, North Carolina, in the summer of 1870. 

Dr. Wakeham writes that lobsters are abundant around the island of Anticosti 
and that a large number of canneries have been in operation on this island for some 
years. He says that lobsters are more abundant on the southern side of the island, 
and concludes that this is "due to the fact that the water deepens gradually on the 
southern side, while on the north side of the island you go abruptly into deep water. 
The lobsters taken at Anticosti and on the north shore of the Gulf are of large size. 
This may be explained by the fact that they have not been overfished to the same 
extent there as elsewhere. At any rate we do not find any small lobsters in the traps. 
The largest lobster that I have seen taken on the north shore weighed 18 pounds." 

Sai'S (176) considers it remarkable that lobsters on the southern coast of Norway 
never become as large as those farther north. It seems to me that the explanation of 
this fact is simple, and applies to both European and American species. The northern 
parts of the range of the lobster have been the last to be fished, and consequently the 
average size is greater than in the south, where the fishery began. 

The bathymetrical range varies with the season and is influenced largely by the 
temperature of the water. It may be also governed in some measure by the abun- 
dance of food and by the reproductive and molting periods. 

Lobsters are occasionally seen close to the shore in very shallow water and they 
are sometimes even stranded on the beach. This was the case with the large lobster, 
weighing upward of 20 pounds, the mutilated shell of which is now preserved in 
the land office of Boothbay Harbor Village, Maine (see p. 114). This great lobster 
was discovered on the beach of Boothbay Harbor, at low tide, about twenty-five years 
ago. 

Professor Verrill related to me his experience with a large lobster at Grand 
Manan, Maine, in 1859. This lobster, which he thinks must have weighed at least 
20 pounds, had established himself so securely under the projecting side of a large 
bowlder that it was not an easy matter to dislodge him, even at low tide ; but with the 
aid of a boat-hook this giant was at last drawn out and captured. When it was finally 
taken to the settlement it attracted very little interest, the fishermen saying that it 
was worth only a penny, 2 cents being then the regular price of lobsters, whether of 
5 or 20 pounds weight. In those days lobsters were never weighed and sold by the 
pound. 

Lobsters, on the other hand, stray out to great distances from the shore, and have 
been recorded on the fishing-banks of Nova Scotia "from the fishing-banks and ledges 
of the Gulf of Maine, such as Jeffrey's Ledge and Cashe's Ledge, and from the more 
southern offshore banks. They have also been taken from the stomachs of cod caught 
on George's Banks." (Bathbun, 155, p. 787.) 

Lobsters are also sometimes driven by severe storms on the beach, where they 
perish in great numbers. In March, 1888, thousands of lobsters were washed ashore 
on the south side of Marthas Vineyard during a south and southwest gale. 



THE AMERICAN LOBSTER. 17 



CHARACTER OF THE ENVIRONMENT. 

Where there is great diversity of natural conditions throughout the geograph- 
ical range of an animal we may expect to find its habits varying in a proportionate 

degree. From Labrador to Maine the Atlantic coast is rocky, and often precipitous, 
with deep bays and harbors, and with Large islands, some like Grand Mauan pre- 
senting sheer perpendicular walls to the sea. The coast of Maine, in its middle and 
eastern sections, is essentially bold and rocky, and diversified to an extraordinary 
degree by channels cut by large fresh water rivers, by long deep inlets, studded with 
islands large and small, by bold rocky promontories, and by groups of larger islands 
farther from shore, such as the Viual Haven or Fox islands. These are masses of gray 
granite, scarred and cut up by glacial forces into an archipelago of smaller islands, 
abounding in long granite basins and inlets, into which pure sea water is driven 
with every tide. Thus are formed the most admirable breeding-grounds for the 
lobster, for fish, and other marine animals. In the region of Cape Cod we meet with 
extensive shoals, which resemble on a smaller scale those of North Carolina. The 
northern part of the Massachusetts coast is rocky, while the southern section is 
greatly diversified, abounding in submerged ledges, sandy and weedy bottom, and a 
great variety of bays and channels in the vicinity of the Elizabeth Islands, where 
lobsters used to abound until their numbers were depleted by overfishing. 

Under the variety of conditions which I have hinted at, we should not only expect 
to find lobsters larger and more abundant in some localities than elsewhere, a condition 
greatly influenced by the number and persistence of fishermen, but also to meet with 
variations in the time of laying and hatching of the eggs, in the season of molting, in 
the time when the semiannual movements are undertaken, in color, and in a variety 
of other details. 

The habits of the lobster as affected by the changes of season and other causes 
in the various stages of its life will be described, as we have been able to interpret 
them, in different parts of this work. Certain habits, however, are often so closely 
interrelated that the mere mention of one requires a consideration of others also. 

INTELLIGENCE OF THE LOBSTER. 

Since the lobster belongs to a less specialized class than the crab, it is not surprising 
to find that its intelligence is of a lower order. Sluggish as it often appears when out 
of water and partially exhausted, it is quite a different animal when free to move at 
will in its natural environment on the sea bottom. It is very cautious and cunning, 
capturing its prey by stealth, and with weapons which it knows how to conceal. 
Lying hidden in a bunch of seaweed, in a crevice among the rocks or in its burrow in 
the mud, it waits until its victim is within reach of its claws, before striking the fatal 
blow. The senses of sight and hearing are probably far from acute, but it possesses 
a keen sense of touch, and of smell, and probably also a sense of taste. We have, 
moreover, seeu that it is quite sensitive to changes in temperature. 

All animals which play the part of scavengers have strong powers of scent, and 
the lobster is no exception to the rule. This is illustrated by the way in which it can 
be enticed into the traps. Thus it is asserted that where traps are set on a trawl 
placed across the tide, the catch is greater than when the trawl is set in the direction 

F. C. B. 1895—2 



18 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

of the current, since in the former case the scent, or tine particles coming from the 
bait, is more widely diffused. Lobsters are sometimes wary and shy of entering 
the trap, and have been seen to crawl about it several times and examine it cautiously 
on all sides before, too weak or too hungry to resist temptation, they finally enter. 
When the pots are hauled, lobsters sometimes escape by darting backward through the 
narrow opening of one of the funnels, but this seldom happens and may be set down 
to accident. 

Many facts will be given in the course of this work which illustrate either directly 
or indirectly the intelligence of the lobster. 1 will add here only the following account 
of a lobster which was kept at the Iiothsay aquarium, in England (Nature, xv, p. 415, 
March 8, 1877). A flounder was unintentionally left in one of the aquaria, in which 
three lobsters were placed. The largest lobster immediately appropriated the fish, 
Avhich was then dead, and buried it beneath a heap of shingle, on which he mounted 
guard. Five times within two hours was the fish unearthed, and as often did the 
lobster shovel the gravel over it with his huge claws, each time ascending the pile 
and turning his bold, defensive front to his companions. 

THE LOBSTER'S POWERS OF MOVEMENT. 

The adult lobster lives and feeds exclusively upon the sea bottom, which it never 
leaves of its own accord in any considerable degree. In traveling over the bottom 
in search of its prey, the lobster walks nimbly upon the tips of its slender legs. The 
large claws are extended forward in Jront of the head, a position which offers the least 
resistance to the water, while the two hinder pairs of walking legs, which end in hard 
spur-like joints, serve as picks to steady the movements of the animal.. In thus going 
about it has the constant aid of the delicate swimmerets, attached vertically to the 
under surface of the "tail," each of which consists of a short stalk and two very 
flexible blades. By the movements of the swimmerets the lobster is impelled slowly 
forward without the aid of the walking legs. The branches of the swimming feet are 
garnished with long, chitinous setai or hairs, to which, as is well known, the eggs in 
the female are attached. Thus these appendages are not only natatory, but play an 
important part in reproduction, and by their almost incessant beating movements 
serve to keep the developing eggs well aerated and clean. 

When taken out of the water the lobster can only crawl, in its vain attempts to 
walk, owing to the heavy weight of the body and claws, which the slender walking 
legs are now unable to sustain. If turned over on its back the animal is usually able 
to right itself when out of the water, but not without great effort. If placed near 
the salt water and left to its own devices, it will almost immediately strike out by the 
nearest path for the sea with as keen a sense of direction as the sea turtle will show 
when upon land. Its power of crawling on land is, however, limited to short distances, 
and the lobster never forsakes the salt water of its own accord and, as has been said, 
never willingly leaves the sea bottom. 

In exploring its feeding-grounds, where an enemy is likely to be encountered, the 
legs which carry the long claws are extended forward in front of the head, or carried 
somewhat obliquely, their tips resting on the bottom, and the long sensitive "feelers" 
are waved constantly back and forth to give warning of any foe or other objects which 
the eye may fail to detect. These are exclusively organs of touch. If the anticipated 



THE AMERICAN LOBSTER 19 

enemy makes his appearance or ii' the animal is surprised, as wbeu it is suddenly 
touched with the blade of an oar or cornered, it will immediately strike an altitude 
of defense. It now raises itself on the tins of its walking legs, and lifts its powerful 
claws over the head after the manner of a. boxer, and strikes with one of its claws at 
the offending object, trying' to crush it or tear it in pieces. [ have several times pulled 
lobsters partially or completely out of their burrows with an oar. You have only to 
thrust the oar-blade into their holes, when, if a lobster is present, it will immediately 
seize it with a firm grip; but it often shows its intelligence by relaxing its hold before 
becoming completely exposed. By far the most powerful organ of locomotion in the 
lobster is its "tail." By the flexion of this, aided by the extended tail-fan, the animal 
is able to shoot backward through the water with astonishing rapidity, sometimes 
going, according to one observer, 25 feet in less than a second. If tossed into the water 
back or head first, the animal, unless exhausted, immediately rights itself and, with 
one or two vigorous flexions of the tail, shoots off obliquely toward the bottom, as if 
sliding down an inclined plane. 

The lobster, though less active and keen-witted than the higher crabs, can not be 
regarded as a sluggish animal in any sense. In the water its movements are graceful ; 
it is wary, resourceful, pugnacious, capable of defending itself against enemies which 
are often larger than itself, and, if the occasion requires it, of running about with the 
greatest agility and speed. 

On calm evenings in summer at about sundown I have seen lobsters very close to 
shore lying on little patches of sand, surroundtd by eelgrass, probably waiting their 
opportunity to seize a passing fish or crab. If approached in a boat on such an occa- 
sion, they soon become aware of your presence and put themselves in an attitude 
of defense, but press them too close, or attempt to piu them down with an oar, they 
immediately dart backward into deeper water among the seaweed. If still pursued, 
the lobster rises and flies in another direction, thus zigzagging its way over the bottom 
until it finds safety in some denser tangle or rocky crevice. 

Of the English lobster, Travis remarks: 

In the water they can rim nimbly upon their legs or small claws ami, if alarmed, can siting tail 
forward to a surprising distance as swift as a bird can fly. The fishermen see them pass about 30 feet, 
and by the swiftness of their motion suppose that they go much farther. Atheneeus remarks this 
circumstance, and says that incurvated lobsters will spring with the activity of dolphins. When 
frightened they will spring from a considerable distance to their bole in the rock, and, what is not less 
surprising thau true, will throw themselves into their bole in that manner, through an entrance barely 
sufficieut for their bodies to pass; as is frequently seen by the people who eudeavor to take them at 
Filey-bridge (191). 

When a lobster is surprised it seems to disappear with a single leap or bound as a 
locust or grasshopper might do. This habit, added to their appearance, explains why 
lobsters were called by Pliny and the ancient writers locustce, or "locusts of the sea." 
The lobster, however, never rises more than a few inches or at most a few feet above 
the bottom, and it is evident that swimming at the surface would be impossible on 
account of the great weight of the body. The "traveling lobsters," or fterd-hummer, 
which jSTorwegian fishermen, as Sars tells us {176), have described as swimming at 
the surface of the ocean in large schools, often many miles from the coast, were, 
without donbt, some large species of surface-feeding shrimp. 

Lobsters kept in an aquarium often thrive well, and will live for a long period if 
they are properly cared for. In the hatchery of the United States Fish Commission 



20 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

at Woods Hole, Massachusetts, sea water is kept running through the tanks, in the 
larger of which we have kept lobsters and watched their habits for several months at 
a time. If the tank is provided with a pile of stones the lobster very soon investigates 
this with care, seeking out the most attractive holes. If several individuals are 
placed in the same aquarium, each will select its own hole or corner over which it 
establishes a sort of proprietary right. In these they lie during the greater part of 
the day with their antenna? and a part of the body and large claws projecting, ready 
when a good chance offers to strike at a fish, or if an enemy should approach, to retire 
at a safer distance into their retreats. If the occupants of the same aquarium are of 
about equal size, and if they show no weakness, they usually live in peace; but if one 
has been disabled in any way, as by the loss of a claw, he is attacked by the strong 
and forthwith destroyed. 

As the lobster lies in its corner of the aquarium — always with its tail folded, if a 
female "in berry" — it slowly sweeps the water with its long, sensitive antennae, which 
it now holds erect, now lowers until they lie horizontal and extend almost directly in 
front of the body. The smaller pair of antennas are elevated, while the larger outer 
branch of each is constantly beating with a slight up-and-down movement ; this branch 
supports the delicate filaments which have been regarded as the terminal organs of the 
sense of smell. If one watches this lobster he may see it deliberately lower the branches 
of the first pair of antennas and clean them by drawing them through the bunches of 
stiff bristles of the third pair of maxillipeds, the large prominent appendages which 
project forward at the sides of the mouth immediately in front of the chelipeds. The 
large claws are held in readiness for use, their tips resting close together on the bottom 
and their opposite ends raised obliquely upward. 

PERIODICAL MIGRATIONS AND THEIR RELATION TO CHANGES IN THE 

ENVIRONMENT. 

The adult lobster never moves up and down the coast like the migratory fishes, 
but is of a far more sedentary disposition. In the spring months of April and May, 
however, large numbers appear to move from deeper water toward the shore. In the 
fall they retire to deeper water again. 

The movements of such anadromous fish as the mackerel and the menhaden are 
influenced by the spawning period, by the temperature conditions, and by the abun- 
dance of food. The mackerel is said to thrive in a water-temperature as low as 
40° F. or even less. The same causes, of which the influence of temperature may 
sometimes be the most potent, probably determine the migration of both fish and 
crustacean. 

When the question of food is paramount, the lobster will remain in considerable 
numbers in the relatively shallow water of harbors, but only on a rocky bottom, where 
food is most abundant. The extent of the migration is also naturally influenced by 
the depth of the water and the general character ot the bottom, being more extended 
on a gradually sloping bottom where deep water is less readily accessible. The exact 
period at which the semiannual migrations of the lobster occur varies at different points 
on the coast and also at the same point for different seasons. 

In the vicinity of Rockland, Maine, and to the eastward as far as Eastport, the 
summer fishery begins in the latter part of May and lasts until the first of November, 



THE AMERICAN LOfeSTEE. 2l 

During tins time, lobsters are caught in from 3 to 10 fathoms of water. For the rest 
of the year the winter fishing is conducted in 35 to 40 fathoms. In general, the spring 
migration along tin* entire coast of Maine and in the Maritime Provinces is accom- 
plished in April and May, and the fall movement into deeper water in October and 
November. 

When the spring is late and the water cold, the lobster keeps away from the shore. 
Thus tli e spring of 1884 was a month later than usual in Prince Edward Island, says 
the inspector of fisheries in his annual report (56'), " and the ice hung long about the 
coast." The first lobster was caught on the 3d of June. " The hands about the 
factories had been idle for fully four weeks, but the first batch or run of lobsters came 
in quite as fast as they could be utilized. 1 have noticed this to have been the case in 
previous years, as if when ice remained long the lobster congregated in large bodies 
on the outer edge of the frozen belt ready to run for the shore as soon as it was clear 
and the temperature suited. Subsequently the batches fell off to a little less than the 
average." Ice is said to remain so long on this coast that few lobster fishermen begin 
work until the first or second week in May. In 1892 the ice left early, and some lobsters 
were landed on the north side of the island the 29th of April. Packing was begun 
as early as the 10th of May. (Fishery Statements, 1891, p. 97.) 

At Cape Breton, in late seasons, very little lobster fishing is done before the 1st 
of June, or even later. Lobsters probably do not, as a rule, move in schools, but 
approach and leave the shores gradually with the change of temperature, yet a sudden 
cold snap seems to cause them to disappear promptly from any locality. It is probable 
that their disappearance under such circumstances may be explained by their burrow- 
ing in the mud. (See pp. 20 and 29.) Mr. M. B. Spinney, of Cliffstone, Maine, informed 
me that in May or June in 1869, at Prince Edward Island, while sailing in a small boat 
from Georgetown into Grand River, lobsters were seen for the distance of several 
miles crawling over the bottom in very large numbers and often very close together, 
the water being 10 or 12 feet deep. 

Mr. Adolph Nielsen writes, in reply to certain questions, that as the coast of 
Newfoundland is affected by the polar current, a spurt of northeast and easterly 
winds often brings down the temperature of the water, and this causes the lobsters to 
move off into deeper water or bury themselves in the sand or mud in the midst of 
the season. At such times the fishermen can not take them in their traps. 

The sudden appearance of lobsters in the spring in relatively shallow water lends 
color to the supposition that they sometimes move in large numbers together. Thus, 
Mr. A. C. Smith says that in 1884 the proprietor of a lobster factory in New Brunswick 
"set his traps on the 20th of April, keepiug them baited, but caught nothing till the 
night of the 5th of May, when the lobsters suddenly ' struck in ' as plentiful as at any 
time of the season." 

It is certain that lobsters do not indulge in any considerable northward or south- 
ward migrations. This is proved, as Rathbun has pointed out (158), by the depletion 
of the lobster fishery at certain points on the coast, as at Provincetown, Cape Cod, 
Massachusetts. He states that the fishery was begun here in 1800, and that between 
1845 and 1850 New York City received nearly its entire supply of these crustaceans 
from the Provincetown region. A marked decrease in their abundance was noticed 
in 1865, and this was followed by a gradual annual diminution, until in 18S0 there were 
but eight men eugaged in the business. If there were any considerable coastwise 



22 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

migration, it is evident that regions once depleted would in time be restored naturally 
by accessions from neighboring sections. This does not appear to be the case, and 
we may look upon each geographical region on the coast as inhabited by a distinct 
school of lobsters, which hold their ground fairly constantly, so that if their numbers 
are depleted by overfishing they would under natural conditions be stocked but 
slowly. If this argument is sound, and it certainly looks as if the Cape Cod region 
were a case in point, it must follow that the young are not widely distributed, but 1 
can hardly accept this as probable. It would seem as if the young, which, to be sure, 
have little powers of locomotion, would always tend to find an extra local distribution 
by tides, winds, and currents. Furthermore, if this were the case, it would follow that 
restocking under natural conditions is a slow process at best. Writing iu December, 
1885, Rathbun says (158): 

The Cape Cod lobster fishery has been at a low standing for many years and, although but few men 
have engaged in the fishery of that region for a long time, there are, as yet, no signs of improvement. 

That lobsters move up and down the coast to some extent is inevitable, although 
such a migratiou may be regarded as accidental rather than deliberate or instinctive. 
They may also return suddenly, as some believe, to places where they have not been 
seen for years. Thus a correspondent wrote to the United States Fish Commission 
from South Amboy, New Jersey, February 15, 1880, that lobsters had made an appear- 
ance there after an absence of about twelve years. "I discovered them late in October, 
and captured a hundred before the cold weather set in, after which I could not catch 
any." (Bull. IT. S. F. C, vol. VI, p. 407.) Statements of this kind must, however, be 
received with much caution, since what appears to be a sudden arrival may be due 
to desultory observations. 

The subject of the schooling of lobsters is one about which it is very difficult to 
get accurate information, and we need to use much caution in drawing conclusions 
from too slender data. The only region which I have been able to study for a number 
of consecutive seasons is that about Woods Hole, Massachusetts, including Marthas 
Vineyard, No Man's Land, and the Elizabeth Islands, and I will give in some detail 
the observations which I have been able to make in this limited area, believing that 
they will shed some light upon this interesting and perplexing question. 

The fishermen of a part of this region set their traps from the last of April to the 
middle or last of June on rocky bottom in the vicinity of Gay Head and No Man's 
Land, while from the middle or last of June until September they generally fish upon 
the sandy bottom of the Sound in much shallower water. A few lobstermen fish 
during September upon the rocks. They distinguish "rock lobsters" from what they 
call "school lobsters." The latter are also called "sand" or "June lobsters," and are 
considered more migratory than the "rock lobsters" or "ground-holders." "School 
lobsters" are most abundant in summer from the middle of June to the middle or last 
of July on a sandy bottom in Vineyard Sound in 5 to 10 fathoms of water. 

On June 28, 1890, 1 found the fishermen at Menemsha 1 setting their traps both off 
Gay Head on a rock bottom and on the sandy bottom of the Sound. The difference 

'Menemsha is a small fishing settlement iu the town of Chilmark, Marthas Vinevard, about 2 
miles due east from Gay Head, on Vineyard Sound. Gay Head, the remarkable promontory forming 
the western extremity of Marthas Vineyard, is 14 miles southwest of Woods Hole Harbor aud 6 miles 
north of No Man's Land. 



THK AMERICAN LOBSTER. 



23 



in the lobsters caught at the same time under these conditions was sufficiently marked 
to attract attention. The lobsters captured on the rocks had hard shells and frequently 
bore old eggs, while those taken in the Sound had in no single instance, up to this 
time during the season, borne external eggs, either old or new, and a large number 
of them had soft shells. These are often called "paper shells," or "buckle shells," 
the shell being relatively soft, so that it is easily compressible with the thumb and 
linger, and the colors are very bright, showing that they have molted within four or 
five weeks. Special care was taken to save all egg lobsters caught, since the United 
States Fish Commission purchased them for use in its hatchery. These "buckle shells" 
or "school lobsters" were said to appear rather suddenly about the middle of dune or 
first of July, and to retreat into deeper water during the first half of September. 

On the 9th of July I again visited Menemsha, and found that since the first of 
the month only six lobsters with old eggs had been obtained. These were caught in 
the Sound, where the majority of all lobsters now taken had soft shells. Ou the 16th 
and 28th of July, when I made further visits to the locality, the fishery was conducted 
almost wholly in the Sound. At the later period the fishermen had begun to shift 
their traps to slightly deeper water, following up the lobsters in their retreat from the 
shore. On the 1 1th of August they were fishing both in Vineyard Sound and off Gay 
Head in 8 to 15 fathoms. A large proportion of these lobsters taken in the Sound had 
soft shells, but au examination of the ovaries of the soft-shell females proved beyond 
a doubt that they had hatched their old eggs and molted during the present season. 

Some very interesting facts have been brought out by the record of the fishery at 
No Man's Land during the months of May and June, 1894. Mr. Vinal Edwards found 
that egg-lobsters of large size could be taken there in abundance, and accordingly 
the Fish Commission drew the supply of eggs for its hatchery from that place. Mr. 
Edwards carefully recorded the catches of the smackmen, examining nearly every 
lobster himself. The result is given in table 1. The traps were set on ledges of rock, 
15 miles from land, in about 15 fathoms of water. Besides the extraordinary dispro- 
portion of the sexes — only 6.4 per cent of males being obtained out of a total of 1,318 
lobsters captured in May — we notice the equally remarkable and probably correlated 
fact that 63.7 per cent of the total number are females with eggs soon to be hatched. 



Table 1. — Becord of lobsters caught off Xo Man's Land in Mai/, 1894. 



Total catch 


1,318 


Per cent of females with eggs 


63.7 


Females with eggs 


840 


Per cent of females without eggs 


29.8 


Females without eggs 


394 


Per cint of males 


.... 6.4 


Males 


84 


Per cent of females 


93.5 



Another striking fact which the fishermen noticed was the persistence with which 
the lobsters at this time of the year clung to the rocky areas. When set ou a rock 
bottom the traps were certain to catch lobsters in abundance, but when sunk upon a 
saudy or muddy bottom, though but a few feet away, not a lobster was trapped. In 
fishing on trawls, where a long line of traps was put out, it sometimes happened that 
some of these would strike a sand bottom, often not more than a narrow streak or bar, 
but they were always found empty. Mr. Edwards systematically fished for lobsters 
in Woods Hole Harbor from December, 1893, to the June following. lie found them 



24 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

in the winter months abundant on the rocks, but when the traps were placed on the 
mud not a lobster was taken. 1 

The disproportion of the sexes noticed at No Man's Land is due, I believe, to the 
fact that the females find it more advantageous to remain on a rocky bottom wbile 
they are encumbered with their old eggs. As soon as these hatch, the female lobsters 
press on in large numbers toward the shore, coming up into the sounds and bays and 
on to sandy bottoms during the summer. The lobster can probably protect herself and 
eggs better while on the rocks, but almost immediately after the hatching of the eggs 
the molt occurs, for some time after which the female is helpless. Now the molting 
lobster seems to prefer the sandy bottom while in this critical state, probably 
because it can shield itself better from its enemies. On the sand the molting lob- 
ster may hide in tangles of seaweed, or scratch a hole and partially bury itself, as it 
often does, and remain tolerably secure, but let the soft lobster try to conceal itself 
among the rocks, and what is the result? There are hosts of bottom-feeding fish which 
haunt the rock-piles, none of which are probably more troublesome than the cunner, 
which can go almost anywhere, and would soon surround the soft lobster in its retreat 
and nibble at its legs, or snip off its eyes, which means death. The dinners, eels, and 
other fish may attempt to pick off the eggs, but these are on the under side of the body 
and except in extraordinary cases, where the ova are excessively numerous, the lobster 
can fold them between the segments of its tail and thus rest tolerably secure (seep. 
31). This theory is supported by the fact that the " school lobsters" caught on the 
sand bottom of Vineyard Sound rarely have old eggs and very commonly possess 
soft shells. Eocky bottoms furnish food in greater abundance, at certain seasons, 
which explains their preference for these areas in winter. Where on the other hand, 
as in the region about Provincetown, Cape Cod, the bottom is uniformly sandy, the 
lobster has little or no choice of environment. 

To sum up the preceding observations, what seems to take place at the western 
end of Vineyard Sound during the season of migration is as follows: The general 
movement of lobsters toward the shore is here modified by the fact that lobsters with 
old eggs find it advantageous to remain on the rocky ledges until the young are 
hatched, while the males press on in their inward movement. After the hatching 
period the females make their appearance in large numbers in the Sound toward the last 
of June or first of July, and form a large part of what fishermen call " school lobsters" 
or "buckle shells." Their appearance is probably not as sudden as it often seems. 
Fishermen, as a rule, work only one set of traps, putting them down now here, now 
there. In order to follow the movements of these animals systematically, it would be 
necessary to set traps simultaneously in different places and on different bottoms, and 
to keep them there for a considerable time. 

Some females with old eggs come into the Sound before the young are hatched, but 
the majority do not. It must be borne in mind also that many lobsters remain in the 
Sound and harbors the year round, and that these observations refer only to the move- 
ments of the larger number. Toward the latter part of August the pendulum begins 

'Speaking of the lobsters captured iu February, Mr. Edwards says: "The lobsters taken this 
month have been caught on rocky bottom in five lobster pots. I have sot five others in deep water on 
sandy bottom, and also on the mud, but find none. I have tried in shoal water in eelgrass, but there 
are none there. I also tried for them iu the middle of Vineyard Sound and in Buzzards Bay, but 
found none.'' 



THK AMKIMCAN LOBSTEK. 



25 



to s\vin»- the other way, and the Lobsters move into deeper water or to a rocky 
bottom. This outbound movement is continued during the months of September and 
October, but, as already pointed out, it is by no means general and is probably more 
pronounced in cold than in mild .seasons. 

Tablk 2. — Showing the monthly mean temperature of tin- ocvun at ll'oixls Hole, Massachusetts. 

\ i Computed from daily observations of tomporatnro of bottom, I a ken at liigli water, I 
I al United Stairs Fisli Commission Station, by Vina) N. Edwards. 5 



Time. 



January 

February 

March 

April 

May 

June 

July 

August 

September 

October 

November 

December 

learly mean 



1889. 


1890. 


1891. 


1S92. 


1893. 
°F. 


Means 
1889 93. 


'/■'. 


°F. 


F. 


F. 


°F. 


30. n 


38. S 


3::. o 


36.8 


29.5 


35.0 


32. 1 


39.!) 


34. 7 


31.2 


29. 7 


33. 5 


35.0 


3(1. 


35. 3 


33. 2 


32.5 


34. 


42.7 


43.2 


14.3 


42.0 


40.0 


42. 5 


55. G 


53.2 


52. 1 


51.0 


51.2 


52.7 


<;:s. 3 


02.0 


01.1 


62.1 


61.2 


62. 1 


68.7 


09.3 


04.8 


08.0 


69.5 


08.1 


70.0 


71.1 


711.9 


73.3 


70.9 


71.4 


07.1 


08. 5 


01. 1 


00.9 


07. 5 


00.6 


55. :i 


59.0 


59.0 


58.0 


60.5 


58. 


40.9 


48.0 


47. 4 


48.3 


52.4 


49.2 


43.0 


30.7 


43.5 


37.2 


40.9 


40.2 


51.7 


52. 2 


50.0 


50.8 


50.5 






The mean temperature of the water at Woods Hole, Massachusetts, was 52.08° F. 
for May, from 1889 to 1S93 (v. table 2), the extremes of monthly averages varying from 
51° in May, 1892, to 55.0° in May, 1889, and the range was similar for the latter part of 
October during the same period. The greatest heat is reached in August (70.0°, 18S9, 
to 73.3°, 1892), while the temperature of the water in September is but little lower 
than that of July. In the latter part of October the water becomes cooled to 
about the same degree it had reached during the latter half of May. We may 
therefore conclude that the optimum temperature for the lobster lies between 50° and 
00° F. When the temperature of the sea water marks 50° to 55° in spring large 
numbers of these animals have already begun to creep nearer the shores into 
shallower and warmer places, and again in the fall, when the temperature has fallen 
to this point, many have already been impelled to recede to greater depths. Many 
lobsters, however, remain in the relatively shallow water of harbors all winter, a fact 
which has already been emphasized; so it is certain that temperature is not the only 
influence at work in directing these semiannual movements. The question of food 
may be of equal or even greater importance. 

The winter catch of lobsters in relatively shallow water is often considerable. 
Thus, on December 13, 1888, Mr. Edwards set two lobster pots ' in the harbor of Woods 
Hole, in about 25 feet of water, and hauled them fifteen times during the month, 
taking an average of 15 lobsters to a haul, or 223 in all. In December, 1S8!>. 54 
lobsters were taken in a fyke net at the head of the harbor, 36 were captured in 
January, while none were caught in February. 

In December, 1893, Mr. Edwards began to collect more systematically facts relat- 
ing to the winter habits of the lobster, the results of which are discussed in another 
place (see pp. 30, 31, 44, 45, 79, 80). Five traps were set in the harbor of Woods Dole 
in 25 to 29 feet of water on rocky bottom (it being impossible to get any lobsters on the 
mud); 221 were taken in December, 501 in January, 240 in February, and 34S in 



In these and all other traps used, the space between tho laths varied from 1 to 1, inches. 



26 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

March. Only 6.1 per cent of the total catch were egg lobsters, and while this number 
would have been increased if the traps had been scattered instead of kept in definite 
spots, it would contrast markedly with the results at No Man's Land, where more than 
half of the total catch were lobsters with external eggs (table 1). 

In severe winters lobsters are driven into deeper water or forced to protect them- 
selves by burrowing in the mud. The effect of sudden or extreme cold upon these 
animals may be witnessed in lobster pounds, where they are kept iu large numbers 
to supply the winter market. On the Vinal Haven Islands, near Rockland, Maine, 
there is a large pound belonging to Messrs. Johnson and Young, of Boston, of 12 to 
15 acres in area. It is said to have an average depth of 18 feet at low water. In 
January, 1S93, during a cold snap, ice was formed over this pool to the thickness of 31 
inches. At this time many of the lobsters died. All the pollock also, which had been 
placed in the pond, were killed, some of them being 2 J feet long, and large numbers 
of hake at the same time succumbed. 1 

Lieut. W. M. Wood (207), while transporting live lobsters from New York City to 
Chesapeake Bay, tried some experiments upon the effect of reducing the temperature 
of the water. Lobsters placed in water at the freezing-point were just alive after 
one hour's immersion. He was of the opinion that lobsters could be kept alive for a 
number of days in a cold chest, with a temperature of from 40° to 50° F. The practice 
of transporting lobsters by the aid of ice is now generally adopted. 

The annual range of temperature throughout the stretch of coast inhabited by 
the lobster is less than might be supposed. The temperature of the surface water of 
Winter Quarter Shoal, Virginia, ranges from 35° to 76° F.; at Five Fathom Bank, 
New Jersey, the range is 37° to 76°. Delaware Breakwater, which is practically the 
southern limit of the lobster, is situated between the light-ships anchored upon these 
two shoals. At Sandy Hook light-ship, north of the Five Fathom Bank, New Jersey, 
we have an annual range of 33° to 74°; at Bartlett Reef and Hartford Shoal light- 
ships, on Long Island Sound, it is 33° to 70°. The middle portion of Vineyard 
Sound, farther east, has a similar range, while at the Brenton Reef and Vineyard 
Sound light-ships, the region of Block Island, the Elizabeth Islands, and Marthas 
Vineyard, tlie temperature varies from about 32° to 09°. The range at Woods Hole 
(see table 2) is about 29° to 73°, taking the means for each month, while the actual 
extremes are greater. At Pollock Rip light-ship, at the southern end of Cape Cod, 
the mean range is 32° to 62°; in the Gulf of Maine the same range is obtained by 
combining the results of observations at all stations. In some places the maximum is 
only 54°. The preceding data are extracted from a paper by Mr. Rathbun (157). 

Mr. J. H. Duvar says that from 1878 to 1880 the average temperature on the north 
shore of Prince Edward Island was 56.56° in June, 63.40° in July, and 62.27° in 
August. The temperature of the water at bottom in 6 to 8 fathoms he estimated 
roughly at 55°. Lobsters spawn in July on the north shore; in August on the south 

'The inspector of fisheries of Prince Edward Island has an interesting note on the capture of 
lobsters through the ice in his annual report for 1882 {210). He says that on March 10 of that year 
there were brought to him "a number of lobsters of a uniform length of body [probably meaning 
carapace or shell of the back] of 4 inches, and one weighing 3 pounds that had been taken throuo-h 
the ice by the scoop of a mud-digging machine in a creek off Cascumpeque Bay. They seemed rather 
sluggish, but not torpid." It is evident that these lobsters preferred to burrow in the mud rather 
than migrate into deeper water. 



THE AMERICAN LOBSTER. 27 

shore. This is explained, lie thinks, by the current and by the rise of the tides in the 
straits of Northumberland, which make the southern water cooler, and hence delay 
the spawning- (,805, p. 233). 

Nielsen finds that the temperature of the water along the coast of Labrador ranges 
very low and does not exceed 46.05° F. on the warmest summer days. The lobster is 
thus debarred from this coast north of Henley Harbor, where it conies more directly 
under the influence of ice and the arctic current (see p. L5). 

SENSIBILITY TO LIGHT. 

The lobster is essentially a nocturnal animal, exploring the bottom in the quest of 
food mainly in the night, when it is far more active than during the day. This can be 
proved by anyone who watches their habits in aquaria or in lobster ponds or cars. It 
is tine that they show some activity in the daytime, especially if they are fed, but at 
night they become very restless. Moving nimbly about, they explore every part of the 
car or investigate anew the resources of the aquarium. I believe that the eggs are 
laid and that the pairing takes place at that time, and this inference is strengthened 
by the fact that this is the common habit of shrimp and many other Crustacea. The 
crayfish, according to Chantran {37), usually lays its eggs in the night. 

According to Forel, light can not penetrate in the ocean below a depth of 400 meters 
of tolerably clear water, but even in 50 fathoms off the Atlantic coast the difference 
between day and night can not be very considerable. This is not the case in shallow 
bays or sounds with sandy bottom, which lobsters freqneut in summer, and where we 
may expect to find the greatest difference between their diurnal and nocturnal habits. 
The lobster, like many other marine invertebrates, is very sensitive to the extremes of 
heat and cold. If exposed to direct sunlight out of the water, or to the nipping air 
of a winter's day, it weakens and succumbs in a short time. 

The large floating cars in which lobsters are generally stored alive, in readiuess 
for market, are always kept closed. When they are particularly shallow and the 
lobsters are exposed to the glare of the sun they always suffer and sometimes die in 
consequence. The majority of lobsters probably spend the greater part of the year 
in depths where the effect of sunlight is but very slight, and during the course of its 
evolution the eye of this animal has become sensitive to a minimum quantity of light 
For this reason alone we should expect that the adults would avoid intense sunlight 
The effect of light upon the colors of the shell is considered in another place. (See 
pp. 135. 136.) 

DIGGING AND BURROWING HABITS OF THE LOBSTER. 

The lobster not only digs up the sea bottom in its search for shellfish and covers 
itself with mud in cold weather, but burrows, under some conditions at least, as 
extensively as the muskrat. I have observed this interesting habit only in lobsters 
confined in pounds where they are obliged to adapt themselves to new conditions, it 
is true, but since they burrow while in these inclosures in summer as well as in winter, 
we may infer that the habit is one which is often practiced when the animal is free to 
roam at will. This has been observed, moreover, by fishermen who have frequently 
taken lobsters from their holes. 



28 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

The lobster pound at the Vinal Haven Islands is a granite basin with a clay or 
mud bottom, and with low mud banks in certain parts of the shore. At low tide it 
has an average depth of 3 fathoms, while the difference between tides is 10 feet. On 
the 26th of August, 1893, 1 explored this pound in a boat, in company with Mr. Thomas 
Barton, an intelligent lobster fisherman, and had an excellent opportunity to observe 
how lobsters behave under such conditions on a bright summer afternoon. It was 
quite common to see these animals partially buried in the mud in shallow water, 
their antennae, eyes, and part of the shell projecting from the muddy surface. We 
could rely upon finding lobsters in the holes which they excavate beneath stones, and 
rarely failed to discover one or more individuals in every good-sized chink among 
the rocks. Others lay at the mouths of burrows which they had dug straight into the 
banks. Comparatively few lobsters were seen lying upon the bottom or crawling 
actively over it. Occasionally two or three lobsters could be dislodged from a common 
place of retreat, and Mr. Barton said that in the spring, when the ice was breaking up, 
he had taken five lobsters from a single hole in the mud. Some years ago the lobsters 
made their way out of this pound, as I was told by an old fisherman formerly employed 
there, by excavating a submarine passage beneath the dam. In order to effect their 
escape, they had dug down beneath the stones to a depth of from 2 to 3 feet. 

At one of the pounds in Southport, Maine, I had a still better opportunity to 
study the burrowing habits of the lobster. The larger pound at this island is under the 
charge of Mr. A. P. Greeuleaf, a man of much experience in fishing the lobster and 
a very intelligent observer of its habits. 1 He finds that the lobster burrows most 
extensively in winter, when it is far less active in the pounds than at other times. 
When the water is drawn off from the pound in winter the lobsters often remain in 
their holes, the mouths of which are then exposed along the banks, but in summer 
they are more careful tinder these conditions to forsake their burrows and crawl into 
deeper water. 

In digging, lobsters probably make use of their large claws and walking legs, and., 
possibly the tail-fan may be brought into service as a scoop or shovel, but I have 
no observation in support of this latter supposition. In some cases, however, I have 
noticed the under side of the tail-fan to be scratched and scarified and the marginal 
fringe of hairs worn down in such a way as to suggest the xirobability of such a use. 2 

That lobsters transport stones with their large claws, Mr. Greeuleaf had the oppor- 
tunity to observe, while watching a lobster one day in the pound. The animal was 
maneuvering about a hole, in 3 feet of water. It was seen to crawl up to the burrow, 
possibly one which had been dug by another lobster, and cautiously put in first one 
claw and then the other. Finally it went in so as to conceal about half the length of 

1 Mr. Greenleaf is the only fisherman -whom I have met who has independently determined the 
period during which the female lobster regularly carries her eggs. 

-The process by which the hole is said to be excavated solely by means of the tail has been 
described by a writer on the habits of the lobster {181). This paper abounds in errors, and leads one 
to suspect that the author has drawn too largely upon the accounts of others; still, this fact need not 
discredit this particular observation. He says: "The tail is slowly drawn up at first, taking as much 
of the mud as possible on its under side; then, when well under the body, a final powerful jerk sends 
the mud or sand from out in front, and at the same time draws the lobster farther back into the cavity 
thus made, enabling him to get a better grasp for repeating the process over and over again, till by 
degrees lie disappears from sight." The statement that " these holes arc for the shelter of the lobster 
during the period of exuviation," however plausible it may be, is contrary to observed facts. 



THE AMERICAN LOBSTER. 29 

its body and brought out in ils large '-club claw" a small stone, which it deposited 
near the mouth of the burrow. Having thus removed this obstruction, it laced about 
and '-backed." tail first, into its newly acquired shelter. 

The east pound at this place has 18 feet of water at half tide and an average depth 
of about S feet. On one side are low rocky cliffs, the talus of which gives shelter to 
many lobsters, while the low clay banks of the opposite shore arc so completely under- 
mined by their burrows as to afford, in some places, a very insecure foothold. I 
examined these banks carefully from a boat, and had the opportunity of satisfying 
m\ self of the extent to which the tunneling operations had been carried on. The holes 
were driven horizontally into the mud bank to a distance of from 1 to 5 feet, and in 
each a lobster could either be seen, the tips of its large claws and its antennae standing 
out, or could be felt by inserting the end of an oar, the lobster fixing its large claws 
on the blade and sometimes allowing itself to be dragged out clear. 

'fhe holes had sometimes a relatively large opening of 8 to 10 inches in diameter, 
which allowed of their being readily probed and measured with an oar blade. I did 
not observe that they ever had an upward or downward curve, but they sometimes 
swerve to the right or left, which is explained, perhaps, by the presence of some obstacle 
in the path. In some cases the holes were made beneath rocks, and the entrance was 
often much larger than that described, owing, perhaps, to the union of the mouths of 
two originally distinct burrows. The pile of dirt and the broken clam shells which 
are sometimes seen near the hole of the lobster recall the excavations of the muskrat. 
It is exceptional to sec a lobster with its tail projecting from the burrow. I saw one 
or two under these circumstances, and when touched they immediately disappeared. 
1 thought that possibly they might be engaged in digging while in this position, but 
this was evidently not the case, as the water about the hole was very clear. These 
pounds are often much roiled, so energetically do the lobsters turn over the bottom 
and dig into the banks. On this account it is not easy to watch the process of 
excavation, which in all probability is carried on at night. 

I was informed by one fisherman, who had hunted lobsters quite extensively along 
the north Atlantic coast, that he had frequently taken lobsters out of holes in the 
mud and eelgrass, while wading in shallow water. It has been observed in pounds 
that a cold snap in winter will cause the lobsters to burrow suddenly in the mud, so 
that they can not be taken in traps for several days. We have already noticed the 
probable occurrence of the same thing in Newfoundland, when the temperature of the 
water is abruptly lowered. (See pp. 21, and 2G, note 1.) 

The burrowing habits of certain species of crayfish are well known, while those 
of the Stomatopods, which have been described by Professor Brooks, (20.]) are equally 
characteristic. We meet with the same habit in many shrimp, such as Alpheus. 
expressed in a greater or less degree; in crabs, and in a great uumber of the lower 
Crustacea. 

THE FOOD OF THE LOBSTER AND HOW IT IS PROCURED. 

The food of the lobster consists principally of fish, alive or dead, and of inverte- 
brates which inhabit the bottom and come within its reach. It is not unusual to find 
bits of alga?, such as the common eelgrass, in its stomach, and sometimes in such 
quantities as to show that it is not an accidental occurrence. Vegetable matter, 
however, forms, at most, but a small part of its diet. Fragments of dead shells are 



30 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

frequently met with, and in lobsters from 3 to 4 inches long-, under very peculiar cir- 
cumstances. (See pp. 89 and 90.) Coarse sand and gravel-stones, occasionally as large 
as duck shot, may also be found in tlie stomach, but with no marked regularity. 
These are not necessary for grinding the food, as in the gizzards of fowls, since the 
walls of the lobster's stomach are furnished with an admirable masticatory apparatus; 
still, whether of accidental occurrence or not, they can hardly fail to serve a useful 
purpose. 

In the course of this investigation of the habits of the lobster, the stomachs of 
large numbers of these animals were carefully preserved during a period of seven 
months (December to June). They were all captured in the harbor of Woods Hole, 
Massachusetts, under the conditions described on p. 25. A considerable number 
of these stomachs were empty; more than half contained remnants of recently devoured 
fish, a mass of scales and bones, mixed with fragments of the indigestible parts of 
other organisms. In many cases it was quite evident that the bait of the traps 
formed the only food found in their stomachs. 

The lobster undoubtedly regurgitates the insoluble and indigestible parts of 
its food. That the crayfish possesses this power was shown by the experiments of 
Lemoine (118). When the buccal cavity was stimulated by electricity, antiperistaltic 
movements were set up in the remaining parts, until the contents of the stomach 
escaped by the mouth. It was thus proved that the oesophagus was capable of two 
kinds of movements — peristaltic and antiperistaltic. Some such outlet for waste 
matter is absolutely necessary in an animal where the fluid or finely divided and 
digestible parts of the food only can pass into the delicate intestine. The hard parts 
of fish, mollusks, and Crustacea appear to be retained until they have given up a good 
deal of their lime, thus contributing to the calcareous supply of the exoskeleton. 

The stomachs examined contained remnants of the following organisms placed in 
the order of their relative abundance: fish (procured independently of the traps); 
crustacea, embracing chiefly isopods and decapods; inollusca, consisting largely of 
small univalves; alga?; echinoderms and hydroids. The bones of fish showed them 
to belong, as a rule, to small individuals or species. Among the crustacean remains 
parts of the small mud-crab, Panopajus (P. sayi and P. depressus, the common species 
in Vineyard Sound) were almost invariably recognized, and it was not unusual to find 
parts of the skeletons of small lobsters. The isopod, Civolana concharum, is frequently 
eaten by the lobster, often in large numbers. This species is a scavenger, and 
devours the bait used in the traps, which explains its common occurrence in the 
stomachs of lobsters recently caught. In one case, that of a female captured in January, 
the stomach was filled with fresh lobster eggs in an advanced stage of development. 
These were not taken from any lobsters in the trap, but under what circumstances 
they were obtained one can easily conjecture. The egg-lobster is undoubtedly a shining 
mark, not only for outside enemies, but even for members of its own species. The 
larger mollusks are eaten by crushing the shells and picking out the soft parts, while 
many of the smaller species are swallowed entire, and afterwards pulverized in the 
gastric mill. Echinoderms probably enter largely into the diet of the lobster, wher- 
ever they abound. Parts of the common starfish (Asterias forbesii) and rarely a few 
spines of the sea-urchin (Arbacia punctulata) were detected, but it might be that the 
latter were swallowed together with other calcareous fragments. Very little change 



THE AMERICAN LOBSTER. 31 

in the food was noticed during the winter and spring mouths, and there was little 
evidence that the appetites of these animals sensibly abated during the cold weather, 
yd it is probable that food is less abundant and less necessary in winter. (See pp. 
24, note 1, and 25.) 

That lobsters catch lish alive there is no doubt, but lew have ever seen this feat 
performed. Fish which inhabit the bottom, like the flounder, would naturally fall an 
easy prey to their powerful claws. They are said to catch the sculpin, and I have 
known a lobster which was con lined in an aquarium at the United States Fish Com- 
mission station in the summer to seize and devour the sea-robin (Prionotvs evolans). 

The common blue crab [Gallinectes hast&tus) is said to capture fish, and fishermen 
report having taken haddock on trawls with the heads almost nipped off, as if cut by 
the claws of the lobster. 

The smaller of the large claws is essentially a pair of toothed nippers, the hard 
tips of which are incurved so as to enable the auimal to secure and hold every 
object which it can fairly seize. This is sometimes called the " fish claw " or the u quick 
claw" by fishermen in Maine, while the heavy crushing-claw is called the "club claw," 
and according to Travis (191) it was known in England in the last century as the 
"knobbed" or "numb claw." 

While lobsters are great scavengers, it is probable that they always prefer fresh 
food to stale. Some fishermen maintain that there is no better bait than fresh herring. 1 
Fresh codfish heads, flatfish, sculpins, sea robins, menhaden, and haddock are also 
used, as well as salted fish. The flesh of the shark is occasionally utilized by the Gay 
Head fishermen on account of its firmness and lasting qualities. 

In the lobster pound at Southport, Maine, the lobsters are fed chiefly upon herring 
and sculpin. The fish are scattered around the shore and over the pond. They stop 
feeding them after the 1st of December, and the fall stock is taken out for the winter 
market in January, February, and March. 

In the large lobster pound at the Vinal Haven Islands 1 have seen the muddy 
bottom scored in all directions — the work of lobsters in their search for clams. One 
is there reminded of a pasture in which the soil has been rooted up by pigs. As a fish- 
erman remarked, if you put lobsters in a- pound and do not feed them, they will soon 
turn over the bottom as effectively as it could be done with a plow. Some of the holes 
which the lobsters had made in digging clams were 2 feet in diameter and 6 inches 
or more in depth. Here they had dug up the eelgrass, or loosened it so that it had 
floated to the surface, and cartloads of it had been cast ashore. We have already 
seen that lobsters sometimes eat parts of this plant, 2 but they had plainly rooted it up 
in this case with another object in view. The broken and often comminuted shells 
of the long-necked clam (Mya arenaria) could be seen strewn everywhere about their 
excavations. 

The lobster probably attacks such large and powerful mollusks as the conchs, 
which live upon hard bottom, in deep water, and devours their soft parts. Anillustra- 



'I am told by Mr. M. B. Spinney, of Cliffstone, Maine, that many years ago, when lobsters were 
very abundant, hi' and bis father used "wash bait" in taking them. Fish, such as the mackerel, were 
minced up and put overboard. Then, as lobsters came flocking from all directions about the boar, 
they would gaff them. 

-The grass- wrack, or eelgrass (Zostera marina), belonging to the pond- weed family (Naiadacece), is. 
with one or two exceptions, the only flowering plant found growing submerged in salt water on the 
New England coast. 



32 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

tion of this was afforded in an aquarium at Woods Hole iu the summer of 1892, when 
a conch (Sycotypus canaliculattis) was placed in the same tank with a female lobster 
which was nearly 10 inches long aud which had been in captivity about eight weeks. 
The conch, which was of the average size, was not molested for several days, but at 
last, when hard pressed by huuger, the lobster attacked it, broke off its shell, piece by 
piece, and made quick work of the soft meat. 

On many parts of the coast the lobster does not find any lack of dead fish for 
food. This is notoriously the case where seining is conducted on a large scale, as on 
the coast of Maine. One of the great evils attending this method of taking fish is 
the destruction wrought upon the young. In seining mackerel the catch is hoisted 
upon deck, where the fish are sorted, the larger, which are marketable, being saved 
while the smaller fry are thrown overboard. Owing to the rough treatment which 
they receive, and especially the exposure to the suu, the smaller fish are thus said to 
be destroyed by thousauds. The lobsters in the vicinity profit by this evil, playing 
the part of scavengers. 

If a lobster which has fasted for a number of hours is fed with a little fresh meat, 
such as a piece of clam or fish, the process of feeding will be found to be one of no 
little interest. The lobster eagerly seizes a piece of food with the chela? of the third 
and fourth pairs of walking legs, and passes it up to the third pair of maxillipeds, 
which are held close together, each being bent at the fourth joint and folded on itself. 
With the third maxillipeds thus pressing against the mouth, the food is kept in 
contact with the other mouth parts, all of which are in motion, and their action is thus 
brought to bear upon it. By means of the cutting spines of the appendages external 
to the mandibles — maxilla; aud first and second pairs of maxillipeds — the meat is as 
finely divided as in a sausage machine, and a stream of fine particles is passed con- 
stantly into the mouth, being previously submitted to the action of the mandibles. 

If one wishes to watch the movements of the complicated mouth parts more 
closely, he has only to take a lobster out of the water, place the animal upon its back, 
aud when it has become sufficiently quiet stimulate the mandibles or the broad plate 
of the large maxillipeds with the juice of a clam or the vapor of ammonia, which can 
be squirted with a pipette. Masticatory movements are immediately set up in the 
appendages, those belonging to the side stimulated usually working independently. 
The two small chelate legs are also drawn up rapidly to the mouth, as if to hand 
up pieces of food. 

When stimulated in this way the plates of the first pair of maxillpe come together 
over the lower posterior half of the mandibles. The movements of the masticatory 
parts of the second maxilhe are synchronous with the beating of the scaphognathite. 
These project somewhat obliquely over the convex surfaces of the appendages in front, 
inward, and slightly upward. The large plates of the first maxillipeds work up and 
down, and at the same time inward toward the middle line, describing an ellipse. The 
second pair of maxillipeds move alternately or together, inward and outward, with 
slight up-and-down movement. The large maxillipeds move together, the toothed 
margins meeting like the edges of a nutcracker (compare fig. 68, pi. 30), while the 
three terminal joiuts are bent inward and somewhat downward, as in the case of the 
second maxillipeds, so as to meet on the middle line below and hold the food up to 
the mouth. 



Chapter II.— REPRODUCTION. 

THE REPRODUCTIVE ORGANS. 

The breeding habits of an animal are not only of great scientific interest, but of 
the utmost practical importance, in view of any experiments which we may under- 
take in its artificial propagation. When this work was begun the breeding habits 
of the lobster were very imperfectly understood, and until now no exhaustive study 
of the subject has been attempted. In questions of this kiud, one may be led to 
draw conclusions from too slender data, since an abundance of carefully attested 
tacts gathered from a sufficiently wide area can be attained only with great difficulty. 

In the summer of 1891 I made as full a study as the time would allow of the 
reproductive organs and habits of the lobster at Woods Hole, Massachusetts, and iu 
the summer and fall of 1893 I was able to add to my knowledge of this subject by 
materials gathered at different points along the northern Atlantic coast. 

The reproductive organs will now be briefly considered, reserving a description of 
their structure and development for another part of this paper. (See Chapter X.) 

The ovaries, or "coral" as they are sometimes called, consist of two cylindrical 
rods of tissue united by a transverse bridge in the upper part of the body, and are 
immediately exposed upon opening the dorsal body wall. The uniting bridge of tissue 
probably represents the first trace of a fusion, which is expressed in various degrees 
in different Decapods. The ovarian lobes extend over about two-thirds the length of 
the animal, from behind the head to the third, fourth, or fifth segments of the "tail," 
and when approaching maturity are of a rich, dark-green color (plate 36, fig. 123; see 
also plate 38). The ripe ovaries are so much swollen that they fill all the available- 
space in the upper parts of the body-cavity. The bead-like eggs are clearly seen 
through the thin ovarian wall, and when this is cut they flow out, if perfectly ripe, in 
an uninterrupted stream. When the congested ovary is not mature the loosened eggs 
stick together and can not be easily disengaged without injury. A female with eggs 
approaching maturity can be readily distinguished by extending the translucent 
membrane between the "tail" and carapace, through which the deep-green color of 
the ovary is at once apparent, but since the eggs can not be pressed from the unyield- 
ing body of the animal, there is no way of telling when these are ripe short of actual 
dissection. 

The secondary organs of reproduction in the female are: (a) The oviducts, two short 
membranous tubes, which lead from the ovaries to the exterior, and open,- one on each 
side, upon the basal segments of the second pair of walking legs; (b) the copulatory 
pouch or seminal receptacle, for storage of spermatozoa (plate 7, and plate 38, fig. 130), 
situated between the bases of the third pair of walking legs; (c) cement glands, which 
secrete the material by which the eggs are fixed to the swimming legs (plate 40. fig. 
141, and plate 49, figs. 211, 212): (cl) the first pair of abdominal appendages, which 
are so reduced iu size and modified as to be useless for swimming. 

P. C. li. 1895—3 

■s:i 



34 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

The male reproductive organs are the testes (plate 36, fig. 120), the duets of which 
open at the base of the last pair of walking legs. The sperm which is inclosed in 
gelatinous capsules or spermatophores, the secretion of the seminal ducts, is thus 
ejected in packets. There is no penis or tubular extension of the integument from the 
opening of the duct, as is the case with the Brachyura. 

The first pair of legs of the tail are also modified in a peculiar way in the male, as 
if. they served for conducting the spermatophores through the elastic, slit-like orifice of 
the seminal receptacle. 

There are numerous secondary sexual distinctions, the most striking of which is 
seen in the abdomeu. The latter is conspicuously broader in the female, a variation 
which is correlated with the greater size of the ovary as compared with the testis; 
its lateral plates are deeper and it is more conspicuously hollowed below to form an 
incubatory pouch for the ova. A discriminative fisherman can thus distinguish the sex 
at a glance. ^Compare plates 4 and 6.) The large claws are more voluminous in the 
male than in the female, and the male attains the greatest size. This would imply 
that the male molts often er than the female, which, according to the observations of 
Brook (26), is actually the case. 

In addition to these distinctions G-ouriet (82) found that in the crayfish the 
antennae were longer in the males than in the females; that while the length of the 
abdomen of the male was relatively shorter, it was heavier than in the female. He 
found the length of the abdomen, compared with that of the carapace, to be in the 
proportion of 7 to in the female, while in the male this difference in length did not 
exceed -£% inch. 

In the male lobster the second pair of swiminerets carries a small spur on its inner 
blade, the function of which is obscure. The reduction of the first pair of abdominal 
appendages in the female is in all probability correlated with their use in reproduction. 
If they were of the normal size they would catch so many eggs at the time of oviposi- 
tion that it would be next to impossible for the female to completely flex the abdomen. 
Locomotion would thus be interfered with, and the eggs would be constantly exposed. 
As it is, it sometimes happens in very large females, where the ova are excessively 
abundant, that it is impossible to completely fold the abdomen. (See p. 54.) 

Each testis consists of a slender, grayish-white, sacculated tube filled with devel- 
oping sperm cells (fig. 120, plate 36), and its coiled duct usually contains sperm in 
abundance. The spermatophore can be easily pressed from the duct, when the latter is 
dissected out. The sperm cells have a characteristic shape (fig. 129, plate 37) and are 
absolutely immobile in the conditions under which they are ordinarily observed, but 
it is impossible to suppose that this is always the case. Their complicated form, 
recalling that of the bell-shaped medusa, leads one to suspect that under the influence 
of some subtle and unknown stimulus, possibly of a chemical nature and coming from 
the cement glands or some other organ, they are able to execute independent and 
rapid movements through the water. 1 



1 Cano states that lie once detected amoeboid movements in the rayed sperm-cells of the crab 
Maia. See observations quoted on p. 49. 



THE AMERICAN LOBSTER. 35 



THE PAIRING OF THE LOBSTER AND OF OTHER CRUSTACEA. 

The copulation of the lobster has never been seen, as far as r am aware, in any of 
the species, but we know that it takes place- in spring and summer at least, it' not at 
other times of the year*. If ripe females, or females even Avith newly laid eggs, are 
examined in June or July at Woods Hole, the seminal receptacle is found to be almost, 
invariably charged with spermatozoa, and it is evident that copulation takes place, 
certainly in many cases, without immediate reference to the condition of the animal. 
Thus on August 19 T examined a female lobster which was 9 inches long and found 
her seminal receptacle loaded with sperm. The ovaries were of a light, greenish -yellow 
color, and in a very immature condition. This lobster had been impregnated at least 
two years before her eggs would be ripe. 

I was surprised to find the seminal pouch of another lobster, which was examined 
about the same time, to be charged with freshly deposited sperm, althoughit had just 
hatched a, brood and was preparing to molt. It therefore seems probable that the 
male lobster has no means of discriminating the sexual condition of the female. This 
lobster, in the ordinary course of nature, would soon have lost in the molt the sperm 
with which she had been so recently supplied. The first copulation, which had occurred 
either before or shortly after the hatching of the brood, must have been followed by a 
second union in order to secure the fertilization of the next batch of eggs. These 
would not be due, moreover, until one year from this time. It is thus evident that 
the female lobster is not impregnated once for all and compelled to take the chances 
of fertilizing her eggs, but is approached more than once by the male. The molting 
of these animals, although subject to less variation in the adult female than in the 
male, renders this necessary. Females usually molt shortly after the hatching of a 
brood. Where the molting is accomplished just before the eggs are laid, which 
happens very rarely — I have noticed only two cases in the lobster — (see p. 80), copu- 
lation can precede the act of extrusion by a few days at the most. 

A lobster which had been kept in an aquarium for upward of two months in the 
summer, without access to the male, laid eggs which were normally fertilized. This 
and other facts which have just been mentioned show that the female lobster must in 
some cases be impregnated more than once before each reproductive period, and also 
that the spermatozoa retain their vital activities for a long time, perhaps, as Bumpus 
suggests (30), from one to two years. This is not so remarkable, when w , onsider 
the longevity of spermatozoa recorded by Sir John Lubbock (Weismann's Essays, 
vol. 1, p. 52), who succeeded in keeping a queen ant until she was 15 years old, 
during which time she continued to lay fertile eggs. Fertilization must have taken 
place at the latest in the season when the insect was captured. "There has been no 
male iu the nest since then," writes Lubbock, "and, moreover, it is, I believe, well 
established that queen ants and queen bees are fertilized once for all. Hence, the 
spermatozoa of 1874 must have retained their life and energy for thirteen years, a 
fact, I believe, unparalleled in physiology." 

Observations on the copulation of the crayfish (Potamobius fluviatilis) have been 
made by Gerbe (43), Chantran, and other naturalists. The latest and most detailed 
account of Chantran, published in 1872 (.5.9), is as follows: 1 

1 In quotations from works in foreign languages, I shall give, for convenience, the English trans- 
lation. The extract can he verified by reference to the original. 



36 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

The male crayfish deposits its fertilizing matter in the form of sperniatophores upon the plates 
of the tail-fan and upon the plastron of the female. The time of egg-laying varies from two to 
forty-five days after copulation. When the time comes for the extrusion of the eggs, the female raises 
herself upon her feet, and then the abdominal appendages secrete for a number of hours a grayish, 
somewhat viscous mucus. She thereupon lies upon her back, bends her "tail" toward the opening 
of the oviducts, so as to form a kind of cistern or chamber, as described by Lereboullet, into which 
during the following night the eggs are received as fast as they are expelled from the genital organs. 
This expulsion lasts from one to several hours. These eggs, which are always turned so as to present 
their whitish spot or cicatricula uppermost, in order to be fertilized the more readily, are thus found 
engulfed in the grayish mucus which fastens, in some degree, the swimmerets and the borders and 
extremity of the "tail" to the thorax. This also helps to bound the pocket or chamber, in which there 
is a certain amount of water inclosed with eggs aud mucus. Immediately after egg-laying we can 
find in the water and mucus spermatozoids exactly like those contained in the spermatophores which 
are attached to the plastron, and from which, in fact, the sperm-cells proceed. The spermatozoids are 
thus in direct contact with the eggs and are in the presence of a vehicle which assists them to penetrate 
the ova. Fecundation is effected in this chamber, that is, outside of the genital organs of the female. 

The spermatozoids found mixed with the eggs and mucus in the egg-chamber are like those 
found in the spermatophores and male sexual organs. In the course of the first three days after 
egg-laying these spermatozoids become spherical, pale, and continue immobile. After this they wither 
and become smaller, darker, and more irregular. Finally, when, after the fixation of the eggs, the 
excess of mucus has completely disappeared by means of pressure exerted by the incessant contractions 
of the abdomen, which takes place in from six to eight days after egg-extrusion, those spermatophores 
which still remain attached to the plastron consist of small white coriaceous filaments. The latter 
are either isolated or composed of several adhering together. They have nothing to show but a 
central cavity, in which the microscope can detect nothing but a few spermatozoids, more or less 
withered. The wall of the spermatophores preserves its thickness and remains, as before, composed 
of a hard, striated, tenacious mucus. 

On the lOtli of October a small species of Oambarus copulated in an aquarium, in 
the following maimer: The animals lay on their sides, and the sternal surface of the 
thorax of the male was pressed closely against that of the female. The abdomen of 
the female was folded beneath that of the male. The male grasped with his great 
claws the large pincers of the female, and thus held her securely, bringing also into 
service the walking legs. According to Andrews (Johns Hopkins Univ. Oirc, vol. 
xiv, p. 74), the spermatophores, which I did not observe, are deposited in the annulus 
of the female, and the animals are firmly adherent by means of definite hooks and 
ridges on the appendages of the male and female respectively. 

The following notes are interesting as showing how popular errors in regard to 
the breeding habits of lobsters have arisen. Some of these statements, mixed with a 
minimum of accurate observation, have been repeated so many times that they have 
almost assumed the semblance of truth. 

Travis (191) writes to Thomas Pennant, in a letter on the habits of Homarus gam- 
marus, published in 1777, that lobsters "begin to breed in the spring and continue 
breeding most of the summer; they propagate more humano and are extremely prolific. 
Dr. Baster says he counted 12,444 eggs under the tail, besides those that remained 
in the body unprotruded. They deposit these eggs in the sand, where they are soon 
hatched." This curious contradictory statement is repeated by Herbst (88), who says 
that "they lay their eggs in the sand, where they are hatched by the sun." 1 

'The same notion existed in regard to the breeding habits of crabs. Thus, Herbst says: "The 
sea crabs do not show so much care for their young as the crayfish. They try to deposit their eggs 
either on the shore in the sand or they commit them to the sea, which washes these eggs thus extruded 
in on the beach, where they are soon hatched by the sun, and the young seek again their proper 
element." Of the laud crabs, he says : "They carry their eggs to the sea, where the females wash them 
off from their tails. They are then cast up by the sea on the beach, where they are hatched by the sun." 



THE AMERICAN T.OBKTUR. 37 

Boeck asserts (20) in liis history of the Norwegian lobster fishery, that a real act of 
copulation takes place, the male placing its double male member (modified appendages 

of the first abdominal somite) into the outer genital openings of the female, and 1 hat 
the eggs are impregnated while they are yet in the ovary. 

Fraiche (70) says that the union of the sexes takes place in the fall of the year 
(Oetober and November) for the common and Norwegian lobsters, and in the case of 
the former species extends into winter: 

As with the crayfish, the sexual act is accomplished belly to belly, aud so closely and firmly do 
thov clasp each other, that, if taken from the water at this period, it is with difficulty that they can 
be separated. 

He thinks that the seminal fluid is introduced directly into the oviducts, and 
says that the sides of the abdomen secrete a viscous substance which incloses the 
eggs and attaches them to the body of the female. 

The question, How is the fertilization of the eggs effected in Crustacea? is one 
which has been asked by naturalists from the days of Aristotle down to the present 
century, and it has received the most varied and contradictory answers. A brief 
account of the history of opinion on this subject has been given by Brocchi in his 
thesis on the male organs of the decapod Crustacea, published in 1875 (25). One 
source of difficulty lay, as recent studies have proved, in supposing that the process 
was essentially the same in both Macrura and Brachyura. 

Porzio 1 and Oavolini (36) * among the older writers, as Brocchi shows, had (dearer 
ideas upon this question than their immediate successors. Thus the Neapolitan 
physician, Porzio, says, in his study on the lobster: 

Organa anteni propagations et generationis sic constructs, sunt, ut facilem non inveniam 
rationem qua maris semen, in femime corpus ejaculari, infundi, vel introiri possit. 

Oavolini also remarks in his memoir on generation, published in 1787, that — 

The Crustacea copulate face to face, with the penis on the outside of the body; there is no intro- 
mission, for the papilla which we have shown to he present on the base of the last jiair of legs can 
scarcely serve to make a passage for the semen; the eggs are glued to the hairs of the female and are 
bathed in the semen (36). 

Milne Edwards (58) in his Histoire Naturelle des Crustaces, published in 1834, 
expressed some true ideas upon the reproductive processes in the Crustacea which were 
not comprehended by many subsequent writers. At the same time he falls into errors 
in regard to certain organs and their functions. He says that the first two pairs of 
abdominal appendages in the male, which are often so different from the following 
pairs, seem to serve as exciting organs in the act of reproduction, but that naturalists 
have been mistaken in regarding them as representing the penis. In many cases, as in 
Gegarcinus, their size would make it impossible for them to penetrate into the vulva, 
and he says " we have proved, by direct observation, that in others it is the lower end 
of the efferent canal which is alone introduced into the body of the female." These 
appendages apparently assist in directing the penis toward the vulva, and possibly in 
exciting the latter. (See note 1, p. 39.) He calls attention to the important fact that 
in the Anomura and Macrura there is no copulatory pouch such as he had discovered 

1 1 have been unable to consult the origin;il works of these writers, and give the quotations from 
them on the authority of Brocchi and Cano. 



38 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

in the Brachyura. In the Brachyura he found that a true copulation took place: "The 
wands of the male penetrate into the copulatory pouches situated below the vulvae of 
the female, and deposit there the semen, which is so held and preserved in that part 
that it may be turned over the eggs as fast as they pass out." On the coasts of Brittany 
Milne Edwards found a female Cancer pagurus, which was fertilized, "and in which the 
extremities of the wands of the male were broken off after copulation, as happens in 
many insects; these organs remained inclosed in the copulatory pouches." As 
Brocchi (25) observes, Milne Edwards seems to have foreseen the presence of sperma- 
tophores, for in a subsequent work (59) he says, in reference to this observation, that 
since his attention has been directed to spermatophores it has seemed possible "that 
the sort of stopper in question left in the vulva may have beeu a body of that nature 
rather than a fragment of the penis." 

In regard to the reproduction of • the Macrura, where there is no internal seminal 
receptacle, the fecundation of the eggs, says Milne Edwards (58), is less easily under- 
stood : 

It is generally admitted that in all these animals there is a true copulation, in consequence of 
which the seminal fluid is introduced into the interior of the generative organs of the female. If it 
were not so, it would be difficult to understand how the eggs, which fill the entire ovary, the first of 
which are laid a long time before the last are developed, come in contact with this fluid, as a necessary 
condition of their fertilization. But there is not, so far as I know, any direct observation which proves 
the existence of such a copulation, and the absence of a copulatory pouch leads us to suppose that in 
these animals the eggs are fertilized as in the cricket, or very shortly after they have left the body of 
the mother. After being received into the cavity of the ovary, the egg is directed little by little 
toward the external orifice of one of the oviducts, the walls of which secrete in spring a rather thick, 
albuminous liquid, which, hardening after the eggs are laid, forms a second external envelope. 

This error of attributing the viscous secretion to the oviducts has been repeated 
by subsequent writers, notwithstanding the fact that it was corrected by Milne 
Edwards (60) in a subsequent work. He says in a note following a recapitulation of 
the observations of Lereboullet, that the glue by which the eggs are attached does not 
come from the walls of the oviduct, but is secreted by subcutaneous glands situated on 
the under side of the abdomen, between the bases of the appendages. A membranous 
penis is said to be formed by the subdermal portion of the seminal tube, which is here 
enlarged and has thickened walls. This dilated portion of the canal, the " vecteur" of 
the sperm, ''is capable of evaginating and passing outside beyond the genital opening, 
to the borders of which it is inserted. It thus forms a tubular appendix, having the 
function of a penis." 

Milue Edwards was undoubtedly mistaken in supposing that the large glandular 
segment of the vas deferens of the Macrura was evaginated in copulation. This, as 
Grobben remarked, would be mechanically impossible (83). 

Duvernoy (57) in 1850 again raised the question whether fertilization in Decapod 
Crustacea took place at the moment the eggs were laid, and comes to the conclusion 
that in Macrura and some Brachyura, where there is no seminal reservoir, fecundation 
takes place without a true copulation. He says : 

The way in which the oviducts are stuffed like sausages with large numbers of eggs arranged in 
line, when they have reached maturity, would not admit of an internal fertilization, except for those 
eggs which were brought near the orifice, unless there was a copulatory pouch or a seminal reservoir? 
before the mouth of which they must successively pass at the time of egg-extrusion, in order to be 
fertilized, as is the case with insects. 

He supposed that in all cases where internal fecundation was impossible, the eggs 
were fertilized at the moment they were laid, as occurs in the tailless Batrachians; he 



THE AMERICAN LOBSTER. 39 

had also the notion that the male helped the female to place her eggs under the 
abdomen and glue them to the swinnuerets. 

Apart from the physical impossibility of an internal copulation and fertilization, 
in the way which many have conjectured, the absence in the Macrura of two important 
accessory reproductive organs, the vagina and i>it<r>i<tl seminal receptacle, points at 
once to the fact that the eggs are fertilized outside of the body. With the discovery 
of an external seminal pouch in the lobster, the function of which had been curiously 
overlooked or misunderstood until Bumpus called attention to it in 1891 (30), this is 
still further emphasized. 

As Brocchi and, more recently, Cano (32) have pointed out, the vagina and inter- 
nal seminal receptacle always occur in the Brachyura in relation to the presence of a 
male penis (the terminal portion of the efferent duct which is said to be capable of 
evagination), and imply a different method of copulation. 

The common green crab (Garcinus mcenas), the pairing of which has been repeat 
edly observed, illustrates this process among the Brachyura. A pair of these crabs 
was brought into the laboratory at the United States Fish Commission at Woods 
Hole on the 27th of July. They were adherent solely by the intromitteut organs' 
of the male, which were introduced into the orifices of the oviducts of the female. 
The male had a hard shell; the female, which was smaller, a soft shell, conditions 
which seem to be necessary for copulation, as Oavolini (36) long ago showed, and as 
Bouchard-Chantraux (21) and Lafresnaye (111) independently observed (25). 

Cano gives the following account of the copulation of Maia (33) : 

The male crab runs to meet the female, lifts her up and places her beneath him, embraces her 
closely with his feet, and his claws hold her by the margin of the orbits or iu the region of the 
antennas. In other cases the male turns upon its back, catches hold of the female and draws her 
upon his belly. The whole action lasts about an hour. 

It is undoubtedly true, as Cano has remarked, that in all the Macrura and Ano- 
mura, which have no internal receptaculum seminis, penis or vagina, there is no internal 
copulation and the sperm is never found in the ovary or its ducts. 

THE LAYING OF EGGS. 

In order to determine the time and limits of the breeding season of the lobster, it 
is necessary to collect and examine a large number of their eggs at different places 
and at different times of the year. The examination of the winter or summer eggs 
alone will not suffice to solve the problem, as I have learned by my own experience, and 
this explains why the question has been the subject of so many conflicting statements 
and has remained uusettled down to the present day. (For a review of this question 
see jSos. 98 and 101 of Bibliography.) 

The following quotations illustrate the confusion which has surrounded this 
important subject. Verrill (196) remarks: 

There is a great difference iu the breeding season on different parts of the coast. The lobsters 
from New London and Stonington often lay their eggs as early as the last of April or first of May ; 
while at Halifax Mr. Smith found females with recently .laid eggs in September. At Eastport, Maine, 
the females carry their eggs in midsummer. 

1 The only intromittent organs noticed in this cnse were the slender wand-like appendages of the 
first abdominal somite. The penis is probahly introduced after the former have been withdrawn. 
(Compare p. 37.) 



40 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

At the time this was written it was not known that the lobster usually carries 
her eggs for a period of ten or eleven months. It was. therefore, quite natural that 
Verrill should misconstrue the discriminative statement of Smith (182), who says: 

The season at which the female lobsters carry eggs varies very much on different parts of the 
coast. Lobsters from New London and Stonington, Connecticut, are with eggs in April and May, 
while at Halifax, Nova Scotia, I found them with eggs, in which the embryos were just beginning to 
develop, early in September. A corresponding variation is noticed in the lobster of the European coast. 

Verrill further says {196, p. 745): 

Subsequent observations have shown that the breeding season of the lobster extends over a large 
part of the year. Mr. Vinal N. Edwards has forwarded two living females, of medium size, 

taken in Vineyard Sound, December 12, both carrying an abundance of freshly laid eggs. He states 
that he finds about one in twenty carrying eggs at that season. 

Wheildon says, in a paper published in 1875 (20,2), that the assumption that the 
lobster has a definite annual spawning season is an error, and that in February of that 
year he had obtained "spawn in several stages of development from newly laid eggs 
to the swimming larvae." 

The following statement of a member of the local government of Prince Edward 
Island expresses an opinion upon the breeding habits of the lobster, which is as 
misleading as it is common: 

I feel certain that the close season has not and can not accomplish anything toward the first 
object [protection for lobsters while spawning], as it is now admitted by everyone who has had any 
experience in packing, that lobsters in spawn are caught at all seasons of the year and that they 
have no particular season for spawning. 

Bumpus concludes that — 

The eggs are normally deposited during the months of July and August, and develop rapidly so 
long as the water is relatively warm. Large numbers of eggs collected during the winter 

months, both from the colder waters of Nahant as well as from the warmer waters of Woods Hole, 
were almost invariably in the same advanced stage of development — the eyes large and bright, the 
appendages well outlined, and the yolk occupying but a fraction, perhaps one-third of the surface 
exposure. 

Out of hundreds of lobsters found "in berry" in May, 1890, at Woods Hole, " not 
a single one had eggs in early stages of development." (30) 

After fluctuating from one view to another, I came to the conclusion that the 
breeding season was limited as defined in the paragraph just quoted, but as my obser- 
vations had been restricted to the summer months and to the region about Woods 
Hole, I determined to extend them to other points of the coast and to other seasons 
of the year. The results of these inquiries I will now give in detail. They may be 
summarized as follows : 

For the majority of lobsters there is a definite breeding season, which is the 
summer, July and August being the months in which the greatest number of eggs are 
laid. A minority, on the other hand, perhaps 20 to 25 per cent of the entire number 
of spawners, lay their eggs at other times of the year, in the fall and winter at least, 
if not also in the spring. The fall and winter eggs are normally extruded, and do not 
appear to be necessarily the product of the first reproductive period. A glance at 
table 12 shows that while the average size of the females is small, it is fully up to the 
average of all females captured during the same time. 

I received an "egg-lobster," which is not recorded in the following tables, from 
Woods Hole early in December. It was 12£ inches long, and its eggs were just past 
the egg-nauplius stage. If laid in July or August, they would Lave reached this stage 
in about 18 days. 



THE AMERICAN LOBSTER, 



41 



SUMMER EGGS IN VINEYARD SOUND. 

The following tables illustrate the time of spawning of the lobster in the vicinity 
of Woods Hole, in Vineyard Sound, and about Gay Head. The date of the extrusion 
of the eggs is, of course, only approximately determinable. It is estimated from obser- 
vations on the rate of development of embryos at Woods Hole. The parent lobsters 
were confined in floating latticed boxes, which were exposed to the wash of the waves, 
in one instance, for nearly a year. (See table 18, p. 50.) 

Table 3. — Time of spawning of the lobster in Vineyard Sound and vicinity in 1S8U. 



No. 



3 
4 
5 
6 

7 
8 
9 
10 
U 
12 

13 

14 
15 

1G 
17 

18 

19 
20 



Locality. 



Woods Hole Harbor. 
Menemsha 



.do . 
do 



Woods Hole Harbor.. 

....do 

Menemsha 

do 

do 

Woods Hole Harbor.. 

do 

do 



Date of 
capture. 



Stage of development, 



July 10 
J nly 11 



.do. 
.do. 
do. 
.do. 
.do. 
.do. 
.do. 
.do. 
.do. 
.do. 



Age of embryo. 



do July 16 

do I 



Thoracic abdominal plate well marked ... 8 to 9 days. 

At least four pail sof appendages behind 20 to 21 days. 

mandibles. 

Egg nauplius : second antenna; bilobed.. 14 to 15 days. 



.do 
do 



.do 
do 



.do. 



.do 
do 



do. 
.do. 



...do.... 
July 18 

July 20 

July 28 
Aug. 3 



Close of yolk segmentation 

Yolk segmentation : CO to 100 segments. . . 

do 

do ... 

do 

do 

Early egg nauplius: second antenna; not 

bilobed. 
Egg nauplius, later stage: second anten- ! 14 to 15 days. 

use bilobed. 
Close of yolk segmentation 3 days . 



do. 
.do. 
3 days .. 
1$ days . 

do .. 

do . . 

do.. 

do.. 

10 days . 



Thoracic abdominal plate becoming prom- 
inent. 

Yolk segmentation: 50 to 100 segments... 

Large thoracic abdominal plate. Pit ob- 
scured. 

Very slight invagination: nuclei close to 
surface. 

Eye pigment developed 

..'..do 



days. 



1$ days 

8 "to 9' days. 



4 days . . 

27 days . 
.. .do.. 



Date of 
extrusion 

of eggs. 



July 1 

June 20 

June 26 

Do. 

Do. 
July 8 
July 9 

Do. 

Do. 

Do. 

Do. 
July 1 

Do. 



July 13 

July 10 

July 14 

July 9 

July 16 

July 1 

July 7 



Table 4. — Time of spawning of the lohster in Vineyard Sound and vicinity in 1890. 



No. 



Locality. 



1 

2 

3,4 

5 

6-14 

15-17 

18 

19 

20 

21-26 

27-45 

46-51 

52,53 

54 

55 

56-60 

61 

62 

63 

64 

65 

66-68 

69,70 

71-73 

74 

75 

76.77 

7K-81 

82-84 

85,86 



-Menemsha . 

....do 

....do 

do 

....do 

....do 

....do 

....do 

....do 



...do 

....do 

....do 

....do 

do 

....do 

do 

do 

do 

Woods Hole Harbor. 
do 

Gay Head 

...'.do 

do 

do 



Date of 
capture. 



July 7 
July 9 
July 28 

. . .do 

...do ... 

...do .... 

...do ... 
July 30 
July 30, 
1.45p.m. 
July 30 

...do.... 

...do .... 

...do .... 

...do .... 
Aug. 1 

...do— . 

...do .... 

...do .... 
Aug. 5 
Aug. 11 

. . .do 

...do .... 

...do .... 

...do .... 



Stage of development 



Woods Hole Harbor... I Aug. 14 

do ...do ... 

do i Aug. 18 

Menemsha [ Aug. 20 

.....do '.. .do 

do Aug. 21 



Age of embryo. 



Date of 

extrusion 

of eggs. 



Yolk segmentation probably not begun. . . I 24 hours . 

Yolk unsegmented J .Few hours. 

Post-nauplius stage 

Eye pigment just visible 

Close ot yolk segmentation 

Invagination stage, small pit 

Yolk segmentation: 16 to 60 seguients. 

Yolk unsegmented 

do 



Early segmentation of yolk 

Close of yolk segmentation 

Invagination stage 

Egg nauplius 

Eye pigment formed 

Egg nauplius 

Close of yolk segmentation 

Yolk segmentation: 16 to 60 segments 

Thoracic abdominal plate formed 

Invagination 

Egg nauplius 

Eye pigment formed 

Invagination 

Thoracic abdominal plate formed 

Egg nauplius 

Invagination 

Post-nauplius stage 

Invagination •) 

Egg nauplius 

Post-nauplius stage 

Early egg nauplius 



21 days . 

27 days 

3 days 

4 to 5 days 

24 to 30 hours.. 
A few hours . .. 
About. 8 hours . 

24 to 30 hours . . 
;i days 

5 days 

15 days 

27 days 

15 days 

3 days 

24 to 30 hours.. 

8 too days 

5 days 

15 days 

27 days 

5 day's 

8 to 9 days 

15 days 

5 days 

20 days 

5 daj 9 

15 days 

21 clays 

10 days 



July 
July 9 
July 7 
July 1 
July 25 
July 24 
July 27 
Julv 30 
Do. 

July 29 
Ju!'\ 27 
July 25 
July 15 
July 3 
July 17 
July 211 
July 31 
July 23 
July 31 
July 27 
July 15 
Aug. G 
Aug. 2 
July 27 
Aug. 
Julv 25 
V. n a 13 
Aug .'. 
Julv 31 
Aug. 11 



42 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Table 5. — Time of spawning of the lobster in Vineyard Sound and vicinity in 1891. 



No. 



11,30 

11-13 

14-16 

17-21 

22 

23 

24 

25,26 

27 

28 

29, 30 

31 

32 

33 

34 

35, 36 

37, 38 



Locality. 



Gay Head . . 

do 

Menemsha. 

....do 

do 



Date of 
capture. 



July 

July 

July 

do 

do 



Gay Head ; July 

...'.do do . 

do do . 

Menemsha Aug. 

do ]...do . 

do j...do . 

do ! ... do . 

do ...do . 

Woods Hole Harbor . . Aug. 

Gay Head j Aug. 

do . . .do . 

do .do . 

do '.. -do . 

Menemsha : Aug. 

Woods Hole Harbor . . ' Aug. 

do , Aug. 

Gay Head ! Au, 



.do 
.do 
.do 



Aug. 
do 
do 



Stage of development. 



Age of embryo. 



Yolk segmentation 

Close oi' yolk segmentation 

Invagination 

Late stage with eye pigment 

Close of yolk segmentation 

do... T. 

Eye pigment formed 

Egg nauplius 

Invagination (?) 

do 

Close of yolk segmentation 

Egg nauplius 

Late stage, eye pigment conspicuous 

Before formation of eye pigment 

Invagination 

Thoracic abdominal plate 

Egg nauplius 

Post-nauplius stage 

Early egg nauplius 

Invagination 

Egg nauplius, late stage 

Eggs free in ripe ovary 

Egg nauplius, late stage 

Eye pigment forms large, nearly oval spot 
Egg nauplius 



1 | days. 

3 clay's.. 

4 days . - 
29 days. 
3 days . . 
3 days . . 
27 days. 
15 days. 
4days . . 
4days.. 
3 day s . . 
15 days. 
30days. 
25 days. 
4days.. 
8days.. 

15 days. 
20 days. 
10 days. 
4 days.. 

16 days. 



18 days. 
42 days. 
15 days. 



Date of 

extrusion 

of eggs. 



July 17 
July 20 
July 24 
June 29 
July 25 
July 26 
July 2 
Julv 14 
Aug. 1 

Do. 
Aug. 2 
July 21 
July 6 
July 14 
Aug. 7 
Aug. 3 
July 27 
July 22 
Aug. 2 
Aug. 8 
Aug. 2 



Aug. 3 
July 10 
Aug. 6 



Table 6. — Time of spawning of the lobster in Vineyard Sound in 1892 and 1893. 



No. 



l 

2 
3 
4 
5 
6 
7 
8 

1-3 

4 



Locality. 



"Woods Hole Harbor 
do 



.do 

.do 

.do 

.do. 

.do 

.do 



Menemsha 

Woods Hole Ha r 



.do 
.do. 



Date ot 
capture. 



1892. 
July 29 
July 3U 
Aug. 1 

...do 

Aug. 3 
...do.... 
...do .... 
Aug. 6 

1893. 
Julv 25 
Aug. 11 

Aug. 15 
...do.... 



Stage of development. 



Invagination 

Egg nauplius 

Beginning of yolk segmentation. 

Invagination 

Close of yolk segmentation 

Post-nauplius stage 

Before eye pigment is formed. . . . 
Yolkunsegmented 



New eggs : stage not determined 

Eggs laid in aquarium at United States 
Eish Commission station. 

Close of yolk segmentation 

Eive pairs of appendages behind mandi- 
bles; no eye pigment. 



Age of embryo. 



4 days . . 

1 5 days 

1£ days 

4 days 

3 days 

20 days 

26 days 

About 1 day . . 



Date of 

extrusion 

of eggs. 



July 25 
July 15 
July 31 
July 28 
July 31 
July 14 
July 8 
Aug. 5 



About 
Aug. 10 

3 days ' Aug. 12 

23 days July 23 



Table 7. — Variation in time of spawning of lobsters in Vineyard Sound and vicinity in the years 1889-93. 



Period of spawning. 


1889. 


1890. 


1891. 


1892. 


1893. 


Total. 
















16-30 


5 
14 

1 


11 
62 
13 


1 

6 

12 

18 

1 






6 
34 
80 
34 

1 


July 1-15 


3 
4 
1 


1 
2 




16 31 














20 


86 


38 


8 


3 


155 





The data afforded by the preceding tables lead us to conclude that the summer 
eggs are produced in this region during a period of about nine weeks, extending from 
the middle of June to the middle or last of August, the largest number being laid 



THE AMERICAN LOKSTER. 



43 



(lining the latter half of July and the first two weeks ot August. The summer 
spawning of each year lasts about six weeks, but may fluctuate from year to year, 
backward or forward through an interval of a fortnight. 

The observations for the years 1890 and 1891 only, are large enough to make a 
comparison of much value. Of the 8G lobsters with new eggs examined in July and 
August, 1890, 81 per cent extruded eggs in July and 15 per cent in August, while in 
the following year, out of 38 females, one-half had laid in July and half in August. 
In 1890, however, 72 per cent of the eggs were laid in the latter half of July and 15 
per cent in the first half of August, while iu 1891 47 per ceut were extruded in the 
first part of August and 31 per ceut in the latter half of July. The season of 1891 
thus appears to have beeu somewhat later than that of the former year. 

The record of ocean temperatures given in table 2 (p. 25) shows that the water 
was cooler in 1891 than iu the preceding year, the difference of the mean annual 
temperatures being 1.6°. This difference is slightly raised by eliminating the mouth 
of June, when the smallest number of lobsters carry eggs. It is possible that so small 
a variation as is here recorded in the mean annual temperature of the sea water woidd 
sensibly affect the rate of development, yet a larger number of observations would be 
required before this could be satisfactorily shown. 

There are undoubtedly other causes than the temperature changes which influeuce 
the growth of the ovarian eggs, which it must be remembered require at least two 
years to reach maturity. Anything which affects the individual during this interval 
may affect also the time of spawning, and this affords a partial explanation of the fact 
that eggs are sometimes produced at other seasons of the year than the summer. 

SUMMER EGGS ON THE COAST OF MAINE. 

Tables 8, 9, and 10 throw more light on the time of spawning upon the coast of 
Maine, where the water is somewhat cooler than at Woods Hole. The range of tem- 
perature in the Gulf of Maine is about the same as that obtained at Pollock Eip 
light- ship, off the southern end of Cape Cod, namely, 32° to 62° F. 

Table 8. — Time of spawning at Southport, Maine. 
[Many of the lobsters were captured in Nova Scotia and brought to Southport before laying their eggs.] 



No. 



1 
2-3 
4-8 
il-10 
11-16 
IT -Jl 
22-23 
24-25 



Place of spawning. 



Southport, Me 
do 



.do 
.do 
.do 
.do 
do 
do 



Date of 

exami- 
nation of 
eggs. 



1893. 
Sept. 7 
...do.... 
...do .... 
...do .... 
...do.... 

do .... 

.do .... 
.do .... 



Stage of development. 



Days. 
61 
35 
33 
30 
29 

Eye-spot, linear 27 

Before formation of eye pigment 25 

Egg nanplius, late stage 18 



Telson in front of optic lobes : Eye-spots oval . 

Eye-spots lenticular or nearly semicircular 

Eye-spot narrower than in X'os. 2-3 

Eye-spot, small crescent 

do 



of em- 
bryo. 



Date of 

extrusion | 

of eggs. 



July 8 
Aug. 3 
Aug. 5 
Aug. 8 
Aug. 9 
Aug. 11 
Au;r. 13 
Aug. 20 



44 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Table 9. — Time of spawning of the lobster at different points on the coast of Maine. 



No. 



Locality. 



1-2 

3 

4-7 

8 

9 

10 

11 

12-13 

14-n 

18 
19-20 
21 
22 
23 
24 
25-26 



1893. 

Vinal Haven Aug. 26 

do Aug. 28 

.do Aug. 31 

North Haven Aug. 28 

Vinal Haven Aug. 26 

do Aug. 31 

do do 

do do 

do Sept. 2 

do Aug. 26 

do Aug. 6 

do Aug. 31 

do Sept. 1 

Millbridge Aug. 26 

Vinal Haven | Sept. 2 

.do | Aug. 31 



Date of 

exami- 
nation of 
eggs. 



Stage of development. 



Eye-spot, small crescent . . . 
Late segmentation of yolk. 



Eye-spot a small crescent . 

..'..do 

.... do 

do 

do 

do 

Post-nauplius stage 

Eye-spot linear 

Post-nauplius stage 

do 

Egg nauplius 

do 

Segmentation of the yolk. 



Age 


i 

Date of 


of em- 


extrusion 


bryo. 


of eggs. 


Days. 




29 


July 28 


3 


Aug. 25 


33 


July 30 


29 


July 31 


29 


July 29 


29 


Aug. 2 


28 


Aug. 3 


29 


Aug. 2 


29 


Aug. 4 


21 


Aug. 5 


27 


July 10 


21 


Aug. 10 


21 


Aug. 11 


15 


Do. 


15 


Aug. 18 


li 


Aug. 29 



The results given in tables 8 and 9 are combined in table 10, which may be 
compared with table 7. in the first column, taken from table 8 (in which some of 
the lobsters were brought from Nova Scotia to South/port, Maine), all but three 
individuals extruded eggs during the first half of August. In the second column 
46 per cent laid eggs during the same period. Combining the results of the obser- 
vations at Woods Hole for five years, 1889-1893 (table 7), we find that 52 per cent of 
egg-bearing lobsters, in all cases observed, laid in the latter half of July, while about 
21 per cent spawned during the first half of July and an equal number in the first half 
of August. We find that 06 per cent of the individuals recorded in table 10 laid eggs 
during the first half of August. These results tend to show that the summer spawning 
season in the middle and eastern districts of Maine is about two weeks later than in 
Vineyard Sound. 

Table 10. — Time of spawning of the lobster on the coast of Maine for the summer of 1893. 



Spawning period. 



July 1-15 

July 16-31 

August 1-15 

August 16-31 

Number examined 



Data from 
table 8. 



Data from 
table 9. 



Totals. 



1 


2 


3 





8 


8 


22 


12 


34 


2 


4 


C 


2S 


26 


51 



FALL AND WINTER EGGS AT WOODS HOLE. 

The catch of egg-bearing lobsters in the harbor of Woods Hole for seven consecu- 
tive months is given in table 11. Out of a total of 168 captured, 21 per cent were 
taken in January, 6 per cent in February, and 20 per cent in April. Of the entire 
number, 25.5 per cent bore eggs which had been laid during the fall and winter months. 
This fact was determined in the following way. Some of the eggs of every lobster 
captured were preserved and carefully examined. Where no eye pigment was present 
it was at once evident that the eggs had been laid at a comparatively recent date. In 
all other cases the pigmented areas of the eyes were drawn to scale and compared with 

'For the collection of eggs at various points on the coast and islands north of Massachusetts I 
am particularly indebted to Messrs. F. W. Collins of Rockland, M. B. Spinney of Cliffstone, J. W. Fisher 
of Eastport, and also to Mr. Greenleaf of Vinal Haven, Maine. 



THE AMERICAN LOBSTER. 



45 



a series of similar drawings of embryos developing under normal conditions from 
summer eggs. 

The eye pigment furnishes the most convenient scale for the measurement of the 
rate of development of the embryo as a whole, since it appears early, is clearly dehued, 
and since the development of the eye is correlated with that of the other organs of the 
body. Where the ocular pigment forms a thin crescent in eggs taken in January, 
the embryo will be found in a stage of development similar to that reached in the 
summer eggs four weeks after fertilization. In such a case, it is a safe inference that 
the ova have been laid in the fall. Again, when in May or early June the area of 
ocular pigment is not greater or is less than that observed in summer eggs by the first 
of September (cut 36, pi. J), we may be confident that such eggs were extruded later 
than the previous summer. 

Table 11. — Number of ego-lobsters taken at Woods Hole. {See table il.) 



Females 

Females ! with eggs 

Time. with eggs. ' laid in 

(b) July and 

1 August. 


Females \ 
with eggs p er „ ent ._ fi 
laid out of fSffigf? 

season. 
'(a) 


1893. 


22 

36 
11 
12 
33 
34 
20 


17 

24 
9 
9 
26 
26 
13 


5 

12 
2 
3 

7 
8 
7 


22.7 

33J 

18 

25 

21 

23.5 

35 


1894. 












Total 


168 


124 


44 


25.5 





Table 12 shows the stage of development of the eggs of 41 lobsters taken under 
the conditions described (p. 25) and compared with the normal condition of summer 
eggs shown in table 18, lobster jSTo. 3 (1) to (20). These comparisons are rendered 
clearer by a series of drawings (cuts 23-38) made from the eggs of this lobster. 

Table 12. — Stage of development of eggs laid in fall and winter at Woods Hole. 







Length 










Length 




No. 


Date. 


in 


Stage of development. 


No. 


Date. 


m 


Stage of development. 






inches. 











inches. 






1893. 






1894. 






1 


Dec. 20 


10i 


No eyo pigment. Like stage 3 


22 


Mar. 


15 


9* 


Like 3 (11), table 18. 








(7), table 18. 


23 


Apr. 


16 


10 


Little earlier than 3 (10) , table 18. 


2 


Dec. 23 


9J 


Forked telson overlaps brain. 


24 


Apr. 


17 


10 


Like 3 (9), table 18. 








Like preceding. 


25 


Apr. 


17 


10 


Little earlier than 3 (10), table 18. 


3 


Dec. 25 


8 


Like 3 (11), table 18. 


26 


Apr. 


18 


11 


Little earlier than 3 (9), table 18. 


4 


Dec. 26 


10i 


Like 3 (7), table 18. 


27 


Apr. 


19 


81 


Like 3 (91, table 18. 





Dec. 27 


8 


Trifle later than 3 (9), table 18. 


28 


Apr. 


20 


10§ 


Like 3 (10), table 18. 




1894. 






29 


Apr. 


21 


9 


Little earlier than 3 (9), table 18. 


6 


Jan. 1 


IU 


Like 3 (9), table 18. 


30 


May 


1 


lOi 


Little earlier than 3 (10), table 18. 


i 


Jan. 2 


9i 


Like 3 (10), table 18. 


31 


May 


1 


7J 


Like 3 (10), table 18. 


8 


Jan. 3 


m 


Like 3 (9), table 18. 


32 


May 


3 


10J 


Little earlier than 3 (9), table 18. 


9 


Jan. 3 


9* 


Like 3 (11), table 18. 


33 


May 


8 


9J 


Like 3 (9), table 18. 


10 


Jan. 4 


9 


Eye pigment just visible. 


34 


May 


9 


10 


Like 3 (9), table 18. 


11 


Jan. 9 


10 


Like 3 (6), table 18. 


35 


May 


10 


10 


Little later than 3 (9), table 18. 


12 Jan. 11 


10J 


Like 3 (10), table 18. 


36 


May 


11 


7 


Little later than 3 (9), table 18. 


13 Jan. 12 


10 


Like 3 (10), table 18. 


37 


Mas- 


12 


9 


Little earlier than 3 (9), table 18. 


14 I Jan. 13 


10 


Like 3 (9), table 18. 


38 


June 


7 


9 


Like 3 (11), table 18. 


15 


Jan. 20 


9 


Like 3 (10), table 18. 


39 


June 


i 


11 


Like 3 (11), table 18. 


16 


Jan. 27 


10 


Like 3 (10), table 18. 


111 


June 


9 


8} 


Like 3 (11), table 18. 


17 


Jan. 31 


10 


Like 3 (9), table 18. 


41 


June 


8 


11 


Little earlier than (11), table 18. 


18 


Feb. 19 


94 


Like 3 (11), table 18. 


42 


June 


11 


10J 


Like 3 (11), table 18. 


19 


Feb. 5 


9 


Like 3 (9), table 18. 


43 


Juue 


12 


10 


Like 3 (11), table 18. 


20 


Mar. 10 


10J 


Like 3 (11), table 18. 


44 


June 


14 


9 J 


Like 3 (11). table 18. 


21 


Mar. 13 


10i 


Like 3 (11), table 18. 













46 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



FALL AND WINTER EGGS IN OTHER PLACES. 

The conclusion that the production of eggs in the fall and winter is of general 
occurrence throughout the entire range of the lobster is supported by the observations 
recorded in table 13. Here are eggs, none of them laid during the summer months, 
coming from a wide area from the middle and eastern parts of the Maine coast, from 
the outward islands, and from the province of New Brunswick. They are compared, 
as before, with the rate of development of summer eggs observed at Woods Hole 
[lobster No. 3 (1) to (20), table 18]. In one instance, No. 20, the yolk is uusegmented, 
though taken in February; in others the egg nauplius, which in summer appears at 
about the fourteenth day, is barely outlined. 

Table 13. — Stage of development of eggs laid in fall and winter on the coasts of Maine and Province of 

New Brunswick. 



No. 



Bate. 



1893. 
Nov. 10 
Nov. 15 



3 Nov. 25 



Locality. 



Isle au Haute . 
York Island - - 



4 


Bee. 


11 




1894. 


5 


Jan. 


11 


6 


Jan. 


13 


7 


Jan. 


15 


8 


Jan. 


17 


9 


Jan. 


18 


10 


Jan. 


18 


11 


Jan. 


19 


12 


Jan. 


20 


13 


Jan. 


20 


14 


Jan. 


21 


15 


Jan. 


22 


16 


Jan. 


24 


17 


Jan. 


27 


18 


Jan. 


29 


19 


Jan. 


17 


20 


Feb. 


4 



Cranberry IsU' 



Matinicus Island 



Beaver Harbor. Bay 

of Fundy. 

Mount Desert 

Cranberry Isle 

Isle aa Haute 

Eastport 

Musquash Bay, 35 m. 

east of Eastport. 
Seeley Basin, 24 m. 

from Eastport. 

Baker Island 

Otter Creek 

Eastport 



Stage of 
development. 



10 miles from St. 

John, N. B. 
18 miles from St. 

John, N. B. 
Brimstone Isle 



Isle au Haute 

Spoon Island 

Matinicus Island 



Like 3 (9). 

Late segmen- 
tation of 
yolk (?)■ 

Egg nauplius. 
Earlier than 
4(3). 

Like 3 (9). 

Like 3 (10). 

Like 3 (9). 
Like 3 (10). 
Like 3 (9). 
Like 3 (10). 
Like 3 (9). 

Like 3 (10). 

Like 3 (10). 
Like 3 (9). 
Eye pigment 
just visible. 
Like 3 (10). 

Like 3 (10). 

Like3(4).Late 
egg nauplius. 

Like 3 (6). 
Like 3 (9). 
Yolk un seg- 
mented. 



No. 



Date. 



1894. 

Feb. 5 

Feb. 8 

Feb. 10 

Feb. l'O 

Feb. 14 

Feb. 17 

Feb. 21 

Feb. 22 

Mar. 1 

Mar. 1 

Mar. 10 

Mar. 13 

Mar. 15 

Mar. 20 

Mar. 22 

Mar. 27 

Mar. 29 

Mar. 30 

Apr. 1 

Apr. 5 

Apr. 10 

Apr. 1 5 

Apr. 24 

Apr. 26 

Apr. 30 
Apr. 30 
May 1 
June 10 
June 8 
June 13 
June 20 



Locality. 



Matinicus Island .... 

Ragged Island 

Isle au Haute 

Isle au Haute 

Long Island 

Matinicus Island 

Mount Desert 

Cranberry Isle 

Cranberry Isle 

North Haven 

Isle au Haute 

Matinicus Island 

York Island 

Cranberry Isle 

Ragged Island 

Fox Island 

Matinicus Island 

Brimstone Island 

Swan Island 

Fox Island 

Eastport 

Baker Island 

Eastport 

Deer Island, 4 miles 
from Eastport. 

Eastport 

Islesboro 

Green Island 

Matinicus Island 

York Island 

Vinal Ilavea 

High Island 



Stage of 
development. 



Like 3 (10). 
Like 3 (8). 
Like 3 (10). 
Like 3 (9). 
Like 3 (4). 
Like 3 (10). 
Like 3 (8). 
Like 3 (9). 
Like 3 (10). 
Like 3 (5). 
Like 3 (10). 
Like 3(9). 
Like 3 (9). 
Like 3 (9). 
Like 3 (9). 
Like 3 (9). 
Like 3 (9). 
Like 3 (11). 
Like 3 (9). 
Like 3 (10). 
Like 3 (10). 
Like 3 (10). 
Like 3 (10). 
Like 3 (Hi. 

Like 3 (11). 
Like3 (11). 
Like 3 (11). 
Like 3 (9). 
Like 3 (9). 
Liko3 (10). 
Like 3 (11). 



Mr. N. F. Trefethen, of Portland, who deals extensively in lobsters, and who has 
a lobster pound in South Bristol, 35 miles east of Portland, believes that some lobsters 
in that vicinity spawn in June. In support of this view he cited the following case: 
In the latter part of May, 1893, he placed 20,000 lobsters in his pound and took them 
all out at intervals in the month of July, beginning the first of the month. All the 
lobsters had been examined before they were placed' in the pound, and none of them 
were known to be with spawn. At the most only a relatively few egg-lobsters could 
have been put into the pound by accident. When taken out about one-third of the lob- 
sters had spawn attached to the body. It is thus evident that some of these females 
must have laid their eggs in June or in the first part of July. No tally was kept of 
the proportion of egg-lobsters taken out during the first part, the middle, aud the 
latter part of July, and it is possible that the great number of egg-lobsters, which 



THE AMERICAN LOBSTER. 17 

caused surprise, may have laid their eggs during the last half of July, and thai very 
few in reality extruded their eggs during the firsl part of this month. It is not 
probable that any eggs were laid in June. 

In the second week of August, 1893, a vessel came into Portland, Maine, bringing 
lobsters from Seguin island and Georgetown. Very few lobsters were at this time 
i August 13 to 20) with spawn. 

I have been told by fishermen and others that lobsters are sometimes taken out 
of the wells of smacks in winter with very dark, external eggs, when it had been the 
rule to carefully exclude every egg-lobster in loading the boat, the inference being 
that lobsters had laid while in the well. Allowing a wide loophole for error in such 
cases, it is very evident from the facts already recorded that this is quite likely to 
happen. 

Mr. Nielsen gives the spawning period for lobsters in Newfoundland as extending 
from the 20th of July to the 20th of August (Annual lieport of the Newfoundland 
Fisheries Commission, 1892), but also states, in reply to certain questions which I 
endeavored to have answered, that lobsters were taken with newly laid eggs up to 
the latter part of September. 

The spawning months for the lobster in Prince Edward Island are said to be July 
and August. We have no data whatever upon the spawniug habits of the lobster on 
the coast of Labrador, or in the extreme southern parts of its range. 

Considering the fact that the lobster is distributed through 20 degrees of latitude, 
there is less variation in the time of spawning than might be expected. 

THE LAYING OF THE EGGS AND THE ABSORPTION OF OVARIAN OVA. 

I have not seen the process of egg extrusion and consequently have no direct 
observations to record. It has, however, been witnessed in other Crustacea where it is 
undoubtedly similar. In two instances lobsters have laid eggs while kept in small 
aquaria in the laboratory of the United States Fish Commission. Since these animals 
were under constant surveillance during the day, it is almost certain that the eggs 
were deposited in the night or early morning, as is the well-known habit of many 
decapods. In each case the mother lobster scratched off nearly all of her eggs in the 
course of a few days. 1 In other attempts to observe this process, where the eggs seemed 
to be overdue, I dissected the animals and found that the ova were retained and partially 
absorbed. This led to other attempts with similar results. 

Two "ripe" female lobsters, measuring 11.5 and 9 inches, respectively, were cap- 
tured July 30 in Woods Hole Harbor, and placed in a large floating car, which was 
kept covered so that the lobsters were not exposed to direct sunlight. Fifteen days 
later, August 14, their ovaries were examined. In the smaller individual more than 
half the ovarian eggs, which were overdue, were in various stages of degeneration, 
thus giving the ovary a remarkable appearance. Instead of the uniform dark green 
hue, it was of a light yellow or straw color flecked with darker green areas, where 



1 Ehrenbaura (61, p. 287), who mentions a single case of a female lobster -which was found lyiug on 
its back shortly after the eggs had been extruded from the body, says: "The mass of eggs lay in the 
mold formed by the folded abdomen without being fixed, since the cement bad not as yet hardened. 
When the animal, in consequence of a disturbance, soon made movements and tried to get upon its 
feet, most of the eggs were left at the bottom of the aquarium, and only a small uumber were already 
so firmly fixed that they clung to the swimming feet.'' 



48 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

the eggs had not yet broken down. The ovary of the larger lobster was similar to 
this, but the process of histolysis had not advanced quite so far. 

The eggs are sometimes absorbed under natural conditions, but why this happens 
is not understood. A very interesting illustration of this fact came to hand on July 
16, 1894, when, on account of its very dark color, my attention was directed to a 
hardshell female lobster, about 11 inches long. The membranes of the joints of the 
limbs and under surface of the body were of a dull-green color, very unlike the 
appearance which these parts assume in a molting lobster. Examination showed 
that the ovarian eggs were almost completely absorbed and that the blood of the 
animal had a very distinct greenish tinge. The ovary was of a bright lemon-yellow 
tint, the color of the degenerated eggs, flecked lightly with green, where an egg had 
not lost its normal appearance. The ovarian lobe had shrunken to less than one half 
its former size. The green pigment which was dissolved in the blood had undoubtedly 
come from the eggs, and had been taken up into the blood faster than it could be 
eliminated from it. I was told by Professor Eyder that the ovarian eggs of the 
sturgeon are sometimes absorbed in a similar way, and the same phenomenon is 
probably met with throughout the animal series. 

In the lobster there are always a few ripe ovarian eggs which fail of extrusion at 
the proper time, which are invariably absorbed and give to the mature ovary at the 
next reproductive period a characteristic appearance. (See p. 69 and plate 38, 
fig. 136.) 

One of the females which laid eggs had been kept by herself for several weeks. 
When discovered, on August 21, the ova were in an advanced stage of yolk segmen- 
tation. They were somewhat undersized and of a peculiar light-grayish color. The 
eggs were fertile, although the segmentation was generally abnormal. The lobster, 
which was placed in an aquarium on July 30, was found to have external eggs on the 
11th of August, in a very early stage of development. They had probably been 
extruded during the previous night. These eggs were rapidly attacked by fungi and 
their development was retarded in consequence. Long fungoid filaments grew over 
the surface of the eggs, and diatoms attached themselves in great numbers to the 
egg-capsule. The eggs of lobsters taken under natural conditions are always clean 
and, so far as I have observed, free from vegetable growths of every kind. 

The eggs are fertilized after ejection from the oviducts by the spermatozoa, a 
supply of which is always stored up in the seminal receptacle of the female. There is no 
internal copulation, and no possibility of an internal fertilization in either the ovaries 
or their ducts, as already explained (p. 39). The ova are probably immersed as soon as 
they are extruded, in a liquid cement substance, which is secreted in special glands 
situated in the swimmerets of the female. The "tail" is folded so as to form a closed 
pouch or chamber, as has been observed in the crayfish and other decapods (see 
note 1, p. 47), and the eggs received within it are mixed with the liquid cement and 
sea water. Fixation to the hairs of the swimmerets is finally effected by means of the 
cement, which gradually hardens. How the sperm cells are conveyed from their 
receptacle to the eggs, whether through the medium of the sea water or the glue, or 
whether or not by a motion of their own, is not definitely known. (Page 34, note 1.) 

That the cement is incapable of fixing and holding the eggs until after exposure 
to sea water for some time (perhaps a few hours) was shown in the case of a lobster 






THE AMERICAN LOBSTER. 49 

taken from the well of a lishing smack, after extrusion had been partially accomplished, 
at Rockland, Maine, August t>, 181)3. The lobster, 1 was told, was taken out and laid 
on the deck, when the soft, dark-green mass of eggs began to flow away from the body 
from their own weight. (Compare note 1, p. 47.) 

Cano (32) gives the following detailed account of the laying of the eggs in the 
crab Maia : 

The time tb;it intervenes between copulation and the doposit of the eggs inay be eight, ten, fifteen 
days, or even longer, and can not be fixed, since copulation happens before the eggs mature in the 
ovary. The eggs, at the time of ovulation, pass the opening of the reccptaculum seminis, and are here 
invested with a coat of cement, which is secreted and held in the receptacle. The eggs then revolve 
on their axes in the vaginal canal, and are expelled, one at a time, by means of the valvular apparatus. 
This is formed by a prolapsus of the vaginal canal. Besides the proper muscles of this canal 

there exist spocial muscles which, by lowering the membranous covering, provoke the expulsion of 
the eggs through the valvular orifice. The eggs thus ejected fall into the abdominal chamber. The 
female beats them about with repeated blows of the tail, while the pleopods, keeping them in 
continued agitation, make them converge toward the center of the abdominal pouch. The deposition 
of eggs is effected in Maia in the course of twenty-four hours, but sometimes in Lissa it takes a longer 
time. On the next day all the eggs adhere in groups, by means of one or two peduncles, to the hairs 
of the internal branches of the pleopods, while the external branch agitates them continuously. 
This movement, besides renewing the surrounding water, probably assists in rupturing the egg shell, 
when the embryos are ready to hatch. Fixation could not be explained without the interaction of 
the sea water. The cement at first becomes more viscous, then hardens and forms a very thin pellicle, 
which, with the growth of the embryo, becomes quite hard and resistant. It would seem that the sea 
water might explain the chemical change which the cement undergoes, a change analogous to that 
which is observed in the exoskeleton after the molt. The cement may be regarded as a substance 
very like chitin, both being of ectodermic origin. The cement serves not only for fixation, but 
unquestionably as the vehicle of the seminal elements toward the eggs. 

If we examine the zone of cement which invests the eggs at the moment the latter traverse the 
short vaginal canal, there is seen a large quantity of seminal corpuscles, some of these still in the 
spermatophoral envelope, others free and swimming in the homogeneous mucus. These vary both in 
shape and dimensions. All the elements are immobile, but once I noticed that some of these cells, 
especially those with radial prolongations, were endowed with amoeboid movements. Whether these 
movements are the same as those which impel the sperm into the egg I can not say from direct observa- 
tion. The question then remains open as to when and how the spermatozoa pass into the eggs, which are 
unprovided with a micropyle. If they are able to penetrate through the poral canals of the chorion, 
and if this penetration can happen during the very brief passage of the egg through the vaginal 
canal or at the moment of deposition of the eggs, as in the Macrura, then the sea water must exert 
unknown physico-chemical actions on the cement, which makes the egg itself adhere later to the hairs 
of the pleopods. 

The typical phenomena of fecundation — the expulsion of the polar bodies and formation of 
pronuclei — I have not been able to observe directly. 

When the eggs have reached the receptaculum seminis the nucleus has become invisible. The 
first segmentation nuclei are found in the central part of the eggs and move toward the periphery. 
Segmentation begins almost as soon as the eggs are fixed. 

Cano (33) observed cases in Carcinus and Portunus where the eggs were laid at 
different periods, one-third of the eggs being in the morula stage and the rest ready 
to hatch. Again, it was rarely found that the eggs were laid just before the molt, in 
which case they were cast off and destroyed. This anomalous condition was first 
noticed by Lo Bianco in Palinurus (18). 

!■'. C. B. 1895—1 



50 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



NUMBER OF EGGS LAID AND THE LAW OF PRODUCTION. 

The production of ova among animals is directly correlated with the condition of 
the young at the time of hatchiug. Where eggs are very small and present in large 
numbers, as in some of the crabs, we may look for a long larval period ; when the ova 
attain a much greater size and are at the same time very abundant, as in the lobster, 
we And the larval period abbreviated; in other cases, as in some shrimps, where eggs 
are relatively very large and few, the young hatch with the external characteristics of 
the adult. 

The production of a large number of eggs always means great destruction under 
natural conditions. In such cases, however, the opportunity is afforded of increasing 
the supply of adults, provided we are able to tide the larvae over their earlier stages 
of development. The number of eggs produced by the lobster is thus a subject which 
deserves careful attention in view of its economic bearings alone. 

The numbers here recorded are based upon the records kept at the United States 
Fish Commission station. The eggs of each individual were carefully removed from 
the "tail" of the female lobster and measured in a graduate (having sloping sides), 
and the whole number of ova was estimated on the basis of the number contained in a 
fluid ounce. .Mr. Edwards found the number of new eggs in one fluid ounce to be about 
6,440 (in one ounce 6,461, in another 6,419), and the number of old or well-developed 
eggs in an ounce to be 6,090. This is a relatively rough method of determination, and 
the results are of course only approximately accurate. 

I estimated by weight the number of fresli eggs carried by a lobster 13 inches long 
to be 17,623; total weight of eggs, 54.9 grams; number of living eggs to the gram, 321. 
These eggs were in an early stage of development. 

The number of eggs borne by a large and a small lobster, carefully determined 
both by the wet and dry methods by my assistant, Mr. F. C. Waite, is given in the 
following table: 

Table 14. — The production of eggs determined by different methods. 



Observations. 


Lobster No. 51, 

table 20 ; from 

Gay Head. 


Lobster No. 69, 

table 20 ; from 

Woods Hole 

Harbor. 




Late segmen- 
tation. 

15J 

815 
1. 2255 
68. 8092 
220 
6,248 


Post-nauplius; 
about three 
■weeks old. 
94 
1,009 

0. 9893 
10. 4029 
211 
5, 992 
10, 507 
10, 514 
10, 919 














Number of eggs determined by the dry method (a) . 
Number of eggs determined by the dry method (b) . 
Number of eggs determined by the wet method (c) . 


56, 079 
56, 148 
58, 500 



Mr. Waite estimated the number of eggs in a fluid ounce (en the basis of 2,110 
to 10 c.c, the number obtained by count) to be 5,992. These eggs had been in strong- 
alcohol for upwards of three years. They were about three weeks old when preserved, 
and in alcohol had an average diameter of 1.625 mm. (1.56, 1.69 mm.) 

In the wet method (c) employed, the number of eggs was estimated upon the 
actual number, obtained by counting, in 10 c, c. In the dry method the number was 



THE AMERICAN LOBSTER. 



51 



determined either (a) on the basis of the number of eggs to the grain, or (ft) by the weight 
of 1,000 eggs. The numbers obtained by the last two methods agree very closely, and 
it is plain that the dry method is the most reliable. The wet method gives a number 
which is from 3 to 4 per cent greater than that obtained by the dry method. There 
is probably a constant error of this amount in the wet method, 1 and this slight error is 
due to the presence of the stalk of the secondary egg membrane, which has a tendency 
to keep the wet eggs apart, but which shrivels and cracks oil' when dry. It increases 
the buoyancy of the fresh eggs and is the cause of the bunching commonly observed. 
The excess due to the bunching of the eggs is about 0.3 per cent. This source of error 
was eliminated in No. 09 of the table, where the eggs were separated with needles 
before measuring. 

THE LAW OF PRODUCTION. 

In table 15 I have reduced the results of a very large number of observations 
made upon lobsters varying from 8 to 19 inches in length. The total number examined 
is 4,045. Of these, 1,078 were taken on the ledges 1 5 miles southwest of No Man's Land 
Island from April 20 to June 16, 1894. The remaining 2,967 were captured in Vineyard 
Sound and in the vicinity of the Elizabeth Islands from April to June, 1889-94. A 
smaller number were taken in February during the same years. The eggs went to 
supply the hatchery of the United States Fish Commission. 



Tahle 15. — Production of eggs. 



Length of 

lobster. 


Smallest, 
number 


Largest 
number 


Average 
number 


Number of 
lobsters 


Length of 
lobster. 


Smallest 
number 


Largest 
number 


Average 
number 


Number of 
lobsters 




oi eggs. 


of eggs. 


of eggs. 


examined. 


of eggs. 
6,090 


of eggs. 


"f eggs. 


examined. 


8 inches 


3,045 


9,135 


4,822 


6 


13 inches 


48, 720 


28, 610 


321 


8^ inches 


6,090 


7.612 


6,851 


2 


13J inches 


24,360 


48, 720 


33, 495 


5 


8J inches 


3, 045 


12, 180 


6, 935 


9 


13i inches 


6,090 


54, 810 


32, 858 


146 




6,090 


9,135 


7,105 


3 


13J inches 


42, 630 


42, 630 


42, 630 


2 




3,045 


18, 270 


7,902 


143 


14 inches 


6, 090 


85, 260 


36, 960 


426 


9£ inches 


6.090 


12, 180 


9,083 


35 


14A inches 


21,315 


00, 900 


42, 968 


90 


9A inches 


3,045 


20, 792 


9,297 


241 


15 inches 


12,180 


97,440 


46, 524 


280 


9J inches 

10 inches 


3,045 
3.045 


15, 225 
24, 360 


9.947 
10, 555 


55 
514 








54, 810 

53,795 


1 

45 


15i inches 


24,360 


97,440 


lOJiuches 


6,090 


22, 838 


11.622 


61 


15|- inches 


48, 720 


54, 810 


50, 750 


3 


10A inches 


3,045 


36, 540 


12, 905 


532 


16 inches 


24, 360 


97, 440 


57, 146 


103 


10| inches 


6,090 
3,045 


24, 360 

48, 720 


14, 067 
15.410 


45 
568 








66, 990 
66, 053 


1 
13 


16& inches 


36, 540 


85, 260 




6,090 


25, 882 


17, 102 


43 


17 inches 


12. ISO 


85, 200 


63, 336 


30 


lli inches 


3,045 


42, 630 


18, 668 


307 


17A inches 


60, 900 


73, 080 


64, 960 


3 




12, 180 


24, 360 


17, 993 


11 


18 inches 


60, 900 


91,350 


77, 430 


7 


12 inches 


3,045 


54, 810 


21, 351 


414 


19 inches 


54. 810 


91, 350 


77,647 


4 


12£ inches 

123 inches 


18, 270 
9,135 
18, 270 


27, 405 
42, 630 
.42. 630 


23, 396 
24,812 
26, 390 


8 

156 

12 


Total num 


her exami 


ned 






4,645 

i 







The average number of eggs of a lobster %f a given length has little value unless 
obtained from a large number of individuals. While the small number of eags 
occasionally recorded for lobsters over 12 inches long may be the result of loss, in 
lobsters under this size it is probably, more often due to belated sexual maturity. 

1 This excess will probably about offset the slight loss of eggs which must always occur. The 
numbers given in table 15 do not therefore require correction on this account. 



52 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



In casting tbe eye down the column of averages ' in table 15, we are immediately 
struck by the fact that a 10-inch lobster bears about twice as many eggs as one 8 
inches long, and that a 12-inch lobster has double the number borne by one which 
measures 10 inches. 

It is therefore suggested that in the early years of sexual vigor there is a general 
law of fecundity or production which may be formulated in this way: The numbers of 
eggs produced by female lobsters at each reproductive period vary in a geometrical series, 
while the lengths of the lobsters producing these eggs vary in an arithmetical series. It is 
safe to assume that the avearge number of eggs laid by a lobster 8 inches long is not 
above 5,000. If such a law prevails we would have the following: 



Terms. (1) 


(2) 


(3) 


(I) 


(5) 


(6) 


Series of lengths in inches. . 8 
Series of eggs 5,000 


10 
10, 000 


12 
30, 000 


14 

40, 000 


16 
80, 000 


18 
160, 000 



An examination of table 15 shows how closely the first four terms of this series 
are represented in nature, and that when the 14 to 10 inch limit is reached, there is a 
decline in sexual vigor. Yet the largest number of eggs recorded for lobsters of 

Length of 

animal in inches 
is 



10 



14 



12 



to 



O I I 1 I I /l I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I II I I I I I Ill 

O ,'\ lOOOO 20000 30000 4QOOO 50OOO OOOOO lOOOO 80000 Eggs 




Cut 1. — Curve of fecundity of the lobster. 

I division on ordinate corresponds to 2 inches m length of lobster. 1 smaller division on abscissa represents 1,000 eggs. 

aa, curve deduced from law of production as theoretically stated. 

bb, curve of fecundity deduced from observations recorded in table 15, for lobsters 8, 10, 12, 14, and 16 inches long. 

this size shows that there is a tendency to maintain this high standard of production 
even at an advanced stage of sexual life. 



1 It is a conspicuous fact that in the fifth column of table 15 the largest numbers refer to 
individuals whose length is expressed in even inches or half inches. This is of course the result 
of inaccuracy in taking measurements: the quarters have been somewhat neglected. 



THE AMERICAN LOBSTER. 



53 



A graphic representation of the fecundity of the lobster tells more forcibly than 
words or figures can how closely it is in conformity with the law just enunciated. If 
a curve is constructed in accordance with the latter, we obtain, as in cut 1, the curve 
aa, which is the wing of a parabola. Neglecting for the present all data in table 15 
but those corresponding to the arithmetical series of lengths, 8, 10, 12, 14, 16 inches, we 
obtain the curve of fecundity represented by the dotted line bb, cut 1. This curve is 
parabolic and follows the curve aa with remarkable uuiformity up to the region of the 
fourth term, where the ratio of production is distinctly lessened. This becomes still 
more marked in the fifth and sixth terms. 

In cut 2 the details of the curve bb are given, including all the data of the table. 
We see in the line bb 1 the same remarkable conformity to the parabolic curve required 
by the law. Beyond the fourth term (length 14 inches) the irregularities in the curve 
become greatest, owing to the small number of individuals represented. 

I believe the law above formulated expresses the propagative powers of the lobster 
during the height of its sexual activity, although it must not be supposed that the 
latter conforms uniformly to any arithmetical standard. 



Length of 



im 

19 
18 
17 
16 
15 
Lb 
13 
12 


mat in 


inches 












b' 




l 














\ 




; 


















- 
















, f 


1 












_...--- 


..---"" 




\ 








r . --"' 


,.-—''' 














** 












; 




_/ r "" 
















/, 
J 
















10 
9 
8, 




















J_ 


















~i i i i VTi i i 


1 1 1 1 1 1 1 1 1 


i 


1 1 1 1 1 1 1 1 1 


i ■ ii 


1 1 1 1 


iii 


in 


1 1 



O I \ lOOOO 20000 3O000 40000 50000 60O0O 7OO00 8000 O Eggs 
b' a 

Cut 2.— Curve of fecundity of the lobster. 

4 smaller divisions on ordinate correspond to 1 inch in length of lobster. 1 smaller division on abscissa represents 
1.000 eggs. 

aa\ curve deduced from law of production as theoretically stated. 

66', curve of fecundity deduced from all the data contained in table 15, or from number of eggs produced by 4 645 
lobsters. ' 

After the lobster has reached a certain age, determined by its early or late sexual 
maturity, its reproductive energy tends to decline, as is the case with the higher 
animals, and the ratio of increase, maintained at an earlier period, begins to fall. 
Whether the highest point of production is ever reached at 14 or 1G inches it is 



54 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



difficult to say, and whether the sexual decline is gradual or not it is impossible to 
decide from the data at hand. In this connection, however, it is interesting to recall 
the fact that the male lobster attains greater size than the female. The large lobsters, 
weighing upward of 20 pounds and measuring upward of 20 inches in length, are 
invariably males, so far as my observation extends. 

The largest egg-bearing lobsters of which I have any record were taken 15 miles 
southwest of No Man's Land, June 9, 1894, and examined by Vinal N. Edwards. One 
19 inches long, carried 91,350 eggs, which weighed 15 ounces; another, 16 inches in 
length, bore 97,110 eggs, which measured 16 fluid ounces and weighed nearly a 
pound. Mr. Edwards said that the mass of eggs was in these cases so great that the 
animals were unable to completely fold their "tails." (See p. 34.) A lobster with 
external eggs was taken at Green Island, Maine, in November, 1892, which, according 
to Mr. F. W. Collins, weighed 18£ pounds. 

Individuals 



115 
HO 
105 
100 
95 
90 
85 
BO 
75 
70 
65 
60 
55 
50 
45 
40 
35 
30 
25 
20 
15 
lO 
5 
t 




















































































































1 '* 1 










1 ' I 


























1 










1 










I 




















1 










1 









































lOOO 5000 lOOOO 15000 20000 25000 Eggs. 

Cut 3. — Curve showing the relative fecundity of 352 lobsters, each 10 inches long. 

Number of individuals laid off on ordinate. 
Number of eggs laid off on abscissa. 

The No Man's Land lobsters seemed to carry rather more eggs than those of the 
same length captured elsewhere. Thus 234 lobsters, 13 inches long, from No Man's 
Land produced on the average 29,526 eggs (extremes 6,090-48,720), while for 79 
lobsters caught elsewhere the average production was 26,518 (extremes as above). 
The small number examined in the last instance shows, however, that the comparison 
has little or no value. 

The variation in the number of eggs borne by lobsters of the same length is often 
very great, and is as marked in large as in small individuals. Thus in 152 cases the 
average production of lOJ-inch lobsters was about 11,000 eggs (the average in 532 
cases, table 15, is nearly 13,000); 32 per cent of this number bore from 12,000 to 13,000 



THE AMERICAN LOBSTER. 



55 



eggs; 15 per cent carried from 15,000 to 16,000; 6 per cent had 18,000 to 19,000; one 
individual carried upward of 21,000, while 4.0 per cent bore only 3,000 to -1,000. This 
is further illustrated by cut 3, which shows the variation in fecundity of 352 lobsters 
each 10 inches long. In this case 20 per cent laid 9,000 eggs, 30 percent 12,000, not quite 
1 per cent 18,000. The curve drops and keeps well down after the 12,000 limit is 
reached, which possibly implies a loss of eggs in those lobsters having more than the 



average number. 



Table 16. — Production of eggs by volume. 



Length 
of lobster. 



8 inches 
8^ inches 
8J inches 
8J inches 

9 inches 
9J inches 
9A inches 
9| inches 

10 inches 
10.} inches 
lOt inches 
lOf inches 

11 inches 
11 J inches 
11J inches 
11"; inches 

12 inches 
124, inches 
12. V inches 
122- inches 



Smallest Largest 

number | number 

of 11 aid j of tin id 

ounces, ounces. 



Average 
number 
of fluid 
ounces. 



.78 
1.12 
1.14 
1.17 
1.30 
1.50 
1.53 
1.63 
1.73 
1.91 
2.12 
2.31 
2.53 
2.79 
3.06 
2.95 



Number 
of lobsters 
examined. 



6 

2 

9 

3 

143 

35 

241 

55 

514 

61 

532 

45 

568 

43 

307 

11 

414 

8 

156 

12 



Length 
of lobster. 



13 inches. 
13 J inches. 
13.;, inches. 
13^ inches. 

14 inches. 
14i inches. 
15" inches . 
15 J inches. 
15J inches- 
15! inches. 

16 inches. 
164, inches, 
ltii inches. 

17 inches. 
17A inches. 
18" inches - 
19 inches. 



Smallest 
number 
of fluid 

ounces. 



6 
2 

10 

10 



Largest 
number 
of fluid 
ounces. 



Total number examined. 



Average 
number 
of fluid 
ounces. 



4.70 
5.50 
5.39 
7.00 
6.07 
7.05 
7.64 
9.00 
8.83 
8.41 
9.38 
11.00 
10.85 
10.40 
10.67 
12.71 
12.75 



Number 
of lobsters 
examined. 



321 

5 

140 

2 

426 

90 

280 

1 

45 

3 

103 

1 

13 

30 

3 

7 

4 



4,645 



The data collected in table 16 will show in still another way the variation in the 
quantity of eggs produced by lobsters of different sizes. The average weight of a 
lOi-inch female lobster with eggs is If pounds (table 31), the eggs weighing about 
2 ounces. A 15-inch lobster which weighs upward of 4 pounds (table 31), sometimes 
carries a burden of a pound of eggs. As already remarked, a fluid ounce of fresh 
eggs weighs about 1 ounce avoirdupois. 



PERIOD OF INCUBATION AT WOODS HOLE AND RATE OF DEVELOPMENT. 

The freshly laid eggs are somewhat irregular in shape, but soon plump out and 
become nearly spherical. Some, however, have the form of elongated spheroids (plate 
17, fig. 24). They measure approximately -^ inch in diameter, or 1.5 to 1.7 mm. In 
color they are dark olive-green, 1 sometimes almost black, hence the use of the term 
"black egg-lobster," common among fishermen, to distinguish the "new egg- lobster" 
from the "old" or the "light egg-lobster," in which the dark-green food yolk has 
been more or less absorbed by the growing embryo. In England the female lobster 
with external eggs is spoken of as being "in berry," or is sometimes called a "berried 
hen." 

The rate of development of the summer eggs at Woods Hole is illustrated by 
tables 17 and 18, and by cuts 23-38 (plates G to J). 



1 For variation in the color of the egg, see p. 137, and plate 17, rigs. 23 and 24. 



56 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Table 17. — The rate of development of the embryo at Woods Hole. 



No. 


D.iy. 


Hour. 


Tempera- 
ture of 
water. 


Age stage of development. Remarks, 
of egg. 6 


Id) 
1(2) 
1(3) 
1(4) 
1(5) 
1(6) 

1 (7) 
1(8) 

1(9) 

2 (1) 

2(2) 

2(3) 
2(4) 
2(5) 
2(6) 


1890. 

July 30 
...do... 
...do.... 

July 31 
...do..-. 
...do... 

Aug. 1 

Aug. 2 

Aug. 3 

1889. 
July 11 

July 12 

July 13 
July 14 
July 18 
July 19 


1.45 p.m. 

6.00 p.m. 
10.00 p. m. 
10.00 a. m. 

2.00 p.m. 

6.00 p.m. 

9.30 a.m. 

12.00 ni. 

11.00 a.m. 

5.30 p.m. 

9.30 a.m. 

1.00 p.m. 
5.45 p.m. 
9.50 a. m. 
12.20 p.m. 


°F. 
72 
72 
72 
72 
72 
72 

72 

72 

72 

68 

68 

69 
69 
68 
68 


Hours. 
8(?) 
121 
16J 
281 
32J 
36i 


5Tolk unsegmented 

...do 


2 to 4 cells present. 


do 




Segmentation of yolk . 
rlo , ....' 


Few eggs only, with yolk unsegmented. 

Very few eggs still with yolk uhseginented. 

Several stages of yolk segmentation, some 
eggs with about 30 segments ; others with 
very small and numerous cells; in a few 
.egg's yolk still unsegmented. 

Majority of eggs with at least 160 segments ; 
some with irregular segmentation; some 
with yolk non-segmented. 

Majority of eggs with periphered layer of 
very small cells ; rarely an egg with unseg- 
mented yolk. 

Majority of eggs in this stage. 

Late stage, about equivalent to 1 (7) above ; 

cells not quite superficial. 
Protoplasm generally at surface, and cells 

most numerous on one side of egg. 

Pit at surface. 

Depression on surface very marked. 

Nauplius embryo not yet outlined. 


do 


51J- 

77| 
100J 


do 

do 




Segmentation of yolk, 
do 


16 h 

43£+ 
72| + 
1601+ 
174|-t- 




do 


. do - - 


do 





Table 18. — Bate of development of the embryo at Woods Role. 



No. 



3 (1) 

3 (2) 

3 (3) 

3 (4) 

3 (5) 



3 (6) 



3 (7) 
3 (8) 

3 (9) 

3(10) 

3(11) 
3(12) 
3 (13) 
3(14) 

3(15) 
3(16) 
3(17) 
3(18) 
3(19) 
3 (20) 



Day. 



Hour. 



Tempera- j 
ture of Age of < 
water. 



1890. °F. 

July 9 j 3.45 p. m. ' 71 

July 11 I 12.45 p. m. 69 

July 15 ' 10.30 a. m. 69 



July 17 
July 22 



..do. 



July 27 
July 29 

Aug. 3 

Aug. 12 



Sept. 
Oct. 

Nov. 
Dec. 

1891. 
Jan. 
Feb. 
Mar. 
Apr. 
May 
June 



12 m. 

12 m. 



o p. in. 
10.30 a. m. j 
12.30 p. m. | 



71 » 
70 



70 

71 



72 



Days. 
8 

10 
14 

16 

21 



26 

28 

33 

42 

61 
91 
122 
152 

183 
211 

242 
273 
303 
334 



Stage of develop- 
ment. 



Remark* 



llrs. 

3(0 



31 
31 



24 



21 
8J 



1C1 



Invagination . 
Egg-nauplius 
....do 



....do 

Post-nauplius 



Pit at surface very conspicuous. See cut 25. 
In some eggs, second antennae not budded. 
Second antennas bifid; thoracic abdominal 

fold formed . See cut 31. 
Late egg-nauplius. See cut 32. 
4 to 5 pairs of post-mandibular appendages; 

tip of "tail" conspicuously forked; optic 

disks lobular. Cut 34. 
Optic lobes very large; telson overlaps 

brain; 6 or 7 pairs of post-mandibular 

appendages ; antennae and telson tipped 

with rudimentary setae. 
Telson reaches base of optic lobes. 
Eye pigment present for about 24 hours. 

'Cut 35. 
Eye-spots crescentic or semicircular; telson 

overlaps bases of optic lobes. 
Eye-spots oval; telson considerably behind 

optic lobes. 
See drawing, cut 36. 

See drawing, cut 37. 



See drawing, cut 38. 



Larvae hatching out. 



The lobster (No. 3, table 18) which laid eggs about July 1, 1890, was kept under 
observation at the Fish Commission station at Woods Hole for a period of 11 months 
or 334 days, until -Tune, 1891, when, as we see, the eggs had begun to hatch. Under 
natural conditions the period of incubation of the summer eggs at Woods Hole is 
nearer 10 months— (from July 16th- August 15 to May 15-June 15). 



THE AMERICAN LOBSTER. 



57 



The very fresh eggs can be usually detected by examination with a hand lens. 
The transparent egg capsule closely invests the yolk, which then presents a uniform, 
finely granular texture. The external segmentation of the yolk follows in twenty to 
twenty live hours after oviposition, and the large yolk-segments can be easily distin- 
guished by the uaked eye. At the close of this process, or after the invagination has 
begun, the living egg, when examined with a low power, resembles the fresh egg, 
excepting that the yolk has now a coarser and more irregular texture. The embryo is 
distinctly marked off in the egg-nauplius stage in about ten days, and when from 
twenty-six to twenty-eight days old the eye pigment can be seen at the surface. 

THE HATCHING OF THE EGGS. 
THE HATCHING OF LOBSTERS AT WOODS HOLE. 

We have seen that the period of incubation or fosterage lasts from ten to eleven 
months in the case of the summer eggs. As yet nothing is known about the hatching 
of the fall and winter eggs. The bulk of the eggs which are taken for the Woods Hole 
hatchery complete their development in the McDonald jars in June, as shown in the 
following table: 

Table 19. — Time of collection and hatching of the eggs of the lobster at the United States Fish Commission 
station, Woods Hole, Massachusetts ; compiled from records of the station. 



Time of collection of the eggs. 


Hatching begun. 


Hatching 
ended. 


Time of hatching of 
majority of eggs. 


1890. Apr. 16 to June 13 ; majority taken 
in May. 

1891-1892. Dec. 1, 1891, to Apr. 28,1892... 
1893 Apr 19 to June 26 


May 17 


June 23 

June 15 
June 29 
July 15 


June. 

June. 
June. 
June 15 to 30. 


May 25 (eggs taken Apr. 28) . 
May 30 (eggs taken Apr. 25) . 







These results agree with what takes place in nature when the lobster is permitted 
to keep her eggs for the full time. The eggs from several lobsters are usually placed in 
a single jar, and the jars are replenished while the hatching goes on. 1 The dates in 
the second and third columns of table 19 therefore indicate the general range of the 
hatching period, not that of the hatching of a single brood. 

Lobsters with light eggs, or eggs of the previous summer, were last caught iu 
Vineyard Sound and vicinity iu the summers of 1890 to 1893, at the following dates : 

1890, July 9. One female lobster taken in Woods Hole Harbor with eggs batching; several hundred 

eggs not yet batched. 

1891, July 16. Six female lobsters, with nine-tenths of the eggs hatched, taken at Menemsha. On 

July 11 a lobster was taken at that place with eggs in process of batching, and on June 
30 two lobsters with old eggs were caught in Woods Hole Harbor. In one of these the 
eggs had begun to hatch ; in the eggs of tbe other there was still considerable unabsorbed 
yolk. 

1892, .Time 28. Four lobsters with old eggs were taken. 

1893, June 30. No lobsters with old eggs were taken at Menemsba after June 30. At this time they 

had in tbe past few days obtained 16 lobsters with old eggs, and in half of these tbe eggs 
bad meantime hatched. 

1894, .July U. A lobster was brought from Menemsba. having been caught some time before, with eggs 

about fonr-hfths hatched out. 



1 Tbe temperature of tbe water in the batching jars in summer is about one degree higher than 
that of the water outside. 



58 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

The last lobsters with light eggs were taken by the Gay Head lobsteriiien iii 1890, 
July 7. This was also the date of the capture, at that point, of the first lobster with 
new eggs. 

The time occupied by the hatching of a single brood was upward of a week, in 
the following case: On June 30, 1891, a lobster with old eggs, taken in Woods Hole 
Harbor, was stripped, and the spawn was placed in a " McDonald " jar. On July 3 one 
larva had appeared; by July 5 a dozen larvae had been hatched; on the 13th of the 
month hatching was still progressing slowly, and some of the young had molted and 
were in the second stage. 

In another lobster taken at Menemsha, July 11, 1891, with young just hatching 
out, the eggs, treated in the same way, were nearly all hatched in one week's time. 
On July 12 a large number of the first larvae were swimming about the jar, and on 
July 18 the eggs were mostly hatched and many of the young were in the second 
larval stage. 

In July and August, 1892, Mr. A. P. Greenleaf placed 300 egg-lobsters from Nova 
Scotia with newly laid eggs in one of the lobster pounds at Southport, Maine. In 
April, 1893, he seined, and found the females stdl bearing eggs. He seined the pond 
again in June, when it was evident that the larger part of the eggs had hatched. 

Mr. Thomas Garrett, who began to fish for lobsters in the Vinal Haven Islands 
over forty years ago, caught in July a large, old egg-lobster, which weighed about 
pounds, in the " Basin" near the present lobster park. He returned it to the water, 
caught it a second time, liberated it again, and about the 1st of August caught it for 
the third time, when the eggs had all hatched out 

THE DISPERSAL OF THE YOUNG. 

With the hatching of the young the period of fosterage comes to an end. 1 By the 
fanning movements of her swimmerets the young are driven away from the body of 
the mother as soon as the egg-membranes have burst and are immediately dispersed ; 
thenceforth they lead a free and independent existence. 

The hatching of the eggs of the lobster has been often witnessed by smackmen 
and keepers of lobster pounds. In May, June, and July "the surface of the water in 
the wells of the smacks often becomes perfectly alive with the young, and they may be 

Nothing very definite seems to be known about the ovulation and hatching of the young in 
the European lobster, Astacus gammarus. Rathke's observations in 1840 did not settle the question 
(see p. 167), and Sars's paper {175), published over thirty years later, left it still in doubt. Sars 
says that "the reproduction of the lobster does not appear, as is generally held, to be confined to any 
definite period of the year, yet the youug are mostly hatched in summer. It is not unusual, however, 
to find the lobster with external eggs at other times of the year." Mayer (138) remarks that there is no 
definite breeding season, but that Homarus (Astacus gammarus) and Palinurus extrude their eggs mostly 
in November and December. These conflicting statements show that the European lobster carries her 
external eggs for a long period, and I have no doubt that when this subject is carefully investigated 
it will be found that the breeding habits of Astacus gammarus are very similar to those of the American 
species. 

When this work was in press and after the preceding note was written I received Dr. Ehren- 
baum's paper, to which I have already referred (61). He says that the eggs are laid and the young 
are hatched from about the middle of July to the middle of September. In one of two cases observed 
the eggs were laid August 1, 1893, and the first larva? hatched July 20, 1894; in the other, the eggs 
were extruded August 28, 1893, and the larva} hatched July 21, 1894. The period of incubation is thus 
about 11 months, as in the American form, and the times of the laying and hatching of the eggs in the 
two species very nearly agree. 



THE AMERICAN LOBSTER. 59 

scooped up by the hundreds of thousands," and, as Rathbun says (158, p. 32), "a sort of 
transplanting of young lobsters has been going on along the New England coast, and 
especially the southern portion of it, ever since the well-smack lobster trade began." 
As the vessels sail along, the newly hatched lobsters " work out through the holes in 
the bottom of the well, and are thus constantly adding to the supply of the regions 
through which the smacks pass." 

Peter Kalm relates in his Travels, under date of October, 1748, the following 
interesting anecdote of the transplanting of lobsters around New York by the New 
England fishing boats, which it seems carried wells: 

Lobsters arc likewise plentifully caught hereabouts, pickled much in the same way as oysters, 
and sent to several places. I was told a very remarkable circumstance about these lobsters, and I have 
afterwards frequently heard it mentioned. The coast of New York had already European inhabitants 
for a considerable time, yet no lobsters were to be met with on that coast; and though the people 
fished ever so often, they could never find any signs of lobsters being in this part of the sea. They 
were, therefore, continually brought in great well boats from New England, where they are plentiful ; 
but it happeued that one of these well boats broke in pieces near Hell Gate, about 10 English miles 
from New York, and all the lobsters in it got off. Since that time they have so multiplied in this part 
of the sea that they are now caught in the greatest abundance. {108, vol. 1, pp. 240-241.) 

It is well known that the crayfish protects her young after they are hatched and 
carries them about under her tail, as Roesel so well described over a hundred years 
ago. He says: 

If the mother of these little crayfish, after they begin to stir about, becomes quiet with her food 
at any time, or for some other reason sits still, they begin to move away from her somewhat and to 
crawl about her, but if they spy out the slightest danger, or there is any unusual movement in the 
water, it seems as if the mother called them back by a signal, for they all at once quickly return under 
her tail and gather into a cluster again, and the mother hurries off with them to a place of safety as 
fast as she can. After a few days, however, they gradually leave her. {169, p. 336.) 

Huxley was the first to observe that the euds of the forceps or large claws of the 
young crayfish are bent into "abruptly incurved hooks," by means of which the young 
cling to the mother. He says: 

Immediately after the young are set free, they must instinctively bury the ends of their forceps 
in the hardened egg glue which is smeared over the swimmerets, for they are all found to be holding 
on in this manner. They exhibit very little movement, and they bear rough shaking or handling 
without becoming detached, in consequence, I suppose, of the interlocking of the hooked ends of 
the chelas embedded in the egg glue. Even after the female has been plunged into alcohol the young 
remain attached. I have had a female, with young affixed in this manner, under observation for five 
days, but none of them showed any signs of detaching themselves ; and I am inclined to think that 
they are set free only at the first molt. After this it would appear that the adhesion to the parent is 
only temporary. {103, pp. 43-44.) 

The young lobster has no organs for attaching itself to the mother. Its large claws 
do not end in sharp hooks (fig. 33, plate 20), as in the crayfish, and when once set free, it 
never again finds shelter under the body of the parent. I have noticed that the young 
of Pontonia domestica (a delicate West Indian prawn, which lives as a commensal in 
the shell of the Pinna), when hatched in an aquarium, usually keep together in a ball 
or cluster, like a swarm of gnats, a habit which is doubtless shared by many of the 
prawns, but they never seek protection from the mother, who lives in the mantle 
chamber of the mollusk. Young lobsters which are hatched and kept in the aquarium 
swarm up to the surface or go to the bottom of the jar when closely confined, but if 
given greater liberty they tend to scatter. A swarming or gregarious habit would be 
fatal to this species, on account of its inborn pugnacity and cannibalism. 



60 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Bell (14, pp. 248-249) has given the following account, furnished him by Mr. Peach, 
of the way in which lobsters were supposed by fishermen to protect their young. 
Hardly a word of it is true, but it is a good example of the pseudo-scientific literature 
to which I have referred, aud on this account is worth quoting: 

I have heard the fishermen of Goram Haven say that they have seen in the summer, frequently, 
the old lobsters with their young ones around them. Some of the young have been noticed six inches 
long. One man noticed the old lobster with her head peeping from under a rock, the young ones playing 
around her : she appeared to ratble her claws on the approach of the fisherman, and herself and young 
took shelter under the rock; this rattling, no doubt, was to give the alarm. I have heard this from 
several, some very old men, who all speak to this without concert, and as a matter of course; and they 
are men I can readily believe. 

Young lobsters 6 inches long hardly require protection; smaller ones (an inch 
long) are rarely seen by fishermen, and old and young separate as soon as the latter 
are hatched. 

The writer of a popular magazine article, in quoting a fisherman, thus speaks of 
the habits of young lobsters: 

The mother is often seen surrounded by baby lobsters a few inches in length, who take refuge 
under her tail in case of danger. (The Lobster at Home, by William R. Bishop, Scribner's Monthly, 
vol. xxn, 1881, p. 212.) 

Erdl (62) says of the green crab (Carcinus maenas), that it often appears to play 
with small, round stones and with empty snail shells, just as cats play with balls. 
("Manchmal scheint init kleinen runden steinen, mit leeren Schneckenkausen wie die 
Katzen mit den kugeln zu spielen.") Here, doubtless, the writer was misled by his 
imagination: in the former instance we have a popular error which seems to have 
crossed the Atlantic Ocean with emigrants to the New World. 

Of the hatching of the eggs of the European lobster, which were thought to be 
laid in the sand by some of the older naturalists (see p. 36), Travis (191) curiously 
remarks : 

Though the ova are cast at all times of the year, they seem only to come to life during the warm 
summer months of July and August. Great numbers of them may then be found, under the appear- 
ance of tadpoles, swimming about the little pools left by the tides among the rocks, and many also 
under their proper form, from half an inch to 4 inches in length. 

VARIATIONS IN THE TIME OF HATCHING. 

According to Mr. Nielsen, the hatching period of the lobster in Newfoundland 
begins about the first week in July and continues until the 15th or 20th of August, 
the majority of the eggs hatching from the 15th or 20th of July to the 20th of August. 
It is thus from three to six weeks later than at Woods Hole, which is what we might 
expect from the difference in the temperature of the ocean at these points. It is not 
yet known to what extent the time of hatching and period of embryonic development 
varies from the normal course at the most divergent points on the coast; but it would 
not be surprising if young were hatched at almost any time from late summer until 
spring, owing to the irregularity in the production of eggs already pointed out. 

Mr. Melsen hatched a number of lobsters in floating incubators during November 
in Newfoundland, and Mr. Rathbun (158) gives the following account of the hatching of 
some lobsters at the Woods Hole station by Capt. H. C. Chester, in November, 1885: 

The eggs were detached from the lobster and placed in the "McDonald" jar November 5. They 
began to hatch November 8, three days afterwards, and continued hatching for a few days longer, but 



THE AMERICAN LOBSTER. fit 

only .'ilitnit 50 young ours were observed. The remainder of the eggs arc still in jars in good condi- 
tion. A few of the embryos were transferred to an aquarium with running water, and others to a 
small vessel iu which there was no change of water. The former lived about 24 hours, the latter about 
:i(i hours. The temperature of the water in the hatching jar November 5 was 54.3° F. ; on the 6th, 
55°; and on the 7th and 8th, 56°. * The conditions under which the eggs were kepi were 

perfectly normal, the water being of about the same temperature as that of the harbor outside. 

I have learned of another very interesting case of the artificial hatching of the 
eggs of the lobster out of the regular season. This happened during the latter part 
of January and the first ten days of February, 1889, at the hatchery of the United 
States Fish Commission at Ten Pound Island, Gloucester, Massachusetts. Mr. E. M. 
Bobinson, to whom I am indebted for these facts, was at that time superintendent of 
the station. He says that the eggs were clipped from the lobster at about Christmas 
time, and suspended in aquaria through which sea water was constantly running. 
The temperature of the water was very low, at least as low as 36° F., and as many as 
10,000 lobsters were hatched under these conditions. 

Mr. IS i el sen, who visited the station at that time, corroborates this account, so 
far as the actual hatching of young lobsters is concerned. He writes that he examined 
with the microscope a young lobster which had been hatched on the day of his visit. 
The larva had perished in breaking out of the egg and in passing its first molt, but 
was perfectly developed iu every way. 

These facts clearly show that the hatching period varies in the same way that the 
time of egg-laying varies. The one must be correlated with the other. 

William H. Wheildon gives some interesting facts about the lobster in a short 
paper published in 1875 {202), already referred to. He says: 

In February of the present year we exhibited spawn in several stages of development from newly 
laid eggs to the swimming larvse. 

The fact that the lobsters are with eggs in every month of the year, and that young 
sometimes make their appearance in winter and fall, does not prove, however, as this 
writer, like so many others, inferred, that the animal has no particular breeding season, 
but from these facts alone it would never have been possible to have arrived at a clear 
understanding of the reproductive habits. To the circumstance that egg-lobsters are 
taken at all seasons and often with eggs in very different stages of development is 
due, more than to anything else, the confusion which had settled down upon this most 
important phase in the life-history of this animal. 

In the case of the lobsters hatched at Woods Hole in early November, 1885, the eggs 
were probably laid in the late winter or spring of the same year. I have the record 
of a lobster which had in all probability spawned as early as June 20 (table 3, No. 2). 
Supposing these ova to have been extruded by the first week in June, they would 
have had five months, including the warmest period of the year, for their development. 
For five months, from the first of December to the first of May, the eggs are subjected 
under natural conditions to a relatively low temperature, and their development is 
greatly retarded. Consequently a batch of eggs which is extruded at the first or 
middle of August and hatched in May or June following is not, in all probability, 
subjected to a greater number of heat units than eggs which are laid in June and 
hatched in November. The embryos grow very slowly during the winter months, but the 
advancement may be sufficient, when development has already proceeded far enough 
in the fall, to bring the embryo to the point of hatching under favorable circumstances 
in winter. 



62 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



DESTRUCTION OF THE EGG-LOBSTER AND ITS SPAWN. 

The berried lobster has many enemies, of which man is the chief, but if we except 
the latter, she seems to avoid them with remarkable skill. At least it is true that 
during the long period in which the ova are carried the losses are relatively slight. 
You detect but rarely a bad egg in the whole lot, and when, after ten months, the 
mother's fostering care is about to end, one is surprised to see how healthy every 
egg appears and how few seem to have been torn off. I have found that lobsters will 
scratch off and devour their own eggs when confined in aquaria; and we often see the 
spider crab (Libinia canaliculata) industriously picking off its eggs, as if for its own 
amusement, when it seems to have no lack of other food. The eel has a decided 
partiality for the eggs of the lobster, but the cautious way in which she keeps her 
tail folded up when crawling over the bottom, and the lightning like speed with which 
she can dart about when disturbed, must often circumvent her most wily adversary. 
On July 5, 1890, 1 placed three egg lobsters, from which I wished to obtain embryos in 
progressive stages of development, in a small floating car. One of these was a large 
perfect female, a second was a small perfect female, and a third was disabled by the 
loss of its claws. The next morning I found that the smaller female lobster had been 
killed and eaten. The large one had cut its body in two, at the junction of the " back" 
and ''tail," and eels had eaten out the flesh and picked off' nearly every egg, only two 
or three being left. I afterwards found that lobsters kept in a similar way were liable 
to lose their eggs while still active, and the aggressor was undoubtedly the eel. 

Fishermen have maintained (28, p. 11) that egg-lobsters, if put together, devour 
each other's eggs, but this is not true. At least I am certain that this never occurs 
unless the lobster is first killed by its companions. 

At Small Point, Maine, "berry" lobsters used to be considered the best kind of 
bait for certain fish. The "tail" of the lobster was cut oft", a part of the upper shell 
removed, and the eggs left clinging to the under side. This practice was probably not 
confined to a single locality. 

The pernicious destruction of the egg or spawndobsters is wisely prohibited in 
most of the States, and it is to be regretted that an attempt to enforce such a law has 
not been made in the Maritime Provinces and in Europe. This should certainly be 
done even if the law is often evaded, owing to the ease with which the eggs can be 
scraped off with a mitten or brush. 

Ignorance of the fact that the lobster carries her eggs for a long period has been 
an element of confusion in the establishment of close seasons. Thus in Connecticut 
the law of 1878 forbade the destruction of females with spawn from July 1 to July 15. 
In Massachusetts, in 1880, the sale of females with eggs was prohibited during July. 
In 1883 the Maine legislature made a close time for egg-bearing females from April f to 
August 1; this was changed in 1885 to from October 1 to August 35. In both Maine 
and Massachusetts it is now, as it should be, illegal to take spawn-lobsters at any time. 

The destruction of the spawn of lobsters is a terrible waste of life, and this is of 
itself sufficient reason for the adoption of any measure which may tend to lessen the 
evil. In certain parts of England lobsters in berry have been considered as in the 
very best condition for eating, and the eggs are highly prized for salad. On this 
account and because it was thought too great a hardship to compel the fishermen to 
throw back the "berried hens," the commissioners were not inclined to recommend 



THE AMERICAN LOBSTER. (J3 

any legislation on this point. The following extracts from the testimony relating to 
this subject is interesting. A witness from London says (28): 

There is a difficulty in throwing back the berried hens. They are generally worth twice as much 
as any other lobsters. The spawn is bruised and put into sauce, and makes better sauce than tho 
Lobster itself. In salads it is boilod, and sprinkled over tho salad. It is a capital article of food. 
flu- spawning hens are of value to the cooks, who won't have lobsters without spawn. The sale of 
berried hens must not be prohibited, as it would be preventing the fishermen from taking the most 
fish. The production of the lobster is so enormous that if a gauge were lixed the taking of a few 
berried hens would make no appreciable difference. Berried hens arc in the best possible condition 
as food. They form fresh spawn immediately after they have cast their spawn. If they have no spawn 
outside, they are full of red coral inside. 

In his Report on the Fisheries of Norfolk, Bucklaud (2D) says: 

The lobster is never so good as when in the condition of a berried hen. Berried heus occur most 
frequently in April, May, and June. They begin to lose their berries about July, but still many 
berried hens occur in July. The use of the berries is almost entirely devoted to cooking; they are 
used in many preparations by the West End chefs, especially for coloring and enriching sauces. Tho 
"chefs" are also fond of coral out of the body of the lobster. 

The evidence of a manager of a shellfish factory in the Haymarket is quoted as 
follows (29) : 

Mr. Sheppard, who boils lobsters for Scotts', at the top of the Haymarket, informs me that he has 
taken from one lobster (weighing 3 to 3i pounds) 6 ounces of berries in the month of May. In August, 
out of 100 lobsters he would not be able to get 6 ounces of eggs from the whole. On the 5th of August 
he had 26 crabs, not one of which carried any spawn. In the mouth of May a great proportion of 
these 26 hen crabs would be full of sp iwn. The eggs from the berried hens are used for coloring 
various sauces; the berries are often mashed up in the sauce, a little anchovy added, and then it 
is called "lobster sauce." In order to supply these eggs for sauce to the cooks, Mr. Sheppard has 
collected in April and May from 14 to 18 pounds of lobster spawn. I find that there are 6,720 [eggs] in an 
ounce of lobster spawn. Here, then, we have destroyed eggs which might have represented, say, in 16 
pounds of eggs, no less than 1,720,320 lobsters. A very good substitute for lobster spawn could be 
made by boiling logwood (!). He considers that all berried hens should be returned to the water all 
the year round. 

The number of eggs borne by the female lobster is considered on pp. 50-55. A 
15-inch lobster sometimes carries nearly 100,000 eggs, which weigh a pound. 

The reasons urged by the commissioners for not indorsing the recommendation to 
prohibit the sale of berried lobsters are remarkable as examples of logic. Thus, they 
said "if it were illegal to take berried lobsters it would not pay the fishermen in many 
cases to pursue the lobster fishery. In the next place, the lobster, when berried, is 
in the very best possible condition for food; and it would be as illogical, therefore, to 
prohibit its capture as to prohibit the taking of full herrings." Furthermore, it is said 
that if the sale of berried lobsters were made illegal " the fishermen would probably 
remove the berries. The berries would no longer be seen in the market, but berried 
lobsters would be killed as much as ever. Berried lobsters are, it must be remembered, 
especially valuable; the berries are in great demand for sauce and for garnish for fish 
and salad." (28, p. xvi.) "Accordingly," says a writer in the Quarterly Review (213), 
" we must run the risk of exterminating a valuable animal to please our cooks." 

Mr. Bucklaud says again, in his Report on the Fisheries of Norfolk : 

There are, I regret to say, many difficulties in the way of preventing berried hens being destroyed, 
the principal one being that, unlike the salmon, lobsters when carrying eggs are at their very best for 
human food. Notwithstanding this.it must be evident that the destruction of so many lobsters in 
the form of eggs must of necessity greatly tend to produce that scarcity of lobsters which is now being 
felt in the London and other markets. 



64 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

The concession to the cooks contained in the previous extracts is no more defen- 
sible than the idea that the lobster when in berry is necessarily at its best as an article 
of food. The reviewer just referred to, thus speaks upon the latter point: 

We were under the impression — a common one, we believe — that as the spawning season began 
to come on all the food eaten went chiefly to aid the growth of the innumerable eggs in the female or 
of the soft roe in the male. 

Travis (191), writing in 1768 from Scarborough — a place which still abounds in 
lobsters — says : 

It is a common mistake that a berried hen is always in perfection for the table. When her 
berries appear large and brownish she will always be found exhausted, watery, and poor. * * * 
Cock lobsters are in general better than hens in winter. 

It should be borne in mind that there is no organic connection between the 
external eggs, which are carried under the " tail," of the lobster, any more than 
there is between a plaster and the skin to which it is made to adhere by an adhesive 
substance. 

The case of the berried lobster and of the roe-herring are not strictly analogous, 
since the lobster is carrying her eggs which have been extruded, perhaps months 
before, while the herring is yet in the active process of producing the spawn within the 
body. 

One would suppose that the only time when the lobster could be compared as to 
the effects of spawning with fish like the salmon would be for a short period after the 
eggs were laid. But this is not exactly the case, and Travis was nearer right than 
his successors, when he maintained that the egg-lobster was an inferior article of food. 
The fact is that the egg-lobster is in poorer condition or weighs relatively less than 
the female of the same length without eggs. This point is illustrated more fully in 
another part of this work (see p. 119). 

The lobster at the time of egg-laying is not in as poor condition, however, as the 
shotted herring or the salmon, which at this period is worthless as food, and the 
reason is plain. The ovary of the lobster ripens slowly during a period of at least 
two years, and the production and emission of the eggs is not so severe a drain upon 
its vitality as in the case of the fish. After the eggs have been laid for some time, the 
lobster gains in flesh; the ovary resumes its slow growth, but it is a year before the 
"coral" becomes very conspicuous. The testes, corresponding to the "soft roe" of 
fishes, are always very small, and produce sperm, not at a particular period, as is the 
case with many species of fish, but probably throughout the entire year. The time 
when the adult lobster is in the poorest condition for food is when the animal is 
getting ready to cast its shell, and for a few weeks after the molt while the new shell 
is still soft. 

The destruction of a few hundred thousand eggs, or even a few millions, would 
have no appreciable effect upon the supply of lobsters at any point on the coast; but 
where the practice of taking lobsters with eggs is general throughout the range of the 
fishery, the total amount of ova or embryos which are thus killed is prodigious, and 
can not fail to lessen the number of adults. 



THE AMERICAN LOliSTEli. 



65 



PERIOD OF SEXUAL MATURITY. 

To determine the size which is usually attained by the sexually mature lobster is 
of the first importance in studying the economy of this animal. If the female lobster 
is not allowed to reproduce at least once before she is caught and destroyed, a deple- 
tion of the fishery must inevitably result. 

In some of the States and in the Maritime Provinces of Great Britain, where 
lobsters still abound, or were abundant in the past, protective laws have been enacted, 
prescribing a definite limit to the length of marketable lobsters. In Newfoundland 
this limit is set at 9 inches. (The Royal Gazette, May 27, 1893.) In Maine the limit is 
placed at 9 inches for the months of May and June, and 10i inches for the remainder 
of the year. 1 In Massachusetts, New Hampshire, and New York the limit is fixed at 
10.} inches; in Rhode Island at 10, and in Connecticut at inches. It is thus evident 
that very uncertain and contrary opinions have been entertained in regard to the 
size which is reached by the sexually mature lobster. In order to settle this question 
upon the solid ground of anatomy, and at the same time work out a number of other 
problems relating to the reproductive organs, I made in the summer of 1890 a large 
number of dissections, aud have embodied some of the results in table 20. 

Table 20. — General condition of the sexual organs, of theexternal and internal eggs, and of the shellin lobsters, 
chiefly females, ranging from 2 to 16 inches in length, in June, July, and August. 




Condition of sexual 
organs. 



22 Female 



23 . . do . . 

24 ...do.. 

25 ...do.. 

26 . do .. 



Ovary pea-green color; 

extends nearly to end 

of third abdominal 

segment. 
Ovary nearly ripe; ex 

tends to end of third 

abdominal segment. 
Ductsof testes charged 

with ripe sperm. 
Ovaries pea-green color. 

Compare fig. 138, pi 

38. 



Ovaries approaching 

maturity. 



Condition of swim- 
merets. 



With old eggs, 
now hatching. 



All with old eggs, 
hatched t li i .s 
year. 



Clean. 



Remarks 



11J . July 9 Menernsha, 
sand bot- 
tom. 



12 i ..do I do 

11 . ..do i do 



10£ ... do 



10 



do. 



.do 
do 



Testes filled with solid 
masses of ripe sper- '■ 
matozoa, which are 
surrounded by a gela- 
tinous secretion. 

Ovaries dirty, yellow Clean, 
color ; very immature. 



Ovaries dark green; do . 

nearly ripe. 
Ovaries immature; do 

very light green. 
Ovaries dark green; do. 

like No. 23. 
Ovary straw color; very do 

immature. 



Shell hard. Compare 
fig. 138, pi. 38. 

Oviducts not distended 
with eggs. 



The gluey threads still 
attached to the hairs 
of the swimmerets 
show conclusively 
that young have been 
hatched this season. 

All about to extrude 
eggs this season. In 
one case eggs nearly 
ripe. Size of internal 
egg, 1.33 mm. 

Spermat o p h o r e s— or 
packages of sperm, 
wrapped in a gelati- 
nous substance— can 
be pressed out of the 
ducts. 

Apparent'y no young 
hatched ' this year. 
Probably never sexu 
ally mature. 

Hani shell. 

Do. 

Do. 

Animal not reached 
sexual maturity. 



1 The legislature amended this law in 1895, so that it is now illegal to destroy lobsters measuring 
less than 104 inches in length at any time of the year. 

F. C.B. 1895 5 



66 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Table 20. — General condition of the sexual organs, of the external and internal eggs, etc. — Continued. 



No. 


Sex. 


Length. 


Date of 
capture. 


Locality. 


Condition of sexual 
organs. 


Condition of swim- 
merets. 


Kemarks. 






Inches. 


1890. 










27 




11J 


July 9 








Soft shell. 








sand bot 
torn. 








28 


do 


10§ 


do 


do .. 


Ovary straw color ; like 
No." 26. 


Clean 


Has probably molted 
this season. 














29 


...do 


iu 


..do 


do 


Ovary very light green . 


Old eggs, hatched 
this year. 


Do. 












30 


do -. 


101 


do .. 


do . 


do 




Soft shell. Ha t c h e d 
















youngbeforemolting. 


31-32 


...do.... 


lOg, lOi 
10" 


...do.... 


do 


do 


do 


Do. 


33 


...do-... 


...do 


do 






Shell hard. Hatched 
young, but has not 
























yet molted. 


34 


..do . 


9i 


do 


. . do 


Ovary nearly ripe 

Ovary light green; im- 






35 


. . do ... . 


10J 


...do .... 


do 


Old eggs, just 


Do. 












mature. 


batched. 




36 


..do.... 


10£ 


..do.... 


do 


Ovary straw color; very 


Clean 


Fairly hard shell. An- 












immature. 




imal never sexually 
mature. 


37 


.. do.... 


m 


. . .do 


do 


Ovary pea-green color. 


Old eggs, hatched 
this year. 


Fairly hard shell. 


38 


. do 


log 


do 


do 


Ovary light green ; im- 
mature. 




Soft shell ; probably 
batched old eggs and 




























molted this season. 


39 


..do 


16 


July 22 


Gay Head, 
rock bot- 


Ovary nearly ripe; ex- 
tends to end of third 


do 


Hard shell . Ovary 
flecked with yellow 


















tom. 


abdominal segment. 




spots, the remains of 
degenerated eggs be- 
longing to last sexual 
period. 


40 


...do.... 


15 


...do 


do 


Ovary pea-green color. 


Gluey ; old eggs, 
hatched this 
year. 


Hard shell. Degener- 
ated old eggs in ovary 
and oviduct. 


41 


Male 


10J 


..do .... 


do 






Soft shell. Molted in 
















car June 22. 


42 


Female . 


4 T 3 g 


...do .... 


do 


Ovary very small; 


Smooth 


Hard shell. 












opaque white. 






43 


Male 


3| 


...do 


do 


Testes not found in 
gross dissection. 








44 


do 


9J 


...do 








See drawing of repro- 
ductive organs, fig. 






























120, pi. 36. 


45 




7 IB 


...do 


do 


















white; extends to 
middle of second ab- 
dominal segment. 




Ovarian lobe, 3 mm. 
in diameter. 


40 


. do .. 


±1 


...do .... 


do 


Ovary opaque white; 
extends into third 
















lobe 0.8 mm. in diam- 












abdominal segment. 




eter. 


47 


do 


9^ 


...do 


do 


















extends to end of 
third abdominal seg- 
ment. 






48 


do 


5J 


...do 


do 


Ovary opaque white; 
very immature; ex- 




























tends to end of third 
















abdominal segment. 






49 


do 


7ft 
12§ 


...do 


...do 


do 






50 


...do.... 


July 29 


do 


Ovary light greenish 


External eggs; 


Hard shell. Degener- 












white, flecked with 


embryos with 


ated old eggs in ovary 












orange. 


eye pigment. 


and oviduct. 


51 


...do.... 


15£ 


. . .do 


do 


Ovary opaque whitish, 
with many mature 
unextruded eggs. 


External eggs in 
late segmenta- 
tion stage ; laid 
about 3 days. 


Oviducts filled up to 
external opening 
with ripe, unex- 
truded eggs. For 
number of eggs see 
table 14. 


52 


...do .... 


12 


...do .... 


do 


Ovary soft, jelly like; 
opaque dirty-white 
color, flecked with 
yellow and orange. 


External eggs in 
early segmenta- 
tion; about 36 
hours old. 


Hard shell. A few un- 
extruded eggs, with 
remains of degener- 
ated ova of last sex- 
ualperiod. Figs. 134, 
136, pi. 38, and fig. 
139, pi. 39. 


53 


do . 


HJ 


Aug. 11 


.. do ... 


Ovary light pea green, 
flecked with yellow. 




Soft shell. Has proba- 
bly hatched and 




























molted this year. 


54 


...do 


10j 7 B 


...do 


do 


Ovary very light pea 
green. Ova very 


do 


Soft shell. Has proba 
bly hatched external 
























small. 




eggs and molted. 



THE AMERICAN LOBSTER. 



67 



Table 20. — General condition of the sexual organ*, of the external and internal eggs, etc. — Continued. 



No. 



55 



56 



67 
63 

63 

70 
71 
72-73 



76 



77 



80 



85 



Sex. 



Female 



..do .... 



.do 



58 ...do 



59 ...do 

60 i...do . 



6] ...do. 

02 ...do. 

63 ...do 

64 ...do 

65 ...do 

66 . . .do 



...do .. 
...do .. 

...do .. 

...do .. 
. . -do . . 
...do .. 



74 .. .do . 

75 ...do. 



.do ... 



.do 



78 ...do 

79 ...do 



..do 



..do 
..do 



..do. 
..do. 



...do. 



Length. ! D:l l eot ' 
fa I capture. 



Inches. 
ioj 



121 



10 



10J 

on 

10J 



Hi 

12 1; 
12$ 

12J 

"i 
10 

10 

Hi 

12i 

iii, loj 



log 

12 S 



12}; 



10§ 



11 
10J 



10| 



HI 
lOg 

10i 
104 



1890. 
Aus. H 



..do . 



..do. 



...do 



...do. 
...do. 



..do. 
..do . 

..do. 

..do. 

..do. 
..do. 

..do. 

..do. 



Locality. 



Aug. 14 

Aug. 19 
..do... 

..do... 



..do . 
..do. 



Aug. 21 



.do 



...do. 
...do. 



.do 



.do. 
.do. 



.do 
.do 



.do. 



Gay Head, 
rock bot- 
tom. 



.do. 



.do . 



.do. 



.do. 
.do 



.do. 
.do 

.do 

.do. 



Condition of sexual 
organs. 



Ovary olive green ; di- 
ameter or ovarian 
egg more than half of 
that of mature ovum. 



Ovary rather dark 
green, flecked with 
yellow; about half 
its size at maturity . 

Ovary light pea green ; 
small. 



Ovary cream color ; 
small. 

do 

Ovary light pea green 



Ovary soft, grayish 

white. 
Ovary green ; diameter 

about one-half inch. 

Ovary soft, whitish... 



...do. 
...do 



.do 
.do 



-do. 
.do. 

.do . 

.do . 
.do. 
.do. 



Condition of swim- 
merets. 



Smooth . 



.do 



.do 



Clean . 
Clean . 



Remarks. 



With external 

eggs- 
Smooth, clean 



.do. 
.do. 



do 



.do . 



.do 
.do 



.do 



.do. 
.do . 



.do . 
.do. 



.do. 



Ovary small ; cream 

color. 
Ovary small; light : do 

orange yellow. 
Ovary light pea green do 



External eggs in 
egg- nauplius 
stage. 

External eggs ; in- 
vagination stage 

....do 

Clean 



Soft shell. Probably 
has not hatched eggs 
this year; would prob- 
ably have laid eggs 
for first time the next 
summer. 

Soft shell. Has proba- 
bly hatched eggs and 
molted this season. 

Shell fairly hard. Has 
possibly shed this 
season; may or may 
not have hatched ex- 
ternal eggs. 

Fairly hard shell. Ani- 
mal not mature. 
Do. 

Soft shell. External 
eggs due in following 
vear; not certain 
that young have been 
hatched this year. 

Soft shell. 

Soft shell. Probably 
hatched brood this 
year. 

Shell fairly hard. 



Ovary light pea-green 
color; very immature 

Ovary deep green; im- 
mature. 

Ovaries flesh color; 
very immature. 

Ovary bright yellow. . . 

Ovary dark green; 
swollen, ripe," eggs 
flow out when ovary 
is cut; diameter of 
lobe, one-half inch. 

Ovary light green 



External eggs 
about 3 weeks 
old. 

Clean 



Ovary dark green, 
nearly ripe; largest 
ova, 1.3 mm. in cham- 
fer. 

Ovary nearly ripe 

Ovary light pea green ; 
diameter of ovum 
about one-third that 
of mature egg. 

Ovary light yellow. 
Ov. lobe 7 mm. in di- 
ameter. 

Ovary light pea green. 

Ovary yellow 



-do 

.do 

-do . 



External eggs in 
egg- nauplius 



Clean . 
....do 



.do 



Soft shell. 

Hard shell. 
Animal not mature. 

Shell fairly hard. 

Soft shell. May or 
may not have had 
young this year. 

For number of eggs, see 
table 14. 

Shell very hard. 

Soft shell. 

Have probably molted 
this season ; never 
mature. 
Do. 

Shell colors bright; has 
probably molted this 
season. ' Degenerated 
eggs of former sexual 
period present. Fig. 
141, pi. 39. 

Hard shell. Ova light 
green about nucleus. 
Figs. 150 and 151, pi. 
41. 

Hard shell. See draw- 
ing, fig. 123, pi. 36. 



Shell moderately hard. 

Shell moderately hard ; 

probably not mature. 



Shell moderately hard ; 
immature. 



.do. 



Ovary yellowish, small. 
Ovary pea green 



-do Soft shell. 

.do Molted this season. 

Immature. 

-do Shell hard. 

-do ! Probably molted this 

season. Immature, 
-do I Probably molted this 

year. May have had 

young. 



68 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Table 20. — General condition of the sexual organs, of the external and internal eggs, etc. — Continued. 



No. 



Sex. Length. 



86 : Female 

87 ...do..., 



.do. 



89 i ... do . . 

90 '...do.. 



Date of 
capture. 



Inches. 
11 



1890. 
Aug. 21 

..do . .. 



.do 



91 ...do.... 

92 ...do ! 



99 

100 



..do... 
.do ... 

..do ... 



...do... 

...do... 
...do... 

...do ... 
...do ... 



...do .... 
...do... 

1891 
July 22 

...do .... 



Locality. 



Gay Head, 
rock bot- 
tom. 

do 



.do 



.do 
.do 



Woods Hole 

Harbor. 
do 



July 24 do . 

July 30 do 



July 30 



Aug. 4 



Aug. 5 



.do 



.do. 



Menenisha. 



June 30 Woods Hole 
Harbor. 



11J July 18 j Menemsha. 



Condition of sexual 
organs. 



Ovary cream color . 



Ovary liglit green, 
flecked with yellow 
(degenerating eggs) 
and white (young 
eggs). 

Ovary whitish , flecked 
with yellow spots, 
and dark green un- 
extruded eggs. 

do 

Ovary same as in No. 87. 

Ovary white, 15mm. in 
diameter. 

Ovary whitish, with 
tinge of pink, 3 mm. 
in diameter. 

Ovary white, about 
3mm. in diameter. 

Ovaries nearly ripe; 
seminal receptacle 
charged with sperm. 

Light green. Ova light 
yellowish green. No 
sperm in seminal re- 
ceptacle. 



Ovary nearly ripe. Fe- 
male impregnated. 

Ovary light pea green. 

Female impregnated. 
Ovary white; length If 

in. ; diameter J* in. 



Condition of swim- 
merets. 



Clean . 



External eggs 
about six weeks 
old, extruded 
about July 10. 

External eggs in 
egg - n a u p 1 i u s 
stage, laid about 
August 6. 

do 



Clean 



Remarks. 



Immature. 



Very hard shell. See 
drawing of ovary and 
ova, figs. 137 and 135, 
plate 38. 

Soft shell. 



External eggs in 
late segmenta- 
tion. 



Shell fairly hard. 
Ho. 

Hard shell. 

Do. 



Do. 

Hard shell. For sec- 
tion of ovary, see tig. 
140. 

Shell hard; to molt 
soon; eggs hatched 
this season. See 
drawing of ovary and 
ovum, figs. 138 and 
133, pi. 38. 



Hard shell. See draw- 
ing of ovary, fig. 132, 
pi. 38. 



Eggs laid about. July 25. 



These results, with those giveu in table 15, show very clearly that on the coast of 
Massachusetts female lobsters become sexually mature and produce eggs for the first 
time when they have attained the length of from 8 to 12 inches. Very few lobsters 
under 9 inches in length have external eggs, while only few have attained the length 
of 10.J inches without having them. The limits of 9 and 10 inches, which have been 
variously adopted, are therefore too small, and should be increased if the lobster is to 
receive the benefit which is intended by this form of legislation. It is clearly illogical 
to protect the very small lobster and not to extend protection to the lobster which is 
about to spawn, in view of the natural increase of the species, since the latter has the 
greater chance of survival. It is highly probable that the majority of female lobsters 
10i inches long are sexually mature. It is possible that the limit is sometimes extended 
at both extremes and that very rarely a lobster produces eggs before it is 8 or even 7£ 
inches long or fails to produce them until it is over 12 inches in length. Out of over a 
thousand egg-bearing lobsters which have been examined at the Woods Hole station 
during the past four years there have been found only 20 lobsters measuring from 8 
to 8f inches, or less than 2 per cent of the total number with external eggs. (For 
statistics of the majority of these, see table 15.) The hundred lobsters, the dissec- 
tions of which are tabulated above, were not, however, taken at haphazard, but were 
selected in many cases to illustrate the development of the ovary and its growth 
between two successive sexual periods. 



THE AMERICAN LOBSTER. 



69 



(lulling from table 20 all lobsters 9 inches long- and upward which are immature 
or have not as yet spawned, the record is as follows: 



Number m table 20. 


Length in 
inches. 


47 


9 Id 
a i0 

10 
101 

log 

10 J 

10| 

11 

111 


83 


59 


20, GG, G7 


58,84 


74,82 


28,36 


80 


73 


86 


72 


22 





Total number, 17. 

The following would have laid eggs during the current season — that is, they were 
within a few days or a few weeks of their first spawning : 



Number in table 20. 


Length in 
inches. 


; 34,94 


9i 

91 

log 

10J 

11 

11* 

12 


90 




25 


78 


27 


23 





Total number, 8. 

We thus find that 25 females, a large number out of the entire list, varying from 
9fg to 12 inches in length, had either never reached maturity or were mature for the 
first time. Of the 17 immature females, G are 10£ inches or upward in length, and 
the ovaries in most cases would not have matured for at least two years. In order to 
be on the safe side I have purposely omitted from the enumeration all doubtful cases. 

It may be asked, How can you be certain that a lobster has never spawned? The 
answer to this cpiestion is easily found by examining the ovary. If the surface or 
interior of the ovaries or their ducts are flecked with small yellow or yellowish orange 
spots, in however slight a degree (see fig. 336), it is an infallible sign that external 
eggs have already been carried. If these specks are examined under the microscope 
(fig. 150, plate 41), it will be seen that they are the remnants of old eggs which failed of 
extrusion at the last sexual period. At every such season of egg-laying there are 
always, as Ave have already seen, a few residual eggs, out of the thousands which are 
laid, which stick fast in the ovary or in its ducts, or for some cause are not driven 
outside of the body. These remain in the organs and undergo degeneration in situ. 
It is, perhaps, not surprising that traces of these eggs persist in the ovary for upward 
of two years without being completely absorbed, when it is remembered that the semi- 
fluid contents of the egg are surrounded by a tough bag of chitin, the primary egg 
membrane. 

Another means of determining the sexual condition of the female, which, I consider 
to be also infallible, is the color of the ovaries. The ovary immediately after egg-laying 



70 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

is always of an opaque grayish-white tint (plate 38, fig. 136). The ovary of a lobster 
taken at the time of the hatching of the brood (plate 38, fig. 138), or several weeks 
after it, is invariably, so far as my observation goes, of a light pea-green color, and 
possesses definite histological characteristics which will be considered in another place. 

The ovary of a female which is approaching maturity for the first time (see Nos. 22, 
26, 47, 58, 67, 74, 83, etc., table 20), on the other hand, is variable in color. It may have 
a flesh or almost salmon tint, a cream color, a dirty yellow, bright light-yellow, light 
olive-green color, or one of many intermediate tints. 

The interesting fact has already been pointed out that the percentage variation in 
the numbers of eggs produced by lobsters from 8 to 12 inches is excessively great. 
This points to the conclusion, which is confirmed by anatomical evidence, that the 
period at which lobsters reach sexual maturity is a variable one, extending over 
several years, over a period, at least, in which lobsters vary from 8 inches, or slightly 
under, to 12 inches, or slightly over, in length. 

THE FREQUENCY OF SPAWNING. 

Is the lobster an aiinual spawner, or, to put the question in another way, what 
percentage of mature female lobsters produce external eggs each year"? These ques- 
tions, although of much importance, have generally received erroneous answers. 

In the summer of 1890 I first demonstrated, upon the ground of anatomy, that the 
lobster did not and could not breed annually, as had been commonly supposed. This 
is proved, first, by the growth of the ovarian eggs, and confirmed by the relatively small 
percentage of females with external eggs captured during the winter and spring. 

The growth of the ovarian eggs was followed from the time of hatching of the 
brood until the ova of the next generation were ripe and ready for extrusion. (See 
note, p. 152.) These results are embodied in table 20. In some notes published 
in May, 1891, 1 pointed out that three-fourths of the whole number of egg-lobsters exam- 
ined in the summer of 1890 in Vineyard Sound had extruded eggs during the latter 
part of July (see table 7). It was also shown that the eggs which are then laid are 
"carried by the female throughout the fall, winter, and spring, and are not hatched 
under natural conditions until the following summer" {92). The hatching period 
was given as extending over a period of about eight weeks, from May 15 to July 15. 
This agrees, for the most part, with the experience of recent years. 

Bumpus (30) gives correctly the periods of spawning — with the exceptions I have 
noted— of incubation, and hatching of the young. Garman (72), in a report upon the 
lobster to the fishery commissioner of Massachusetts, summarizes his results as follows : 

(1) The female lobster lays eggs but once in two years, the laying periods being two years apart. 

(2) The normal time of laying is when the water has reached its summer temperature, varying in 
different seasons and places, the period extending from about the middle of June till about the 1st of 
September. 

(3) The eggs do not hatch before the summer following that in which they were laid, the time 
of hatching varying with the temperature, and the period extending from the middle of May till 
about the 1st of August. 

These conclusions— subject to the corrections which I have pointed out— are essen- 
tially a repetition and confirmation of facts which were already known. 

Mather emphasizes (135,136) the facts that the lobster carries its summer eggs all 
winter and that it breeds once in two years. 

In order to prove with certainty that the lobster can not breed every year, we 
have only to dissect a female which has recently produced a brood, or has external 
eggs nearly ready to hatch, in June, July, or August. In table 20 records of over 



THE AMERICAN LOBSTER. 71 

twenty-one such dissections are given (Nos. 1, 4 to 10, 29 to 33, 35, 37, 38, 40, 53, 56, 
02, 1)5) which illustrate the condition of the ovary before the eggs hatch, up to about 
the middle of August, or from six to eight weeks after hatching. The ovarian eggs 
have had, in all these cases, from ten months' to a year's growth, this interval having 
elapsed since the last sexual period, when eggs were extruded. 

The colored drawing, tig. 13S, plate 38, represents, in natural size, the ovary of a 
lobster (No. 95, table 20) four to six weeks after the hatching of its eggs. In figs. 130, 
137, and 138 I have given representations of the ovaries of the lobster as they appear 
thirty-six hours, six weeks, and one year after egg-laying. Figs. 134, 135, and 133 
show the average size and form of the ovarian eggs, drawn to the same scale, at these 
various periods. The ovarian eggs are in about the same condition of immaturity in 
figs. 133 and 135, and it would seem that immediately after egg-laying the ovary grows 
very rapidly, and then enters upon a long period of rest. In the following summer, 
when the external eggs have hatched, another period of rapid growth is experienced 
in the ovary, and at the beginning of the third summer after ovulation there is a third 
period of active growth which continues until the new ova of the next generation are 
ripe. That the spawning periods are thus two years apart is a valid inference drawn 
from the study of the anatomy of the reproductive organs. (See note, p. 152, and in 
particular the description of fig. 138, p. 246.) 

If the spawning period of the lobster is a biennial one, and if the sexes are equally 
divided, we should expect to find half of the adult females carrying eggs each year. 
In other words, one in every four mature lobsters (of both sexes) captured would carry 
external eggs. Since lobsters do not mature at a uniform period, or when of a uniform 
size, it is impossible to get perfectly accurate data upon this point. It would be 
impossible, furthermore, to trust any data, unless we could be certain that the egg- 
bearing lobsters were uniformly distributed. The facts which we have, relating to 
this point, are however, worth considering. 

In April, 1889, a number of lobster pots were set in the harbor of Woods Hole 
by Vinal 1ST. Edwards, and a daily record of the catch was made. A total of 3,230 
lobsters were captured, as described in table 21. About one in every seven bore eggs. 
The percentage of females with external eggs to the whole number of females taken was 
40 in April, while it dropped to 36 in May. This slight fall might or might not be owing 
to the hatching of some of the eggs, while it is evident that the drop to 9 per cent in 
June is due to this cause, by far the larger part of the eggs being hat ched in this month. 

It is seen that in the total catch of 2,657 lobsters, from December 1, 1893, to 
June 30, 1894, the sexes are very nearly equally divided, and that about one in every 
fifteen lobsters captured bore external eggs. Neither this nor the percentage of 
females with eggs to the whole number of females has any special significance, since 
both mature and immature are included. Striking out the months of May and June, 
when the eggs are mostly hatched, and eliminating the smaller lobsters, we find the 
percentage of egg-bearing lobsters 10 inches long or over to the whole number of 
females of the same length with or without eggs (that is, mature female lobsters), to be 
21.79. If the limit is taken at 9 inches, we find the percentage to be 19.81. In other 
words, about one-fifth of the females 9 inches or more in length bore eggs. 

The catch off No Man's Land in May, 1894 (table 1), illustrates very well how 
the conditions are affected by the locality. Out of 1,318 lobsters taken 93.5 per cent 
were females, and 63.7 per cent carried eggs; moreover, 68 per cent of the total number 
of females bore eggs. 



72 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Table 21. — Percentage of male to female lobsters and the percentage of egg-bearing females taken in 

Woods Hole Harbor. 





Time of capture. 


For 
w hole 
period. 




1889, 
Apr. 24 
to 30. 


1889, 
May. 


1889, 
June. 


1893, 
Dec. 


1894, 
Jan. 


1894, 
Feb. 


1894, 
March. 


1894, 
April. 


1894, 
May. 

434 
197 
237 


1894, 
June. 




104 
49 
55 
49 


9J2 
440 
502 


2,184 

1,009 
1,175 


224 
123 
101 


501 
250 
251 


246 
116 
130 


348 
161 
187 


457 
247 
210 


447 
219 
228 


5,887 

2,811 

3, 070 

49 

2, 529 

233 

55 

2,625 

396 

483 

2,593 


Males 


Males under 10 inches 




418 
22 


976 
33 


97 
26 


215 
35 


107 
9 


137 
24 


210 
37 


173 

24 


196 
23 


Males over 10 J inches 




Females under 10 inches 


55 


Females under 101- inches 


439 
63 

185 
317 


1,099 

76 

108 

1,067 


78 
23 
22 
79 


194 
57 
30 

215 


106 
24 
11 

119 


147 
40 
12 

175 


163 
47 
33 

177 


207 
30 
34 

203 


192 
36 

20 
208 


Females over 10J inches 






22 
33 

22 




Females under 10 inches with 


Females under 10£ inches with 


131 

54 

36 

19.6 
114.3 


63 

45 

9 

4.9 
116.4 
















Females over 10£ inches with 




















Percentage of females with eggs 
to total number of females 

Percentage of females with eggs 
to whole catch 

Percentage of females to males. . - 


40 

21 
112.2 


21.78 

9.82 
82.1 


14.34 

7.18 
100.4 


8.46 

4.47 
112. 07 


6.42 

3.45 
116. 15 


15.71 

7.22 
85.02 


14.35 

7.83 
120. 30 


8.77 

4.47 
104. 11 


17.48 

8.99 
106. 30 



The inspector of fisheries for the Province of Prince Edward Island says: 

In 1879 returns from almost all the factories then in operation gave, for the whole catch, only 
from 3 to 10 per cent in spawn, much the larger portion being in July. 

This agrees closely with the results obtained at Woods Hole, but it does not 
follow, as Mr. Duvar supposes, "that one-fifth of the females carry ova each year," 
or that "there are four times as many youug breeders coming forward as there are 
egg-bearers," and "that one-fourth of the number come into breeding year after 
year" (209, p. 234), since the adult lobster does not breed annually, as he erroneously 
supposes. 

From December 1, 1893, to May 1, 1894, 358 female lobsters measuring 10 inches 
or more in length were taken in the harbor of Woods Hole, and 1,234 were captured 
during the same period at No Man's Land, in all 1,592 lobsters, 57 per cent of which 
bore external eggs. If we include the 9-inch lobsters, we find that the total number 
of females taken at both places is 1,779, and that 53 per cent carried eggs. This 
supports the conclusion already reached from the study of anatomy, that the lobster 
breeds once in two years, in which case 50 per cent, or fully one-half, of all sexually 
mature female lobsters spawn in some part of each year. It also shows very forcibly 
that valid inferences respecting the breeding habits can not be drawn from observa- 
tions made in a restricted area. Thus, had our attention been confined to Woods 
Hole it would have appeared that only one-fifth of adult females bore eggs (from 
December to May), or that the lobster spawned only once in five years. ] 



1 Ehrenbaum (61) found that only 25.4 per cent of females supposed to be of adult age caught at 
Heligoland carry eggs, and hence concluded that the European lobster becomes productive onlj once 
in four years. Besides the objection that the data are derived from one locality, which, as table 21 
shows, is a serious one, there is the further difficulty that over 10 per cent of these female lobsters 
were captured during the months of July, August, and September, when, according to Ehrenbaum, 
both the laying and the hatching of the eggs occur. This alone might vitiate the result. The best 
way to test this question by experiment would be to take a female which had recently hatched a brood 
and keep her alive until the following summer, when the next batch of eggs would be due, in case the 
spawning period is a biennial one. So far as I know, this has never been done. 



THE AMERICAN LOBSTER. 



73 



It should be borne in mind that, as we have already seen, a certain number of 
lobsters from 9 to 12 inches long have never borne eggs. Thus the chances for error 
in making estimates of this kind are further increased. 

The percentages given in table 21 must therefore be greatly increased to express 
the ratio between the actual spawners of the current year and those which have 
reached the spawning age, since in the total number of females there were undoubtedly 
included many which were not mature. While the percentage of egg lobsters taken 
in the same locality may vary considerably from year to year or from month to month 
it seems probable that if we could average the results taken from many different 
localities along the coast we should find that the number of spawners each year 
represents about half the total number of mature females. 

RELATIVE ABUNDANCE OF THE SEXES. 

Some species of Crustacea are strictly monogamous, such as the beautiful tropical 
shrimp, Stenopus hispidics, which is always seen swimming in pairs, the male and 
female being rarely separated. This is also true of another delicate shrimp, Pontonia 
domestica, which lives in the mantle chamber of the mollusk Pinna. In such cases the 
sexes are of necessity about equally divided. But in the lobster there seems to be 
no attachment of this kind. It is probable that a given male fecundates more than 
one female, and it is certain that the sexes are distributed with great irregularity, at 
certain seasons of the year at least, as I shall presently show. ^Nevertheless, if an 
extended census could be taken, at different points on the coast, it is very probable 
that but little difference would be found in the numbers of the sexes. 

The following table shows the relative abundance of male and female lobsters 
found in Woods Hole Harbor and at JSTo Man's Land: 



Table 22. — Relative abundance of male and female lobsters at Woods Hole and Xo Man's Land 



Date. 



Total 
catch. 



Woods Hole : 

188!). Ayril 24-30 '• 104 

May ! 942 

June ' 2, 184 

189:!. December 224 

1894. January | 501 

February I 246 

March 348 

April I 457 

May -. 434 

June 447 

Totals j 5, 887 

No Man's Land: 

1894. May ' 1,318 



49 
440 
,009 
123 
250 
116 
161 
247 
197 
219 



2, 811 



Female. 



84 



55 
502 
1,175 
101 
251 
130 
187 
210 
237 
228 



Per cent 
of females 
to males. 



112.2 
114. 3 
116.6 

82.1 
100.4 
112.07 
116. 15 

85. 02 
120. 30 
104.11 



3,076 



106. 30 



1,234 1,469 



In the monthly catches at Woods Hole in 1889 the females preponderated by 12 to 
10 per cent, while in the total catch for 1893-1891 the sexes are very nearly evenly 
divided. During this period the percentage of females to males fluctuated from 82.1 
minus to 120.30 plus, a variation of about 38 per cent. The traps were stationary, 
but the lobsters were constantly moving about over the bottom; yet there was no 
segregation of the sexes, and such variation as we find in the monthly catches has tio 
special significance. 



74 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

When, however, we glance at the data from No Man's Land, it is evident that 
something besides chance has caused the overwhelming preponderance of females, 
1,469 per cent. It seems almost certain that this condition of things is only tempo- 
rary, and it may be explained, as I have suggested in another place (see pp. 23,24), in 
relation with the inshore migration and the hatching of the eggs. 

Regarding the relative abundance of the sexes of the lobster, Verrill (196) remarks : 

Among those which I have examined from New London, Waterford, and Stonington, Connecticut, 
in our markets, I have not noticed any marked inequality in the number of the sexes. Mr. Smith 
examined the lobsters in the market at Provincetown on two occasions, in August and September, 
without finding any decided differences in the number of males and females. He also repeatedly 
examined those in the fish-markets at Eastport, Maine, in summer, with the same result. 

(Japt. N. E. Atwood published in 180G a paper on the habits of the lobster in 
the proceedings of the Boston Society of Natural History (5), in which he makes 
the following remarks: 

From Plymouth northward and eastward [lobsters] are caught in deep water in the months of Feb- 
ruary and March, but not in large quantities; as the season advances they come near the shore and 
remain through the spring, summer, and autumn, and are very plentiful. Along this range of coast 
three-quarters at least are males at all seasons of the year. At Cape Cod (Provincetown) their habits 
differ very much from the habits of the lobsters on the north shore. They do not come there until 
June and remain until October, when they disappear and go to parts unknown. One very singular 
fact I have noticed is, that the lobsters which visit Cape Cod are nearly all females; they appear to 
come near the shore for the purpose of depositing their young, after which they pass away and others 
in turn take their places, as is indicated by the change that is constantly taking place, for when the 
fishermen are catching great quantities of large, good hard-shelled lobsters — and they are unusually 
abundant — perhaps the next day there will be a new kind, smaller and not of so good quality, the 
former ones having passed away and others come to take their places. 

In Boston the number of lobsters sold annually can not be much short of a million. The 
male lobster is preferred and is the most salable, as this city has always been supplied from the 
northern shore of Massachusetts and coast of Maine, where the males are most plentiful. It is a great 
advantage to the fishermen that the people prefer males. In New York it is very different in this 
particular, the city being supplied from Cape Cod after June, and the female lobsters thus considered 
much the best. I have sold many lobsters in New York, and males sell at only about half price. The 
male is much poorer than the female in meat. 

I have quoted the foregoing passages at some length, not because they are free 
from error, but because they were written by an intelligent fisherman at a time when 
scarcely anything was known of the habits and general biology of the American lobster. 
If such a preponderance of females actually occurred on the shores of Cape Cod it may 
have been a seasonal phenomenon, similar to that observed at No Man's Land. It 
did not exist in August and September, when the observations of Professor Smith 
were made at a later period. 

The statement that males are more plentiful than females on the northern shore 
of Massachusetts and the coast of Maine is without doubt an unsupported generali- 
zation. Conflicting statements in regard to this subject are often given by fishermen, 
who, as Verrill suggests, probably do not often discriminate the sexes when the females 
are without eggs. The only detailed facts which we possess on this subject are those 
recorded in tables 21 and 22, and they seem to point to the conclusions already drawn. 



Chapter III— MOLTING AND GROWTH. 

EARLIER OBSERVATIONS 

The process of molting, which makes growth possible to the arthropod, is of such 
interest and importance that it deserves very careful attention. There is much to be 
added to our knowledge of this subject in the lobster, and I shall deal with it at 
full length. Aristotle knew very well that crabs and lobsters shed their shells (The 
History of Animals, Book vni, c. xix), although his observations were not accurate; 
but the fact was forgotten and finally denied altogether. 

It is only necessary to go back to the beginning of the last century (in 1712) to 
find Reaumur (161) demonstrating that the river crayfish periodically cast its shell, 
yet iu the early part of the seventeenth century, a hundred years before, Olaus 
Wormius, according to Couch (47), speaks of the molting of crabs as a thing not to 
be doubted. 

The regeneration of the lining of the stomach of the crayfish was reported by 
Van Helmont, but this writer's reputation did not lend much weight to the statement 
until it was confirmed in 1709 by Geoffroy (74). 

To that marvelonsly acute observer, Reaumur, we are indebted for the best account 
of the exuviation of the crayfish. He took crayfishes which appeared to be ready to 
molt and placed them in jars of water in his museum and watched them carefully. 
Others he put into boxes, the bottoms of which were pierced with holes, and moored 
them in the river Marne, which flowed past his garden. The crayfishes in the river 
were under more favorable conditions than those kept in the house, and molted more 
frequently iu consequence. He gives a very circumstantial account of the external 
process of molting in the crayfish, which took place in June, July, and August. The 
time occupied in the final act of casting the shell by crayfishes kept in the river was 
from seven to fifteen minutes, while those in the house often struggled for several 
hours before they were free. Sometimes they died in the operation, especially the 
young ones. Some would lie on their sides, some on their bellies or backs, and in the 
latter case he observed that they frequently died. 

However, as Couch remarked, Reaumur's paper produced so little effect that 
when, many years later (1756), Peter Collinson communicated some cursory remarks 
on this subject to the Royal Society, his account of the molting of the crab was received 
with so much doubt that his second paper was chiefly employed in furnishing evidence 
of the fact. 

Observations on the molting of the higher Crustacea have since been made by 
Couch (45, 46, ^7),Gosse (81), Chantran (37), Max Braun (22), Vitzou (197), Sars (176), 
Hyatt (101), Brook (26), and others. The histological changes involved in the molting 

75 



76 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

process have been studied by Max Braun (22), and more recently by Vitzou (197). As 
so often bappens, there are many observations on this subject which either ignore the 
earlier and often better ones, or add nothing of value to our knowledge of the process. 
Hyatt, in remarking that, while the molting of the lobster had been previously de- 
scribed several times, "do professional naturalist" had "actually seen the process and 
recorded his observations," appears to have overlooked the account of Sars (176), which, 
however, is not particularly circumstantial. 

Sars saw a lobster in the act of molting in July near Tananger, in Norway. He 
says : 

It had just been taken out of a lobster box, and could be handled without its offering the slight- 
est resistance. The shell on its back was burst in the middle, and the tail and the feet were nearly out of 
the old shell, while the largest claw stuck out only half its length. This latter portion of the change is 
evidently very dangerous, and, although I observed it for quite awhile, I could see little or no progress. 

This lobster was not a good exponent of the molting process. As soon as the 
larger claws begin to be withdrawn from the old shell the exuviation, under normal 
conditions, is speedily brought to a close. Nor is it true that the lobster " only reaches 
its former size after a considerable time has elapsed." According to Sars, the lobster 
on the Norwegian coast molts chiefly in July. 

Both Couch (45) and Salter (174) have given accounts, at secondhand, of the 
molting of the European lobster. Couch, writing in 1837, says that the newly molted 
lobster shows great activity in effecting its escape, which is undoubtedly true in some 
cases, but not in all. The lobster whose cast shell is described escaped "through an 
aperture too narrow to have allowed it to pass if its new covering had possessed a 
very moderate degree of firmness." He supposed that escape was effected by the 
cracking open of the shell, in the middle line, where he noticed that in life a faint 
stripe was perceptible. He observed in a lobster prepariug to molt that absorption 
took place along this area, and inferred that the two halves of the shell were com- 
pletely separated when the critical moment came. Of the molting, he further says that 
" it is not improbable that the general opinion is correct which limits the exuviation of 
the adult animals to once in the year," and " general opinion" does not seem to have 
made much progress in clearing up this matter during the last fifty years. 

Salter's account, published in 1860, is interesting on account of some extraordi- 
nary statements, such as that in molting the legs are extracted pair by pair, which of 
course is a physical impossibility, as Hyatt pointed out, and that the abdomen is the 
part first withdrawn from the old shell. This latter statement expresses exactly the 
reverse of what has since been found to occur. 

Wheildon (202) published in 1875 a short paper containing some interesting facts 
on the molting habits of the American lobster, which will be referred to again. 

The work of Vitzou, which appeared in 1882, is the best yet done on this subject. 
He treats of the histology of the old and new shell, and of the organic and "inorganic 
reserves," which are supposed to be laid down in certain tissues with reference to the 
molting period. 

Hyatt's paper (104), appearing in 18S3, gave an accurate account of some of the 
phenomena of exuviation in this species. 

Packard in 1886 published some notes (147) in which very little is added to our 
knowledge of the subject. He says that "the integument of the legs is molted last, 
and when, owing to rough handling, the process is delayed, the extremities of the legs 



Bull.U. S. F. C. 1895. The American Lobster. (To face page 77. ) 



Plate A. 



BIS. 




Cut 4. — Part of transverse section of exopodite of pleopod 
of female lobster (the cuticle removed), showing the dis- 
tribution of the cement glands. July 19, 1891. 

Bl. S, blood sinus, ep, chitlnogenous epithelium. T. G, 
tegumental eland. 




Cut 5. — Diagram of vertical section through skin, showing a tegumental gland (relatively much smaller than represented) 
in section and its duct opening to the exterior, also hair pores perforating the cuticle, with the superimposed hairs or set*. 
The structure of the cuticle or shell is diagrammatically shown. 

Bl. S, blood sinus, cap, capsule of tegumental gland. D, dermis, d, duct of gland, d 1 , mouth of duct. ej>, chitiuogenous 
epithelium. Gd. C, gland cell. H. p, hair pore. IfM.muscle. JV", nerve, supplying gland. SC, central nerve cell, s', plumose 
hair, s, simple hair. 2, enamel layer of shell, 2, calcified pigmental layer of shell. 3, calcified non-pigmented layer. 4, inner 
non-calcified layer of shell. 



Drawn by F. H. Herrick, 



THE AMERICAN LOBSTER. 77 

slough off." The remarkable statement that "the abdominal legs are molted before 
the thoracic ones " would imply that the hinder part of the body is first withdrawn 
from the old shell, which is not true. 

The statement that the lobster "remains inactive for nearly or quite a week, until 
the new crust becomes hard," can not be accepted without modification, since the soft 
lobster is frequently caught in traps, and the newly molted lobster often displays 
surprising agility, and besides it requires more than one week for the shell to become 
hard. 

Brook (26), writing in 1SS7 on the reproduction of the lost parts of the lobster, 
has some interesting notes on the growth of the European lobster which he kept and 
observed in an aquarium for nearly a year and a half in one instance, during which 
period the animal molted four times. The ecdysis usually occurred at night, and the 
exuvium was buried. 

No one, strange to say, has ever examined the cast-off .shell and observed with 
sufficient care the areas of absorption. This has resulted in much useless discussion 
as to whether the carapace splits along the middle line when it is cast off. I shall 
refer to this hereafter. 

We are now concerned with the adult animal only. The molting of the embryo 
and larva will be considered in Chapter xn. 

THE STRUCTURE AND GROWTH OF THE SHELL. 

The phenomena of the molt are unintelligible without a knowledge of the struc- 
ture of the skin or integument. The histology of the shell in the Crustacea has been 
studied with varying degrees of success by a number of naturalists — by Carpenter (34), 
Lavalle (116), Williamson (205), and Tullberg (191$). The most accurate statement is in 
the paper by Vitzou (197), on which I shall mainly rely in giving the following account. 

The skin as a whole is composed of dermis and epidermis, and consists of the 
various parts shown in the diagram (cut 5). The epidermis is made up of a single 
layer of chitinogenous epithelial cells, and of the shell which they secrete; the dermis 
is composed of connective tissue, blood vessels, nerves, pigment cells, and glands. 
The shell consists of four layers, namely: (1) the thin outermost layer, which I shall 
call the enamel layer, apparently structureless; (2) the pigment layer, composed of 
parallel lamella?, traversed by caualiculi and filled with pigment and lime salts; (3) 
the calcified layer, devoid of pigment but otherwise like the last, forming the greater 
part of the carapace; (4) a noncalcified inner layer, composed of very thin lamella?. 

The chitinogenous epithelium corresponds to the Malpighian layer of the epi- 
dermis of the vertebrate, while the layers of chitin represent its horny cuticle. 

The vertical caualiculi correspond, as Vitzou has shown, in certain decapods, 
to the boundaries of the chitinogenous cells; but this is not the case in the lobster, 
where they are close together and very numerous. 

During the molting period the cells of the chitinogenous epithelium undergo a 
great change. They grow out, vertical to the surface, into very slender and exceedingly 
long rods. (Compare Cut 11, and figs. 171, 173, plate 43.) The epithelium formed 
over the surface of a budding limb is of the same character. The chitiuous layers of 
the new shell are formed by discontinuous thickenings of what, according to Vitzou, 
maybe regarded as the upper wall of the epithelial cell. Thus are formed parallel 
lamellae of varying density, which fuse with those of adjoining cells and make a contin- 
uous shelly crust. 



78 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

At the time the shell is ready to be cast the tegumentary covering consists of 
(1) the old shell; (2) the new shell; (3) an intermediate structureless membrane, 
besides the chitinogenous epithelium, and (4) the dermis. The new carapace, according 
to Vitzou, is composed of the enamel and pigment layers only. The calcified layer is 
not formed until after the molt. 

The connective-tissue cells are now of large size and contain granules of glycogen. 
Claude Bernard first demonstrated the presence of glycogen below the carapace in 
Crustacea. Glycogen was extracted by Vitzou from the connective tissue, liver, 
lymph, and ovaries, during the molting period. Besides acting as a pancreas, the 
liver was found to be a great producer of glycogen during the molt. Glycogen is 
thus an organic reserve, which furnishes material for the growth of the new shell and 
tissues. According to Vitzou, Schmidt and Berthelot have shown that the chitin of 
the Crustacea contains a principle belonging to the same group as cellulose and lignin. 
This substance, under the influence of sulphuric acid, may be transformed into a body 
analogous to glucose. Hence the remark of Claude Bernard, that " without forcing 
the metaphor one may say that the Crustacea are enveloped in a carapace of wood." 
(Lecons sur les phenomenes de la vie, 1879. t. 2, p. 113. — 197.) 

The enamel is plainly the first product of the secretions of the skin which goes into 
the new shell, and when once laid down can not be competely removed except by a 
molt. The enamel is often partially removed by friction, as is seen in the abrasions 
on the shells of old lobsters or those about to molt. 

The surface of the shell, particularly that of the carapace, has a decided punctate 
appearance, due to the hair pores. These mark the points where setse either pene- 
trate the shell now or did so at an earlier stage of development. In the adult lobster 
the seta? of the carapace have disappeared or are worn down except upon its margins 
and in the orbital regions. In the fourth larva, however, the whole carapace is seen 
to be studded with hairs (fig. 113, 115, plate 35). 

If the carapace — better one without pigment — is examined with a hand lens, the 
surface is seen to have a beautiful though somewhat irregular mosaic appearance. 
It is divided into polygonal areas which inclose the hair pores. These markings are 
probably due, as Professor Patten has shown to be the case in Limulus, to shallow 
depressions in the enamel, dependent upon a peculiar bendiug together or clustering 
of the outer ends of the canaliculi. The hair pores open on the inner side of the 
shell in small blister-like elevations. 

A very minute pore of another character is scattered among the hair pores on the 
inner side of the shell. It has the appearance of a symmetrical crater with a minute 
tube issuing from it. This is the duct and opening of the tegumental gland. The 
distribution of these two kinds of pores would probably repay careful study. But 
few parts of the carapace, such as the white tendon marks (see p. 135), are wholly 
free from them. Toward the lateral margins of the carapace they become exceedingly 
small and numerous. Some of the superficial pits in the dorsal region, on the other 
hand, are very large. 

We thus see that the dense shell is a veritable strainer, being perforated by 
hundreds of thousands of minute passages, which lead from the surface to the parts 
below it, to the tegumental glands on the one hand, or to the sensory cells which lie 
at the roots of the hairs, on the other. The bearing of these facts will be better appre- 
ciated when we discuss hereafter the function of the tegumental glands themselves. 



THK AMERICAN LOBSTER. 



79 



THE SHEDDING OF THE SHELL IN THE LOBSTER. 
THE MOLTING PERIOD. 

The hard-shell lobster is heaviest, has the firmest flesh, is hardiest, standing 
transportation best, and therefore most valuable for the market. A large percentage 
of all lobsters taken during the fall and winter months are of this character, and all 
or nearly all lobsters caught iu March, April, and May belong also to this class. 
Shedders and soft-shell lobsters are taken in greater or less abundance from June to 
October, varying somewhat with the season and locality and surrounding conditions, 
such as the nature of the sea bottom and the temperature of the water. By far the 
greater number of lobsters in all seasons, and in all places, cast their shells during the 
months of July, August, and September. However, the time of shedding varies con- 
siderably on different parts of the coast, being from four to six weeks earlier in some 
seasons in western Maine than in the extreme eastern section. Shedders are not fit 
for the market, being lean and watery, and soft lobsters are in a similar condition and 
will not bear much handling or transportation. Until the shell becomes tolerably 
hard the soft lobster is in constant danger of attack from its companions, and is 
easily wounded and killed. Lobsters with very soft shells aud those which have been 
mutilated are often kept in the lobster preserves or pounds until the shell is hardened 
or the injury repaired. 

No systematic data have hitherto been gathered at any point along our coast upon 
t he molting habits of the lobster. I am therefore glad to be able to give the results of 
a series of daily observations made at Woods Hole, Massachusetts, during the space 
of seven months, from December 1 to June 30, 1894. During this interval 2,657 
lobsters were captured in traps set at fixed points in the harbor. As shown in table 
23,' there was no month in which either shedders or soft lobsters were not caught. 

Table 23. — The molting of the lobster. 



Months. 


Tempera- 
ture of 

water in 
harbor. 


No. of 
days for 
which 
average 
tempera- 
ture is 
given. 


Nature of 
bottom. 


Catch. 


Shell hard 
and bright. 


Shell hard 
mid dull. 


Shell soft. 


Male. 


Fern. 


Total. 


Male. 


Fem. 


Male. 


Fem. 


Male. 


Fem. 


December . . . 

January 

February 

March 

April 

May 

J une 


F. 
37.71 
35.48 
32.54 
37.40 
42. 52 
53.65 
62.20 


14 
27 
24 
27 
25 
26 
25 


Rocky 

do 

....do 
....do 
....do 
....do 
....do 


123 
250 
116 
161 
247 
197 
219 


101 
251 
130 
187 
210 
237 
228 


224 
501 
246 
348 
457 
434 
447 


117 
239 
115 
154 
232 
194 
185 


101 
250 
130 
186 
206 
236 
202 


2 
7 

7 
14 

3 










4 

1 
2 


4 
4 
1 

1 

34 



1 

1 


24 



Only one soft-shell lobster was taken in February out of a total catch of 246, and 
no "shedders" (shell hard and dull) were captured during this month. Again, one 
soft-shell lobster only was observed in March and April, and none in May. In June, 

'Lobsters with shells "hard and dull" are nearing the molting period; those with "soft shells" 
have recently shed, and in those with "hard and bright" shells the molting time is most distant. 
See p. 82. 



80 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

on the other hand, the number of lobsters which have recently shed jumps suddenly 
to 58. These observations may be summed up for the whole period as follows: 



Total catch. 


Shell cl „ 

hard ami Shell 

dull. : soft " 


Total. 


( 1, 313 males 


33 44 


77 1 
33 


2, 657 < 

1 1, 344 females 


7 26 



Of the entire catch, 110 have either recently molted or are preparing to molt; 77 
of them are males, 33 females. The total number of males is smaller, yet the number 
of soft shells among them is nearly twice as great as in the other sex. This fact implies 
that the males molt oftener than the females, which would be an a priori deduction 
from the greater size which the male attains (see p. 34), or that they molt more frequently 
during those months. It is interesting to recall in this connection the observation of 
Ohantran (57) that the male crayfish molts twice in the year, while the female molts 
but once. Females molt, as a rule, shortly after the young are hatched, and very 
rarely just before the eggs are laid (see p. 35). 

When I was in Portland, Maine, on the 24th of August, 1893, soft-shelled lobsters 
were being caught in that region, while fishing smacks were bringing hard-shelled 
lobsters from Jonesport, near the eastern border of the State. Soft-shelled lobsters 
are still taken in the Portland district, as I was informed by Mr. N. P. Trefethen, for 
four or five weeks before they are received in large numbers from Jonesport. 

Mr. F. W. Collins, of Eockland, thinks that lobsters shed earlier in the shoal mud 
coves, which are full of eelgrass, than on rocky bottoms. The shedding commonly 
occurs there on muddy bottoms in the latter part of July and the first part of August. 

Shedders in small numbers are occasionally taken in Eockland in January and 
February, and sometimes shed in cars at this time. In deep water outside, as at Seal 
Island, Matinicus, Green, and Eagged islands, where lobsters are caught in winter in 
40 to 50 fathoms, and in shoal places in summer in 3 to 10 fathoms, very few soft-shell 
lobsters or shedders were taken in the summer of 1893, up to the 26th of August, not 
more than a dozen among thousands examined each week. The majority of the soft- 
shell lobsters from these localities come later in the season, from the last of September 
to the middle of October. 

Mr. A. P. Greenleaf said he had rarely seen soft-shell lobsters at Southport, Maine, 
but that in the winter of 1893 (in January and February) he had taken dozens of them. 

At West Jonesport, Maine, on September 4, 1893, I was told by a fisherman at 
Beal Island that hard-shell lobsters had prevailed up to that time, but that soft-shells 
were becoming common. He thought that the shedding was rather later than usual. 
This confirms the reports made at Eockland and Portland. 

Molting lobsters were very common at Woods Hole in October and November, 
1890, particularly in the latter month, when Mr. Vinal N. Edwards says that more were 
caught than during the earlier part of the season. In December, 1891, Mr. Edwards 
found lobsters in all stages of shedding, some that appeared as if they would be ready 
to molt in a few weeks, and others as if they might shed in a few days. Thus it was 
probable that the lobsters continued to molt to some extent in winter, which is shown 
by table 23 to be the case. 

The abundance of shedders which was noticed in the late fall of 1890 at Woods 
Hole has not since been observed, and it seems clear that there is considerable varia- 
tion in the molting of lobsters in a single locality at this season of the year. 



THE AMERICAN LOBSTER. 81 

It is stated in the animal report of the inspector of fisheries of Prince Edward 
Island {209, p. 23(5) for 1880 that soft-shell lobsters " are seldom seen on the north side 
of the island, while on the south side almost all that are caught in the month of July 
are soft and unfit for canning." A cauner in Queens County says that scarcely a 
lobster can be caught before the 20th of May. Soft-shell lobsters begin to abound by 
the 1st of August and continue abundant during this month. One-third of the lobsters 
caught during August are said to be soft-shelled. The fishery officer for Gape Breton 
states in his report for 1S88 (210) that no soft-shell lobsters were captured during the 
fishing season which closed July 28. 

THE MOLTING PROCESS. 

Next to reproducing its kind, the act of molting is the most important in the life 
of this animal. The whole body is covered, as we have seen, by a chitinous shell, in 
which salts of lime are deposited, giving to parts of it the hardness of stone. Molting 
consists of two distinct phenomena: (1) the formation of anew shell and (2) the rejection 
of the old. When once formed the shell admits of no increase in size, since it is a 
dead structure, excreted by the skin below it, and when it is outgrown it must be 
cast off and replaced by a new and larger shell. The new shell is gradually excreted 
under the old one, and when the latter is discarded the new shell is soft and flexible 
and is easily distended to meet the requirements of growth. The growth of the lobster, 
and of every arthropod, thus apparently takes place, from infancy to old age, by a series 
of stages characterized by the growth of a new shell under the old, by the shedding of 
the outgrown old shell, a sudden increase in size, and the gradual hardening of the 
shell newly formed. Not only is the external skeleton cast off in the molt and the 
linings of the masticatory stomach, the oesophagus and intestine, but also the internal 
skeleton, which consists for the most part of a complicated liukwork of hard tendons. 
This is rendered possible from the fact that these structures are derived from infolded 
portions of the skiu, and in molting they are simply drawn out of their original folds 
or pockets. It is thus easy to see why the molting process is critical. 

The frecpiency of the molting period depends directly upon the physiological 
condition of the animal, which varies with its environment. The molting process is 
both an expensive and dangerous operation, and calls for a considerable excess of 
energy. Since it is largely dependent upon the condition of the individual, which is 
subject to wide variation, the molt does not take place at any stated time, but may 
occur in any month of the year, though but rarely in the spring. Warmer weather, a 
more active life, and a more vigorous appetite, which are characteristic of the lobster 
during the warmest part of the year, are most favorable, as we have seen, to the 
renewal of the shell. The lobster, though a carnivorous and voracious animal, 
feeds less in winter, when its habits are relatively sluggish. Broken limbs and 
injuries to the shell are then but slowly repaired, and there is less energy to be 
drawn upon in molting. 

The growth of the crustacean takes place during the period of the molt, while the 
new shell is being formed, and not immediately after the ecdysis, as is commonly 
believed. It was clearly shown by Vitzou that the old shell is gradually thrown off 
in consequence of the growth during the molting period, when the animal tends to 
become larger than its envelope. The rapid swelling out of the body after the old 
shell is gotten rid of is due to the absorption of water through the new shell into the 
blood and tissues, not to cellular growth. 

F. 0. B. 1895—6 



82 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Before the molt takes place the lobster has been for a long time preparing for it, 
while growth, has been going on. After molting, it is several weeks before the new 
shell is as hard as the old one, so that the lobster is, for a large part of its life, either 
preparing for a molt or recovering from one. It is therefore not remarkable that 
lobsters have acquired many popular names among fishermen, such as "hard shell" or 
"old shell" lobster; " shedder," "black shell," or " crack back" (lobsters preparing to 
molt); "soft shell," "new shell," "shadow," "rubber shell," "paper shell," "buckle 
shell" lobster, etc. (lobsters which have recently molted). 

HABITS OF MOLTING LOBSTERS. 

Shedders can be readily distinguished by the dark, dull colors of the old shell 
hence the common name of " black lobster," and by the deep reddish tint of the 
membranes at the joints, where the flesh is now seen through the old and new cuticle. 
The lobster is now naturally sluggish, though not too inactive to enter a trap. When in 
this condition they very commonly haunt shallow water with a sandy, muddy, or weedy 
bottom, and at low tide have been taken out of bunches of eelgrass in a few inches of 
water. When in this condition they frequently dig a shallow hole in the mud under 
stones, where they can await the coming change with greater security from enemies. 
Fishermen frequently see a shed shell lying on the bottom and a soft lobster close by 
under a rock or bunch of kelp. 

It is well known that many prawns habitually molt in the early morning while it 
is yet dark. The lobster when kept in an aquarium molts either by day or night, and 
it probably does the same in nature. In those which Brook observed {26) the shells 
were cast off in the night and partially buried. 

Shedders and soft lobsters used to be a favorite bait with fishermen who knew 
where to look for them and could then find them in abundance. The shell of the black 
lobster was peeled off, and the soft, pulpy flesh formed a tempting bait which fish 
found difficult to resist. Mr. Vinal N. Edwards says that in 1869 or 1870 he used to 
take molting lobsters for bait at Menemsha, in Vineyard Sound, in October, sometimes 
a barrel of them at a time. He says that he never found a molting lobster buried in 
the sand, but they were usually under bunches of seaweed, such as the common kelp 
(Fucns vesiculosus) with their bodies only partially surrounded by the sand, and in 5 to 
9 feet of water. It was not uncommon formerly to catch shedders in fyke nets, but he 
has taken none in recent years. He used to take them occasionally with hook and line. 
The lobster probably requires greater freedom in getting free from its old shell than 
could be found in the most carefully constructed burrow. 

While at the Vinal Haven Islands, August 26, 1893, 1 saw in the pound at that place 
a number of soft lobsters which had molted but a few hours before. One was found 
lying in the eelgrass ; another, a male, was exposed on the mud bottom in 2 feet of 
water. A shedder, weighing upward of 10 pounds, was caught by Mr. M. B. Spinney 
in Seal Cove, Small Point, Maine, in the month of August, in very shallow water; and 
in Sagadahoc Bay, near the mouth of the Kennebec Biver, a large soft lobster was once 
found and close beside it its cast-off shell. The lobster lay buried under roots of 
eelgrass and was out of water, when discovered, at low tide. 

In the Peabody Academy of Science, at Salem, Massachusetts, there is a crushing- 
claw of a lobster said to have come from Gloucester and to have weighed 39 pounds. 
An outline drawing of this claw is given in plate 15 (see p. 115). This lobster probably 



THE AMERICAN LOBSTER. 83 

weighed not over 25 pounds. The shell of the last three joints of the claw-bearing 
limb (the parts represented in fig. 20), weighed 16| ounces. It has the thickness of 
thin pasteboard, excepting at the tips of the claw, where it is denser, and probably 
belonged to a lobster which had molted within three months of the time of its capture. 
Putnam (154) records some interesting facts in regard to the molting habits of the 
blind crayfish, Cambarus pellucidus, and of the eyed crayfish, Cambarus bartonii, cap- 
tured in Mammoth Cave November 13. The blind species was of a milk white color. 
One molted on January 29 and a second time April 20. Another specimen of this 
species, exposed to the light over niue months, had eaten little and molted once. One 
of the specimens of C. bartonii molted about February 20, and when observed was 
eating its own shell. It had devoured about half of it. This habit of eating the remains 
of the old shell is very interesting, and is undoubtedly induced by the need of lime. 
It was noticed in the crayfish by Baker (7) over a hundred years ago, but it is so 
seldom recorded that it would hardly seem to be a fixed habit. It is probably 
occasionally practiced by the lobster and all the higher Crustacea, especially when in 
confinement. Warrington (199) estimated that the molting period of prawns (Pahemon 
serraUis), which he kept in aquaria, varied from twelve to twenty- four days, depending 
upon food, the temperature, and other conditions. When the cast skius were not 
removed the prawns devoured all the soft parts. Young lobsters, immediately after 
molting, fill their stomachs with any calcareous matter at hand, such as the fragments 
of the shells of mollusks and Crustacea. Pieces of the integument of the lobster are 
commonly found in the stomach-bag, so that it is not at all improbable that the young 
lobster sometimes devours its cast-off skeleton. Brook (26) thus speaks of a lobster 
the day after ecdysis : 

It had partially buried its cast shell under the gravel. During the previous fortnight this 
specimen has shown great irritability and pugnacity, and when offered food seized it savagely, but 
instead of eating proceeded immediately to bury it. 

Spence Bate (3), who tried without success to observe the common green crab 
(Carcinus mccnas) in the act of molting, concluded that this animal had the power of 
inhibiting the process until a favorable time arrived. 

THE CASTING OF THE SHELL. 

A male "shedder" was caught in the harbor of Woods Hole July 13, 1891, and 
placed in an aquarium. At exactly 2.48 p. m. this lobster began to molt and in six 
minutes was out of its shell. 

Wheu the lobster is api>roachiug the critical point the carapace or shell of the 
back gapes away a quarter of an inch or more from the tail. Through the wide chink 
thus formed the flesh can be seen glistening through the old and new cuticle, giving 
it a decidedly pinkish tinge. Take the lobster up in the hand now and the tail 
drops down as in death, the strong muscles which bind the pleon to the carapace being 
completely relaxed. When this stage is reached the time of exuviation is at hand 
and the process becomes purely automatic, the animal having lost all control over its 
own movements. There are other signs, though not equally infallible, which point to 
the same conclusion — the dull, faded colors of the old shell, scratched and marred 
often with the marks of many conflicts. The shell is frequently of a dark, dirty green 
color, the mottled tints having become very much obscured. The contrast in color is 
very great if the shedder happens to be among a lot of new-shell lobsters, and the 



84 BULLETIN OF THE UNITED STATES 1'TSH COMMISSION. 

term " black lobster," used by the fishermen on the coast of Maine, is not altogether 
inappropriate. The old shell is also brittle, owing to the absorption of organic matter, 
and if the carapace or large shield wnich covers the anterior half of the body is 
pressed between the fingers, it will sometimes split down the back in the longitudinal 
median furrow. In most cases the shell does not crack in this place unless artificially 
compressed. In the course of the preparation for the molt the lime salts of the 
shell are absorbed along the middle line of the carapace, leaving a narrow perfectly 
straight gutter, extending from the spine or rostrum to the posterior margin of the 
shield. The chitinous portion of the cuticle still remains, forming an inelastic hinge, 
on which the lateral halves of the carapace bend without breaking asunder. In the 
molted shell there is also a linear membranous area on either side of the rostrum. 
Absorption of the hard matter of the shell at these points tends to give greater latitude 
to the movements of the two halves of the carapace. If you examine a hard-shell 
lobster you will find in place of the median furrow a blue line, drawn as if with a fine 
pen and rule. Below this line the epidermic cells of the skin become so modified as to 
bring about the total absorption of the lime salts of the cuticle. In sections of the 
skin, however, it is difficult to detect any histological change in this linear area. 
Other areas of absorption, to be described hereafter, occur, which are of even greater 
importance to the success with which the lobster comes out of his old covering alive 
and whole. 

The period of uneasiness, which foreshadowed the molt and was very marked, 
ended in this lobster by its rolling over on its side, agitating its appendages, and 
bending its body in the shape of the letter V, the angle of the V coinciding with the 
gaping chink between the dorsal shield and " tail." Presently the old cuticle, holding 
these parts together and through which the new shell is seen, began to stretch, the 
wall of the body pressing against it with considerable force, and the hinder end of the 
shell being slowly lifted up, while its anterior part remained attached to the rest of 
the skeleton. The slow but sure pressure of the parts within cause an increasing 
tension in the yielding cuticular membrane, which finally bursts, revealing the brilliant 
colors of the new shell. The legs and other appendages are occasionally moved, but 
no marked convulsive movements are to be seen. The carapace has now become raised 
upward to an elevation of perhaps 2 inches behind, in consequence of which, the 
anterior end being fixed, the rostrum is bent downward and the animal now has a 
very singular appearance. 

When this much has been achieved the lobster becomes quiet for a few seconds 
and then resumes its task with renewed vigor. From this time on until free its 
muscles work intermittently. The doubled-up fore part of the body is with each effort 
of the animal more and more withdrawn from the old shell, and this implies the 
separation of the skin from the complicated linkwork of the internal skeleton and the 
freeing of the twenty-eight separate appendages, which are attached to this portion of 
the body, from their old cases, and at the same time the release of the muscles from the 
internal tendons of the large claws and other parts. The cuticnlar part of every ecto- 
dermic structure is stripped off. This exoskeleton folded up to fit such a complicated 
mold is in reality a continuous structure, and from the method of its regeneration the 
sloughing of one part necessitates the shedding of the whole. 

The carapace is now elevated to such an extent behind that the rostrum is 
directed obliquely downward and backward. The lobster is still lying in comparative 



THE AMERICAN LOBSTER. 85 

quiet upon its side, but the muscles of all its appendages are undergoing violent con- 
traction as the animal tugs and wrestles violently as if to free itself from ropes which 
bind it down firmly on every side. The carapace is unbroken, yet the two halves bend 
as upon a hinge along the median furrow. Presently the pressed-down bases of the 
antenna}, the eyestalks, and the bent-down rostrum of the new shell can just be seen. 
No part of the covering of the large claws or of any of the legs has been split or 
cracked. The muscular masses of the powerful claws have been withdrawn through 
their narrow openings without a rent. Finally a few kicks free the entire anterior half 
of the body, the antennae, chelipeds, and various other parts, which now lie above or 
to one side of the old covering. The "tail" has been gradually breaking away from 
its old case, and as soon as the forward part of the body is withdrawn the lobster gives 
one or two final switches and is free. The newly molted lobster has a very sleek and 
fresh appearance, and its colors were never brighter or more attractive. Try to take it 
up in the hand, after some time has elapsed, and it feels as limp as wet paper; but 
immediately after casting the shell the muscles of the crustacean are hard and tense, 
probably from being in a state of cramp or tetanus. Every part of the old shell down to 
a microscopic hair has been reproduced in the new one, but in the latter the fringes 
of stiff setre are as soft as silk, the strong ends of the claws, the rostrum, and every 
spine of the body so soft as to easily bend beneath the finger. The large claws are 
considerably distorted, as well as some of the other parts, being squeezed and drawn 
out to an unnatural length. After getting clear of the old shell the animal is not 
inclined to activity. It soon orients itself, however, resting in the usual way, and is 
capable of moving about with some degree of agility by the flexure of the tail. Fisher- 
men who have had lobsters shed in cars and traps have often been surprised by the 
ease with which they sometimes slip through their fingers. 

The length of the cast shell of this lobster was 11J inches. Shortly after the 
molt the lobster was 12 inches long. On July 17, four days after molting, the length 
was a little short of 12^ inches. The increase in length was thus very nearly 1 J inches. 
The actual increase in size of the different parts of the body can be best appreciated 
by comparisons of plates 45 a, and 45 b, which represent life-size drawings of a lobster 
before and several hours after the molt. The measurements in this case were 5i and 
6£ inches, the increase in length beiug just 1 inch. 

Reaumur remarked on the hardness of the flesh of the crayfish immediately after 
exuviation, and, as Huxley says (103): 

In the absence of the hard skeleton there is nothing to bring the contracted muscles at once back 
into position, and it must be some time before the pressure of the internal fluids is so distributed as 
to stretch them out. 

Hyatt (104) said of the large claws of a molted lobster : 

They were exceedingly hard and firm, and I have no doubt would have been extremely good 
eating if we had dared to indulge in such extravagance. This is entirely contrary to the usual 
accounts, but it agrees with my former observations on the common blue crab, of which I have seen 
hundreds directly after molting, and they are always firm and delicious eating if taken at this time. 
In fact, the watery aspect usually attributed to the newly molted crustacean did not appear until some 
time after the lobster was placed in our live tank. 

Very soon after molting the lobster is ready to take food, the body, owing to the 
absorption of water, plumps out to its natural shape, and the limit of increase in the 
volume of the body is reached. 



86 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

The interesting observations of Hyatt on the molting of a lobster were made at 
Matinicus Island, Maine, July 21, 1880. The ecdysis was accomplished at 9.30 a. m., 
and the lobster lived forty hours, when the shell had become but little hardened, being 
still papery and pliable. In twenty-four hours after shedding the claws had swelled 
out and assumed a transparent, watery aspect. An under tint of green was observed 
in the shell. The crowns and points of the spines and teeth of the large claws had 
become whitened. The ratio of increase in bulk was found to be 1.211; the ratio of 
increase in breadth, 1.192; the ratio of increase in length, 1.010. This lobster came 
out of its shell without splitting the carapace, and the "tail" was the last part to be 
set free. 

Vitzou describes the molting of a lobster which he watched in the marine labora- 
tory at Eoscoff on the 21st of July. He speaks of the membrane between the carapace 
as being early ruptured, and points to this as a sign that the animal is about to molt, 
but this can not be a normal occurrence. 

WITHDRAWAL OF THE LARGE CLAWS. 

The shell of the large claws is molted entire without a rupture in any part. This 
means that the great mass of muscles which fills the terminal joints must undergo 
distension and compression to an extraordinary degree. This will be better appre- 
ciated by an examination of cuts 6 and 7, plate B. Out G represents the cast shell of 
the left cheliped of the lobster (No. 7, table 24) which molted on July 13, and cut 7 
cross-sections of the shell with their plotted areas, in the planes indicated in cut 6. 
The flesh which fills the area la is drawn through the opening of the joint II (plotted 
area shown in Ha), and later through III, the smallest part of the claw. The shell is 
here distensible, however, owing to the absorption of lime from the upper surface, so 
that probably in this part the area of the cross-section is increased until it equals that 
of Ha. Finally the compressed and distorted limb is drawn through the quadrilateral 
opening at the base IV (plotted area, IVa), as Salter says, much as a wire is drawn 
through the contracting holes of a draw-plate. The latter is somewhat larger than 
the opening of the subtermiual joint II. The area of the section of the largest part 
of the claw (I, la) is more than four times that of the opening Ila, through which all 
the tissues of the claw must pass. The muscles appear to be stretched out like a stick 
of candy, but, apart from their elasticity, they are probably aided in accomplishing 
this by the removal of water from the blood. The parts are very much distorted 
immediately after they are free, and are quite hard, but they soon take up water and 
assume their natural form, with a proportional increase in size. 

The areas of absorption in the three basal joints of the limb are easily distin- 
guished, though less plainly circumscribed, in the hard-shell lobster. The shell of the 
basal joint becomes a slender ring, which is not broken, as has been inferred, but 
remains intact, as Salter (174) has already observed. 

In the crayfish, on the contrary, Reaumur (161) maintained that in molting the 
shell of the " second and third" joints (meaning, as shown by his figure, the meros and 
carpus — fourth and fifth joints) opens by a longitudinal fissure on the outer side. 

The two pieces are so perfectly adjusted to each other that they appear as one, hut at the time 
of the molt, when the crayfish subjects them to strain, these tubes gape apart and thus permit the 
passage of the extremity of the limb. 

After the molt the crack closes up and appears to be glued together again, as if 
no rent had been made. This explanation of the withdrawal of the large claws is 



Bull. U. S F. C. 1895. The American Lobster. (To (ace page 86 ) 



Plate B. 



m iv 




Cut 6. — Left eheliped of lobster seen from the dorsal side. From specimen which molted in an aquarium 
July 13, 1891, and which is described in Chapter III, pp. 83 to 85. See No. 7, table 24. One-half nat- 
ural size. 

The Roman numerals I-IV correspond to the planes of section illustrated in cut 7: Arabic num- 
erals 1-7 to segments of limb, mb, area of absorption, on upper surface of third and fourth joints, 
x, plane of fracture. 



882 mm 2 



211mm '• 



93mm s 



274mm- 




Cot 7. — I-IV represent transverse sections of chelipcd shown in cut C in the planes indi- 
cated by corresponding immerals.ll and IV showing the natural openings at the proximal 
ends of the sixth and first segments respectively. Ia-IVa represent the areas of the 
respective sections expressed graphically and numerically. (The plotted areas are 
two-thirds natural size: the numerical expressions above them refer to actual areas.) 
At mi. cuts 6 and 7 (III), the lime salts of the shell have been absorbed, so that the 
cuticle is capable of distention, and the area of the transverse, section is thereby 
slightly increased. The muscles and other tissues which fill the transverse section la 
must be drawn through an opening the size of IIii, then through one but little larger 
than Ilia (allowing for the distention of the membrane), and finally through the small 
ring, IV. ITri. at the base of the limb, since there is no rupture of any of these parts. 
Drawings two-thirds natural size. 



Drawn bij F. H. Herrick, 



THE AMERICAN LOBSTER. 87 

repeated by Eymer Jones (106) and others. It is, without doubt, erroneous, but 
possibly based originally upon an exceptional occurrence. 

At the time of the casting of the shell the large claws must be practically free 
from blood, since, as Vitzou has pointed out, if the claw were to be increased in size 
it would be next to impossible for it to be withdrawn without rupture. The older 
naturalists used to explain the withdrawal of the large claws by a wasting of the 
tissues. The lobster was supposed to become sick and emaciated, which, of course, 
was an error. The most significant fact in this process is the displacement of the 
liquids which normally belong to these appendages. 

Couch (47), in his account of the exuviation of the common edible crab of Great 
Britain, Cancer pagur us, maintains that the membranes in the areas of absorption at 
the base of the chelipeds split along the edges and open like hinges, thus freeing 
the limb from its constraint. This does not happen in the lobster, as Couch inferred, 
and even if it did no benefit would arise, since there is the unbroken ring of the 
coxopodite, through which the tissues must still pass. Spence Bate (10) thought that 
the splitting of the walls of the cheliped, alluded to by Couch, might be to enable "the 
animal to withdraw the great osseous tendon." It is difficult to understand what is 
here meant. The great osseous tendons are never withdrawn at all (past the absorp- 
tion areas at the base of the limb), but remain attached to the old shell, of which they 
form a part. 

THE CAST-OFF SHELL. 

At the time of the molt there is an intermediate membrane which makes its 
appearance between the new and old shells. It is non-cellular, has a gelatinous appear- 
ance, is very transparent, and may be found adherent to the old shell after the molt is 
past. When examined microscopically it has the appearance shown in fig. 177, pi. 44. 
It bears the impress of a mosaic of cells, which can be none other than the cells of the 
chitinogenous epithelium. Vitzou is thus in error in supposing that this substance is 
a secretion of the chitinogenous epithelium underlying the new carapace, which it 
traverses by endosmosis. It must be either the first secreted product of the new shell 
or the innermost layer of the old shell modified by absorption. 

In this cuticular membrane the parts which correspond to the cell boundaries (of 
the chitinogenous epithelium) have the form of elevated ridges on the under side, and 
m the center of each polygonal area there is a slight thickening. Beauinur (162) had 
in view a similar structure in the crayfish when he spoke of a glairy matter, "as 
transparent as water, which separated the parts which the crayfish was soon to 
cast oft' from the rest of the body, and which allowed these to glide smoothly over one 
another." 

There is normally no rupturing of the shell in any part in the course of the molt. 
The entire exoskeleton, with the linings of the oesophagus, stomach, and intestine, 
comes off as a whole, 1 and the animal leaves it by drawing the anterior parts of the 
body backward, and the abdomen and its appendages forward, through an opening 
made by the elevation of the carapace. When the old carapace falls back into its 

1 The lining of the alimentary tract is of course ruptured. In small lobsters, at the fifth or sixth 
molt, I have noticed that the break takes place not far behind the stomach-bag, and that while the 
linings of the masticatory stomach and oesophagus come out by way of the mouth, as in the adult, the 
lining of the intestine is withdrawn from the anus. 



88 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

natural position one might, at the first glance, as Reaumur said of the crayfish, mis- 
take the empty shell for another lobster. 

In old lobsters, where the membranes are thick, a rupture of the carapa.ce may 
arise possibly from want of complete absorption of the lime, but this rarely happens, 
and the lobster gains nothing from the complete dehiscence of the parts. 

It has been stated so many times that it has come to be generally believed — the 
result of the reiteration of error — that the carapace of the lobster is ruptured along 
the middle line to assist ecdysis. A careful examination of the cast-off shell, which 
would have settled in short order the disputes over this subject, is the very thing 
which apparently has not occurred to anyone to make. Wbeu this is done, we find 
that rupture of the shell is guarded against in the most ingenious way. The areas of 
absorption of lime salts in the carapace, which we have only to consider in this 
connection, are as follows : (1) The wide lateral margins of the branchiostegites, 
including what in life appears as a light blue area, about three-eighths of an inch wide 
in a lobster 10 inches long; (2) a narrow median stripe extending from near the apex 
of the rostrum to the posterior margin of the carapace; (3) the endotergites (three 
small teeth like projections from the under side of the carapace, on which muscles are 
inserted); (4) a linear area on each side of the rostrum ; (5) two small round areas in 
front of the endotergites — not always noticeable. The linear area (2) extending down 
the back acts as a hinge, rupture in the rostral region being provided against by the 
narrow absorption areas on each side of it (4), while the softening of the margins of 
the carapace makes the lifting of this from the body an easy matter during the molt. 
The result of such areas of absorption is plainly to prevent the rupture of the shell, 
which, however, does accidentally occur from other causes. The softening of the endo- 
tergites is also necessary to prevent injury to the soft tissues. 

THE GASTROLITHS. 
THE GASTROLITHS OF THE LOBSTER; THEIR STRUCTURE AND DEVELOPMENT. 

The gastroliths, though often called crabs' eyes, are found only in the crayfish and 
lobster, so far as is known. Discovered first in the river crayfishes, they early figured 
in the old pharmacopoeia as oculi seu lapides cancrorum, and have excited the interest 
of naturalists from early times. Owing, however, to their very transitory nature, they 
have been generally overlooked in the lobster. A satisfactory explanation of the 
function of the gastroliths has, in my opinion, never been given, and in the following 
section I shall offer one which I think is in harmony with the facts. 

The first reference to these bodies, which I have found, is by Greoffroy the younger, 
in 1709 (74), who says, in his paper on the molting of the crayfish: 

Although I have spoken only of the stones which are found in the river crayfish, there is, more- 
over, a kind of crayfish, called Astacus marinus, in French Ho mar, in which they also occur. 

More particular reference was made to them in 1874 by Chantran (41), and they 
are mentioned for the first time in the American lobster by Wheildou in 1875 (202), 
who says that "just before shedding a white substance, the size of a 5-cent coin, is found 
on either side of the stomach. These bodies harden into limestone and are absorbed 
in the process of forming the new shell." They are described by Vitzou (197) as an 
inorganic reserve composed of small truncated rods, free or delicately bound together. 



Bull. U S. F. C. 1895. The Amercan Lobster. (To face page 89.) 



Plate C. 




Cut 8. -The gastrolith of a lobster nearly ready to raolt, removed from the wall of the 
stomach. 

a, seen from the outside; 6, from the inside (toward cavity of stomach), and c, in 
transverse section. From adult rnale, lobster Xo. 2, table 24. For chemical analysis 
of this gastrolith, see Appendix II, ~So. 4a of table. Natural size. 




X)G 



Cut 10. — Section of the deciduous portion of old cuticular 
lining- of stomach overlying gastrolith. See cut 9, oc'. 
89 diameters. 



,SIC 



^^mMSMii^^ 



Cut 11. — Section of gastrolithic sac from wall of stomach 
underlying gastrolith, as it appears while the latter is 
still in place in the stomach. From a lobster nearly 
ready to molt. August 2, 1894. See cut 9, gp. 89 diam- 
eters. 

D, connective tissue of dermis, ep, chitinogenous 
epithelium, no 1 , new cuticle. 



Cut 9. — Diagrammatic section through the wall of the 
stomach of a molting lobster, cutting gastrolith. 

ep, chitinogenous epithelium, gg, gastrolith, a differ- 
entiated part of the old cuticle, gp, gastrolithic sac. n. 
c 1 , new cuticle of gastrolithic sac. iw, outer side of 
stomach-wall next body -cavity. New 0, new cuticle. 
oc 1 , the deciduous part of cuticle overlying gastrolith. 
Old 0, old cuticle. S, interior of stomach. WS, wall 
of stomach. 



Drawn by F. H. Herrick. 



THE AMERICAN LOBSTER. 89 

[f the shell of a lobster which is nearly ready to molt is carefully removed, there 
will be seen two glistening snow-white masses, one on either side of the stomach 
(fig. 184, pi. 14, and cat 9, pi. C). The shape and dimensions of the gastrolith are 
shown in cat 8 a-c, pi. 0. This particular one, from a, lobster 11 inches in length (No. 2> 
table 24), was an inch long, three-quarters of an inch wide, and a quarter of an inch 
thick. Its outer, convex side is applied to the sac in which it lies, while its concave 
surface is separated from the cavity of the stomach by the old cnticnlar lining of this 
organ (cut 9, pi. O). When the stomach is raised the gastroliths almost break through 
its delicate outer wall by their own weight. They lie between the old cuticular lining 
of the stomach, which may be stripped off, and its delicate outer wall, next the body 
cavity. The impression of the gastrolithic plate is seen on the new cuticular lining 
only (n. c. x ) If the sacs in which they are formed are cut open, each mass separates 
into a large number — a thousand or more — of ossicles or columns. The majority of 
these are slender, truncated prisms of irregular shapes, and 5 mm. or more long. 
Each ossicle resembles a piece of milk-white glass, with transparent edges, and is 
faintly marked with transverse and longitudinal striations, like those seen in the 
cuticle (fig. 165, plate 42). 

On August 2. 1894, I examined a lobster which was very nearly ready to molt. 
The old shell came off easily. The gastroliths were fully formed. We can detect upon 
the new cuticular wall of the stomach the gastrolithic plate, from which the nest 
gastrolith will be formed. When the old cuticular lining of the stomach is removed 
the new teeth appear of the same brown color and nearly of the same hardness as the 
old. The supporting calcareous parts are, however, quite soft. (For analysis of these 
gastroliths, see No. 3a of table, Appendix II.) 

The gastrolith shown in its natural position in the sac (fig. 184, pi. 44) was from a 
male lobster 7.5 inches long. This is the smallest animal in which I have found these 
structures, and it is possible that they are not developed until the lobster is several 
years old, although I have not obtained enough material to establish the time of their 
first appearance with definiteness. A female lobster 3\\ inches long, which was taken 
in Small Point Harbor, Maine, by Mr. M. B. Spinney, was as soft as wet paper, and had 
apparently just molted. Upon dissecting this animal I was surprised to find the 
stomach stuffed full of fragments of calcareous matter, consisting chiefly of waterworn 
pieces of the shells of dead mollusks, such as are commonly thrown upon a beach. 
The largest of these fragments was a quarter of an inch long. Many of the shells 
were softened or corroded and were easily broken by needles. There were, besides, a 
considerable number of small mollusks, such as the young stages of Mytilus edulis. 
Some of these shells, when devoured, were undoubtedly alive. No trace of gastroliths 
could be seen. The old cuticular skeleton of the stomach had been discarded, and the 
new "teeth" were but little hardened, save upon their brown, horny surfaces. 

Another small lobster, a male, 4-^- inches long, taken at the same place and at 
about the same time, had recently molted, probably within a few days. The shell was 
very delicate and fragile. In this case, also, the stomach was loaded with fragments 
of the dead shells of mollusks, crabs, and small lobsters. The hardest parts of the 
shells of the latter seem to have been chosen, such as the stony mandibles, spines, and 
teeth of the large claws. There was no fleshy substance which might serve as food in 
this stomach. It is possible that these shells are swallowed by the young lobster, after 
each molt, to furnish lime for the hardening of the cuticular skeleton. The absence of 



90 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

gastroliths may have no significance in these cases, but in order to determine this 
one should examine the stomachs of larger animals which have recently molted under 
natural conditions. 

The gastroliths, though a part of the cuticle, are not cast off during the molt, hut 
are retained in the stomach. Wheu the old lining of this organ is withdrawn, the 
gastroliths are soon set free, and breaking up into their constituent parts are speedily 
dissolved. 

In the lobster referred to above (No. 2, table 24), which was preserved immediately 
after the old shell was shed, the gastroliths were still in place in the stomach, and 
unchanged. (For chemical analysis of these, see table, Appendix II, No. 4a.) The 
horny parts of the gastric ossicles agree closely with those of the cast shell, having 
the same light-brown color and approximately the same hardness. The supporting 
calcareous parts are, however, quite soft. In every case which I have examined, the 
old teeth are expelled from the stomach at the time of ecdysis, and not left with the 
gastroliths, as Keaumur (161) said was true of the crayfish. 

Experiments upon the crayfish have seemed to show that the gastroliths are 
necessary for the hardening of the new shell, but this is undoubtedly an error. 

The length of time required for the development of the gastroliths of the lobster 
has not been determined. It is probable, however, that the latter part of their devel- 
opment is rapid, and that they are conspicuous objects for a few days only before the 
shell is cast off. 

A female lobster which was examined August 10, 1893, had a very hard, dull- 
colored shell, which one might infer would be shed before many weeks. In place of 
the gastrolith there was a very thin gastrolithic plate in the lateral wall of the stomach 
(fig. 183, pi. 44). A section through this plate (fig. 171, pi. 43) shows how the gastrolith 
is developed. The cuticular epithelium is columnar, consisting of very long, slender 
cells. The thick excreted cuticular product is traversed by undulatory striations, 
which mark off the columnar ossicles, the separation of which begins at the outer 
surface. 

The inner section of the gastrolithic plate (G P) appears much more homogeneous 
than the outer portion, although the demarcation is not quite so sharp as appears in 
the figure. The striations in the inner part are only conventionally represented. The 
undulatory striae extend inward, and with the deposition of lime the ossicles are 
developed and completely separated. When the gastroliths are fully formed (cut 9, 
plate (3) the deciduous cuticle of the gastrolithic sac is differentiated into two parts, 
the gastrolith (gg) and a thin outer layer (oe\ cuts 9 and 10) corresponding to the 
outermost part of the cuticle shown in figure 171 and in continuity with the old lining 
of the stomach (Old G). The new cuticle of the stomach (New C) is represented in 
the gastrolithic sac by a thin stratified layer (nc 1 , cuts 9, 11), from which the next 
gastrolith will be developed. 

The condition of the gastrolith at this stage bears a resemblance to that which is 
finally reached in the crayfish, where, according to Huxley (103) : 

It is a solid body which, in vertical section, is seen to he composed of thin superimposed layers, 
the densest of which form the hard projections of the outer surface next the epithelial substratum. 

The outer side of the gastrolith in the crayfish is roughened with irregular promi- 
nences, so that it resembles a "brainstone" coral. When from any cause the stones 
are not dissolved, they lose their normal blue or white color and become brown or green ; 
the shell remains soft and the animal, according to Ghantran, soon dies. When the 



THE AMERICAN LOBSTER. 91 

formation of the stones is arrested, as Chantraii had often observed in October and 
November, the crayfish was unable to molt, and died. 

Chautran (42) presented to the Academy of Sciences of Paris a paper, giving an 
account of the natural concretions, called " crayfishes' eyes, 1 ' produced from the time 
of birth in this crustacean up to the age of six years — that is, during 22 successive 
molts. It was found that the stones are not absorbed at the moment they become free 
in the stomach, but that they are gradually worn down by reciprocal rubbing and 
contractions of the stomach. The plane faces of the stones are thus rubbed together 
until they are gradually woru down, and at the tenth hour after ecdysis they are 
reduced to pellicles of 1 to 2 mm. in diameter. The destruction of the concretions 
may be complete at this time, or they may persist up to the eightieth hour. 

According to Chantran (41, 42), the number and succession of molts in the Euro- 
pean crayfish are as follows: First year, 8; second year, 5 or 6 ; third year, 3. After the 
third year the males molt twice and the females once annually. He further believed 
that every molt involved the formation of calcareous masses in the stomach, and that 
these numbers consequently show how often the gastroliths have been formed and 
used up. The time occupied in their formation increases with age, being 10 days the 
first year, 15 days the second, 25 days the third, and 40 days in subsequent years. 
The time which elapses after the molt before the stones are reabsorbed also varies 
with the age of the individual, from 24 to 30 hours in the young, which have not 
molted more than twice, to from 70 to 80 hours in adults. 

HISTORY OF THE GASTROLITHS — THEIR PROBABLE FUNCTION. 

The gastroliths were the subject of much curious speculation among the older 
naturalists — Gesner, Bellonius, and Agricola — who, according to Herbst, assigned 
to them a position in the brain. Van Helmont, who first described their true position, 
was not far from right in thinking that they were formed by a milky secretion which 
was poured out between the old aud new linings of the stomach. Geoffroy's observa- 
tions (74), published in 1709, were the best made up to his time. 

I have opened [Geoffroy says] vigorous crayfishes which had entered upon the process of molting 
and have found in the place of each stone ascale or white plate, which swims in the middle of a mucus, 
and which was apparently the undeveloped condition of the stone. This stone and the glairy liquor 
were enveloped in a small, membranous, aud very delicate sac. 

In crayfishes which have recently molted the stones are not in their usual places, 
but lie in the stomach, joined together by their concave parts. No vestige of a stone 
was found in the stomachs of crayfish in which the shell had hardened after molting. 
He concludes however that the stones play no part in the formation of the new shell, 
although they appeared to serve as food after the molt. 

Keaumur (162), besides repeating Geoffroy's observations, added much that was new 
to the subject, and placed the general facts of the molting of Crustacea beyond the 
doubts which had existed up to his time. By dissecting crayfishes which had molted 
he found that the stones gradually dwindled and disappeared. He says: 

Is it not natural to suppose that these stoues are dissolved, and that their substance is then 
carried anil laid down in the interstices of the fibers of which the skin is composed ? 

Boesel (168), in his beautiful Insecten Belustigung, published in 1755, discusses at 
some length the function of the gastroliths, coming to the conclusion that they are 
useless material which is formed during the molt, to be afterwards expelled from the 



92 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

oesophagus. According to Mayer, whom Roesel quotes with some reserve, it was the 
custom of the inhabitants of Asiatic Tartary and Ukrania to collect crayfish at the 
time of the year in which they were in the best condition and place them in large pits 
in the ground. Here they were broken up and allowed to remain all winter, during 
which time the evil odor kept everybody away. In the spring the owners would 
return, wash out the remnants of the crayfish in water, and sift out the stones with a 
sieve which they used for this purpose. It was formerly the custom also in Poland 
and Russia, on the River Don, to collect crayfish in large quantities and allow them 
to rot in the fields or in pits. The stones were afterwards carefully collected and sent 
to market to be used as medicine. 

Mr. Baker (7) communicated to the Royal Society on February 25, 1748, an inter- 
esting letter on "crabs' eyes" from Dr. James Mouusey, a Russian physician. He 
noticed the seal-shaped spots on the wall of the stomach, which mark the position of 
the developing gastroliths, and concluded that the latter helped to form the new shell, 
which, he says, " does not greatly recommend the opinion that these stones have a 
dissolving quality of service against the stone in the human kidneys and bladder." 
"The price comes to a groat or sixpence a pound. All the apothecary shops through- 
out the whole Russian Empire are furnished with them, and great quantities are 
exported." Notwithstanding their cheapness, "fictitious bodies, made of chalk" and 
" tobacco-pipe clay " were cast in molds and substituted for real " crabs' eyes." In 
this case the counterfeit undoubtedly possessed all the virtues of the genuine article. 

K. E. von Baer (6) thought that the gastroliths were salivary stones, developed 
in the lumen of a salivary gland, an idea which was not destined to bear much fruit. 
Some writers even pretended that they were cast out through a fissure in the walls of 
the stomach and body. 

Van der Hoeven (195) seems to have been one of the first in the present century 
to protest against the theory that the sole function of the gastroliths was to provide 
lime for the new shell. In his Handbook of Zoology, a translation of which was 
published in 1834, he says : 

The part, however, which the crabs' eyes take in the secretion [of the hard shell] can not he 
great when we compare their weight with that of the calcareous matter of the shell. During the 
time that the shell is still increasing in hardness no new crabs' eyes are produced; but only after 
the shell has attained its greatest hardness is calcareous matter again secreted on the walls of the 
stomach, and new crabs' eyes again appear. Thus the production of crabs' eyes would seem to be 
a vicarious secretion of such constituents of the blood as, if too abundant, would be injurious to the 
organs, like the secretion of urine for instance, but with this difference, that the calcareous matter is 
not set at liberty shortly after its secretion, but remains accumulated for a long time in continuance. 

Max Braun, in his work on the molting of the crayfish (22), concluded that the 
gastroliths were cuticular products analogous to the integument, but paid no attention 
to their function or growth. 

Vitzou (197) says that shortly after the molt in the lobster the gastroliths are dis- 
solved in the acids of the stomach and, entering the lymph, form an inorganic reserve 
comparable to the phosphatic plaques which are found in the membranes of the foetus 
in ruminants. 

The problem of the gastroliths has recently been attacked by Irvine and Wood- 
head (105) in one of their valuable communications on the secretion of carbonate of 
lime in animals. They conclude that, if the gastroliths play any part at all, they must 
be converted into phosphates and thus carried in the lymph. If the brachyura have 



THE AMERICAN LOBSTER. 93 

a lime reserve, it must be in the lymph, in the form of calcium phosphate, since they 
have no gastroliths. "We think," they say, "that this theory [of the gastroliths 
contributing to the formation of the new shell] may be dismissed as of comparatively 
little importance, since, even if the teeth and whole calcareous structure could be 
absorbed by the animals, the amount of carbonate of lime at their disposal from this 
source is so small (a very small fraction of the outer covering) that it could not account 
for any considerable part of the new structure. Consequently such an explanation 
must be abandoned." 1 

These writers are undoubtedly right in attributing little importance to the gastro- 
liths as a source of lime for the new shell. Lime is usually at hand in abundance in 
the form of the dead skeletons of mollusks and other animals, and, as we have seen 
(see p. 80), young lobsters make free use of it at the time of the molt. The fact that 
the bracliyura have no gastroliths should also possess some significance. 

I have already shown that there are considerable areas in the shell where the lime 
is completely absorbed preparatory to the molt. What becomes of the lime thus 
removed ? So far as known, there is no means of eliminating it directly from the body, 
and it is not likely that this amount of lime can be retained in the blood in addition to 
that which the latter is constantly receiving from the food. It seems to me much more 
probable that the gastroliths in the lobster represent the lime which has been removed 
by absorption from the old shell preparatory to the molt, as well as, possibly, a small 
amount which may have entered the blood from the food during the molting period. 
The blood probably contains a maximum quantity of lime at this time, so that very 
little can be absorbed from the food. Upon this hypothesis the absorption of the gas- 
troliths is a purely secondary phenomenon and of comparatively little importance in 
the vital economy. In the bracliyura, where no gastroliths are developed, we should 
expect to find the absorption of lime from the shell to be relatively much less, which, 
so far as I can ascertain, is the case. It seems to be a fact also that the absorption of 
lime from the old shell proceeds pari passu with the growth of the gastroliths. 

Chantran observed (see p. 90) that when the formation of the stones was 
arrested in the crayfish the animal died. This might be true of the lobster, and 
would not conflict with the theory proposed. When once formed, the question of the 
subsequent absorption of the gastroliths is not of vital importance. Vitzou speaks 
of a lobster which died six days after the molt, without absorption of the gastroliths 
having occurred. It would, of course, be very illogical to conclude that the gastroliths 
were necessarily in any way concerned with the death of this animal. 

1 In an interesting letter from Dr. Irvine, describing some of his recent experiments, he says in 
reference to a former attempt to determine the proportionate quantities of carbonate of lime in the 
exoskeleton : "But as these experiments were made with the common shore crabs, containing much 
less carbonate of lime proportionately to a full grown animal, I have repeated the determination, 
using a full-sized lobster which weighed 15,000 grains. On carefully separating the stomach, and 
freeing it from merely fleshy appendages and drying it, I find it to weigh about 50 grains or T gxy of 
the whole animal, while the gastroliths weighed only 20 grains or yJ^ of the whole. I then carefully 
dried the outer calcareous structure and found it to weigh 3,720 grains, the proportion between 
the carbonate of lime in the gastroliths and in the outer structure being 20 grains to 3,720 gr ains 
The CaCo 3 in the gastroliths thus stood in proportion to the CaCo 3 in the exoskeleton as 1 part in 186, 
an amount too trifling to be of any practical service in providing calcareous matter for it." 



94 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



CHEMICAL ANALYSIS OF THE SHELL AND GASTROLITHS. 

It seemed to me that a chemical analysis of the shell of the lobster in its differ- 
ent conditions imposed by the molting habit might prove of interest, especially when 
compared with the composition of the gastroliths, and I am fortunate in being able to 
add as an appendix of this work the results of several analyses made by my friend, 
Professor Albert W. Smith. 

The most striking facts brought out by Professor Smith's work are, first, that lime 
salts, carbonates and phosphates, form about half the constituents of the hard shell, 
there being from three to five times as much carbonate as phosphate. We also find 
that in the cast shell of the lobster, the brittleness of which we have already noticed, 
the proportion of organic matter present is considerably less than under other condi- 
tions. An absorption of organic matter thus takes place during the period in which 
the new shell is formed, and this fact explains the fragility of the cast-off shell. 

It is also interesting to notice that small quantities of alumina and silica are 
normally present in both the shell and gastrolith. 

The composition of the gastroliths is very like that of the shell, a conclusion 
which we would be led to draw from the fact that the gastrolith is but a specialized 
part of the dead chitinous integument. The same substances are found in both, but 
in different proportions. The gastroliths are far richer in lime, chiefly in the form of 
carbonate (0a0O 3 ), than is the shell, and the amounts of magnesium carbonate 
(MgOO^), alumina ( A1 2 :! ), ferric oxide (Pe20 3 ), and silica (SiO>) are more or less reduced. 

Lime estimated as carbonate (0aCO 3 ) constitutes about three-fourths of the 
gastrolith, but less than two-fifths of the carapace. Lime reckoned as phosphate 
(0a 3 (PO 4 ) 2 ) forms about 10 per cent of the gastrolith and but little less in the case of 
the shell; about 10 per cent of the gastrolith is water and organic matter, probably 
mainly chitin, and the rest is made up of the various salts and oxides given in the table. 
In the only molted shell analyzed about 38 per cent was water and organic matter, while 
in two hard-shell lobsters this percentage was considerably greater, 42.21 in one case 
and 51.80 in the other. 

The gastroliths of the crayfish were analyzed by Dulk (54) in 1834, 1 but apart from 
this rough determination no later work has been done on this subject. 

He also analyzed the contents of the stomach of a crab newly molted, and found 
a free volatile acid, probably hydrochloric, present, besides lime salts (53). 

THE HARDENING OF THE NEW SHELL. 

Since the total quautity of lime contained in the gastroliths is insignificant com- 
pared with the amount necessary for building up the hard crust, the rapidity with 
which the new shell hardens depends, in some measure, upon the individual, and 
particularly upon the quality of its food. We have seen that the adolescent lobster, 
under 4 inches long, after molting swallows fragments of shells and other calcareous 
materials, which are dissolved in the stomach and help in strengthening the new shell. 
It is possible that older lobsters have the same habit. 

1 The results of Dulk's work were as follows : 

Animal matter soluble in water 11. 43 "| 

Animal matter insoluble in water (probably chitin — Huxley) 4. 33 | 

Phosphate of lime 18. 60 ^98.93 

Carbonate of lime 63. 16 j 

Soda reckoned as carbonate , 1. 41 J 



THE AMERICAN LOBSTER. 95 

According to the researches of Irvine and Woodhead lime salts, in whatever con- 
dition absorbed, are changed daring digestion into acid phosphates, and in this state 
are carried by the blood to the protoplasm of the chitinogenous cells. The nascent 
carbon dioxide gas, which the active protoplasm of these cells throws off, precipitates 
calcium carbonate (CaC0 3 ) and calcium phosphate (Oa 3 (PO.,),>). These salts are then 
dialyzed into the dead chitinous matrix, where they are finally laid down. Lime is 
deposited in an insoluble condition only in vitally inactive tissues. They found that 
crabs which began to shed late in the season were retarded by the cold. Heat tlms 
seems to be a necessary factor in the assimilation of lime salts from seawater by these 
animals. They also found that the crabs died in watercontaining only sodium chloride 
(NaOl), but lived without molting in water containing NaCl and magnesium chloride 
(MgCl 2 ); they lived and molted in water which contained NaCl, MgCl 2 , and calcium 
chloride (CaCl 2 ), the latter in the amount equivalent to the lime in normal sea water. 

A lobster which molted while under observation (No. 7, table 24) was watched 
particularly with reference to the hardening of the shell. One hour after the molt 
the cuticle seemed to the touch of the finger to be perceptibly hardened, but this may 
have been partially due to the turgescence of the tissues. Eighteen hours after shed- 
ding the cuticle had a leathery consistency, and the tubercles and spines had hardened 
slightly. The shape of all the parts was perfectly normal. Four days after the molt, 
when the animal died, the cuticle was still coriaceous, and but slight increase in the 
stiffness of any parts had occurred. 

A lobster which also molted in confinement (No. 6, table 24) was kept for a period 
of twenty-five days. The carapace at the end of this time was easily compressible 
between the thumb and finger. The large claws could be made to yield in the same 
way, but not without using considerable force. It was in the state which the fisher- 
men call "paper shell" or " rubber shell." If sent to market it would be classed as a 
soft-shell lobster. It is possible, of course, that in this space of time a lobster under 
natural conditions would have become harder. It is safe to conclude, However, that 
from six to eight weeks are necessary, under ordinary conditions, to produce a shell 
which is as hard as that cast off; and if the lobsters were destined for the market they 
would probably be in a still better condition in ten weeks or three months. Many 
lobsters are caught and shipped to dealers a few weeks after they have molted, but 
their meat is then soft and of inferior quality, as we have already remarked. According 
to the opinion of a canner of lobsters in Maine, 7 pounds of soft-shelled lobsters in 
summer or fall will yield no more than 4 pounds in spring, when the flesh is more solid. 

Eeaumur says of the crayfish (162) that he has seen the new shell become as hard 
as the old in 24 hours, but that it usually takes from two to three days. This observa- 
tion is confirmed by Chantrau (37), who says: 

Twelve hours after the molt, the nippers are already hard enough to pinch sharply, and in 24 
hours they are completely hardened. The sides of the back remain flexible for a much longer time, 
but at the end of 48 hours they have attained a degree of consistency which is almost normal. 

Vitzou remarks that the carapace of the crabs has perceptibly hardened after 24 
hours, but is not completely hardened until after 72 to 80 hours. 

It has been stated that the shell of the newly molted lobster becomes as hard as 
formerly in the space of 24 hours. This and many similar conjectures which have 
been made upon this subject are entirely erroneous, as proved by the statistics of the 
fishery during the summer months. It is probable, however, that under exceptional 
conditions this process is subject to much variation. 



96 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



THE RATE OF GROWTH. 

The question often asked is, How long does it take an adult marketable lobster to 
grow? It is impossible to answer this with certainty, since complete data for solving 
the problem have not been gathered. We can, however, give a tentative answer which 
is probably not far from the truth. 

In order to ascertain the average age of a lobster 10£ inches long (weight, 1| 
pounds), it would be necessary to know, first, the number of molts which the animal had 
passed through, and, secondly, the time interval between each molt. The number 
of molts can be approximately determined by means which I shall presently discuss. 
The time interval can only be ascertained by keeping the animals alive for a period of 
years and carefully recording their growth. Both factors are very variable quantities, 
as I have already shown. The length of one yearling lobster which was raised from 
the egg was only 36 mm., while three other lobsters measured from 35 mm. to 51.8 mm., 
when not over five months old. Lobsters which live in harbors where they find abun- 
dant food undoubtedly grow much faster than those farther from shore. It would 
hardly be expected, moreover, that lobsters kept under artificial conditions would 
grow as rapidly as when free in the ocean. 1 

In table 24 I have recorded the molts of eight lobsters varying from 5£ to 11J 
inches in length. The actual increase in length varied from 1 inch to 1£ inches, and 
the increase percentage (that is, the ratio whicli the increase bears to the total length 
before molting) from 6.66 to 18.18. The average percentage of increase in all these 
cases is 12.01. 

Table 24. — Increase in the length of lobsters at the time of molting. 



No. 


Date. 


Sex. 


Length 

before the 

molt. 


Length 

after the 

molt. 


Increase 
in length. 


Increase 
percent. 


Remarks. 






Inches. 


Inches. 


Inches. 






1 


Oct, 22,1890 


Female . 


5i 


H 


1 


18.18 


Carapace of molted shell unbroken ; 
preserved a few days after molt- 
ing; gastroliths gone; stomach 
filled with pieces of fish, which 
had been ted to it; carapace 
leathery. Plates 45a and 456. 


2 


Oct. 29,1890 


Male 


11 


12 


1 


9.09 


Carapace unbroken ; preserved im- 
mediately after molting; gastro- 
liths in their sacs in the walls 
of masticatory stomach. See cut 8, 
plate C. For chemical analysis of 
gastroliths, see Appendix II, 
No. 4a of table. 


3 


Nor. 6, 1890 


. ..do 


n 


H 


1 


9.68 


Carapace unbroken. 


4 


Nov. 10, 1890 




9 


104 


H 


16.66 


Do. 


5 
6 


Nov. 11, 1890 
Juue 8,1891 




74 


8 
10^ 


h 

1& 


6.66 
13.13 


Do. 

Carapace unbroken; measured July 


...do .... 
















2. See table 28. 


7 


July 13,1891 


...do.... 


Hi 


12J 


li 


11.11 


Carapace unbroken ; measured July 
17. See account of molting of this 
lobster, pp. 83-85; also plate B. 


8 






64. 


n 


2 


Ik 54 


Recorded by Packard (W). 










12.01 









'The best way to ascertain the growth of the lobster would be to fence in securely with wire 
netting a convenient area in a lobster pound, place a few lobsters in the inclosure, and feed them reg- 
ularly. They should be examined every week and carefully measured. They could be distinguished 
by branding the tail-fan. By selecting lobsters of different sizes (3, 5, 8, 10 inches long), the rate of 
growth at different periods of life could be gradually determined. 



THE AMERICAN LOBSTER. 



97 



The increase per cent in the growth of larvae is recorded in table 34. Sixty-six 
molts belonging to more than half as many individuals are tabulated. The average 
increase per cent in length in stages 2 to 10 varied from 11 to 15.84. The average for 
stages is 13.67; for individuals, 13.89. These facts seem to warrant the conclusion 
that the increase percentage in the young is very similar to that of the adult, a result 
of considerable interest. The average length of the young lobster during its first ten 
molts is given in the following table. The data are taken partly from table 34: 

Tablk 25. — Actual length of lobsters during the first ten molts. 



Number of molt or stage. 


Average 
length. 


Extremes in 

length. 


Number of 

lobsters 

examined. 


mm. 
7.84 
9.20 
11.1 
12.6 
14.2 
16.1 
18.6 
21.03 
24.5 
28.03 


mm. 

7. 50 to 8.03' 

8. 3 10. 2 

10 12 

11 14 
13.4 15 
15 17 
18 19. 5 
19. 75 22 
24 25 
26. 6 29. 5 


15 
47 
79 
64 
15 
12 

5 

I 1 


2 


3 


4 . 


5 


6 


7 


8 


9 . 


10 





The rate of growth expressed by the average of lengths in the second column 
of table 25 implies an increase per cent of about 15.3 instead of 13.67 (the average 
increase in stages recorded in table 34). Assuming the average length of the first 
larva to be 7.84 (the average of 15 individuals, table 25), and allowing the increase in 
length at each molt to be 15.3 per cent of the length before molting, we would have 
the following series of lengths attained during the first thirty stages. 

Table 26. — Estimated length of lobsters during the first thirty molts. 



Stage. 


Length. 


Stage. 


Length. 


Stage. 


Length. 


1 


mm. 
7.84 
9.04 
10.42 
12.02 
13.86 
15.98 
18. 42 
21. 24 
24.49 
28. 23 


11 


mm. 
32. 55 
37.54 
43.28 
49.90 
57. 53 
66. 34 
76. 49 
88.19 
101.68 
117. 24 


21 

22 

23 

24 

25 

26 

27 


mm. 
135. 17 
155. 86 
17D.70 
207. 20 
' 238. 90 
2275.45 
317.59 
366. 16 
422. 21 
3486.81 


2 


12 


3 

4 

5 


13 

14 

15 

16 


fi 

7 

8 


17 

18 

19 

20 


28 

29 

30 


9 


10 





1 9.5 inches. 



1 11 inches. 



3 19.1 inches. 



According to this estimate a lobster 2 inches long has molted 14 times ; a lobster 
5 inches in length, from 20 to 21 times; an adult from 10 to 11 inches long, 25 to 26 
times, and a 19-inch lobster 30 times. These estimates do not, I believe, go very 
far astray. We see them practically verified up to the tenth molt by comparing the 
figures given above with those in the second column of table 25. 

The time interval between successive molts is the next point to consider. The 
yearling lobster undoubtedly varies greatly in size. A young female lobster already 
mentioned reached the length of 51.8 mm. by December 10, or when from five to six 
months old (No. 19, table 33). On the 28th of January 16 small lobsters, measuring 
from 39 to 83.7 mm. in length, were driven ashore at Woods Hole during a storm. It is 

F. C B. 1895—7 



98 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

certain that some and possibly all were hatched in the preceding summer. Allowing 
the lobster (No. 19, table 33) whose length was 51.8 mm. long on the 10th of December 
to have molted, in case it had lived, three times before the following June, and this is 
well within the bounds of probability, it would then have attained a length of a little 
over 3 inches. During the first year the young lobster probably molts from 14 to 17 
times and attains a length of from 2 to 3 inches, but it is likely that the length reached 
often exceeds these limits. 

Of the young lobsters recorded in table 32 a few may be the young of the year 
(JSTos. 1-4), that is hatched in the previous June, but the majority are probably from 
one to two years old. It is further possible that some of these were hatched at other 
times of the year than June. 

Brook appears to be the only one who has given a trustworthy account 1 of the 
successive molts of individual lobsters. He succeeded in keeping a lobster (female, 
length 6f§ inches) alive in an aquarium 506 days, from July 1, 1883, until November 
19, 1884, during which time the animal molted four times (on July 1 and December 
25, 1883, July 25 and November 19, 1884) and increased in length 2- 1 3 6 - inches. During 
the first year of its captivity it molted twice, in summer and early winter; again it 
molted in summer and late fall. The lengths at successive stages were as follows: 
611, 7fV, 8, S\i, 9^ inches. 

In another captive lobster (a male, length 7- x - 6 - inches) four molts were also passed, 
one in the spring and fall of two successive years (May 19, September 20, May 13, 
October 13). The lengths at successive stages were as follows: 7- 1 a 6 -, 7-ff, 8^|, 9j%, 9y§ 
inches. There was an increase here in length of 2-^ inches in 414 days. 

These experiments are instructive in showing that in the unfavorable conditions 
of life in an aquarium a lobster from to 7 inches long will make a gain in length of 
2£ inches in 14 to 17 months. It is therefore extremely likely that in nature a 6-inch 
lobster will often attain the length of from 9 to 10 inches in two years. 

How long a time is the 3-inch yearling lobster growing to become 6 inches in 
length? Eeference to the series of molts given in table 26, deduced from study of 
the young, leads us to expect five molts (Nos. 18 to 22) between the 3 and 6 inch stages. 
It is certain that these do not embrace more than two years, and it is probable that 
they require somewhat less. We may therefore conclude that a 10-inch lobster is 
between four and a half and five years old, the higher degree of probability favoring 
the smaller number. 2 The reader is reminded that this is only an estimate, based, it is 
true, upon rather slender data, but upon the only facts which we possess. In future 
years some experiments will be made by which this result can be tested. 



1 Buckland (29) says that " according to some careful observations made at the marine labora- 
tory, Concarneau, it appears that the first year the lobster sheds his shell six times, the second year 
six times, the third year four times, and the fourth year three times." If this were ameuded so as to 
read careless instead of "careful"' observations, no complaint could be made. We have seen that 
the American lobster molts ten times in the space of three or four months, and it is not probable that 
the record is very different for the English species. No crustacean is known in which the molts are as 
numerous during the second year of its life as during the first. A table is also given by Buckland 
showing the rate of growth during successive molts, but it seems to be based upon error. At the eighth 
molt the lobster is said to be 2 inches long, whereas the American lobster is less than 1 inch in length 
at the eighth molt (21 mm., see table 25), and there is no reason to believe that the European species 
is more than twice as large as its near ally at this stage. 

2 Coste maintained that the European lobster was about 5 years old (length 24 em.) before 
becoming sexually mature, and this supposition, though unsupported at the time by any detailed 
facts, seems to be very near the truth. (See 61, p. 285.) 



THE AMERICAN LOBSTER. 



!)9 



Vitzou records the following observations {107) upon the increase iu size and 
weight of molting lobsters. Ln a lobster which was measured immediately before and 
after the molt it was found that the carapace had gained 11 mm. iu length and the 
abdomen 8 mm. The last joint of the right claw was smaller by 3 mm., which is 
explained, first, by the thickness of the chitinous layer in this joint, and, secondly, by 
the almost complete absence of blood in the claw at this time. This is a forced con- 
dition, since if the last joint of the claw were increased in size it would be next to 
impossible for it to be withdrawn (see pp. 86-87). The same lobster 17 hours after the 
molt showed no increase iu size of carapace or abdomen, but the claws had gained from 
12 to 15 mm. in length. No increase in any of these parts was noticed on the third to 
the sixth days following the molt, but there was a gain in weight. 

Table 27. 



Time of observation. 



Immediately alter molt 

The day following molt 

Third day following molt 

Fourth day following molt 

Fifth and sixth daysfollowing molt 



Weight. 
Grams. 


Increase. 


Grams. 


500 
610 




100 


619 


9 


642 


23 


642 






The following measurements show the increase in various parts of the body after 
the molt. They refer to lobster No. 6, table 21 (compare plates 45a, and 45ft) : 

Tablk 28. 



Measurements. 



Before 
molt. 



Inches. 

Length 9. 28 

Length of carapace | 4. 33 

Greatest width of carapace i 2. 2 

Length of crushing-chela (propodus) I 4. 12 

Width of crushing-chela at base of dactyl.. 2.06 

Length of dactyl 1. 90 

Width of dactyl at base .72 

Length of small cutting-chela (right) 4. 53 

Width of small cutting-chela 1. 53 

Length of dactyl 2.53 

Width of dactyl ] .56 



Five days 
after molt. 



Inches. 
10.50 
5.03 
2.33 
5.62 
2.56 
2.25 
1.00 
5.53 
1.47 
3.06 
.65 



Increase. 



Inches. 

1.22 
.70 
.13 

1.50 
.50 
.35 
.28 

1.00 

— .06 

.53 

.09 



Chapter IV.— DEFENSIVE MUTILATION AND REGENERATION OF LOST PARTS. 

AUTOTOMY IN THE YOUNG AND ADULT. 

It is well known that among the invertebrates the Crustacea possess, in a 
remarkable degree, the power of reproducing parts of their bodies which have been 
lost. This is most pronounced in those Decapods, such as the crab and lobster, which 
practice defensive mutilation or autotomy. Thus, if one catches aland crab and holds 
it by the carapace it brandishes its chelipeds in its vain attempts to get free, but once 
seize it by the claws, the crab immediately scuttles off, leaving you in possession of 
its only effectual weapons. The leg is broken off at a definite place near its base; 
there is very little bleeding from the old stump, and a new limb soon sprouts and 
grows again. This power of thus detaching a limb at the right time is a valuable 
means of defense, which, as Pere Du Tertre remarked, would be very useful for pick- 
pockets. The lobster has the power of casting off its legs, but those which carry the 
"nippers" are the most commonly sacrificed. 

The limb (cut 6, plate B) consists of seven joints, two basal ones — coxopodite (1) 
and basipodite (2) — and five succeeding joints, the last two of which form the claw 
(6 and 7, cut 6). In autotomy the five terminal joints are always cast off; that is, frac- 
ture takes place between the second and third segments. In the large chelipeds of the 
lobster the second and third joints — basipodite (2) and ischiopodite (3) — are fused 
together. This is the case in all the pereiopods of the crab. There is a distinct groove 
which marks the union of the two fused joints, and it is always in this groove that 
disjunction occurs (x, cut 13, plate D). This fact was noticed by Eeaumur {161) at the 
beginning of the last century, but he did not offer an explanation. He noticed that it 
was not at the functional articulation that the limb was broken, and that the shell of 
the "second joint" (second and third, cut 13) was "composed of several different 
pieces. The evidence of this was found in the presence of two and sometimes three 
sutures, which occur in this .part. It is in the middle suture, moreover, that the leg 
is broken." He noticed also that the leg could be broken off by exerting very little 
force. The interesting fact did not escape his attention that if you cut off the leg at 
or near the terminal joint you will find after a time that the mutilated limb is always 
thrown off at the suture between the second and third joints. 

Fredericq (71) has published several papers on the defensive mutilation of the 
crab, and has given a physiological explanation of this phenomenon. I will now add 
a brief abstract of some of his experiments, which were performed chiefly upon the 
common green crab, Carcimis mcenas. 

The breaking off of a leg, which so often happens when we handle these animals, 
is not due to their fragility, for experiment proves that the limbs of a dead crab are very 
resistant and that they will support a weight of 3£ to 5 kilograms (7.7 to 11 pounds), 
which represents about one hundred times the weight of the entire body of the animal. 
If one breaks off a leg of a dead crab, it separates either between the cephalothorax 
and first joint, or between the first and second joints, and a mass of muscles is usually 
drawn out of the body Avith it. The fracture of the leg of a living crab occurs, as Ave 
100 



Bull. U S. F. C. 1895. The American Lobster. (To face page 1 00. i 



Plate D. 




Cut 12.— First left pereiopod of adult lobster, seen from in 
front, showing anterior border at base, of limb. Two- 
thirds natural size. 

a, b, constrictions in cuticle of third joint, c, oblique 
linear impression upon upper surface of second joint 
X, plane of fracture. 1-5, segments of limb. 




Cut 13. — Basal portion of first left pereiopod of adult lobster from under side. Two- 
thirds natural size. 

a, b, grooves on surface of third joint external to x. Br, podobranchia. x. plane 
of fracture, y, spur of second joint. 1-6, segments of appendage. 




Cut 14.— Second left pereiopod of female, 10 inches long, seen from under side. 
Two-thirds natural side. 

«., constriction upon second joint immediately in front of x. Br, podobran- 
ehia. x, articulation between second and third joints, corresponding to plane 
of fracture in cuts 12 and 13. y, spur on second joint. 



Drawn bij F. H. Herrirk. 



THE AMERICAN LOBSTER. 101 

have seen in the large cheliped of the lobster, in a definite plane. It involves only the 
nerves and blood vessels of the soft tissues, and is provoked by a vigorous muscular 
contraction, which occurs whenever the nerve of the leg is stimulated violently, whether 
bya mechanical stimulus, as by snipping oil' the terminal joints, or by electricity, heat, 
or chemical action. The nervous mechanism is reflex, and thus beyond the control of 
the animal. Autotomy occurs when the whole of the dorsal and cephalic regions of 
the body, including the supra oesophageal ganglion or brain, is removed. The reflex 
nerve center is found to lie in the thoracic ganglionic mass of the crab, or ventral nerve- 
chain of the Macrura. 

The second compound joint is moved by two muscles, a flexor and an extensor, 
of which the last only is essential to autotomy. Fracture of the limb w as produced so 
long as the extensor muscle and its tendon were unimpaired, but when these were 
sectioned autotomy was suppressed. 

The mechanism of the crustacean limb has been explained by Milne Edwards 
(58, vol. 1, p. 152). The leg consists, as we have already seen in Decapods, of seven 
joints, each of which is a lever of the third order. Any two joints are articulated like 
a hinge, touching at only two points, and are capable of simple extension and flexion 
only. The whole limb, however, is capable of executing complicated movements, since 
the axes of articulation of the several segments are not parallel, but nearly at right 
angles to each other. Each segment possseses two or more cuticular tendons at its 
proximal extremity, upon which its flexor and extensor muscles are inserted, the fibers 
of the latter being fixed upon the inner surface of the next proximal joint. 

Fredericq has shown that the distal extremity of the second joint, or basipodite, is 
separated from the third joint, or ischiopodite, by a diaphragm, perforated near its 
center only, for the passage of the nerves and blood vessels; and Andrews (3) has 
pointed out that li in the spider crab, Libinia canaliculata, there extends from the plane 
of rupture" a distinct membranous fold, "from the epidermis to the central nerve and 
blood vessels." With the rupture of the limb the outer half of the membrane is torn 
away, leaving a clean stump. This double membrane possibly represents, as Andrews 
suggests, the invagination of the body wall, like that seen at an ordinary movable 
joint. This membrane has thus experienced a complete change of function, and has 
become modified so as to prevent excessive hemorrhage. 

In order that autotomy may occur it is necessary that the peripheral portion of 
the limb should offer a greater resistance than the traction of the extensor muscle is 
able to overcome, allowing the traction of the muscle to be equivalent to a weight of 
250 grams. Ordinarily the sides of the carapace, the hard parts of an adjoining leg 
or the clutch of an euemy afford the necessary resistance. 

If the compound — second and third — joint of the cheliped of the lobster be examined 
a fine hair line is seen leading from the small spur next to the articular facet on the 
under side, round the anterior border to the upper side of the joint. It then bends 
forward and abruptly backward, crossing the small proximal end of the joint, to near its 
pointof departure (x, cutsl2, 13, plate D). There are incomplete grooves in front of this 
line (cut 12, a, &,) and a more oblique one behind it (cut 12, c). On the upper side of 
the second joint of the small walking legs of the lobster a delicate hair line is also seen, 
which turns abruptly forward at the anterior border of the appendage and joins the 
arthrodial membrane. This groove looks as if it might mark the plane of rupture in 



102 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

a part of the joint, but it does not correspond to the inter segmental groove (cuts 
13, 14, x) of the cheliped. 

1 have never observed the casting of a claw at any time before the fourth larval 
stage. Autotomy seems to be occasionally practiced at this period, and in the fifth 
and following stages it is common. This is illustrated by the history of larva ~No. 
23, table 34. When this lobster in the fourth stage was placed under observation, July 
25, it was 13 mm. long and had lost both its large chelipeds and its right fii'th and left 
fourth pereiopods. When, fifteen days later, August 9, it molted to the fifth stage 
(length, 15 mm.), the large left cheliped (figs. 92, 96, plate 33) and the fourth and fifth 
walking legs were regenerated; the right cheliped appeared as a rudimentary stump. 
Eight days later, August 21, it had molted to the sixth stage (17 mm. long), when its 
large right cheliped appeared regenerated. The animal was placed in a flat glass dish, 
and in disturbing it, upon changing the water, it shot off its large left cheliped again 
and died two days after. 

In the first larva there is a free articulation between the second and third joints of 
the great chelipeds (fig. 66, plate 30), and there is no true fusion of the segments until 
after the fifth stage. In the fourth stage the articulation is distinct, as represented 
in cut 15. This not only shows that the plane of rupture in the large chelipeds 




Cut 15. — Part of first cheliped of fourth larva, showing the base of the limb and distinct articidation 
between the second and third joints. 
a-a\ piano of section shown in tig. 169, plate 43; br, podobranehia; x, articulatiou between second and third joints, 
corresponding to plane of fracture in adult appendage; y, articular process in second joint; 1-4, segments of limb. Drawn 
from molted shell. 

corresponds to what was formerly a free articulation, but also that this autotomy is a 
comparatively recent acquisition. It may have been acquired independently in the 
Macrura and Brachyura. Autotomy of a pronounced character occurs only in limbs 
where fusion of two neighboring joints has been effected, and was probably produced 
as a result of natural selection while the fusion was taking place. 

The habit of " casting a claw " being of a purely reflex character, and therefore not 
subject to the will of the animal, there is needed only the proper stimulus to call it into 
play. Unintentional experiments in autotomy have often been made by tethering a 
lobster or crab by its large claws. The animal, of course, escapes, leaving only its 
members behind. When lobsters are drawn out of the water by the claws, or when a 
claw is pinched by another lobster, or while they are handled in packing, especially 
for the winter market, they often "cast a claw;" and the transportation of lobsters 
at this season is said to be attended with considerable loss in consequence. The old 
custom of plugging lobsters, which consisted in driving a wooden wedge between the 



THE AMERICAN LOBSTER. 103 

joints of the claws, to prevent them from injuring- each other, lias been generally 
abandoned. Mutilated lobsters are now often placed in pounds, where they are 
allowed to repair their injuries. 

One has only to examine a lot of freshly captured lobsters to be assured of how 
common the practice of casting the claw is. "Out of a hundred specimens," says 
Rathbuu {155), "collected for natural-history purposes in Narragansett Bay in 1880, 
fully 25 per cent had lost a claw each, and a few both claws." In a total of 725 lobsters 
captured at Woods Hole in December and January, 1893-94, 54 or 7 per cent had 
thrown off one or botli claws. 

It is often stated that lobsters sometimes cast their claws during thunder storms, 
but until some proof of the truth of this statement is afforded it must be regarded as 
a fable. One of the earliest versions of this idea which I have seen is that of Travis 
(191), who wrote to Pennant in 1777 that — 

Lobsters fear thunder, and are apt to cast their claws on a great clap. I am told they will do 
the same on firing a great gun, and that when men-of-war meet a lobster boat a jocular threat is 
used, that if the master does not sell them good lobsters they will salute him. 

Since autotomy is the result of a reflex nervous impulse, and has been acquired 
by the animal as a meaus of defense, we should expect to And that the reflex center 
would always be aroused into activity by stimuli coming through the nerves of the 
limb, as is always the case in experiment, and not through a higher center like the 
brain. When an animal is frightened by loud noises it is impelled to flee, and it would 
manifestly be of no advantage to the animal to immediately drop its legs. 

REGENERATION OF APPENDAGES. 

The regeneration of lost limbs in Crustacea has been studied by Reaumur (161) 
Goodsir (80), Ohantran (38, 40), and Brook (26). 

Reaumur's general account of the process in the crayfish is one of the best which 
has been written. He quotes JDu Tertre (55), who had " made similar observations 
on the crabs of Guadeloupe, of which he has giveu a very curious history." Reaumur 
began his experiments on the seacoast, but the sea broke and carried away his boxes 
or filled them with sand. He then experimented with crayfishes with more success. 
He says : 

I took several of them, from which I broke off a leg; placed them in one of the covered boats 
which the fishermen call " Boutiques," in which they keep fish alive. As I did not allow them any 
food, I had reason to suppose that a reproduction would occur in them like that which I had attempted 
to prove. My expectation was not in vaiu. At the end of some months I saw, and this without 
surprise, since I had expected it — I saw, I say, new legs, which took the place of the old ones, which I 
had removed; except in size they were exactly like them; they had the same form in all their parts, 
the same joints, the same movements. A kind of regeneration like this hardly less excites our envy 
than our imagination; if, in the place of a lost leg or arm, another would grow out again, one would 
he more willing to adopt the profession of the soldier. 

He noticed that the time necessary for the production of new legs was indetermi- 
nate, depending upon a variety of conditions: 

These limbs arise and grow more or less rapidly, like plants, according as the season is more or 
less favorable; the warmer days are those which hasten the more their formation and growth. 

Sometimes new legs sprout out in three weeks; sometimes not until after six, and 
when the legs are broken off in winter they do not grow again until summer. 



104 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Reaumur cut off the "tails" of crayfishes in various places, but there was never 
any reproduction of these parts, and the animals invariably died after a few days. It 
sometimes happens that a lobster loses a part of its "tail," and the accident probably 
results fatally in most cases, but not always, according to the statement of Mr. Thomas 
Barton, who is employed at the lobster pound at Viual Haven, Maine. He says that 
in the winter of 1892-93 he caught several lobsters with the tail-fan and the last one 
or two joints of the "tail" gone, apparently bitten off. There was a scar where the 
wound had healed, but no sign of a regenerated tail. 

Chantran (38) says of the crayfish that the antenna? are regenerated in the period 
between two successive molts, while three molts are required to restore the other 
appendages. In the first year of life, seventy days, according to this observer, are 
necessary for the generation of new limbs. The adult female requires 3 to 4 years, 
the male li to 2 years to repair its limbs, and we are told that the adult male molts 
twice and the female but once in the year. 

Chantran has also some interesting notes on the regeneration of the eyes in the 
crayfish (40). This process takes place more or less normally and rapidly according 
to the age of the animal. When the eyes are cut off in October, at the end of the 
season of molting, there is no new growth apparent until the following May. At that 
time a series' of molts is begun, and by July, nine months after excision, the eyes are 
regenerated. If the eyes are operated on in the molting season, the regenerative 
processes are disturbed. In his experiments about one-half of the optic peduncle 
was cut away; with total excision of the peduncle the eye was never regenerated. 

Goodsir (80) explains the production of new limbs from the basipodite in the 
following way: 

A small glaudular like body exists at this spot in each of the limbs, which supplies the germs of 
future legs. This body completely fills up the cavity of the shell for the extent of about half an inch 
in length. The microscopic structure of this glandular-like body is very peculiar, consisting of a 
great number of large nucleated cells, 'which are interspersed throughout a fibro-gelatinous mass. A 
single branch of each of the great vessels, accompanied by a branch of nerve, runs through a small 
foramen near the center of this body, but there is no vestige either of muscle or tendon, the attach- 
ments of which are at each extremity. In fact, this body is perfectly defined and can be turned out 
of the shell without being much injured. When the limb is thrown off the blood vessels and nerve 
retract, thus leaving a small cavity in the new-made surface. [See the account given by Fredericq.] 
It is from this cavity that the germ of the future leg springs, and it is first seen as a nucleated cell. 

These statements, some of which — as the existence of a glandular body and the 
origin of the limb from a nucleated cell — are entirely erroneous, will be discussed 
hereafter (see pp. 107, 108). 

REGENERATION OF LARGE OHELIPEDS. 

The regeneration of the large chelipeds in the fourth and fifth larval stages is 
essentially the same as in the adults. The external changes are illustrated by figs. 
176, 182, and may be described as follows: At the moment the limb is broken off blood 
immediately oozes out and coagulates, forming a dense crust over the stump. In a 
short time a small white papilla which represents the rudiment of the new limb appears 
in the midst of the brown, hardened clot, fig. 176, plate 44. This papilla continues to 
grow, independently of the molting process, though covered with a cuticular mem- 
brane, until a miniature appendage is formed. The papilla lengthens, and gradually 
the constrictions which mark the future joints of the new limb make their appear- 
ance. At first colorless, the new appendage becomes bright, transparent red, with 



THE AMERICAN LOBSTER. 105 

bluish pigment at the constrictions of the joints (fig. 182). In this stage the limb is 
surrounded by a thickening cuticle and soon ceases to increase until after the next 
molt. It may, according to Brook, attain a length in young lobsters of 1^ to li inches. 
If autotomy occurs just after a molt, the appendage will reach a much greater size 
than if it happens a short time before. When the molt finally takes place the new 
stump becomes very much larger and now resembles the normal appendage in all 
respects except size. With each succeeding molt the normal size is gradually 
attained. 

Two stages in the regeneration of the large cheliped of the larva already referred 
to (No. 23, table 34) are illustrated in figs. 92, !t(i. After a period of 15 days, during 
which time two molts had occurred, this limb had become completely regenerated. It 
was reproduced in 12 days after the emergence of the papdlary bud. 

A larva in the fifth stage, length 15 mm., was placed under observation July 28, 
when the first right cheliped was clipped off. On August 12, 15 days after the injury, 
the animal molted and the cheliped appeared restored. The lobster was now 17 mm. 
long. The length of the sixth joint— propodus — of this rudiment at the time of the 
molt was 2 mm., while the length of the same joint of the limb after ecdysis was 
4.V mm., and the length of the corresponding joint of the unimpaired limb was 5 mm. 
In this case the new limb had been developed during a single molting period to nearly 
its normal size. 

A similar result was obtained in the following experiment: A fifth larva, length 
15 millimeters, was placed nude]' observation on July 28, and the first right cheliped 
was clipped. The right antennary flagellum had been previously cropped close to the 
stalk, from which a new bud was growing; 6 days later, on August 3, the sprouting 
antennary flagellum was coiled, and a very small bud represented the right cheliped. 
August 12, 15 days after the first observation, the fiagellum of the second antenna on 
the right side was nearly normal in appearance and size. The rudiment of the right 
cheliped was segmented, and about 3 mm. long. This larva molted on or near August 
15, or 18 days after mutilation, to the sixth stage, when it attained the length of 18 mm. 
The right cheliped was regenerated, but, as in the other case, it was somewhat smaller 
than the other. The measurements are as follows: 

Regenerated right first cheliped: Length of propodus, 5 mm. ; greatest width, 1.3 mm. 
ITnimpairefl left first cheliped: Length of propodus, 6 mm. ; greatest width, 1.5 mm. 

On the one hand, the large cheliped of the young lobster may be regenerated in 
from 15 to 18 days, and after a single ecdysis, and on the other it may require a 
month's time, during which the animal has molted twice. 

The time required for the renewal of a limb thus depends npon the time at which 
an injury occurs with reference to the molt, and also npon the physiological condition 
of the animal. If the tips of the large chelqieds are clipped off, autotomy does not 
always or usually occur, and the limb is completely repaired after one molt. If the 
limb is injured below the sixth joint (propodus or large joint of claw in cheliped), it is 
usually cast off at the plane of fracture. 

REGENERATION OF ANTENNA AND OTHER APPENDAGES. 

The antenme are very liable to injury, particularly the delicate, sensitive fiagella. 
Autotomy does not occur in these appendages, so far as is known, but regeneration 
may take place at any articulation in the flagellum or stalk. 



106 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

In the young the flagelluin of the second antenna may be completely restored 
without a molt taking place; in the adult one molt at least appears to be necessary 
for complete restoration. In the fifth stage already mentioned, the anteunary flagelluni 
was restored in about fifteen days. The fiagellum appears first as a papilla or bud, 
which becomes sickle-shaped and finally coiled (figs. 100, 179). 

Fig. 100 is from the molted shell of a lobster 18 mm. long (No. 34, table 34). It lost 
its right antenuary fiagellum in molting, July 25, and molted again in two weeks' time. 
The drawing shows the condition which the regenerating appendage had reached in 
the interval between the molts. After the last molt it was completely restored. This 
figure illustrates tbe stage which the appendage usually reaches before its complete 
renewal with the next molt. The fiagellum then resembles a small, spirally coiled, 
red-wax taper. In fig. 179 this appendage is being renewed from the first joint. 

The cuticle of the limbs in process of restoration must be elastic or capable of 
considerable distension, although the limit of this distensibility is, in most cases, soon 
reached. 

In the isopod Crustacea the antennae are regenerated in a somewhat different 
manner. In the case of the large Ligea oceanica, illustrated in figs. 180, 181, plate 44, 
the rent is repaired, and the new bud does not grow out from the stump, but coils 
up within it. The cuticular wall of the stump serves as a sort of brood chamber for 
the growing part, until it is set free at the next molt. 

Autotomy often occurs in the secoud to fifth pereiopods, but is much feebler than 
in the large chelipeds. Two stages in the regeneration of these appendages are shown 
in figs. 175, 178. The fourth pereiopod of a fourth larva, drawn from the molted skiu, 
is illustrated in fig. 99, plate 33. 

Reaumur (161) was one of the first to attempt to give a philosojmical explanation 
of regeneration in Crustacea. He says: 

We may suppose that these little limbs which we see grow out were each inclosed in a little egg, 
and that when a limb was broken off the same juices which nourished this part were used to 
develop and bring to the birth the little germ of a limb inclosed in this egg. Moreover, according to 
this theory, we should have to suppose that there was no spot in a leg of the crayfish where there 
was not an egg which incloses another limb or, what is more marvellous still, a part of a limb like 
that near the point where the egg is situated at the end of the limb; in short, at any point in the leg 
which you may name there must be one of these eggs, which contains another part of the limb. The 
eggs which are at the origin of each claw, for example, would contain only a claw : but one egg 
would not be sufficient, since if a new leg is cut off another comes. 

How many times this process could be repeated without exhausting the supply 
of "eggs" he did not determine, but Spallanzaui, according to Weismann, ''observed 
in the case of a young Triton, that the four limbs and tail when they were cut off 
grew again six times in the space of three summer months." (The Germ-Plasm, p. 
120.) Reaumur believed that each new limb must contain an infinite number of eggs, 
and in conclusion says : 

It would seem that the reproduction of the legs of the crayfishes is a matter where we can scarcely 
hope to see clearly ; besides its peculiar difficulties, it has all those which envelop the generation of 
the foetus. 

It is over eighty years since these words were written, and the solution of the 
problem of regeneration seems to some as far away as ever. The new limb is not 
formed from a definite cell or cell-mass recognizable before the time of injury, but 
from a budding growth very much as in the embryo. 



THE AMERICAN LOBSTER. 107 

The power of regenerating a lost part varies in both vertebrates and invertebrates 
in direct proportion to the physiological importance of the part, as Weisinann has 
clearly shown, -hist as the enemies of the lizard seize it by its long' trailing- tail, so the 
lobster is almost invariably caught by a claw, and the life of the animal is often saved 
in either case by the breaking off of the member. The plane of fracture in the limb, 
as in the large cheliped of the lobster and in the five pairs of pereiopods of the crab, is 
a secondary structure which coincides with the plane of articulation of two coalesced 
joints, yet Leydig has shown, according to Weisinann, that the tail of the lizard is 
specially adapted for breaking oft, u the bodies of the caudal vertebne from the 
seventh onward being provided with a special plane of fracture, so that they easily 
break into two transversely.'" (The Germ-Plasm, p. 116.) The regenerative power 
is probably a secondary characteristic which has been acquired by natural selection, 
for the good of the species, while autotoiny is a much more recent acquisition. As 
Weisinann says, "there is no such thing as a general power of regeneration" among 
animals as with crystals, but "in each kind of animal this power is graduated according 
to the need of regeneration in the part under consideration." 

Weismann rejects the idea of a spiritus rector, or external directing agency, and 
assumes that the nisus formativus is situated in the " idioplasm" of the cell, and "that 
each cell capable of regeneration contains an accessory idioplasm, consisting of the 
determinants of the parts which can be regenerated by it in addition to its primary 
idioplasm." He furthermore infers that the general capacity of all the parts for regen- 
eration may have been acquired by natural selection in the lower aud simpler forms, 
and that it is gradually decreased in the course of phylogeny in correspondence with 
the increase in complexity of organization. 

Weismann attempts, in a very ingenious way, to harmonize the facts of regenera- 
tion in animal embryos with the " mosaic theory" of development of Eoux, but, as E. B. 
Wilson (206) remarks, the two fundamental postulates of this hypothesis, "namely, 
qualitative nuclear division and accessory latent idioplasm, are purely imaginary." 
The theory of Eoux and Weismann has its counterpart in the view advocated by 
Whitman (204), that "in the development of the germ, in the repair of injured parts, 
and in the regeneration of lost parts the organism as a whole controls the formative 
processes goiug on in each part." 

While no final explanation of the process of regeneration can now be given, and 
the idea of a formative power is, as Whitman says, one of profound mystery, the 
solution of which appears to lie as far beyond our grasp to-day as at any time in the 
past, yet we are in a better position to-day, if not to give answers to these questions, at 
least to point out the probable direction in which they should be sought. 

1 shall consider the question of regeneration again in connection with the origin 
and perpetuation of deformities in the lobster. 

INTERNAL CHANGES IN REGENERATION. 

The histogenesis of the new limb is not easy to understand, although it can be 
followed without much difficulty after the papilla stage. 

I am unable to find any trace of " glandular-like" bodies such as Goodsir described 
(80) as furnishing germs of the new limb. On the contrary, the new limb appears to 
arise mainly by growth of the connective tissue cells already present in the stump. 

After the blood has clotted over the wound and has produced a hard crust, the 
cuticular cells, in response to the stimulus thus received, grow over the wound and 



108 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

produce a new cuticle wliich has a certain degree of elasticity. My material was insuf 
ficient to trace with certainty the origin of the reticulated tissue which soon appears 
under the new skin. 

A minute papilla grows out, having the general structure shown in fig. 173. It is 
a spongy network of fibers, containing the potential elements of muscles, nerves, con- 
nective tissue, and blood vessels. Blood flows in an irregular system of large and 
small sinuses. The epidermis of the new skin, which is relatively much thinner than 
the old, is composed of a single stratum of very tall, slender cells, the chitinogenous 
epithelium, and of an elastic cuticula. The epidermis of the papilla is thus structurally 
similar to that which covers all parts of the body when a new shell is being formed 
under the old. (See p. 77.) 

As the papilla grows out the fibrous tissue becomes gradually differentiated into 
the muscles, blood vessels, and nerves (fig. 172), as in an embryo, and constrictions in the 
cuticle arise, which mark with absolute precision the limitation of the future joints. 
The cuticle at this stage appears to be destitute of hairs, but it contains pores. In 
the stump at the base of the appendage a great mass of large oval bodies is seen. 
These appear as thin solid discs, and when compressed break like starch grains (fig. 
121, pi. 36). They represent connective tissue cells in a certain stage of metamorphosis, 
and in all probability contain glycogen, which furnishes material for the growth of the 
epidermis — that is, of the chitinogenous cells and the shell which they secrete. (See 
p. 78.) They seem to be the same structures which Leydig has described in the 
integument of crabs, under the name of lime concretions (Kalkconcremente), and 
which Hoeck calls "Krystall Plattchen" {121-122). Mayer (137) has also figured and 
described what are probably similar bodies in the indurated shell of certain swellings 
which are found in the large claws of the male Heterograpsus lucasii. These he desig- 
nates as " amyl-like chitinous inclusions." 

In the lobster these bodies stain very diffusely, and sometimes a central figure, 
possibly the impression or remains of the original nucleus, m ay be detected. The 
histogenesis of these structures and the changes which they undergo have apparently 
never been studied. Their origin is clearly demonstrated by fig. 122, plate 36, from 
a preparation of the maxilliped. It is evident that the large granular mass is the 
product of the parent mesoblastic cell, the protoplasm of which is reduced to a thin 
enveloping shell. 

Fig. 169 represents one of a series of sections cut in a longitudinal plane through 
the first three joints of the right large cheliped of the lobster (sixth stage, length 18 
mm.), the history of which has been already given (p. 105). The appendage of this 
larva had been cut off July 28, and had grown to nearly its full size by August 17, 
when the animal was preserved. Since autotomy occurs in the very young animal as 
well as in the adult, we should be able to determine from this specimen whether 
there is any preformed organ or store of embryonic cells for the supply of the new 
limb at this time. The examination of serial sections through this part of the limb 
reveals nothing but normal tissue cells. Embryonic cells may be present but are 
not discernible. The opening between the basipodite and ischiopodite is reduced to 
a narrow passage by the ingrowth of cuticular cells, to form ectodermic pillars like 
those seen in the carapace of the embryo. The several tissues are bathed in blood, 
which is here confined to no definite channels. Some circumscription of the passage 
leading from the second to the third joint is thus necessary. 



Chapter V.— LARGE LOBSTERS. 

THE GREATEST SIZE ATTAINED BY THE LOBSTER. 

Stories of gigantic lobsters made their appearance at a very early period, and 
one could probably gather as many exaggerated accounts of this animal now as in 
the days of Olaus Magnus. Time, however, has narrowed the bounds of credulity, 
even among the ignorant, and we no longer hear some of the interesting legends 
which, the old writers have carefully handed down. Thus Olaus Magnus tells us in 
his description of northern lands and seas, 1 published in 1555, that between the 
Orkneys and Hebrides there lived lobsters so huge that they could catch a strong 
swimmer and squeeze him to death in their claws. His curious figures are copied 
by Gesner (75), who has many others equal to any which are described in the old 
mythologies. 

Giants are met with in all the higher groups of animals. They interest us not 
only on account of their actual size, but also in showing to what degree individuals 
may surpass the mean average of the race. It may be a question whether lobsters 
which weigh from 20 to 25 pounds are to be regarded as giants in the technical sense, 
or simply as sound and vigorous individuals on whose side fortune has always fought 
in the struggle for life. I am inclined to the latter view, and to look upon the mam 
moth lobster simply as a favorite of nature, who is larger than his fellows because he 
is their senior; good luck has never deserted him until at last he is stranded on the 
beach or becomes entangled in some fisherman's gear. 

Gesner gives a very poor figure of a lobster, but a very good drawing of the large 
crushing-claw of one which he had preserved in his collection on account of its great 
size. The length of this claw is 8^ inches, and its breadth at the junction of the 
dactyl about 4 inches, so that it must have belonged to a lobster which weighed not 
far from 8 pounds. 

Pontoppidans (152) relates a fable, which is repeated by Herbst (88) and others, of 
the Storjer, or lobsters of huge size which fishermen reported having seen in Utvaer 
in the Bay of Erien, Norway. One of these was so large and terrible that no one dared 
to attack it, and it measured between its claws at least a fathom. This, says Herbst, 
probably belongs with the Kracken, the natural products of Norwegian superstition. 

Boeck says that he had seen the claw 2 of a lobster which must have been about 
18 inches long, and Sir John Graham Dalyell (50), according to Boeck, tells us, in The 
Powers of the Creator, published in 1827, that he had seen a joint of the left claw of 
a lobster which measured 9 inches in length. It does not follow, however, as Boeck 
infers, that "the whole claw 2 must have measured 18 to 21 inches, and the whole 
animal 3 to 4 feet." 

The European lobster of to-day seldom attains so great size as the American 
species, and its average weight is considerably less. Buckland (28) gives the following 
account of large lobsters from the British Islands: 

The Skye and Orkney lobsters are probably the largest in the British Islands. At St. Mawes ire 
heard of two lobsters, one 10 pounds and the other 9$ pounds; and at Durgan and Sennen of one of 
13 pounds. A large lobster was caught in a large earthenware pot at Gosport in 1870 which weighed 



1 Historia de Gentibus Septentrionalibus, Rome, 1555. 

-The word claic is here inaccurately used to meau the entire claw-bearing limb (cheliped). 

109 



110 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



8 pounds 10 ounces. In May, 1875, a lobster, weight 12 pounds, was found at Saints Bay, Guernsey. 
I find a record of a lobster exhibited at Billingsgate July 30, 1842, which measured 2 feet 5+ inches; 
the size of the body was 16 inches ; the claws measured upward of 14 inches. In August, 1873, a lobster 
weighing 11^- pounds, caught in Guernsey, was exhibited by Messrs. Grove, of Bond street. In July, 
1874, a lobster, weight 7-£ pounds, was caught on the Fife Banks of the Forth. The lobsters from 
the Lizard ground are one-third heavier than those in Falmouth Bay, but crabs are smaller. 

The largest lobsters that have come under my individual notice are. first, a lobster weighing 10£ 
pounds, sent me from Tenby and now in my museum; secondly, a lobster presented to me by John 
Byatt, of Messrs. Winder's, Haymarket, measuring 8 inches in the barrel [that is shell of back or 
carapace], the total length being 19^ inches and the weight 9% pounds. In the York Museum there is 
a magnificent specimen of a lobster, of which the following are the dimensions: Barrel, 9^ inches; 
tip of beak to tail, 19 A inches; ' left claw, the crusher, length 10| inches; right claw, cutting, length 
10A inches; left claw at widest part, 5 inches. This was an American specimen. 

Another very large lobster we came across in our inquiry was a grand specimen which we exam- 
ined in the house of Mr. Scovell, at Hamble, near Southampton. The following are the dimensions: 
Length of barrel to tip of horn, 9^ inches; length of tail turned under the body, 12 inches; total 
length, 2 feet, all but three-quarters of an inch Right claw, 19A inches- long; girth, 12jr inches; 
weight when killed, 14 pounds, This lobster, Mr. Scovell informs me, was caught in a trammel net on 
the coast of Cornwall. 

Fourteen pounds is the greatest weight recorded in the notes just quoted, and 
European lobsters of this size are undoubtedly very rare. 

In the museum of the Academy of Natural Sciences of Philadelphia there is 
preserved a large lobster, Astacus vulgaris, for the particulars concerning which I am 
indebted to the kindness of Professor Ryder. Unfortunately it is not known where 
or when it was captured, nor what its living weight was; but from the measurements 
given below (table 29, No. 1 a) I conclude that it weighed from 21 to 22 pounds. If 
these measurements are compared with those given in table 30, No. 1, it will become 
evident that this specimen could not have weighed less than 20, and not more than 23 
pounds. This specimen has been carefully examined by Professor Ryder, who writes 
that there is no doubt of its belonging to the European species; that it was normal in 
every respect, and that the skeleton is in an admirable state of preservation. 

Tablk 29. 



Measurements. 



Total length, rostrum to end of telson (not including hairs) inches- 
Length of carapace (rostrum to posterior margin) do... 

Large forceps : 

Length of propodus (straight measurement) do... 

Greatest breadth of propodus do — 

Girth of propodus do... 

Small forceps : 

Length of propodus do 

Breadth of propodus , do... 

Girth of propodus do... 



No. 1 a.— Male; 

20 to 23 pounds; 
obtained from- 
Europe; pre- 
served in the 

museum of the 
University of 
Pennsylvania. 



19.4 
9.29 

13.1 
6.8 
16.8 

12.4 

4.8 

10.15 



No. 2a.-Male; 
10 pounds; cap- 
tured on coast of 

Norway somo 
time between 1850 
and 1865 ; pre- 
served in muse 
um of Bergen, 
Norway. 



18.73 
8.58 

10.23 
4.32 
10.62 

10.03 
3.30 
8.07 



1 The claws of this specimen were considerably undersized (compare tables 29 and 30). 

2 This is intended for the measurement of the entire right claw-bearing limb or cheliped; by 
" total length " is probably meant, as above, the distance measured from the tips of the extended 
chelipeds to the end of the tail. 



THE AMERICAN LOBSTER. Ill 

In speaking of the size attained by the European lobster, Sars says: 

It is ;i remarkable fact thai the Lobsters on our southern coast never get as large as those farther 
north. 1 have never seen an unusually large specimen among the many lobsters which I examined at 
the different fishing stations. The lobsters which are occasionally caught farther north are generally 
much larger, and bo judge from their appearance much older. At Floro I once saw a lobster which 
was not much smaller than the immense specimen in the Bergen Museum. This specimen, as far as I 
remember, comes from a still more northerly point of our western coast. {176.) 

I am able to give some comparative measurements of the "immense specimen" 
to which Sars refers in the passage just quoted, through the kindness of my friend, 
Dr. Einar Lbnnberg, of the University of Upsala. If the length of this lobster and 
the measurements of its large claws (No. 2 a, table 29) are compared witli the -other 
specimen (No. 1 a), and with lobster No. 7, table 30, we shall see that in all prob- 
ability the Bergen specimen did not weigh above 10 pounds. It is nearly an inch 
longer than lobster No. 7, which weighed after preservation in alcohol a little less 
than 10 pounds. On the other hand, the claws of this American lobster are larger 
than those of the Norwegian specimen, and the claws constitute in old lobsters more 
than one-half the weight of the entire animal. (See table 31 a.) The latter probably 
weighed when alive not over 10 pounds. 

In reference to my questions about the Bergen lobster, Dr. Lonnberg writes: 
The specimen is now dry, and, as we never weigh any lobsters in our couutry, the weight is not 
recorded. 

He says the date of capture is doubtful, but it was probably between 1850 and 1865. 

It has been an accepted belief that the American lobster attains a greater size 
than its European counterpart, but it seems to be a fact that the maximum size of 
each species is nearly the same. The lobster fishery is much older in Europe than in 
this country, and the average size has there been long reduced to a minimum by 
overfishing. At the time when Sars's paper was written (about twenty years ago) 
it would not have occurred to one familiar with the American species to look upon a 
10-pound lobster as an "immense specimen," though at present there are comparatively 
few of this size which find their way to markets. In fact the same gradual falling off 
in size, due to the same cause, has been experienced in recent years on the coast of 
Maine and in the Maritime Provinces. It is probable, however, that the American 
lobster is stockier than the European, and that length for length the American species 
will weigh the more. 

Buckland (29) speaks of a "breed" of lobsters caught at Bognor which are always 
small. They are called "chicken lobsters," and it takes 11 to 20 to weigh a pound. 
This merely illustrates how the size may be kept down by the persistency of fishermen. 

Rathbun (155), in speaking of the occurrence of large lobsters in American 
waters, says: 

A dealer at New Haven states that twenty years ago 12 to 16 pound lobsters were common, but 
during the past ten years a lobster weighing 10 pounds has been rarely seen. A Boston dealer writes 
that during the past season (1880) he had received and sold lobsters weighing from 12 to 15 pounds 
each. A specimen taken at Boothbay, Maine, and said to weigh between 30 and 40 pounds, 

had such claws that the meat from one of them was equal to that of an ordinary-sized lobster. 

I have. examined and carefully measured a lobster taken at Boothbay which is 
probably the one here referred to, and will describe it presently. The actual weight 
of this lobster was probably not over 22 pounds. 

A lobster "shipped from Eastport in 1875" is said to have weighed 19 pounds 
and to have "measured 3 feet 5 inches in length (measurement from tips of extended 



112 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

claws to eud of tail), the claws being 18 inches long and 8 inches across." (155.) If 
the weight is given correctly, the measurements are certainly at fault, as I shall 
presently show. 

There can be nothing in literature more unreliable than accounts of the size and 
weights of animals, gathered at random. The first estimate is often a guess, which 
immediately acquires an air of accuracy by being expressed in figures. It does not 
usually get into print until it has been rolled over many tongues, and during the 
process it increases in size like the snowball which is rolled along the ground. But it 
undoubtedly comes hardest for a man who has a large lobster for sale to resist 
temptation. In describing a few very large lobsters I shall therefore limit myself to 
those which I have actually seen and measured or weighed. 

I will now give the history of a lobster which came into my possession in August, 
1893.' It is probably one of the largest lobsters ever taken on the Atlantic coast. 
Its history has been carefully authenticated, and I have obtained some excellent 
photographs of it, which are reproduced in plates 1 and 2. This mammoth specimen 
was captured in Penobscot Bay, southeast of Moose Point, in line with Brigadier 
Island, near Belfast, Maine, May 6, 1891, in about 3£ fathoms of water, by Mr. John 
Condon. Its capture was accidental, since it was brought to the surface on the end 
of a lobster pot, the "tail" of the lobster resting in the funnel of the trap, while the 
huge claws hung down at the sides. The animal, attracted by the bait, had doubtless 
been making fruitless attempts to enter the trap. A dealer in fish at Belfast soon came 
into the possession of this lobster while it was still alive. The shell was then very 
dark in color, almost black on the upper surface, and supported a number of prosperous 
colonies of marine animals. The common barnacle (Balanus balanoides) was growing 
on the shell of the back and also on the upper surface of the crushing- claw, near the 
joint of the thumb or dactyl, where it may be seen in the plate. Several species 
of mollusks, particularly the common mussel (Mytilus edtilis), were fixed to various 
parts of the shell, and hydroids (Pennaria or Eudendrium) were flourishing at the 
articulations of some of the legs. The presence of these messmates pointed to a 
rather sluggish habit of life, which the animal may have possessed. The entire 
upper surface of the shell and both the upper and lower surfaces of the claws are 
scarred, scraped, and gouged like the side of a cliff over which a glacier has passed, 
and present a graphic record of the struggle for life which this animal had so long 
and so successfully fought. 

When laid on its back the lobster could move but little, but when in its normal 
position it would crawl over the floor, and if worried with a stick it seized it savagely 
and crushed it with its claws. It was weighed on a Fairbanks scale in the presence 
of a number of people. Its living weight was found to be a little over 23 pounds. 2 

This lobster was finally killed by boiling in the usual way, the membranes being 
first cut at the articulations to let out the blood and admit the water. It was after- 
wards placed in a large kettle of water to which a bushel of salt was added, and was 
boiled in this brine for more than an hour. 3 After it was boiled, the meat of the 

1 This lobster is now preserved, in excellent condition, in the museum of Adelbert College, 
Cleveland, Ohio. 

2 When I first saw this lobster I was assured that the animal was not weighed until after it had 
been boiled. Allowing a shrinkage of 20 per cent in boiling, I estimated the living weight to have 
been about 28 pounds. (See 99. ) The first statement was not true. I have since ascertained that the 
facts are as given above. 

3 Old-shell lobsters are said to shrink 20 per cent and new-shell lobsters 25 per cent in weight 
after boiling. 



Till', AM Kin CAN LOBSTER. 



113 



"tail" was of a pink color and very lough. The skeleton was perfectly preserved 
by removing the muscles of the abdomen and the "tomally" or "liver," and some of 
the other organs of the body. This lobster was a male, and it is a noticeable fact that 
all very large lobsters which I have records of or have examined belong to the male 
sex. 1 have never heard of a female lobster which exceeded 18.^ pounds being caught. 
The total length of this lobster, whose history I have just given, is only 20 inches 
(measured, as in all cases, from the end of the spine or rostrum to the end of the tail- 
Ian), but would have been nearly 21 inches had the rostrum been perfect. The body 
seems surprisingly short for so powerful an animal, and it is in fact in the large claws 
that the greater part of its weight and strength resides. This may be seen by a 
comparison of the plates (see also table 31 «), and may be possibly explained by the 
fact that as age advances the increase in length, at each molt becomes less, while there 
is a corresponding gain in the size of the claws. Thus Ehrenbauin (61) mentions a 
lobster 42.2 cm. long, which showed an increase in length of scarcely 1 mm. on molting 
The length of the crushing-claw of the Belfast lobster is nearly 14 inches, and its 
greatest girth is 16 A- inches. It was probably powerful enough to crush a man's arm 
at the wrist. 

Table 30. 

General descriptions : No. 1 was a male, 23 pounds, captured at Belfast, Maine, May 6, 1891. No. 2 was a male, 
20 to 22 pounds, captured at, Boothbay, Maine, about 1856. No. 3 was a male, 20 to 22 pounds, captured at Salem 
Massachusetts, iu 1850. No. 4, 23 to 25 pounds, was captured at Gloucester, Massachusetts. No. 5 was a male 20 
to 22 pounds, captured on the Delaware coast. No. 6 was a male, 20 to 22 pounds, captured at Lubec. Maine, Sep- 
tember, 1892. No. 7 was a male, 9g pounds, in alcohol. 



Measurements in inches. 



Total length, rostrum to end of telson (not including 

bail's) 

Carapace : 

Length of rostrum 

Length of carapace 

Length of carapace, including rostrum 

Distance from cervical groove to posterior edge of 

carapace 

Greatest breadth 

Breadth bet ween spines, near base of rostrum 

Breadth between spines, near base of second an- 
tennae 

Girth of carapace behind cervical groove 

Pleon : 

Length of second segment (including facet) 

Breadth of second segment 

Girth of second segment (spine to spine) 

Length of sixth segment (including facet) 

Greatest width of sixth segment 

Length of telson (not including setae) 

Breadth of telson at base 

Antennae: 

Length of stalk of first antenna 

Length of basal segment 

Breadth of basal segment 

Length of eyestalk 

Breadth of eyestalk 

Length of stalk of second antenna 

Length of exopodite (scale) 

Greatest width 

Pereiopods : 
Large forceps (crushing-claw) — 

Length of propodns (straight measurement) 

Greatest breadth of propodus at level with articu- 
lation with dactyl 

Girth of propodus just behind articulation of 
dactyl 



No. 1. 



20 



2ft 
14$ 



m 
i 



2ft 
I 
1 



13| 
16* 



No. 2. 



f 20J 



131 

II 
3il 

81 
in 
L iXS 
3 

2& 
25 



12J 
6 
151 



No. 3. 



t21| 
2ft 



14 

2i 
131 



li 
1ft 



124 

64 

15 



No. 4. 



No. 5. 



13 

*§ 
17* 



13J 

9J 
164 



No. 6. 



•"Body nearly straight. 



t Body somewhat bent. 



20| 
2 



24 
11 

ia 



i§ 

a 

■4 

4 
12 

15 



No. 



17$ 



2i 
21 



10$ 
13i 



F. C. B. 1895—8. 



114 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Table 30 — Continued. 



Measurements in inches. 



Pereiopods— Continued 

Length of dactyl 

Greatest breadth of dactyl 

Greatest,girth of dactyl.. 

Length of carpus (on inner margin, not including 
proximal spine) 

Greatest breadth of carpus 

Greatest girth of carpus 

Length of meros (outer border) 

Greatest breadth of meros 

Small forceps- 
Length of propodus (from tip to spine near prox- 
imal end) 

Breadth of propodus 

Girth of propodus 

Length of dactyl 

Greatest breadth of dactyl 

Greatest girth of dactyl 

Length of carpus (on inner margin, not including 
proximal spine) 

Greatest breadth of carpus 

Greatest girth of carpus 

Length of meros (outer border) 

Greatest breadth of meros 

Second and fifth pereiopods: 

Length of propodus. second pereiopod 

Breadth at articulation of dactyl 

Length of dactyl 

Breadth of dactyl (at articulation) 

Greatest length of carpus 

Breadth of carpus 

Length of dactyl, fifth pereiopod 

Breadth of dactyl 

Length of propodus 

Breadth of propodus (distal extremity) 

Breadth of propodus (proximal extremity) 

Length of carpus 

Breadth of carpus 

Pleopods : 

Length of first pleopod 

Length of distal segment 

Greatest breadth of distal segment 

Length of stalk of second pleopod 

Breadth of stalk of second pleopod 

Length of exopodite 

Breadth of exopodite 

Length of exopodite, sixth pleopod (from angle 
between spines of protopodite) 

Greatest breadth of exopodite at hinge 

Length of endopodite of sixth pleopod 

Greatest breadth of endopodite of sixth pleopod. 



No. 1. 



4| 



12 

n 
a 



2A 



3fs 

Its 

m 



No. 2. 



2i 
If 

I 



2§ 

8i 



13i 

n 



31 



No. 3. 



5f 

-I 



3 

8i 
44 
2* 



12a 

44 



1* 
4 

3| 

n 

8 
44 



11 

H 
2£ 
S 
1 

6 

T5 
2i 



4 

li 3 s 






No. 4. 



24 



4§ 

■■'. 



No. 5. 



5i 

2| 
6£ 



34 
2i 



12J 
3J 
84 
7§ 

14 

a 



4 
2| 



No. 6. 



33- 

°a 

2 is 



94 



11 
6* 

14 



No. 7. 



44 



The detailed measurements of this animal are given in table 30, No. 1, where they 
may be compared with those of the small lobster, seen on plate 2, and with those of 
the large specimens which I have recorded above. 

The large Boothbay lobster, which has already been referred to (p. 16), is 
reported to have weighed as much as 40 pounds. I was told that it tipped a scale 
which weighed up to 25 pounds, and would have weighed somewhat more. Its meas- 
urement, however (table 30, No. 2), jiroves it to have weighed less than the Belfast 
specimen, and a comparison of its length and the dimensions of its claws with the 
large European lobster (No. 1 a, table 29) show that it could have exceeded this in 
weight very slightly, if at all. Its true living weight was probably between 20 and 22 
pounds. The shell of this lobster was cleaned by placing it in an ant-hill, and it is now 
in a bad state of preservation. The claws are furrowed, pitted, and scarred, and the 
carapace is scratched, as is apt to be the case with large old-shell lobsters. 

In the museum of the Peabody Academy of Science at Salem, Massachusetts, there 
is a perfect specimen of a lobster (No. 3, table 30), said to have been taken at Salem 



THE AMERICAN LOBSTER. 115 

in 1850, and to have weighed, when alive, 25 pounds. The body is a little longer than 
the two first mentioned, but it is also slenderer, and the large claws, which count so 
much in the weight of this animal, are, upon the whole, smaller and weigh less. The 
greater length of the Salem specimen is due largely to the long, perfect rostrum. 
The large claws correspond closely in size with those of the Boothbay lobster, and we 
may be almost certain that its living weight did not exceed 22 pounds. 

A lobster but little under the Salem specimen in size is in the possession of Mr. 
George R. Batson, of Campobello Island, New Brunswick. This lobster weighed, 
when alive, according to the somewhat wavering memory of the man who weighed it, 
24i pounds. The measurements fail to corroborate this statement. (No. 6, table 30.) 
The dimensions of the large claws and the girth of the carapace prove conclusively 
that it weighed less than 23 pounds, the authenticated weight of the Belfast lobster 
(No. 1, table 30). It was captured in a hoop pot, a few of which are said to be still in 
use, in South Bay, near Lubec, Maine, in 15 fathoms of water, September, 1892. This 
lobster is a very shapely and perfect specimen. It had a hard shell, and showed 
great activity when alive. 

In the museum of the Peabody Academy of Science there is also the right large 
claw of a lobster marked, "From a lobster weighing 39 pounds; from Moses H. Shaw, 
Gloucester." This is said to have been in the museum for over fifty years. Meas- 
urements of this claw (No. 4, table 30), supposing the animal to have been normally 
developed, show that it could have been but little larger than the Belfast specimen. 
The only available comparisons lie between the large claw and the fifth joint the 
only parts preserved. A full-sized drawing of this huge claw is produced on plate 
15. The crushing claw of the Belfast lobster was nearly an inch longer and much 
broader than the specimen figured, but less by one inch in girth. The claws of these 
two animals must thus have been of nearly equal weight, and I think it a safe con- 
clusion that the Gloucester giant did not weigh above 25 pounds. The shell of the 
claw was very light for so large an animal, weighing only 16f ounces, including the 
fifth joint. (See chapter III, pp. 82, 83.) 

In the museum of the Smithsonian Institution there are fragments of the skeleton 
of a lobster which was captured with hook and line on the coast of Delaware, and is 
said to have weighed over 25 pounds. Measurements of these parts show that its 
weight was probably somewhat less, certainly not much over 22 pounds. (No. 5, 
table 27.) The shell of the large claw of this lobster weighs 1£ pounds. 

In 1863 a large lobster was caught on a hand line at Bald Head Sands, near 
Small Point, Maine, which I was assured by a fisherman weighed 38 pounds. I 
afterwards had the opportunity of examining the large crushing-claw, all that has 
been preserved of this lobster, at the market house of Mr. Lewis McDonald, Portland, 
Maine. The claw is 12^ inches long, has a breadth of 6i inches, and a girth of 15£ 
inches just behind the terminal joint. It was thus of about the same size as the 
crushing-claw of the Salem lobster (No. 3, table 30), and the animal probably did not 
exceed 22 pounds in entire weight. I mention this as an example of how the weight 
of the lobster, though dead, increases with the lapse of time. 

There may be seen at the St. Nicholas Hotel in Boston, Massachusetts, the skeleton 
of a male lobster said to have weighed 35 to 40 pounds. It was captured off Province- 
town, in August, 1894. When I examined this specimen, June 25, 1895, it was 
mounted in a glass case in a very perfect state of preservation. Though not allowed 
to take careful measurements, I could see that its weight had been greatly exag- 



116 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

gerated. The total length of the body, measured from the rostral spine to the end of 
the tail-fan, when the tail was naturally articulated with the thorax, was not far from 
20 inches, and not over 21 inches. The length of the large crushing-claw is from 12 
to 13 inches. The cutting-claw is relatively smaller than in any of the large lobsters 
which I have examined, and it seems fairly certain that the living weight of the 
animal could not have much exceeded 20 pounds. 

I am indebted to the kindness of Professor Leslie A. Lee for the measurements of 
the large crushing-claw of a lobster which is preserved in the museum of Bowdoin 
College, Maine. It was taken from an animal which came from Cape Breton, which 
is said to have weighed 33 pounds 11 ounces. The length of this claw is 13-jV inches, 
its breadth 6| inches, and its girth (measured just behind the first joint) is 16 inches. 
In this case the weight is specifically given, yet it is certainly erroneous. 1 If normally 
formed, this animal probably did not weigh over 23 pounds. I base this opinion upon 
the fact that the Belfast lobster (No. 1, table 30) has a somewhat larger crushing-claw, 
is normally formed, has a hard shell, and therefore could not, in all probability, have 
weighed less and may have weighed more than the specimen from Cape Breton. 

In the museum of Yale University there is preserved the large crushing-claw of 
a lobster, which is said to have weighed 39 pounds. 2 The length of the claw is 12/ 6 - 
inches, the greatest width 6.9 inches, and the greatest girth 16f inches. It is shorter 
by half an inch than the Cape Breton specimen, and but little larger in circumference. 
The length of the crushing chela falls short of the Belfast lobster (No. 1, table 30) by 
one inch. Its weight probably did not much exceed 23 pounds, if at all. 

In the collections of the Smithsonian Institution there is a lobster which weighed, 
after preservation in alcohol, 9 pounds 14 ounces (No. 7, table 30). 3 The cutting-claw 
on the right side was undersized. A few measurements of this specimen are given 
for purposes of comparison. There is far less difference between some of these and 
corresponding measurements of larger lobsters than one might expect. Thus the 
telson in this case has the same dimensions as in lobster No. 6 (table 30), which 
weighed more than twice as much. 

I was informed by Mr. F. W. Collins that a male lobster which weighed nearly 
25 pounds was taken on a trawl below Monro Island, 5 miles east of Rockland, Maine, 
in the summer of 1890. The large claw is said to have measured 16 inches in girth. 

I heard through Mr. Vinal Edwards of a lobster, said to have weighed 27 pounds, 
which was caught off Bretou Reef, Newport, Rhode Island, in June, 1894. This was 
taken by accident, one of its claws having been entangled in a lobster-pot, in 10 to 12 
fathoms of water. It was a male, and its shell was freely sprinkled with barnacles. 4 

I will add a few notes on the occurrence of large lobsters, which I gathered on the 
coast of Maine, in August and September, 1893. I give them upon the testimony of 
others, but believe them trustworthy. 

Mr. J. W. Savage stated that he received from the region of Eastport, Maine, in 

'Professor Lee writes as follows concerning this specimen: "The large lobster's claw in our 
museum was obtained many years ago in Cape Breton. It came into our possession in 1881. The 
weight of this animal is not well authenticated on our records." 

2 I am indebted to Prof. A. E. Verrill for the opportunity of examining this specimen. The 
inscription upon it, which is almost illegible, is as follows: "Boston, Mass., March, 1823; 39 lbs." 

'The weight of th'S lobster was kindly determined by Mr. James E. Benedict of the Smithsonian 
Institution. 

4 1 was unable to obtain any direct information about this lobster, or to verify its weight, which, 
I do not consider authentic. 



THE AMERICAN LOBSTER. 117 

June, 1893, a large wale lobster which weighed 20 pounds. In the same lot was one 
weighing 10 pounds. 

In May, 1891', Mr. N. P. Trefethen obtained a lobster from the vicinity of East- 
port, Maine, which weighed 15A pounds. He weighed it himself, and sent ltto market. 
It had a very hard shell and had lost its smaller claw; if it had been perfect it 
would have weighed considerably more. 

In August, 1891, according to Mr. F. W. Collins, a lobster (sex undetermined) 
was taken at Blue Hill Falls, 10 miles east of Rockland, which weighed 184 pounds, 
and in November, 1892, a perfect female lobster was taken at Green Island, Maine, 
which weighed 18 pounds. This outer island is noted for its fine lobster fishing. Mr. 
Collins states that in August, 1891, he had fifty lobsters at one time in his establish- 
ment which would weigh from 10 to 1S£ pounds. About half of these came from 
Castine and the remainder from Blue Hill Falls, Maine. All of these were "new shell 
lobsters " — that is, they had shed that year, probably in July. 

Mr. Thomas Garrett, who was one of three men who first engaged in lobster 
fishing at Vinal Haven, Maine, over forty years ago, and has been engaged in this 
pursuit most of the time siuce, says that he has taken a great many lobsters which 
would weigh from 15 to 20 pounds. He says that a perfect male lobster weighing 30 
pounds 1 was taken in a hoop-net in Goldeu Cove, in Vinal Haven Harbor, in about the 
year 1858, and that in 1887 a lobster was caught in the basin (near the site of the 
present lobster pound on Vinal Haven Island) which weighed 11 pounds and had only 
one large claw. 

The mouth of the Shillings River is said to have furnished large lobsters in 
plenty in the fall of 1888. It was very common to take lobsters there weighing 15 
pounds. The place had not been previously fished with regularity, but it soon became 
the resort of fishermen and the lobsters were rapidly reduced in numbers and size. 

Fishermen in Rockland, Maine, have gaffed lobsters in the harbor in the past two 
years weighing from 8 to 9 pounds. I heard of a large lobster which was caught on a 
trawl, the hook catching in a joint of the shell, in June, 1892, on White Island grounds, 
near Vinal Haven. It was said to have weighed over 20 pounds. 

Mr. F. W. Collins informs me that he received at Rockland, in 1893, a larger 
number of lobsters than usual measuring about 15 inches in length and weighing 
about 5 pounds. 

These notes furnish evidence, if any were needed, that very large lobsters, weigh- 
ing 20 pounds or more, are even now occasionally taken, but I have never obtained 
any reliable evidence that lobsters weighing over 25 pounds have ever beeu caught. 
Where lobsters are said to have attained a greater weight, measurements of the parts 
of the skeleton which have been preserved invariably prove that the figures have 
been exaggerated. I do not maintain that the American lobster does not reach a 
greater weight than 25 pounds, but that I have been unable, up to the present time, 
to discover any well-authenticated evidence that this is the case. 

Many points on the coast of Maine and the Maritime Provinces still furnish large 
lobsters weighing 10 pounds or more, but not in any considerable number, and lobsters 
of 5 pounds weight are frequently common; yet it is at the same time true that the 
size of the lobster has been declining for many years, until the average weight has, in 
most places, fallen below 2 pounds. 

1 The weight of this large lobster may have been unintentionally exaggerated. One can hardly 
avoid such an inference from the evidence already given. 



118 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



THE RELATION OF WEIGHT TO LENGTH. 

The weights and lengths ' of 2,657 lobsters captured at Woods Hole under the 
conditions already described (p. 25) are recorded in table 31. The weight does not 
bear a constant relation to the length, but is very variable owing to the loss of the 
appendages, particularly the large claw-bearing legs. These alone constitute from one 
quarter to one-half the entire weight of the animal, and probably in the Belfast lobster 
(plate 1), and in all giants of similar size, the weight of the large chelipeds is more 
than two-thirds that of the entire body (see table 31ft). The lost limbs are regenerated, 
as we have seen, but never completely so without the intervention of one or more 
molts, so that a lobster with an undersized claw is a common occurrence. 

The weight also is subject to great variation in consequence of the molt, when a 
dense heavy armor or cuticle is exchanged for a much lighter though larger one. In 
the soft lobster the specific gravity of the solids and fluids of the body is considerably 
reduced. Very few soft lobsters, however, were taken during the period of these obser- 
vations, only about 3 per cent (see table 23), so we may ascribe the great variations 
shown in the table below chiefly to disparity in the size of the large claws. This is 
particularly noticeable in smaller individuals, as in the 9-inch lobsters, where out of 
170 males the smallest weighed only 10 ounces and the largest three times as much. 

Table 31. — Relation betiveen the lengths and weights of male and female lobsters, taken in Woods Role 

Harbor, December to June, 1893-94. 



Length 

in 
inches. 



6i 
64 
6| 

7 



No. of 
males 
exam- 
ined. 



10 
66 

20 
168 



9i 
94 

n 

10 

10^ 

10J 

104 

101 

101 

11 

HI 

llj 

11| 

12 

12J 

124 

12J 

13 

134 

14 

14i 

15 



44 
143 
26 

170 



32 
148 

27 
167 



1,313 



j No. of 
Average Extremes! femaies 
weight of weight j without 
of males. ' of males j eggs ex- 

I amined. 



oz. 
5.33 



7.60 
10.18 



10. 40 
11.86 
12.75 
15.16 



15.30 
16.61 
17.46 
18.96 



19.91 
21.24 
24 
24.41 



4 to 6 



11 28 

16 30 

18 30 

19 32 



27.44 ! 

28.89 

26 

29.94 

34.65 ! 

37. 20 '' 

42.36 j 

36 

43.78 

50 

50.25 



20 35 
22 36 



48 52 



60 



74 



46 

1 

4 

47 

9 

138 

1 

29 

108 

26 

153 



34 
145 
26 

148 



Avera_ 

weigbtof 

females 

without 

eggs. 



8.75 
'7.' 25 



10.76 

10 

10.25 

11.43 

12.44 

15.30 

14 

15.24 

16.36 

17 

18.61 



19.32 
20.51 
21.19 
23.76 



24.63 
27.52 



16 
42 
11 
26 
2 
11 



24.19 
30.48 
32.09 
34.46 
34.50 
42 



42.71 
"47." 25 



65 

69.33 



1,176 



Extremes 
of weight 
of females 
without 
eggs. 



8 to 10 



13 



9 

8 

9 

11 



No. of 
females 

with 
eggs ex- 
amined. 



21 33 
23 41 



24 
23 
27 
30 
34 
36 



36 49 
40 55 



64 66 
66 72 



Average 

weight of 

females 

with 

eggs. 



12.50 



168 



16.14 

17 

18.60 

16 

20 

20.42 

20.67 

23.86 

28 

23.12 

28.11 



26.50 
32.10 



Extremes 

of weight 

of fern ales 

with 



12 to 13 



15 


17 


15 


21 


17 


25 


18 


24 


19 


21 


20 


28 



25 28 
29 37 



32.25 I 30 34 



43. 67 37 



45 



Total 
number 
of males 

and 

females 

examined. 



7 
1 
7 

92 

1 

14 

113 

29 

308 

1 

73 

258 

53 

336 

1 

70 

317 

56 

351 

1 

133 

182 

1 

36 

93 

21 

41 

4 

23 

1 

11 

1 

8 

1 

1 

3 

3 



Average 

weight 

of all 

the males 

and 
females. 



oz. 

7.29 

8 

7.57 

7.60 
10.49 
10 

10.36 
11.68 
12.66 
15.21 
14 

15.27 
16.50 
17.23 
18.79 
16 

19.63 
20.84 
22.52 
24.08 
28 

25. 76 
27.66 
26 

27.19 
32.22 
34.52 
36. 37 
35.25 
42.91 
50 

45.45 
45 

49.75 
0* 
88 
68 
69. 33 



2,657 



1 The length of the lobster is measured from the apex of the rostral spine to the end of the 
telson, not including: the terminal fringe of hairs. 



THE AMERICAN LOBSTER. Il9 

The fact that the male is heavier than the female of the same length is very clearly 
brought out by the observations recorded above. In passing the eye down the 
columns to the left only three cases will be discovered where this is not true, namely, 
in the 6, 7, and S inch lobsters. The difference here in favor of the females, where a 
sufficient number of observations were made to entitle them to much confidence, is 
only a question of fractions of an ounce in average weights. After passing the 8-inch 
limit the balance is in favor of the male. The 10-inch males are about half an ounce 
heavier thau the females of the same length. From this stage the excess in favor of 
the male becomes very marked. The 11-inch male exceeds the female of the same 
length by a full quarter of a pound. In the lobster 12£ inches long there is a greater 
difference in favor of the male, 7i ounces in the cases cited in the table. 

It is evident from the facts here recorded that the greater size of the male, which 
is a sexual characteristic, does not appear until the animal has passed the 8-inch limit. 
At this period the sexes are of about equal weight, but from this point the male 
surpasses ttie female in weight, owing chiefly to the greater development of the large 
claws. 

The average weight of females without and with eggs recorded in columns 6 and 
9 of table 31 brings to the surface a rather unexpected fact, namely, that females with 
spawn are in a poorer condition or weigh relatively less than females without. In 
one-third of the cases here recorded the weight of females with eggs was actually 
less than that of females of the same length without eggs. In the 10-inch series, 
184 females were examined; 3G of them had eggs, and weighed on the average but 
one-tenth ounce more than those without eggs. Turning to table 10, we find that the 
average quantity of eggs borne by a 10-iuch lobster is 1.73 fluid ounces, and since a 
fluid ounce of lobster eggs weighs very nearly an ounce avoirdupois, the average 
weight of the 10-inch female deprived of her eggs is 22.13 ounces, as compared with 
23.76 ounces, the average weight of non-egg-bearing females of this size. There is a 
difference of 1.G3 ounces in favor of the female without eggs. In the case of the 
9i-inch lobsters, where 169 in all and 24 bearing eggs were examined, the average 
weight of the spawuers is less by 0.09 ounce than that of the corresponding females 
without eggs. 

The facts which have just been stated do not support the conclusion of Buckland 
and his associates on the fisheries work in Great Britain, that "the lobster, when 
berried, is in the very best possible condition for food." (28, p. xvi. See p. 64.) 

In the last column of table 31 the average weights of lobsters corresponding to 
definite lengths are given. A lobster of the minimum length at which it can be legally 
sold, lOi- inches, weighs on the average If pounds, while a 12-inch lobster attains a 
weight of 2 pounds 11 ounces, and a lobster 15 inches long weighs from 4 to 4i pounds, 
and probably more in some cases. 

Lobster No. 7, table 30, 17| inches long, weighed nearly 10 pounds (though in this 
case the cutting-claw was undersized), and the mammoth specimens recorded in this 
table, weighing from 20 to 23 pounds, varied only from 20 to 21f inches in length 
(pp. 113-116). 

In the early part of this chapter I mentioned the fact that the disparity in weight 
between lobsters of the same length was due largely to the difference in the size of 
the large claws. This is illustrated by the following table, which is compiled from the 
observations made by Vinal N. Edwards. 



120 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Table 31a. — Variation in the weights of lobsters ivith and without the great claws. 



Length in 
inches. 


Sex. 


No. of 
lobsters 
exam- 
ined. 


"Weight 
with large 
chelipeds, 
in ounces. 


Variation 
in weight. 


"Weight 
without 

large cheli- 
peds, 

in ounces. 


Variation 
in weight. 


7i 

7| 
81 
S-i 
8i 
8| 
8| 
9J 

9* 

10" 

10 

11 
11 


Male 

Fern tie 

Female 

Male 

Male 

Female 

Male 

Male 

Female 

Male 

Female 

Male 

Female 


1 
1 
3 
1 
1 
1 
1 
6 
2 
1 
3 
1 
1 


13 
13 
13 to 15 
17 
17 
16 
17 

22 to 31 

23 to 24 

28 

24 to 27 

48 
39 




10 

10 

11 

12 

12 

12 

12 

15 to 17 

15 to 16 

17 

17 to 18 

22 

22 








2 

















9 

1 


2 

1 


3 


1 











Chapter VI.— ENEMIES OF THE LOBSTER. 

ANIMALS WHICH PREY UPON THE LOBSTER. 

The adult lobster, whether -with eggs attached to the body or not, is the prey of 
numerous fish which feed upon the sea bottom, like the sharks, skates, and rays. 
When of considerable size or in soft condition it is also devoured by the cod, pollock, 
striped bass, sea bass, tautog, and probably by many other species. In fact every 
predaceous fish which feeds upon the bottom may be looked upon in general as an 
enemy of the lobster. 

A flshermau at Beal Island, West Jonesport, Maine, stated that he had caught 
cod on trawls 10 to 15 miles from shore with lobsters 4 to 6 inches long in their 
stomachs. Cod were also caught at Grand Manan, in summer, in 20 fathoms of 
water, by Mr. J. W. Fisher, of Eastport, with very small lobsters, 1 1 to 2 inches long, 
in their stomachs. Lobsters an inch long have also been taken from the stomachs of 
codfish on the shores of Prince Edward Island (209, p. 232), and soft lobsters 3 to 8 
inches long have also been found in the stomachs of these fish taken in deep water 
off shore. 

The observations of Mr. Vinal K Edwards are quoted by Mr. Eathbun (156, p. 782) 
to show the great destruction of lobsters in the Edgartown district, Marthas Vine- 
yard. Out of hundreds of cod caught about No Mau's Land and examined by Mr. 
Edwards, nearly every fish "contained one or more youug lobsters, and in many cases 
the stomachs were almost entirely filled with them." So great did the destruction 
wrought upon the lobster by the cod impress one, fisherman (156, p. 728) that he thought 
the cod a greater enemy than the lobstermen, and said: "I have caught one hundred 
cod in one day that I knew had the amount of one thousand lobsters and shadow's in 
their entrails." 

1 These young lobsters were identified by Professor Baird. 



THE AMERICAN LOBSTER. 121 

The cod lias an equally bad reputation among English fishermen. Frank Buck- 
land says (38, pp. 14, 15) : 

Among tho animate enemies the principal enemy [of the lobsters] I believe are cod. A witness at 
Burghead stated that codfish are great enemies to lobsters; he hardly ever opens a cod without finding 
young lobsters in the stomach, particularly in February and March. He has seen cod throwing up 
lobsters on the deck of a vessel, as many as live or six lobsters in one cod. These lobsters would he 
3 or 4 inches in length or even smaller. Cod eat lobsters all the season. In the spring aud in January, 
February, and March there axe many cod about. Skates and congers, and codling and haddock also 
eat crabs and lobsters. 

On July 16, 1894, Dr. J. I. Peck showed me the "tail v of a soft lobster which he 
had taken from the stomach of the weakfisk or squeteague (Cynoscion regale). The 
lobster had been out of its shell but a few hours when it was snapped up by this fish. 

Verrill (196) records the finding of lobsters iu the following fish: Dusky shark 
(JEJulamia obscura), Woods Hole, in July and August; dogfish (Mustelus canis), Woods 
Hole, in August; saud shark (JEJugomphodus Uttoralis), Woods Hole, July and August; 
peaked-nose skate (Rata Icevis), Menemsha, July; long-tailed stingray (Myliobatis fre- 
minvillei), Vineyard Sound, July; rabbit-fish (Ghilomycterus geometricus), Woods Hole, 
July; striped bass (Boccus lineatus), Woods Hole, August, 1871 ; tautog ( Tautoga onitis), 
"two caught July 8 and 15 contained small lobsters." 

Mr. Mosher, who had prepared striped bass for market for upward of thirty 
years, said: 

Striped bass do not feed upon live menhaden, but upon crabs and lobsters. * * * I have 
always observed that bass fishing was best where lobsters and crabs were most plentiful. (Bull. 
U.S. P.O., vol. 11, p. 410.) 

Small lobsters are probably to some extent the prey of sea-roving birds, such as 
the gulls and terns, but in regard to this nothing is known. According to Boeck 
(30, pp. 227-22S), the Norwegian lobster is sometimes attacked by crows. His account 
is as follows : 

An interesting scene may be witnessed near Bukkeno, north of Stavanger, where an Englishman 
has constructed a large pond between some small islands for keeping live lobsters. Whenever the 
pond becomes too full of lobsters, so that they do not find sufficient food, they leave the water and 
crawl about, seeking to reach the sea, but during their wanderings they fall an easy prey to large 
numbers of crows hovering round, which take them in their claws, fly high up. and let the unfor- 
tunate lobster drop down on the rocks, where their shells are broken, so that the crows can eat them 
in comfort. The crows are not easily scared away, but show a remarkable degree of sense, only 
flying away when anyone approaches with firearms, and later they carry on their depredations in the 
early morning, when they have less to fear. 

That lobsters ever leave the water and attempt to crawl upon the land can not be 
credited, and it is likely that this story passed through several hands before reaching 
its present form. Herbst (88) says that the lobsters have a great enemy in the Stein- 
beisser. ' 

If the lobster is thus attacked and destroyed in large numbers by fish after it 
has acquired the habits of the adult and has many devices to avoid its enemies, what 
shall we say of the destruction which is wrought on the young during the first eight 
or ten weeks of their life? From the time of hatching up to the sixth stage the 
young lobster swims at the surface and becomes an easy prey to all surface-feeding 

1 It is uncertain what fish is here meant. The name is applied to the fresh-water genera CoMtis 
and Lota. 



122 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

fish, some of which, like the menhaden, 1 roam abont in vast schools, straining the 
water as effectively as the towing net. Daring this period the lobster measures 
from one- third to two-thirds of an inch in length, and is not only helpless in the hands 
of its animate enemies, but is subject to a vast amount of indiscriminate destruction 
from the forces of inanimate nature. (For the further consideration of this subject 
see pp. 187-189.) 

PARASITES, MESSMATES, AND DISEASES OF THE LOBSTER. 

One of the two parasites known to infest the lobster is a trematode (Stiehoco- 
tyle nethropis). This was first described by Cunningham, who found it in the intestine 
of the Norwegian lobster. It has recently been discovered in the American lobster 
by Dr. Nickerson, to whom I am indebted for the following particulars. The larva 
of this singular parasite, which is from 3 to 7 millimeters long, is found sometimes to 
the number of 70 or more embedded in the mucous coat of the intestine about the 
coecum. It is relatively rare, hardly more than 2 per cent of the lobsters which Dr. 
Nickerson examined being infested by it. Its position at the hinder end of the 
alimentary tract seems to argue that it comes in by way of the anus rather than 
through the mouth. Its final host is probably some species of fish which feeds upon 
the lobster, but the adult trematode is unknown. It may prove to be of a different 
species from the larva discovered by Cunningham. 

The only other strict parasite which the lobster is known to possess is the large 
Gregarine (G.gigantea), which was discovered in the intestine of the European lobster 
by Van Beneden. (194) 

In 1853 Van Beneden (69) called attention to a small green worm which he found 
on the eggs of the lobster, and which he supposed was a larva of Serpula. Later, 
in 1858, he concluded that the animal was not a larva, but a fully developed indi- 
vidual, which he called Histriobdella homari, placing it among the Hirudineae (69). 
Foettiuger, a later student of this form (69), proposes to change its name to Histrio- 
drilus benerfeni, and concludes that is is an Enterocoelian, allied to Polygordius. It 
is not a parasite in the strict sense. 

Although parasites are rare, the lobster is encumbered with a great variety of 
messmates, which attach themselves to the external shell. 

Whenever the lobster is confined in inclosures, or compelled for any reason to 
lead a sluggish life, the common barnacle fixes itself to the arched carapace and begins 
to secrete its tent-like covering as securely as it might upon a stone; mussels of 
various kinds insinuate themselves in convenient angles of the shell and joints, small 
tunicates sometimes becoming attached firmly to the under side of the shell between 
the legs. Tube-forming annelids, lace-like bryozoa, form incrustations in various 
parts, and red, brown, and green algse often decorate the antennae and carapace with 
long streamers which are waved with every movement of the animal. At each molt 
the lobster of course frees itself completely from these troublesome companions. 

•Regarding the menhaden as an enemy of the larval lobster, I have consulted with my friend, 
Professor J. I. Peck, who has made a very careful study of the habits of these remarkable fish. He 
writes as follows: " I have never found lobster larvae in the stomachs of menhaden, and yet it must be 
remembered that the localities whence my material was nearly all secured were brackish- water inlets. 
Copepods in all stages of growth are abundant and shrimp of the smallest size were common at New 
Bedford, but in the material from Buzzards Bay I have never seen lobster larvae." He thinks that 
the evidence can not be conclusive until menhaden are examined which have fed both day and night 
in localities which abound in lobsters. 



THE AMERICAN LOBSTER. 123 

At the lobster pound in Vinal Haven, Maine, which I visited on August 20, 1893, 

1 examined a number of lobsters whose bodies and free appendages supported a 
surprisingly varied flora. A hard-shelled female which I took out of the mud in 
very shallow water was decorated with algae in a very striking fashion upon the upper 
pari of the body, the big claws, and antenna;. The long whip-like "feelers" were 
weighed down with fronds of the brown laniinaria, or devil's apron, as shown in 
fig. IIS, plate 30. The common green lettuce ( Ulva latuca) was sprinkled freely over 
various parts, and barnacles had gained also a foothold upon the shell. A frond of 
laminaria, which was fixed to the side of the abdomen, was 7 inches long and 2 to 3 
inches in width. Besides the larger fronds, there was a- matted undergrowth upon 
the antennae, composed of several species of algae and attached fungi. One of the 
men employed at this pound said that he had taken hard-shell lobsters with "kelp" 

2 feet long growing upon the shell. 

A lobster now in the Peabody Museum of Yale University was incrusted with 
Nnllipores, when it was captured in Nantucket in April, 1880. This specimen was 
a male and weighed about 10 pounds. 

Mussels sometimes glue themselves in extraordinary numbers to the under sides 
of the bodies of living lobsters, in places where the animal is unable to scratch them 
off. A good illustration of this may be seen in the museum of the Peabody Academy 
of Science at Salem, Massachusetts, where there is a male hard-shelled lobster about 
12 inches long with fifty or more shells of the common Mytilus edulis attached to its 
body. The shells of some of these bivalves are li inches long. They have wedged 
themselves between the bases of the thoracic legs, the plates of the tail-fan, and have 
fastened themselves even to the head between the antennae and about the eyes. 

It is not uucommon to find the barnacle (Balanus bakinoides), as we have already 
seen, attached to the shell of both very old and relatively young lobsters (fig. 1, plate 
1). The large Belfast lobster carried about with it several species of mollusks, as 
well as barnacles and hydroids. 

On July 15, 1891, 1 fouud a lobster which had been kept for several days, or perhaps 
for a louger time, in a floatiug car, with one of its eyes completely hooded by a colony 
of bryozoa. When set free, the eye appeared perfectly normal. 

The messmates of the young lobster consist chiefly of fungi (of which bacteria are 
the most characteristic) and of diatoms. Young lobsters captured at sea seem to be 
peculiarly free from foreign matter of every kind, but when the young of almost any of 
the Crustacea are confined they soon become clogged with solid organic or inorganic 
floating particles and bacteria with which such material is invariably associated. The 
hairs which garnish the body and appendages of crustacean larvae serve to gather 
up and hold solid particles from the water, so that one of the first considerations in 
the artificial rearing of Crustacea is to give them as clean a water supply as possible. 

I have seen larvae in the fifth stage of development literally covered with a mass 
of diatoms (Tabelaria, Navicula, etc.) like those found in the brown sediment at the 
bottom of the jar in which they lived and in the undigested food contained in their 
stomachs. Old lobsters, in which the molting period has become very infrequent, 
are commonly the worst sufferers from enemies of this kind, but the physiological 
condition of the animal is, as we have seen, the most important consideration. 

The crayfish, which is devoured eagerly by numerous species of fish in fresh-water 
lakes and rivers, both in this country and iu Europe, is infested by Trematode worms, 
which become encysted in the tissues of the animal. Bistomum nodulosum has been 



124 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

described from Cambarus propinquus by Wright and Linton, and Ward (198) lias found 
in the same crustacean still another species, Distoma opacnm. a The cysts occupied 
the space in the cephalothorax above the heart and sexual organs." 

The " tomally" or liver of tbe lobster is free, so far as is known, from parasites 
of all kinds, yet this is not the case with all the decapod Crustacea. In June, 1885, 
while dissecting the southern shrimp (Penceus setiferus), I found numerous stages in the 
development of a cestode worm, Tetrarhynchus (species undetermined), in the liver of 
this prawn. The youngest were oval, about TT o inch in long diameter; the oldest 
larvae measured yyinch; they had a round, flattened body, an anterior segment or 
neck, with four well-developed proboscides, and a "tail" of about equal length, and 
unsegmented. Two pairs of bright red pigment spots were borne on the upper ante- 
rior part of the body. 

DISEASES OF THE LOBSTER. 

There are no specific diseases to which lobsters are subject, so far as known, yet 
they sometimes die off so rapidly as to lead one to suspect that they may have fallen 
a prey to some contagious disease. 

Mr. N. F. Trefethen, of Portland, Maine, who owns a lobster pound in South 
Bristol, 35 miles east of Portland, relates the following experience: In May, 1893, 
he placed 100,000 lobsters in this pound, the area of which is about 3 acres. Very 
soon they began to die, and in a few days all of them were dead. There were 12 
to 13 feet of water in this pound at flood tide and not less than feet at low water. 
The pound was probably very much overstocked, but it is difficult to understand why 
these lobsters should have all died so suddenly, uuless they were either poisoned or 
attacked by disease. 

In the summer of 1889 a lobster with a large bunch on the side of the carapace 
was captured in Vineyard Sound. On the top of this tumoid growth was a crater- 
like depression covered with a membrane. This was probably a sore resulting from a 
wound which the animal had received in the back, and which had failed to heal. A 
similar case is mentioned by Rathbun (155). 



Chapter VII.— THE TEGUMENTAL GLANDS. 

The shell of the lobster, as lias been seeu already (pp. 77, 78), is not a solid armor, 
but is everywhere perforated by capillary canals which open by minute pores at the 
surface. One set of these ducts is called the hair pores. These lie immediately 
beneath the hairs or setai of the shell. The other set constitutes the ducts of the 
tegumental glands. 1 

The tegumental glands are very generally found in the decapod Crustacea, and 
they are more widely distributed over the body of the individual than almost any 
other organ. Nevertheless their structure has never been accurately determined, and 
almost nothing is known of their function. They lie in the dermis or in the connective 
tissue and adjoining muscles immediately below the cuticular epithelium. They are 
opaque, subspherical or oblong, not usually over | mm. in longest diameter, and 
each communicates with the exterior by means of a capillary duct, the entire length 
of which — not including the part which traverses the cuticle — is probably not more 
than y 1 ,, mm. (cuts 4 and 5, pi. A, and fig. 208, pi. 49) and its diameter only ji s mm. 
These minute organs are scattered all over the body and appendages; they are 
particularly abundant about the mouth and in the oesophagus, and Vitzou has found 
them in the walls of the intestine of Palinurus (197). As he remarks, "one may 
study these organs indifferently in a macruran or brachyuran, for they have the same 
structure in both. 1 ' 

GENERAL STRUCTURE OF THE TEGUMENTAL GLAND. 

The tegumental gland, wherever found, whether in the appendages or beneath the 
skin of the body proper, has the structure shown in cut 5. It consists of a central 
reticulate body or rosette, the exact nature of which is unknown. In the midst 
of this there is a small cavity, which is continued into a short capillary duct. The 
latter perforates the cuticle and thus places the organ in direct communication 
with the exterior. Grouped about the rosette is a cluster of gland cells of various 
shapes and sizes. Each has a broad base and tapering central end, which is united to a 
process of the rosette. Each organ is supplied with a nerve and contains an eccen- 
tric, bipolar cell, which resembles a ganglionic cell. One of the processes of the 
latter joins the rosette, while the other unites with the nerve. Barely two such cells 
appear in the same organ. The duct and nerve usually issue from the gland together, 
the former possessing apparently, for at least a part of its course, a thin sheath. 
Each organ is usually surrounded with a delicate capsule, probably of connective 
tissue, though it is not always possible to detect such an envelope. 

I have .seen no branching of ducts, each organ opening independently at the 
surface, and I have not succeeded iu determining with any degree of satisfaction the 
relation which the nerve fibers bear to the gland cells. 

1 Similar structures have been called dermal glands, salivary glands, and cement glands. While it is 
probable that they originate in the epidermis, it may be better to classify them under the generic 
term of tegumental glands. 

In the work of this chapter, relating to histology and technique, I wish to acknowledge my 

indebtedness to Professors Patteu and Watase for valuable suggestions. 

125 



126 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

What is the function of these organs which are distributed so widely over the 
surface of the body? It has been found that glands of a similar character play a part 
in excretion. (Text-book of Comparative Anatomy, Lang, part i, p. 330.) Those found 
in the oesophagus were regarded as salivary glands until the embarrassing fact was 
discovered that they were also found in the walls of the intestine. When occurring 
in the swimmerets and ventral abdominal region of the female these organs have been 
considered responsible for the liquid glue or chitin-like cement which is poured over 
the eggs at ovulation, and have been accordingly called cement glands. It seems 
probable that they have such a function, and I shall proceed to describe them in 
detail as they occur in the lobster. 

THE CEMENT GLANDS. 

If we strip off the hard cuticle from the pleopod of a female lobster just before the 
eggs are laid (fig. 144, plate 40), we will see thousands of opaque whitish bodies lying 
upon the strands of muscular tissue. Each is a gland not more than an eighth of a 
millimeter iu diameter, and each opens to the exterior by a capillary duct which 
pierces the cuticle. The grounds for attributing a cenient-producing function to these 
organs lie chiefly in their periodical changes coincident with the sexual condition of 
the female, and in their absence or restricted occurrence in the pleopods of the male. 
Their position upon the swimmerets also favors such a view. We can not look else- 
where for such an organ, unless it is to the oviducts, and I know at present of no 
evidence showing that the latter possess this function in the macrura. 

CEMENT GLANDS IMMEDIATELY BEFORE OVULATION. 

As the time of oviposition draws near, the swimmerets of the female become 
more and more opaque, especially along the free margins of their branches. At this 
time a milky-white substance can be pressed out, upon removing the cuticle. This is 
analogous to what Lereboullet observed in the crayfish (120), and is composed of the 
glandular tissue. 

At this period the glands have the appearance shown in plate 49, fig. 212. Stained 
with the Ehrlich-Biondi auilin mixture the cells have a cloudy, granular appearance. 
Their peripheral ends contain a coarser material, which takes a deeper red than the 
central parts; the latter appear much lighter, and select and hold some of the green. 
The distribution and appearance of the zymogen granules may be compared to that 
seen in the pancreas of a well-fed dog, or the resting cells of the submaxillary gland. 

An attempt to get a secretion from these glands while in this condition by stim- 
ulating the nerve cord by induction currents was not successful, possibly owing to the 
fact that these organs had not quite reached the stage of their periodical activity. 

THE CEMENT GLAND IMMEDIATELY AFTER OVULATION. 

The structure of the exhausted gland, taken shortly after the eggs are laid, is 
illustrated by fig. 211, plate 49. If this is compared with fig. 212, which is treated in 
the same way, we will find a marked difference in its cytological condition. A very 
conspicuous zone of deeply stained zymogen granules surrounds the central rosette, 
while the outer parts of the gland cells are poor in zymogen and stain but feebly. 
This central darker zone is very variable in breadth, being sometimes reduced to a 
thin circle, involving only the apices of the cells, and is often very sharply marked 



THE AMERICAN LOBSTER. 127 

off from the rest of the cells. It should be remarked, however, that in two or three 
days after ovulation (external eggs with segmented yolk) there is a striking lack of 
uniformity in ,'ie condition of the glands, in many the central zymogen zone being 
entirely absent. This may be due to the fact either that some of the glands recover 
from exhaustion raster than others, or that they secrete unequally, or that some are 
not roused to activity at all. 

Fig. 210, plate l!», is from the swimmeret of a female which had probably recently 
hatched a brood and was close upon the point of shedding. As may be seen, the 
glands are much shrunken in size, the cells transparent and non-granular, as if they 
were completely exhausted. This seems to be a perfectly normal case, but whether 
it has any significance in respect to the molt I am not able to say. 

HISTORICAL SKETCH OF THE CEMENT GLANDS. 

Cement glands have been described in numerous species of macrurous Crustacea, 
but their structure seems to have been imperfectly made out. 

Oavolini, 1 according to Cauo {32), maintained that the cement came from the 
oviduct, and Rathke {160) regarded the genital orgaus as the probable source of this 
secretion. Erdl (63), in 1843, described three membranes in the egg of the lobster, 
and considered the outermost of these to be the secreted product of the oviduct. 

Lereboullet {120) barely escaped the discovery of the cement glands of the crayfish 
in 1860, but correctly stated that the cement substance came from beneath the skin 
of the under side of the abdomen. He had indeed communicated this discovery to the 
Natural History Society of Strasbourg in 1S52 (published in a note in L'Institut, 
in 1853. See ref. 120.) As he says, zoologists had up to this time been almost mute 
upon this subject, some explaining the attachment of the ova to an extension of the 
primary egg membrane, others, like Milne Edwards {58), to an albuminous secretion 
from the epithelium of the oviduct. Lereboullet described a milky-white matter rich 
in fat and nuclei, which is present in the epiineral regions of the abdomen of the 
female crayfish at the time of oviposition, but is not found in the male at any period 
of the year. He supposed that this substance oozed through pores in the cuticle, 
coagulated in the water after fixing the eggs, and that all trace of it subsequently 
disappeared until the next reproductive period. 

The true source of this secretion was first recognized by Braun (22), who, in 
1875, described cement glands in the crayfish. He showed that they consisted of 
clusters of cells, which open to the surface of the abdominal appendages by narrow 
ducts penetrating the cuticle — a single duct to each cluster. A little later {23) he 
figured and described these glands in the six species of decapods. Similar structures 
were found in the carapace aud oesophagus. GEsophageal glands (Speicheldrusen) had 
been already seen in several species of crabs, such as Grapsus and Eriphia spinifrons, 
and analogous structures were found in the labruin and maxilla?. 

Vitzou, whose work was published in 1882 {197), found glands generally present in 
the oesophagus of all the crustacea examined, and they appear iu many of his drawiugs, 
but no attempt seems to have been made to study their histology. The oesophageal 
glands were extremely abundant in the lobster and Palinurus. The ducts are said to 

1 Memoria sulla geuerazione del pesci e dei granchi. Napoli, 1787. I have not had access to this 
■work, and quote it upon the authority of Cano. 



128 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

be sometimes united into groups of five or six, and. in the intervals small hairs ' occur 
upon the surface of the cuticular lining*. 

Cano (32) devotes considerable attention to this subject, in a paper published in 
1891, describing the distribution and structure of the cement glands in a large 
number of decapods. Bumpus attributes the "varnish-like layer" which surrounds 
the ovum of the lobster after oviposition to a secretion which is supposed to come 
from the columnar cells lining the oviducts (30). 

In 1893 I gave a short and incomplete account of the cement glands of the 
lobster (96). See also 57, note p. 79. 

TEGUMENTAL GLANDS IN OTHER PARTS OF THE BODY. 

I am not able to map the entire distribution of the tegumental glands, but have 
found them in many parts. The labruin and metastoma are packed almost full (fig. 
208, plate 49). In the latter the ducts open for the most part upon the side next the 
mandible. We find them also in the basal stalk (protopodite) and respiratory plates 
of the maxillae and maxillipeds, where they are already developed in the larval stages 
(plate 29, figs. 59, 62), and in the flagella of the antennae. 2 The skin of the carapace 
and abdomen abound in these organs, and they are clustered in large numbers about 
the anterior lower margins of the former, just below the cervical groove, where the 
surface of the shell is raised into prominences like a grater. The ducts of many of 
these glands open into the respiratory cavity. I have also found a few of the organs 
in the walls of the seminal receptacle. 

In sections through the dorsal posterior surface of the carapace of a lobster nearly 
ready to molt I find glands in precisely the same condition as shown in fig. 211, plate 
49, where there is an inner deeply staining granular zone. Figure 208, plate 49, rep- 
resents an organ from the metastoma, after maceration for three days in Bela Haller 
mixture and staining in methylen blue. The duct, running in the nerve bundle, 
shows very clearly and can be readily traced to the surface of the gland. By focusing 
with care I was able to follow the tubular duct into the central lumen or space, so 
characteristic of these organs. The relative number and distribution of glands in 
any part can be determined from macerated portions of the shell, as in fig. 170, which 
represents the inner surface of the first maxilla. 

By maceration and pressure the structure of the gland can be made out in most 
of its details. In fig. 203, plate 49, the eccentric "ganglion "cell (s. c.) is seen to give off 
two branches, one of which joins the rosette (R), while the other passes into the nerve 
bundle, not shown in this drawing. A single gland cell is still joined to a process 
of the rosette by its attenuated central end. By rolling this specimen under the 
cover slip I was able to confirm the relations here pointed out. In fig. 214, drawn 
from a similar preparation, fewer glandiilar cells are detached, and but one process of 
the "ganglion" cell is shown. In many instances I have noticed that the inner ends 
of the gland cells have a very refractive, tubular appearance where they join the 
central rosette (figs. 209, 213, etc., plate 49), as if they had been snapped off at this 
point of delicate union. Figs. 206, 207 show a single gland cell drawn from opposite 
sides, from a cement gland of a female with nearly ripe ovaries. Besides the promi- 

I I think it probable that the ducts of the glands really open upon these "hairs," as they do in 
the labrum. (See p. 133.) 

-I have seen them in the outer fiagelluni only of the first antenna. 



THE AMERICAN LOBSTER. 129 

nent nucleus at the peripheral end of this cell, there are two other bodies — one near the 
tubular neck — which take up the stain like nuclei and are considerably refractive. 
From the larger end of the cell (tig. 206) a slender process is given off (compare figs. 
201,204 from the maxillae), which suggests a nerve fiber. All that I can say definitely 
is that this process is in continuity with the cell, probably with its wall. I did not see 
many cases of a similar character. 

EXPERIMENTS UPON THE SENSORY AREAS OF THE BODY AND APPENDAGES. 

Before discussing the function of the tegumental organs in general, I will record 
some experiments which were made to determine how the lobster reacts to stimuli 
directed against the dead shell or cuticle. 

The lobsters experimented upon were taken from the sea, placed on their backs 
on a table, and allowed to remain in this position until quiet. At first they move 
their appendages vigorously in trying to right themselves, but soon come to rest. By 
sprinkling them with sea water they may be kept fresh for experiment for a consider- 
able time. 

Various stimuli, such as electricity, heat, weak acetic acid, ammonia gas, clam juice, 
were applied to different parts of the body, with a view to ascertain the most sensi- 
tive areas where the quickest and most vigorous responses were given. 

The degree of sensibility to external stimuli is surprisingly great in many cases, 
where the skin of the lobster with its shelly covering seems quite as sensitive as that 
of the frog. In other cases, however, the animal is much less responsive, a fact which 
we may attribute in some degree to the thickness of the shell. 

To sum up the experiments in a general way, all or nearly all the appendages 
react strongly to chemical stimuli, and in many cases the surface of the body is 
capable of receiving and responding to stimuli of various kinds. If a jet of ammonia 
gas is injected against the intersegmental membranes or appendages of the ''tail," the 
pleopods may be set in very lively motion and violent flexion of the whole abdomen 
may follow. Direct the jet upon the anterior swimmerets, and the last three pairs of 
walking legs are drawn backward and make scratching movements to remove the 
offending object, reminding one of the motions of a "reflex frog" when its skin is 
stimulated in a similar way. 

The reaction is more violent when the stimulus is applied to the swimmerets than 
when directed against the intersternal membranes. The seminal receptacle is very 
sensitive, and when stimulated the walking legs make violent scratching movements 
toward it. If the jet of gas is directed along the surface of the walking legs, the 
reaction is usually greatest at their tips. 

If the extremities of the large chelae, especially the propodus, are touched by the 
gas the claw opens and shuts. The first pair of antennae are much more sensitive to 
the stimuli than the second pair. If the jet is directed over the region of the mouth, 
very violent chewing movements are set up. 

If the ammonium vapors be squirted on the dorsal surface of the carapace or 
abdomen, a vigorous response is sometimes seen by the immediate movements of the 
legs. Both males and females respond to the ammonia stimulus on the abdominal 
appendages and intersegmental membranes. 

Very similar reactions are obtained if a small piece of blotting paper wet with 
weak acetic acid is used. In some cases no response is obtained if the wet paper is 

F. C. B. 1895—9 



130 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

placed on the intersterual membranes of the abdomen, but if laid upon either the inner 
sides of the pleura or upon the surfaces of the pleopods the reaction is more marked 

If clam juice is placed on the mouth parts, as upon the flattened basal segments 
of the second maxilla? or first pair of maxillipeds, vigorous chewing movements are 
immediately begun, and are continued for several minutes. If the stimulus is applied 
to one side, the movements are at first restricted to that side only, but eventually, in 
some cases, the appendages of the opposite side begin to move also. 

If clam juice is dropped upon the swimmerets of the female, a response is usually 
forthcoming, and the same is true if this stimulus be applied to the terminal segments 
of the walking legs. In the case of the large chela? the response may be very slight. 
In one instance, where three females and one male were experimented upon, the 
abdominal appendages gave no response to clam juice, but the mouth parts were 
always extremely sensitive. In this case the pleopods gave a marked reaction when 
touched with weak acetic acid. 

As a rule, the pleopods of the female were more sensitive to the various stimuli 
than those of the male. The abdominal appendages of the body give no reaction 
when breathed upon, and show but slight sensitiveness to heat. Weak electrical 
currents from an induction coil produce marked responses in the maxilla? and first 
pair of maxillipeds, and if the swimmerets are touched by the electrodes, violent 
contractions of the flexor muscles of the abdomen speedily follow. 

The preceding experiments would lead us to suppose either that certain areas of 
the skin of the body and appendages are very sensitive to a variety of stimuli or 
that the skin or parts below it possess special sense-organs. In either case, excepting 
electrical stimuli, the organs must be reached by means of the canals which penetrate 
the inert cuticle. 

Since there are only two possible roads for the entrance of chemical stimuli — the 
hair pores and the pores of the glandular ducts — the question is therefore raised 
whether the glands possess a subsidiary sensory function. If it could be shown that 
the seta? of the carapace were not perforated at their tips, it would be certain that 
ammonia vapor could not enter them 1 and extremely probable that the reaction from 
this chemical stimulus had its seat in the gland. I believe that these organs do 
possess such a subsidiary function, and that this is shown to be the case by a study of 
the sensitive labrum, in which hair pores and their corresponding seta? are entirely 
absent. 

The function of the tegumental glands in various parts of the body has been a 
subject of much embarrassment. Max Braun (22) thought that the oesophageal glands 
of the crayfish were salivary organs. Vitzou inclines to acquiesce in this opinion, 
but admits that the presence of organs of exactly the same structure in the walls of 
the intestine (in Palinurus) is puzzling, to say the least. 

Professor Patten (150) has recently discovered certain organs in Limulus to which 
he attributes a sensory function. They have essentially the same structure as the 
tegumental glands of the decapod Crustacea. There occurs in front of the mouth of 
Limulus, on the middle line, a wart-like swelling, which Patten regards as the cuticular 
portion of an olfactory organ. "Directly beneath the ectoderm", he says, there "are 
a great many — at a rough estimate, from 1,500 to 2,000 — clear, flask-shaped sense buds, 
each of which is connected by a narrow neck with a cuticular canal." The structure 

1 Where the set,B are moist it might be possible for ammonium vapor or any other chemical 
stimulus to reach the sensory cells by diffusion through the thin chitinous wall of the tubular hair. 



THE AMERICAN LOBSTER. 131 

of these "olfactory buds," their cuticular canal, gland-like cells, and large eccentric, 
in this case multipolar, ganglion, prove conclusively that these organs are essentially 
similar to the glands which I have described in the lobster. In discussing this subject 
with Professor Patten we have always been mutually agreed upon this point. What 
the function of these organs in all cases really is, may well be an open question. In 
Limulus the lumen of the organ varied much in appearance, being more sharply 
circumscribed in the young than in the adult, where it might be reduced or even absent. 
The tubule was sometimes coiled and very brittle. It is "undoubtedly composed of 
cliitin, for, as with the gustatory tubules, it can still be seen in the cast-off shells of 
immature specimens and in the fresh shells cleaned with potash." The same is true 
of the cuticular canals of the glands of the lobster, except that the tubule is always 
apparently straight and is never effaced. 

Lang {114) mentions some of the many cases in which glands have been described 
in the body and appendages of various Crustacea, attributing to some of these "der- 
mal" structures an excretory function, a fact which, he says, may be proved by feeding 
with carmine. 

Unicellular glands of a remarkable character have been described in the append 
ages of various amphipods by Nebenski (140), Clans, and others. Here they are found 
in both sexes, but are confined in Orchestia to terrestrial species. Nebenski thinks that 
in the latter they may serve a respiratory function by keeping the gills moist. 

The glands situated in the mouth parts, when stained in Ehrlich-Biondi anilin 
mixture, select the green with more regularity, the nuclei taking up the red. This, 
however, maybe due to slightly different methods of treatment in washing out the stain. 

The differences between what appear to be the resting and active gland, illustrated 
in figs. 212, 211, which are fairly characteristic of the swimmerets, immediately before 
and after ovulation, respectively, should not be given undue importance, since these 
conditions are met with, though less commonly, in other parts of the body. 

Micro-chemical reactions point clearly to the glandular nature of the large periph- 
eral cells of which these organs in certain places are composed. It is probable that 
in the pleopods they are concerned with the secretion of cement, for the reasons 
already given. What, then, is the function of the eccentric bipolar cell 1 ? Is it a reflex 
center for the gland, or is this a sensory cell which conveys impulses received from 
without to a reflex center in the central nervous system governing the secretory 
activity of the glandular cells? If the former supposition were correct, another ques- 
tion would remain to be answered: What are the organs of the sense of taste? The 
remarkably quick responses which are obtained upon stimulating the mouth parts 
immediately suggest the presence of gustatory organs. Such animals as the lobster 
and crab undoubtedly possess the sense of taste, but no organs have yet been 
described to which this function could be ascribed. Huxley says : 

It is probable that the crayfish possesses something analogous to taste, and a very likely seat for 
the organ of this function is in the upper lip and the metastoma; but if theorgan exists it possesses no 
structural peculiarities by which it can be identified. 

The labrum of the crayfish, so far as I could ascertain from a single specimen 
which I sectioned, contains no such glandular organs as occur in the lobster. 

If it is inadmissible to regard any of the tegumental "glands" as gustatory 
organs, we must conclude that no distinct organs of taste can be detected in this 
animal, which has the power of discriminating its food. Is it possible, as Lemoine 
suggested (118), that the sense of taste is in some species blended with that of smell 



132 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

and touch % Lemoine, who experimented with the crayfish, found that even the thickest 
parts of the carapace were sensitive, and that the parts which abounded in hairs were 
the most sensitive. Touching the hairs determined the movement of the claws and 
thoracic legs. 

Milne Edwards considered the buccal cavity as the seat of the sense of taste, but 
although the experiments made by Audouin and himself convinced him that the sense 
was developed, he failed to find any special organs. (55, i, pp. 112-113.) 

Lemoine experimented upon the buccal cavity, and especially the labrum, using 
a great variety of stimulants, such as salt, pepper, tobacco, ammonia, and electricity. 
He describes the labrum of the lobster, but, strange to say, did not discover the organs, 
with which it is packed full. He found that the inner face of this body was extremely 
sensitive. A nerve enters the labrum on each side. This gives off lateral twigs near 
the point of entry and numerous terminal branches toward the median plane. He 
supposed that these terminal filaments supplied the short hairs which were erroneously 
supposed to cover the surface. 

The setse of Crustacea have tactile, auditory, and probably olfactory functions. 
The sensory seta is hollow and stands over a canal, which penetrates the integument, 
and a nerve fiber passes up into the lower part of the canal. (84.) 

The organs of taste in insects, according to Lubbock, are modified hairs, situated 
either in the mouth or on the organs immediately surrounding it. Nine different 
antennal organs have been described in the Hymenoptera. Some of these antennal 
hairs serve as organs of touch and smell, and possibly for hearing also. 

I have already called attention to the fact that while the pleopods are studded 
with thousands of microscopic glands, these appendages in the male are almost devoid 
of them. Their occurrence in the brachyura, where indeed they were first described 
by Braun (23), might support the theory that they had, in such cases, a function to 
perform independent of the production of cement, since it has been shown that the 
crabs possess a special cement-forming organ in the epithelial lining of the glandular 
receptaculum seminis. We must therefore conclude that in the brachyura the work 
of the glandular receptaculum seminis is supplemented by that of the pleopodal 
glands, or that the latter possess another function. 

On the other hand, Leydig (122) has maintained that there is a close relation 
between gland cells and sensory cells, the two kinds of cells resembling each other in 
general structure and in the disposition of the cell contents. He found in the sensory 
cells of the skin of some vertebrates what seemed to correspond to cuticular secre- 
tions in gland cells. 1 

The gland of the type which we have been considering is undoubtedly a very 
primitive organ in Arthropods. It has probably been modified to perform different 
functions, with a minimal change of gross anatomical structure. What the function in 
every case is we can not for the present say with any degree of certainty. While the 
question is a puzzling one, it seems to me safer to regard all such structures, wherever 
they occur, in oesophagus, the intestine, the labrum, pleopods, or outer integument of 
the body, whether in Decapods, Limulus, or in other forms, where they will doubtless 
be discovered, primarily as glands. We may add that in the labrum, and perhaps in 
other parts of the external integument of the lobster, and in Limulus, they may have 

1 Jickeli, according to Leydig, believes that in certain Hydropolyps which he studied sensory 
cells are converted into gland cells. {122.) 



THE AMERICAN LOHSTER. 133 

a secondary sensory function. I have not examined the glands which occur in the 
alimentary tract, and can not say whether they possess a precisely similar structure. 

Upon the supposition that the teguinentary organs are never sensory in function, 
we would have to conclude that the reactions which were obtained upon stimulating 
the dead shell had their seat in sensory elements in the vicinity of hair pores, and that 
the sensory hairs themselves are open at the tip, or at least have thin walls. I have 
usually found sensitive areas covered with setre, 1 and while these do not normally 
open at the tip, the cuticle is so thin at this point that chemical stimuli might be readily 
conducted through them. 

There is, however, one organ which is very sensitive to chemical stimuli, and 
which is entirely devoid of true setae in the adult animal. This is the labrum or upper 
lip. Its structure certainly favors the view that the peculiar tegumental organs which 
it contains in such abundance may be the seat of the sense of taste. 

There can be no doubt that the labrum is very sensitive to various stimuli, as 
Lemoiue clearly showed many years ago. In the specimens which I examined with 
particular care no setae of the ordinary kind were present on either the upper or lower 
sides, and the only direct channel for the passage of chemical stimuli from the surface 
of the dead cuticle to sensitive structures below it were the ducts of the tegumental 
glands. After the labrum had been cleaned by boiling it in a strong solution of potas- 
sium hydrate, the cuticular structures were clearly demonstrated. The only setae 
present lie in four small rounded clusters of 12 to 15 each, near the base of the labrum 
and on its upper surface, where the cuticle has been reenforced by deposits of lime. 
These setae are microscopic, measuring only one- tenth millimeter in length. Moreover, 
each is traversed by a duct which apparently opens at the surface and without doubt 
belongs to a tegumental gland. The upper surface of the labrum is abundantly 
sprinkled in other places, especially about the tip, with the minute pores of glands. 
These are sometimes in clusters, and their aggregate number is very great. When we 
examine the inner surface of the labrum we see it covered with sieve-like patches, each 
sieve containing sometimes as many as 60 or 70 holes, the openings of tegumental 
glands. At the anterior end these merge together so that the openings are exceed- 
ingly numerous. (Compare figure by Lemoiue, 118.) 

Lemoine evidently mistook the ducts in the sieve-like areas for hairs, and has 
figured them incorrectly. The ducts project from the inner surface of the cuticle, 
(compare fig. 170) and in no instance were true setae or hairs present on any part of the 
adult labrum. 

Expei'imental evidence seems thus to point to the possession of a subsidiary gus- 
tatory function on the part of tegumental organs of the labrum, and possibly of other 
appendages about the mouth. This would imply that the stimulating particles are 
conveyed to the lumen of the organ, and thence to the central rosette. It would 
of course be absurd to suppose that the apparently similar organs in many other 
parts of the body, as in the carapace, possessed a similar function. While such a 
conclusion is not perfectly satisfactory, it is at least worthy of consideration. 

'The walls of the seminal receptacle contain very few glands, but are copiously supplied with 
clusters of sette. As I have already shown, they are very sensitive to chemical stimuli. 



Chapter VIII.— VARIATIONS IN COLOR. 

In the study of the color of animals we must distinguish between (a) variations in 
colors themselves and (b) variations in color patterns. The variation in colors, which 
Bateson calls "substantive variation," may be the result of a physical or chemical 
change and has no vital significance, like the change of yellow phosphorus to the red 
variety, of blue to red litmus, or of green to red pigments in autumn leaves and in the 
shell of the living lobster when the latter is boiled. " Different colors," says Bateson, 1 
"are liable to different discontinuous variations; as instances may be mentioned black 
and tan in dogs, olive brown or green and yellow in birds, red and blue in the eggs of 
many Oopepoda," etc. "Discontinuous color variation of this kind is one of the com- 
monest phenomena in nature." The dark green and golden yellow in the eggs of several 
species of Alpheus and many other macrura is a characteristic example (94). Such 
changes can have no protective or adaptive significance. 

The color of the lobster 2 is primarily due to the presence of pigments, either in 
solution in the blood or in the form of granules in the protoplasm of certain cells, 
particularly the chromatoblasts, which lie beneath the cuticular epithelium The 
chromatoblasts are richly supplied with blood, which flows in a system of irregular 
sinuses through the spongy tissues underlying the epidermis. 

In the adult lobster the shell is an opaque, dead substance, and the pigments 
which give it color are excreted by the chromatoblasts lying in the soft skin which is 
exposed upon removing the shell. This skin is flecked and mottled with scarlet, and 
it takes only a simple magnifying glass to see that its color is due to the branching 
pigment cells, accumulations of which correspond to the blotches of pigment on the 
shell. The excreted pigments undergo physical and probably chemical changes in the 
shell, and become of a very different color from that of the chromatoblasts. 

Since the colors of the adult lobster reside in a dead body — the pigment layer of 
the shell (see pp. 77-78) — it is evident that no changes of a vital nature can take place 
after this is definitively formed. A young male, 10 inches long, drawn and colored from 
life, is represented on plate 16, fig. 22. This may be taken to represent the average 
color in lobsters with moderately hard shells. 

NORMAL COLORATION. 

There is no apparent sexual variation in the color of the lobster. The following 
detailed description is drawn from a female 10§ inches long, with elastic or " buckle" 
shell and with nearly ripe ovaries. 

The general cast of color of the upper parts is dark bluish-green, mottled and 
speckled with very dark greenish- black spots; tail-fan light greenish-olive; sides of 
carapace brownish-olive, conspicuously spotted with small greenish-black spots; sides 
of abdomen marked in the same way, spots not as numerous; no spots on upper 
surface of uropods; large chela; above dark bluish-green, almost black, with suffusions 
of orange on propodus; tubercles and spines bright red; spiues of rostrum, antennae, 

1 Materials for the study of variation, treated with especial regard to discontinuity in the origin 
of species, by William Bateson. 1894. 

2 The color variations in the young are discussed on p. 184. 

134 



THE AMERICAN LOBSTER. 135 

pleura of third to sixth abdominal segments, and of appendages generally, vermilion ; 
worn points of spines or worn surfaces of tubercles whitish; orange area of crushing 
chela (on propodus) mottled with dark green; walking legs bluish-green; bright sky- 
blue on basal joints, and tufts of setne reddish. 

Tendon marls: (1) A large porcelain-like whitish spot at junction of the cervical 
and branchio-cardiac grooves. Passing down the cervical groove are (2) numerous 
white or greenish white spots; (3) a large irregular yellowish-white spot occurs in a 
depression which lies about an inch behind the first antenna, and one-half inch from the 
dorsal surface, measured vertically; (4) a small white spot is seen about five-eighths 
inch behind the second antenna and five- sixteenths inch above the cervical groove. 
These spots are very characteristic, and are more prominent in the young than in the 
adults. They first become conspicuous in the fifth stage. (Compare plates 24, 25.) 

The edge of the carapace is scalloped opposite the appendages, probably an 
adaptation for the movement of the legs ; ' largest scallops opposite the large chelipeds ; 
a wide seam-like border, disappearing behind, forms part of the lateral area of absorp 
tion (see p. 8S); color of absorption area light blue; yellowish spots on either side of 
second to sixth terga of pleon, most marked on second, third, and fourth segments. 

Lower surface of large chela? reddish orange ; bright red at the tips ; bluish-green 
at edges, and on hinder parts of the propodus, and on the other joints; basal joints ot 
smaller legs sky-blue varied with brownish-olive ; wing-like pieces of seminal receptacle 
bright blue; swimmerets flesh color, edged with reddish; intersegmental membranes 
of abdomen nearly colorless; lower side of tail-fan brownish-olive; telson and uropods 
edged reddish-brown ; fringes of silky hairs of the same color. 

There is generally an under tint of olive on the body verging into a greenish-blue 
on the one hand or light reddish-brown on the other, the whole upper and lateral 
surfaces being spotted or mottled with dark greenish-blue or blue-black, the spots 
often confluent on the upper surface. 

VARIATIONS IN COLOR. 

The coloration is uniform in plan, but exceedingly variable in details, much more 
so than we see in the case of the intricate color patterns of many insects. The bril- 
liancy and purity of the shell pigments depend largely upon the age of the shell or its 
condition with respect to the molting period. The pigments are usually most brilliant 
immediately after the molt, when the cuticle is thin and translucent, and dullest just 
before ecdysis begins, when the old shell encumbers the body. 

The pigment cells themselves, which, as we have seen, reside in the skin or immedi- 
ately below it, are subject to vital changes, but when the shell is once hardened the 
color of the animal is fixed. It is certain, however, that under the action of light, 
or from other causes, the shell pigments undergo molecular or chemical changes. 
Men who handle lobsters have frequently observed that when they are exposed in 
shallow cars to unusually intense light they become decidedly bluer in color. I 
recently witnessed a very interesting demonstration of this fact. The fishermen at 
Meuemsha, at the western end of Vineyard Sound, saved all the egg-bearing lobsters 
which they caught in June. 1894, for the hatchery of the Fish Commission, placing them 
in a floating skiff, covered only with netting and thus exposed to the full glare of the 
sun. Toward the last of the hatching season, when operations iu the hatchery had 

'The development of the carapace shows that these notches have nothing to do with the primi- 
tive segmentation of the body. 



136 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

ceased, I made no visits to Menemsha from June 22 until July 16, when I found about 
a dozen lobsters in the car, where tbey had been imprisoned from two to three weeks. 
They were without exception of a brilliant blue color, and were very conspicuous 
when placed with other lobsters recently taken in the Sound. They were all old-shell 
females, most of which had hatched their eggs and were approaching their molting 
time. All the green pigment of the shell had become light cobalt-blue, which, inter- 
spersed with the usual Naples yellow tints, gave them a very striking appearance. 

According to the observations of MacMuun (132), the coloring of the skin of the 
lobster (Astacus gammarus) and crayfish (Potamobius fluviatilis) is due to the presence 
of chromogens, which are converted on very slight provocation, as by dehydration, 
oxidation, or some molecular change, into a red lipochrome, resembling rhodophan. 
Everyone is familiar with the wonderful change of color which the adult lobster under- 
goes when boiled, 1 and according to MacMunn the beautiful blue pigment of the larval 
lobster is converted by alcohol into a true lipochrome. 

Alcohol quickly converts the chromogens in the lobster's shell into lipochromes, 
and dissolves them at the same time. This is well seen in recently molted lobsters, 
where the colors are very brilliant. When placed in alcohol, the soft-shelled lobster is 
first reddened, and then in a short time completely bleached, while a lobster with a 
hard shell treated in the same way will retain some of its color for a long time, if not 
indefinitely. The same changes are seen when the dark-green eggs are treated with 
alcohol or boiling water. 

The lipochromes are pigments of a very wide distribution in the living world, 
occurring in green leaves, in yellow flowers and fruits, and it is said that the ver- 
tebrate retina, " egg-yolks of different species of animals, the yellow, green, or red 
pigmented integuments of various invertebrates and vertebrates from fishes to birds, 
owe their coloration, with few exceptions, to dissolved, granular, or diffusely distributed 
lipochromes." (132, p. 95.) 

Lipochromogens are found in a natural state in the gastric glands, blood, soft skin 
(as the blue prismatic cyano-crystals, which are reddened by alcohol or by boiling), and 
in the exoskeleton of Crustacea. MacMunn is of the opinion that they are " built up in 
the digestive gland and carried in the blood current to be deposited in other parts of the 
body." (132, p. 62.) If this is true, it would not be remarkable if the color of the animal 
were affected by the nature of its food, yet this does not seem to be often the case. 

The following substantive variations have been met with: (1) Blue lobsters, in 
which the prevailing color is blue ; (2) red lobsters, which are pure red or reddish-yellow ; 
(3) cream-colored lobsters, characterized by the almost entire absence of color; (4) we 
should also add black lobsters, to include possible cases of melanism, where the colors 
are extremely dark. A specimen of this kind was reported to me at Beal Island, near 
West Jonesport, Maine, where a fisherman recently captured, in 3 fathoms of water 
among the eelgrass, a lobster about 6 or 7 inches long with moderately hard shell and 
almost jet-black. He supposed at first that it was covered with coal tar. It did not 
appear to be preparing to molt. Malard (133) speaks of meeting with cases of melanism 
in crabs, where in consequence of a lesion of the skin the crab becomes entirely black — 
"charbonne," as the sailors describe it. 

■In France the lobster, Astacus gammarus, is said to be called the "red cardinal of the sea," and 
the Norwegian lobster, Nethrops norvegicus, I am informed by Dr. Lonnberg, is called by the fishermen 
in Sweden Eejsar h ummer, or emperor lobster, on account of its color and spines. 



THE AMERICAN LOBSTER. 137 

Changes in color pattern are more elusive. There is (1) the normal variety, in 
which the upper part of the body is mottled with green, blue, and cream color; (2) 
spotted or "calico'' lobsters, the coloration of which is a bold pattern of green and 
light-yellowish or cream-colored spots; (3) pied or particolored varieties, in which 
the contrast of tints is abnormally pronounced. This may perhaps be better classed 
under substantive variation. The changes are due apparently to vital or physiological 
causes, which have at least no adaptational significance. 

We will presently consider in more detail the variations which have just been 
enumerated, but must first speak of the eggs. 

COLOR OP THE EGGS. 

The eggs of the lobster furnish a good example of substantive variation. The 
body of the animal is opaque, so that it is affected but little by the color of the ovaries, 
aud not at all when seen from above, by that of the external eggs. 

The freshly laid ovum is of a dark green (fig. 24, pi. 17), sometimes almost black, 
color, due to the presence of a dissolved lipochromogeu. The golden-yellow variation, 
which is often associated with dark green, as in the eggs of Alpheus heteroehelis and 
A. saulcyi (94, p. 375), has never been observed, but occasionally the ova are of a light, 
almost pea-green color, or some tint between this and very dark green. Rarely the 
new eggs are light grayish green. 1 received a lobster from Woods Hole in December, 
with external eggs of a very light greenish straw-color. (See fig. 23, pi. 17.) These 
were in an early stage of development, and had been laid but a few weeks. It was 
the most striking color variation in the ova which I have yet seen. Such changes as 
these can not be interpreted as having any adaptational significance. 

If the eggs are treated with hot water, alcohol, or other killing reagents the green 
lipochromogeu is quickly converted into red lipochrome. When the water is heated 
gradually the red color appears slowly, and it is interesting to observe that if these 
red eggs are now plunged into cold water the green color is restored. This change 
may be somewhat analogous to the breaking up and reconstruction of the blue com- 
pound of starch and iodine upon the successive application of heat and cold, and to the 
variation in color which sometimes appears in the living animal at the time of the molt. 
Soon after the water has been brought to the boiling point the red color becomes 
permanent. 

BLUE LOBSTERS. 

Lobsters of a deep, almost uniform ultramarine color are sometimes met with and 
never fail to attract attention. 1 The color, which is often of a rich indigo along the 
middle of the upper part of the body, shades off into a brighter and clearer tint on 
the sides and extremities. The upper surface of the large claws is blue and purple, 
faintly mottled with darker shades, while underneath is a delicate cream tint. The 
under parts of the body tend also to melt into a light cream color, and this is also true 
of the spines and tubercles of the shell and appendages, which are usually bright red. 

A lobster of the foregoing description was caught off Hurricane Island by Thomas 
Garrett, in April, 1874. It was a female, had a hard shell, aud weighed about 2 pounds. 
A very bright blue lobster was taken at Grand Manan, Maine, in August, 1893. 



•DeKay (51) speaks of a variety of lobsters called Bluebacks, but his impressions that they are 
derived from one part of the coast, that they have thin shells, and that they are chiefly seen in early 
May, were all erroneous. He also remarked that they were highly prized by epicures. 



138 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

I have never seen a blue lobster of perfectly uniform tint or without markings 
on the shell; yet lobsters which very nearly answer this description are occasionally 
taken, according to abundant testimony. Passing from this condition, there is a graded 
series of colors, from the decidedly blue to the distinctly blackish or bluish greeu. 

There is a well-preserved skeleton of a blue lobster in the museum of the 
Peabody Academy of Science at Salem, Massachusetts. ' This specimen is a male, 
111 inches long, and has a hard shell. The carapace is deep indigo above, but lighter 
on the sides with rather faint spots of light blue. The ''tail" is of a purplish cast, 
with fine spots or marbling of dark blue. The large claws are purplish above, with 
abundant darker blotches, while they are cream-colored below, with some fine blue 
spots. The other legs are cream-colored, washed or speckled with blue. 

Mr. J. W. Savage received at Boston, in June, 1893, about a hundred exceptionally 
blue lobsters from Nova Scotia. They had "hard shells," and would average If pounds 
each in weight. As he expressed it, "they were as blue as bluejays." In April of 
the same year Mr. A. P. Greenleaf, of Boothbay, Maine, received also from Nova 
Scotia, as he informed me, two thousand or more very blue lobsters. He says that 
the usual spots and other markings of the shell were not conspicuous, and that the 
colors were so bright that he was almost afraid to ship them to market. A female 
egg-bearing lobster from Nova Scotia, which I examined in September, was of a dull 
leaden blue color over the whole upper part of the body. The lateral edges of the 
carapace were sky blue, the claws very dark, almost black, above, and dull red below. 
I have already referred to the bluing of lobsters (p. 135), which is due to either a 
physical or chemical change in the shell pigments and has no adaptational significance. 

Blue crayfishes described by Lereboullet (119) were "of an azure or cobalt color 
more or less intense; the claws deeply colored; the legs paler, and the lower parts of 
the body of a pale red." He thought that the shell contained three kinds of pigment — 
red, blue, and green, and that in the red and blue varieties one of these pigments was 
excessively developed. 

RED LOBSTERS. 

Occasionally red living lobsters are seen, which are very rarely as bright in 
color as those which have been boiled. Mr. F. W. Collins, of Rockland, Maine, had 
a lobster of this variety in September, 1890. It was taken in Dyers Bay, near Jones- 
port, Maine. It had a hard shell, and when in the floating car with other lobsters 
was very conspicuous for its bright color. 

Mr. S. M. Johnson informs me that lobsters of this interesting color variety are 
met with "more or less frequently." Speaking of one which was obtained in 1892, he 
says that "although taken by itself the color was somewhat paler than the ordinary 
boiled lobster, yet if put with others that had been boiled it would have been hard to 
distinguish the difference." 

Through the kindness of Messrs. Johnson and Young I received on April 9, 1894, 
a remarkably perfect specimen of a red lobster, of which I have made a drawing 
colored as accurately as possible from life (plate 16, fig. 21). It was alive and active 
when it reached Cleveland, had a fairly hard shell, was without external eggs, and 
measured llg inches. Except in color, it was perfectly normal. It was caught in the 
vicinity of Mount Desert, Maine. The ovaries, which were immature, were of a light 



1 I had the privilege of examining this and other specimens in the museum through the courtesy 
of Mr. John Robinson, treasurer of the Peabody Academy of Science. 



THE AMERICAN LOBSTER. 139 

green color. Messrs. Johnson and Young consider this variety very rare, since they 
have seen but one other in which the red color was so bright and uniform in life. 

The color of this animal, as shown on plate 10, was very brilliant. There was not 
the slightest trace of any blue or green pigment about any part of it, except at some 
of the articulations, nor of any other color except a light-reddish russet or orange. 
The eyes, however, possessed the usual black pigment, and on this account were 
exceptionally prominent. The fiagella of the antennae, the tips of the walking legs, and 
posterior margins of the tail-fan were brilliant red. The color on the upper surface of 
the large claws was rather brighter red than on the lower. A good idea of the natural 
color of this lobster may be had by imagining the color of the whole animal to be of 
the orange-red tint which is normally seen on the under side of the large claws. 

The spines were not brighter red than the other parts, but were worn white at 
the tips, as is usually the case. The setae over the various parts were of the usual 
reddish-brown color. The color of the carapace may be described as light orange-red, 
covered with a reticulate or very delicately lined pattern of darker red, and mottled 
with white. The light spot which is seen midway between the roots of the second 
pair of antenna? and the cervical groove was very large, as were also the whitish 
tendon-marks of the cervical groove itself. 

The sternal calcified portions of the animal were snow-white, washed faintly with 
orange-red. The seminal receptacle, which is usually bright blue, was pure white; the 
swimnierets very translucent and faintly tinged with red; under side of tail-fan a 
uniform pale reddish orange. 

This seems to be a remarkable case of a discontinuous color variation, which is 
the result of a chemical change similar, in all probability, to that which occurs after 
death, as when the animal is boiled. 

Lereboullet (119) says that a red variety of the crayfish was found in certain 
streams in the Rhine valley. It was usually small, though sometimes of the average 
size. "They are all of a uniform brick-red color, without spots, and resemble cooked 
crayfishes perfectly; the legs and lower parts of the body are always very pale." 

CREAM-COLORED LOBSTERS. 

A light cream-colored lobster, without any darker spots visible upon it, was cap- 
tured at North Waldoboro, Maine, about 1882. It was between 10 and 11 inches loug. 
I saw this specimen, but not until it had been preserved in alcohol. 

Mr. J. W. Fisher, of Eastport, Maine, informed me that in the winter of 1893 a 
lobster was caught at Deer Island, Maine, which was 11 inches long and of a light 
cream-color. It appeared very white in the water. There were no visible spots or 
markings upon it. A lobster of similar appearance was taken in Boston Harbor by 
Mr. J. W. Savage, in August, 1892. The under side of the claws was light red, which 
was not intensified upon boiling. 

Perfect albino lobsters, without trace of natural pigment in the eyes, or parts of 
the exoskeletou, have never been captured. " Albinism," or the various stages of an 
approach toward this condition met with among Crustacea, are, according to Malard 
[133), in all probability but particular cases of adaptive coloration. It seems to me 
far more likely that such cases are primarily non-adaptive. In the lobster there has 
been a degeneration, and iu some cases a final loss of pigment. This may be the last 
of a series of changes which we see begun in the live red lobster. The latter is no 
more or less protectively colored than the former. 



140 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

A specimen of a gray lobster (Astacus gammarus) was described at a meeting of 
the Society Pkilomathique of Paris, on December 12, 1891, by M. Martin. It was 
captured at St. Vaast-la-Hougue. in a trap with several perfectly normal lobsters. 
The dorsal part of the carapace of the abnormal specimen was of a dark yellowish- 
green color, with greenish-black spots. The green color disappeared rapidly on either 
side of the dorsal median line, the yellow remaining, and passing into almost pure white 
on the sides. There was not the least trace of marbling and none of the pronounced 
blue color of the average lobster. The pleon was yellowish-green above, and yellow 
on the sides. Large irregular spots of a deep bluish-black color ornamented each 
segment, even in the dorsal parts, but without forming the usual marbled pattern. 

Martin rejects the hypothesis that this deficiency of color may be due to the 
absence of light, supposing the lobster to have lived in a dark crevice in very deep 
water, and regards this variation as adaptive, a conclusion which seems to me 
gratuitous. He says, in a note, that M. Bietrix, of Concarneau, had a white lobster, 
kept in a pond, which recovered its blue color at the next molt. A young male of 
Al/pheus saulcyi, which I once kept for several days in an aquarium, molted and lost 
completely the bright vermilion color of its claws. (94, p. 381.) 

Casual or temporary decoloration occurs in many species of Crustacea, as in Can- 
cer pagarus, of which Malard (133) says that he has met with many cases of young 
individuals living under stones in old oyster parks in the island of Tatihou, while the 
permanent absence of pigment is characteristic of certain well-known burrowing 
Crustacea which live in the sand, such as Hippa, Callianassa, and Gebia. It is doubtful 
if the entire absence of pigment in such a form as Callianassa can be regarded as 
adaptive; first, because the animal burrows, and is for the most part concealed; and 
secondly, because its whiteness makes it a more conspicuous object on the sand than 
it might otherwise be. This condition may, however, be the last term in a series of 
changes, some of which were distinctly adaptive. 

VARIATIONS IN COLOR PATTERNS. 
SPOTTED LOBSTERS. 

The spotted lobsters — "cabco," or "leopard lobsters," as they are variously called 
by fishermen — exhibit an interesting and striking coloration, which is somewhat rare. 
They appear to be occasionally captured, however, all along the coast. An experienced 
fisherman at Rockland, Maine, said that he usually took one or two of this variety in 
the course of the season. 

There is a well-preserved spotted lobster in the museum of the Peabody Academy 
of Science, a female with hard shell, 11£ inches long. The whole upper part of the 
body is of a light-yellow color, with purplish blue pigments (in the dried shell) so 
arranged as to give a spotted or marbled appearance. The light- yellow spots on the 
carapace vary much in size and shape, the largest being half an inch in diameter and 
of a slightly irregular, rounded contour. The spots are confluent at the hinder end of 
the carapace, where they form a marked yellowish area. On the sides of the carapace 
the spots are small and tend to flow together. The "tail" is marbled above with 
irregular yellow spots, in excess of the darker color. The tail-fan is yellow, beauti- 
fully mottled with reddish-purple. The appendages are spotted in the same way, light 
yellow predominating. The large claws are dark purplish-red above, with obscure 
spots; but on the under side, they are of the usual bright reddish-orange color, 
spattered with purple. 



THE AMERICAN LOBSTER. 141 

l'AK.TI-OOLORED VARIETIES. 

Once in awhile a lobster is caught which exhibits a remarkably abnormal colora- 
tion. A lobster which would weigh about 2 pounds was captured near Long Island, 
Portland Harbor, about the year 1SSG. One half of the body was light yellow, clearly 
defined up to the middle line of the back from the color of the other half, which was 
bright red. There were no spots on the shell. This specimen was exhibited in Boston, 
and afterwards sent to Professor Baird. 

De Kay mentions a similar case (51). He says: 

In .June, 1840, I saw in the Fulton Market a lobster which was of two colors, distinctly separated 
by a medial line from the tip of the rostrum to the middle extremity of the plate of the tail. One side 
of the body and all the members were of a light sky-blue, and the other of the usual olivaceous green. 

Mr. S. M. Johnsou informs me that it is not uncommon to get a lobster in which a 
part of the body is pale red while the rest is normal in color, and that a few years ago 
he had a specimen in which this difference in color was marked by the line running 
through the middle of the back, and that even one-half of each u feeler" was light 
and the other dark. 

Buckland (28) mentions the case of a half "albino" lobster, which he received in 
May, 1868. He says : 

One side of the barrel was blue and the other was white. The bine turned red on boiline, but 
the white did not There appeared to be no pigment in the white part of the shell. 

Boeck (20, p. 225) says that in 1868 he found a lobster near Haugesund, one half 
of which was of a greenish-black and the other of a light-orange color, there being a 
sharp and clearly defined line, which ran lengthwise and divided the shell into two 
parts of equal area. This closely resembles the odd variations which we have just 
noticed in the American species. 

Lovett (128) has described a number of color variations in lobsters from the 

island of Jersey. One which is particularly mentioned — a female with eggs was of 

a pale lavender color, with a mauve spot on the carapace and with bright blue claws. 
The usual mottled markings on the sides of the thorax were rather indistinct. He 
speaks also of having observed a full-grown female with eggs of a pale-reddish color, 
with bright antenna?. 

Carrington and Lovett have described the great chromatic adaptability of the 
common green crab, Carcinus mmias (35). 

Boeck says that the European lobster, taken near the mouths of fiords in Norway, 
is lighter in color than is usual, while farther out to sea it becomes much darker. 

Malard thinks that these peculiar color variations are due to the loss of certain 
pigments, in consequence of insufficient light, in the deep grottos or rocky crevices 
where the lobsters may have lived. 

Protective coloration and chromatic adaptability to the immediate environment 
are common to a large number of the Crustacea. It seems to be least observed in 
the highest representatives, the Brachyura. According to Malard this chromatic 
adaptation is effected either (1) chemically, by the modification of pigment under the 
direct action of light, or (2) physiologically, by the action of pigment cells stimulated 
by light, indirectly through the eyes and central nervous system. 

Pouchet has made some interesting observations (see 133) on the variations of color 
in the common shrimp, Palaeinon. It was found to be most variable when 3 to 4 cm, in 



142 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

length. When captured by the fishermen they are usually of a rose or delicate lilac 
color, but lose these tints or become of a light-yellowish hue when kept in vases with 
white bottoms. In black vases they turn to a deep brown. These effects are produced 
by the reaction of two kinds of pigments, the cyanic pigments which are generally in 
a state of solution, and the pigments of the xanthic series (red, orange, and yellow), 
by the action of the chromatoblasts. Malard states that Jourdain has shown that if 
the eyes are removed and the animal is kept in darkness, a red color is always obtained. 

Certainly, one of the most striking cases of protective coloring met with in the 
Crustacea is that of the inhabitants of the floating islands of sargassum which are 
encountered in the Gulf Stream or along its borders. This alga is of a dirty yellowish- 
brown color, often flecked with white, when its floats are incrusted with the bleached 
skeletons of bryozoa. This appearance is emphasized by the numbers of goose bar- 
nacles which are attached to the fronds. A small crab which is an important colonist 
of these islands is brown, with a large snow-white spot on its back; and the shrimp, 
of which there are several species, are colored in a similar manner, the body being 
dappled with brown and white. 

We must place m another category the gaily dressed shore crab of the West Indies, 
Gegarcinus ruricola, whose brilliant hues and bizarre coloration are clearly without 
protective significance. This beautiful crab burrows in the mangrove swamps at about 
the level of high water, and is very common throughout the Bahama Islands. After 
a drenching rain the green boughs of the mangrove suddenly blossom out with crabs. 
Some of them have crimson legs, a dark purple body, with a large yellow spot on each 
side of the carapace, while iu others these colors are reversed. Others again are 
nearly black, or the carapace is orange or straw color, flecked or marbled with purple, 
in an endless series of patterns, so that no two are alike. It is possible that this is 
an example of warning coloration, such as is seen in mauy gaudy insects, serving to 
protect them from the assaults of birds and other enemies, or it may be a case of 
substantive variation, without any vital significance. 

The colors of deep-sea animals which live in total obscurity can not be of any 
utility to the animal as a source of protection. The colors may be very brilliant — red, 
scarlet, orange, rose color, purple, violet, and blue being frequently reported — but 
they appear to be developed quite independently of the light. It has been shown by 
experiment with sensitive photographic plates that luminous rays do not penetrate 
ordinary sea water to a greater depth than 400 meters. In depths of 50 fathoms 
or more there might be an appreciable amount of light on clear days, but even then, 
when the water was loaded with sediment and the bottom composed of dark materials, 
it seems hardly probable that colors would have any protective value whatever. 

The normal colors of the lobster, which are spread like a mantle over its whole 
upper surface, tend undoubtedly to screen its movements while crawling over a weedy 
or rocky bottom. The absence of all color or a more generous display of bright 
pigment would make it a more conspicuous object, especially upon sandy bottoms in 
shallow water, which it is usually careful to avoid in the daytime. The vivid red of 
the claws appears to be overlaid by a darker pigment in spots, particularly on the 
upper surface. The under side of the pleon, which rests upon the bottom when the 
tail is not folded, is very meagerly supplied with pigment, as is usually the case with 
marine animals which inhabit the bottom. 



Chapter IX.— VARIATIONS IN STRUCTURE. 



Deformities in the .adult stages of the higher Crustacea center chiefly in the large 
claws, which are more subject to mutilation than any other parts, owing to their 
constant use as weapons. We will therefore consider first the variations in these 
appendages. 

NORMAL VARIATIONS IN THE LARGE CLAWS. 

Aristotle (4) says of the claws of the lobster: ''In the Astaci alone it is a matter 
of chance which claw is the larger, and this is in either sex." The difference between 
the right and left claws is greatest in the small fiddler-crabs where, as in Gelasimus, 
the large claw, according to Bate, can not reach the mouth, a power which it must 
have originally possessed. 

It seems, as Aristotle remarked, a matter of chance whether the crushing-claw is 
on the right or left side of the body; but this is not really the case. I have shown 
that in Alpheus saulcyi, where the large crushing-chela can be recognized even before 
the animal is hatched, the members of a brood are either right handed or left-handed, 
that is, have the crushing-claw on the same side of the body. This seems to be a case 
of direct inheritance from the parents, though not enough data were collected to settle 
this point. (For a statement of the facts, so far as they are known, see 94, p. 376.) 

The large claw occurs about as frequently upon the right side of the body as upon 
the left, without distinction of sex, as shown by the followiug table, embracing 2,433 
individuals : 



Sex. 


Crushing 

claw on 

right side. 


Crushing 
claw on 
left side. 


Both claws 
similar. 


562 
602 


628 
638 


1 

2 




Total 


1,164 


1,266 


3 





ABNORMAL VARIATIONS IN THE CLAWS. 
SIMILAR CLAWS DEVELOPED ON BOTH SIDES OF THE BODY. 

A variation sometimes occurs in which the normal differentiation of the great 
claws is wanting. Both claws are similar, developed either for cutting or crushing. 1 
In examining over 2,400 lobsters, only 3 were found in which this abnormal variation 
was present. It is, therefore, undoubtedly rare, and apparently has never been 
previously described. Before examining these cases in detail it will be best to notice 
the normal characteristics of the claws. This description is taken from a female — 
length, 11 inches; weight, 24 ounces — with hard shell (compare fig. 20a, plate 15): 

Cmshing-claw : On right side; seven marginal spines on propodus, third spine 
(from peripheral end) depressed; a small spine opposite the latter on upper side of 
propodus. There is a small tubercle on the upper side of propodus, near articulation of 
dactyl; in a corresponding situation below there are two tubercles, one considerably 

1 I have heard of a single case reported by a fisherman, where similar crushing-claws were 
developed on both sides of the body. 

143 



144 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

smaller than the other ; a small tubercle on upper side of propodus, on outer margin, 
near carpus. There is considerable variation in the number and prominence of these 
processes, particularly the marginal ones. 

Cutting -claw; Six marginal spines on propodus, second and fifth depressed; other 
processes present, as in corresponding claw. 

Abnormal Variation. — (1) Female; length, 10J inches; hard shell; cutting- 
claws on both sides similar; Woods Hole, Massachusetts, March, 1894. 

Bight cutting-claw: Small tubercles of propodus, near uactyl, wanting. 

Left cutting-claw: Transverse scar-hke groove on propodus, at level of articulation 
•of dactyl ; one small tubercle on upper surface of propodus, near dactyl ; two very minute 
ones below; five marginal spines, third bent inward, rest turned forward and upward. 

(2) Female; length, 10£ inches; hard shell. 

Right cutting-claw: Five marginal inner spines on propodus, third depressed; no 
small tubercles near joint of dactyl present. 

Left cutting claw: A little smaller than right; 5 marginal spines, none depressed; 
one small tubercle on lower side of propodus near dactyl. 

(3) Male; length, 10 inches; hard shell; both claws relatively small, having been 
regenerated; length of propodus, 3jf inches. (Plate 14, fig. 19, from photograph.) 

Right cutting-claw: Seven marginal spines, second and fourth depressed; one 
small tubercle on under side of propodus, near dactyl. 

Lieft, cutting-claw: Five marginal spines, second depressed ; one very small tubercle 
on upper side of propodus near dactyl; two very minute ones below. 

There seems to be about as much variation as regards the details here mentioned 
in normal symmetrical claws as in the abnormal symmetrical ones, and it is probable 
that in either case the conditions met with are to some extent congenital. 

DIVISION AND REPETITION OF APPENDAGES. 

The curious monstrosities which occur in the appendages, particularly in the large 
claws of the lobster, have attracted the attention of naturalists for a long time. They 
were noticed by Von Berniz (17) over two hundred years ago, and some good figures of 
the deformed claws of the crayfish were published by Eosel in 1755 (168). A careful 
review of crustacean deformities, concerning the lobster in particular, was given by 
Faxon in 1881. His paper was accompanied by valuable figures and a bibliography 
(66). The general subject of variation as it affects the appendages of arthropods has 
been recently treated in a masterly manner by Bateson in his invaluable work on 
variation. 1 The variations which concern the Crustacea, particularly the decapods, are 
fully described and illustrated, with references to the abundant literature. Bateson 
shows that in most of the cases of supposed duplication of limbs in both insects and 
Crustacea the extra parts are double instead of single, as where two dactyls are 
formed at the extremity of the claw instead of a complete claw consisting of dactyl 
and propodus. He has also formulated certain principles according to which super- 
numerary appendages make their appearance in secondary symmetry. If the normal 
appendage which bears the extra ones is a right leg, "the ne rer of the extra legs is 
a left and the remoter a right." 



1 Materials for the study of variation treated with especial regard to discontinuity in the origin 
of species, by William Bateson, 1894. 



THE AMERICAN LOBSTER. 14. r ) 

The monstrosities noticed in the chelipeds of the lobster are mainly the result of 
a secondary outgrowth from one of the two terminal joints. Rarely the appendage is 
duplicated or triplicated ; a case of the crayfish is reported with three extra claws 
(see Bateson, p. 537). In some cases the extra appendages are perfectly formed, while 
in others deformation has been carried to excess, resulting in irregular branching 
processes or grotesque contortions. Injuries to the claws are excessively common, 
while duplication of parts is rare. Defective or deformed claws, the result of injuries 
(see figs. 194, 198) in different stages of repair, are met with every day by dealers, 
while thousands of lobsters may be examined without meeting a single case of repeti- 
tion or duplication of parts. 1 

If the tips of the claws are snipped off near the articulation of the dactyl, the 
lost parts are restored (see p. 105) as we have seen at the next molt. This restora- 
tion is often perfect, but not always so. The condition seen in fig. 198 might have 
been caused by a pinch and arrest of growth while the claw was soft (before the last 
molt), or by the unequal growth from a stump, the end of the propodus haviug been 
cut off by an enemy just before the shell was cast. In the latter case the member 
could be only partially restored, and unequal growth would account for the distortion. 

The dactyl shown in fig. 104 has probably had a similar history. All such cases 
are the results of regeneration after injury. This can not be said of such a specimen 
as that represented by fig. 189, where the dactyl bears upon its inner margin near the 
tip a small conical prominence. This is smooth and is separated from the tip of the 
dactyl by a shallow groove, as if there had been a normal bifurcation or division at 
this point. What the primary cause of such a growth or swelling may be is not known, 
but it is impossible to suppose it to be the result of injury. 

With the appearance of such a simple outgrowth a progressive series of changes 
seems to take place with every molt, such as is illustrated by figs. 189-193, plate 47. 
With the growth of the animal, the superadded part, whether it be upon dactyl or 
propodus, seems to be shifted at each molt farther aud farther back upon the claw, and 
meantime, in most cases, to uudergo fission in a vertical (figs. 190,191) or somewhat 
oblique plane (figs. 187, 188). This fission apparently proceeds until one or both of the 
supernumerary dactyls are entirely separated (tigs. 192, 193). The opposing edges of 
these become gradually toothed, so that each is almost an exact copy of the original 
(see especially fig. 193, plate 47). According to the principles laid down by Bateson, the 
part which is nearer the original joint corresponds with the appendages on the oppo- 
site side — that which is farthest away with those on the same side of the body. This 
is not strictly true in such a case as that shown in fig. 19G, where the supernumerary 
parts do not face each other, aud in some cases the repeated part is single, not double. 
In fig. 190 a short row of teeth marks the median plane of division and the opposing 
surfaces of the incipient fingers are also toothed. In tig. 191 the outgrowth is divided 
nearly to its base into two secondary processes, each of which resembles the joint of 

'In 2,657 lobsters captured at Woods Hole, Massachusetts, from December to June, 1893-94, but 
one case of repetition or formation of extra parts in the large claw occurred. No account was kept of 
injuries, but in the months of December and January 7 per cent of all lobsters caught (54 in a total 
of 725) had thrown off one or both claws. (See p. 103.) 

A man who had been engaged in the business of canning lobsters for a score of years in Maine 
told me. that he had at one time nearly a bushel of deformed claws, which lie had collected in the 
course of his experience. 

F. C, is. 1895—10 



146 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

which it is a part. According to my interpretation, such a case as that shown in tig. 
193 has gone through phases similar to those shown in tigs. 189-191 . 

In figs. 192 and 197 the conditions are somewhat different, since the superadded 
dactyl is single. I think there can be no doubt that a progressive division of the 
propodus takes place in such cases; In fig. 192 the plane of fission in the propodus is 
marked by spines very much as in fig. 190. There may be a line of median, unpaired 
spines at the bottom of the groove, and bilaterally symmetrical spines upon its sides. 
It seems probable that the conditions like those seen in fig. 197 could be derived from 
such as are met in fig. 192 by the intervention of a single molt. 

Faxon describes a very interesting case {66, plate 2, fig. 6) in which there appears 
to be a duplication of the right cheliped down to the meros. The latter is partially 
divided by a deep groove running across its distal end. It seems to me very 
probable that we have here an illustration of the same process which is seen in 
figs. 192, 197, only carried a step or two farther. In the former case the fourth joint 
of the limb is undergoing a process of fission begun nearer the outer extremity, while 
in the latter the sixth segment is involved. The supernumerary carpus in the case 
figured by Faxon bears a stump-like segment, which looks like an abortive propodus, 
corresponding probably to the abortive segment borne on the extremity of the super- 
numerary branch of the propodus in fig. 197. In the latter case it is an undoubted 
dactyl, and is smaller and more rudimentary than in fig. 192, where the fission of the 
propodus has not gone so far. It is thus probable that with the extension of this 
process, emphasized at each molt, the terminal segments may in some cases, as in 
those before us, atrophy and disappear, until we have, as in the example cited by 
Faxon, only an abortive propodus left. Bateson regards this superadded member 
as double, formed of two compounded parts. This may be so, but the same kind of 
reasoning wovdd lead us to regard such an incipient member as that seen in fig. 197 
as double, consisting potentially of two dactyls and two propodi. The only apparent 
reason for doing so lies in the supposition that such a superadded part arose as a 
tubercle or budding growth on some part of the claw, probably in this case on the 
dactyl, and was potentially a double member from the start, or at least capable of 
doubling by a process of fission, as we see actually going on in fig. 190. Whatever 
changes may have taken place precedent to the condition seen in fig. 197, there is no 
evidence of fission in the extra dactyl unless the two spines {8, 8 ] ) be taken as such. 

There seems to be a considerable gap between the condition seen in fig. 193, where 
three dactyls are present, one of which is free, and that shown in fig. 192, where there 
is a single process. The latter is bent downward and toward the primary dactyl. Its 
inner border has a spine (8) like that borne on the normal dactyl, showing this part 
to belong to the left side. It bears also another spine near its articulation with the 
propodus (S 1 ), which might indicate that this toothless appendage was really a 
double member. (See fig. 197, 8, 8 l .) 

Another good example of repetition of the propodus, with division of the bud, is 
shown in figs. 187, 188, plate 46, which are from photographs. In this case the 
bud has grown out obliquely from the under side of the propodus instead of from the 
margin, as in fig. 190. The continuity of the outer margin is interrupted by a deep 
groove which divides the bud into perfectly similar parts. In this case the teeth on the 
inner margins of the supernumerary digits are not opposed. The outer or lowermost, 
which is usually symmetrical with the normal part, makes here an angle of about 42° 
with the normal digit, and the two supernumerary digits make an angle of 12° with 



Bull U. S. F. C. 1895. The American Lobstei. (To face page 147.) 



Plate E. 



S.Cr" 




Out 16.— Double right cutting-claw of female lobster, 11J inches long, 
now in the American Museum of Natural History, New York City. 
Seen from the anterior side. One-half natural size 
S. G, supernumerary claw. 




Cut 17.— Double right cutting-claw of the same lobster, seen from 

above. One-half natural size. 
S. C, supernumerary claw. 



Drawn ~by F. H. HerricV. 



THE AMERICAN LOBSTER. 147 

each other. The pollux is depressed, so that when the claw is closed it falls almost 
exactly midway between (he normal and first superadded digit. The fission is marked 
on the upper surface by a distinct groove. The total length of the propodus is about 
2i inches (62 mm.), so that the lobster was not in all probability over inches long. 
The size of this claw as compared with the basal joints of the limb suggests that it 
has been lately regenerated, and it is unfortunate that this interesting point can not 
be determined with certainty. 

In tig. 196 a similar monstrosity is seen in the dactyl of the Cutting-claw. Here 
the bifurcating brauch is near the apex. Each prong is furnished with teeth on the 
inner side. A trimerous dactyl (fig. 195), one division of which is independent, in 
the second or third pereiopod presents precisely the same relations which occur in the 
first pereiopod (fig. 193), and probably they have been produced in the same way. 

What is now most needed in clearing up questions in the interpretation of 
deformities in crustacean appendages is to watch the molting of the animals and to 
measure and record the change which occurs in the malformed individual at each stage 
of growth. The abnormal developments seen in figs. 189-193 probably represent a series 
of changes such as ordinarily occur in the same individual. What the course of events 
really is between the conditions represented by figs. 193, 192 is not so clear. 

While the true duplication, or even triplication, of limbs or parts of limbs is rare 
in Crustacea, it is occasionally met with; but it is an important fact, which Bateson 
has emphasized, that "in arthropods and vertebrates such a phenomenon as the 
representation of one of the appendages by two identical appendages standing in 
succession is unknown. No right arm is ever succeeded on the same side of the body 
by another arm properly formed as a right, and no crustacean has two right legs iu 
succession where one should be." 1 

In the American Museum of Natural History, iu New York, there is a specimen 
of a lobster iu which the right cutting-claw is perfectly duplicated from the carpus 
or fifth joint. I was recently enabled to examine this interesting specimen and to 
make some drawings of it, which are given in cuts 16, 17, plate E. 

The two cutting-claws resemble each other very closely in every detail and are 
of almost exactly the same size, but each is relatively smaller than normal. The 
measurements of each cutting-claw are as follows : 

Right cutting-claws (abnormal) : Inches. 

Length of propocti 3| 

Greatest breadth of propodi If 

Left crushing-claw (normal) : 

Length of propodus 5 

Greatest breadth of propodus 2 

In the primary cutting-claw the dactyl closes normally on the propodus; iu the 
superadded claw (8. G.) it is bent upward out of line with the cutting edge of the 
latter. The symmetry of the two claws extends, with few exceptions, to the spines 
upon their cuttiug edges and on the inner margins of the propodi. The carpus of 
the limb is apparently single, but it has duplicated spines, and a deep groove at its 
peripheral end shows that it is virtually double. The carpus and meros have been 
twisted through an angle of 90°, so that their posterior surfaces face upward. 

This specimen was obtained some years ago from a marketman in New York City. 

'Materials for the study of variation, p. 539. 



148 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Nothing is definitely known about the causes of repetition. It looks at first sight 
as if the deformities in the appendages of the lobster and other arthropods could be 
explained as phenomena of regeneration, though in this case there is addition rather 
than replacement. 

We have seen that where the cheliped is thrown oft' by reflex muscular contrac- 
tion the bud of anew leg forthwith appears, and under favorable conditions grows into 
a perfect limb. The tissues of this limb are developed out of the formed histological 
elements of the stump. The process of regeneration is begun in this case as a direct 
result of a loss or injury. The plane of fracture lies between the second and third 
joints, and all parts peripheral to the second joint are reproduced. Repetition of parts, 
however, occurs in many insects and vertebrates where no such regeneration of lost 
appendages is known. However, the power of regeneration, which is present in all 
organisms, differs rather in degree than in kind, and Weismanu has shown that it has 
probably been developed in many cases as a means of defense and protection to the 
individual. (See p. 107.) 

In the .specimen of Palinurus (No. 808, Bateson, originally described by Leger 
in 1886), where the left penultimate leg bears two supernumerary legs, both of which 
spring from the basipodite, it certainly looks as if what would have taken place in 
the case of loss of the original limb — namely, the growth of a new one from this joint 
— had happened repeatedly, so that instead of the regeneration of one limb at a 
time there is the superaddition of two; but where the limb is not cast off the first 
superadded one is in secondary symmetry and belongs to the opposite side. If such 
an interpretation will apply to this case, the various other repetitions and abnormal 
growths which arise in more peripheral joints, as upon the sixth and seventh, fall into 
the same general category. In the case of the growth of a new limb in consequence 
of loss, however, all parts which are external to the plane of fracture are reproduced. 
In the cases of repetition this is not usually the case, as Bateson has shown. The 
bud which arises on the propodus (as in figs. 187, 190) may by fission give rise to a 
second propodus, but not usually, if ever, to a dactyl. 

It seems as impossible to suppose that such a deformity as that seen in fig. 187 or 
fig. 189 is congenital as that it is the result of injury. The monstrosities which occur 
in the embryo, which are considered in another place, are, however, in some cases at 
least, the result of injury or unfavorable conditions. 

Autotomy, or the casting of the claw at the second joint, is probably directly 
accountable for the rarity of abnormal growths in the limbs of the higher Crustacea. 
It is extremely improbable that any deformity at the extremity of a limb could sur- 
vive autotomy, but the experiments to settle this interesting point have yet to be 
made. While it would appear that the various deformities which have been described 
can not be explained as the results of injuries and the attempted regeneration of 
injured parts, since the limb is usually thrown off in such cases to be completely 
renewed or it is retained to be completely restored, yet I can not escape the convic- 
tion that the problem is in some way directly concerned with that of regeneration. 
The mechanism by which so complete a structure as a limb is regenerated can not be 
regarded as simple. As Weismanu says, the machinery of a cotton factory can not be 
made out of a few simple levers. It is probably exceedingly complex, and it is no 
wonder that the parts do not always work harmoniously, that the thread is sometimes 
knotted or the product useless. 






THE AMERICAN LOBSTER. 14!) 

VARIATIONS IN OTHER ORGANS. 
ROSTRUM. 

I have met with a single ease of bifurcated rostrum, a small male, represented 
iu figs. 102, 163. The median groove, which corresponds to an area of absorption in 
the shell (see p. 88), divides near the apex, each branch going to a terminal spine. 
Instead of a single spine below the terminal, there are several smaller ones. 

In AVpheus saulcyi the median rostral spine is sometimes wanting, as in the genus 
Betaeus, of Dana. (See 94, p. 384, plate xxh, fig. 11.) 

OVARY. 

Two instances were observed in which the ovarian lobe on one side has suffered 
division, one that of a small female (44 mm. long, fig. 131, plate 38) in which one 
of the posterior lobes is involved, the other an adult lobster (fig. 164, plate 42) with 
similar division of the left anterior lobe. 

HERMAPHRODITISM. 

A malformed hermaphrodite lobster, Homarus gammarus, was described and fig- 
ured by Nicholls in the Philosophical Transactions of the Loyal Society of London 
in 1730 {141). " The specimen," he says, " if split from head to tail, is female on the 
right side and male on the left side." This was true of both the internal and external 
organs. A similar case of hermaphroditism has been described by Gissler (78) in the 
Phyllopod Etibranchipns vernalis. 

La Valette St. George (193) discusses a very interesting case of hermaphroditism 
which he discovered in the crayfish. He found eggs present in the nearly ripe testis 
of Astacus fluviatilis in July and August. The eggs were placed usually at the 
periphery of the testis lobe. They were round or oval, 0.00 mm. to 0.015 mm. in diam- 
eter, and showed the usual constituents of ovarian eggs. They had a larger germinal 
vesicle than the normal egg, were sometimes inclosed in a follicle, and contained yolk 
spheres. He asks how the presence of the eggs in the normal testicle is to be explained 
and gives the following answer: 

These eggs are evidently derived from spermatogonia, which have become unfaithful to their 
original functions. Instead of multiplying by division to form a number of spermatocytes, they have 
chosen a shorter way, which makes it possible for a single egg to arise from them by simple growth. 

Under certain conditions a primitive sperm cell may be converted into an egg 
cell, and this, he says, furnishes a new proof of the relation of spermatogonia and 
oogouia. Follicle cells may arise from a spermatogonium, but the latter can never 
arise from follicle cells. 

The spermatogonia, according to La Valette St. George, produce, chiefly by mitosis, 
the spermatocytes, which eventually give rise to the spermatids. Spermatosomes, as 
well as large follicular nuclei, may be found in the process of degeneration iu the testis. 

Hermaphroditism has also been described in the lobster by Hermann (89), who, 
according to La Valette St. George, was the first to prove the presence of hermaphro- 
ditism in the testes of decapods. Hermann discovered in the anterior parts of the 
testis of the lobster large round or oval cells with granular protoplasm, each pos- 
sessing a large germinal vesicle with nucleoli. Eight or ten such cells, which were 
regarded as undoubted eggs, were found in one specimen. In some of the figures 
given by La Valette St. George the ovum fills nearly the entire lumen of the testis. 



Chapter X.— STRUCTURE AND DEVELOPMENT OF THE REPRODUCTIVE 

ORGANS. 

THE FEMALE REPRODUCTIVE ORGANS. 
THE OVARY. 

In order to understand the structure of the ovary and the changes it undergoes it 
is necessary to examine this organ at different stages of development and in the various 
phases of the sexual life of the animal. The external eggs borne on the swimmerets 
of the female serve as a gauge to determine the age of the developing ovarian ova. 

I have already given an account of this organ in my paper on Alpheus (94, see 
also 90 and 93) and have illustrated the growth of the eggs. Bumpus (30) has also 
devoted considerable attention to this subject and has figured certain structural phases 
of the ovary, but the early development of this organ has not been touched upon and 
there are important anatomical facts which have not yet been noticed or illustrated. 
I shall therefore deal with this subject in detail, though in doing so it will be necessary 
to repeat some facts which are already known. 

The time of the year when the ovary becomes mature and the size which the 
spawning female attains are discussed in other parts of this work. 

THE RIPE OVARY. 

The ripe ovary, which I will first describe (plate 36, fig. 123), occupies, as we have 
seen, the dorsal part of the body cavity. The anterior lobes encircle the stomach, while 
the hinder ones extend sometimes as far backward as the fifth abdominal somite. 
The ovarian wall, though often quite thick, is very transparent, and the ripe eggs 
give it a dark green, beaded appearance. The walls, if mutilated, immediately collapse 
and the perfectly ripe eggs flow out in a stream. 

The structure of a nearly mature ovary is seen in fig. 141, plate 39. Most conspic- 
uous are the massive ova filling the lumen of the thick, tubular wall. Immediately 
next to the latter are seen very characteristic structures which I shall call ovarian 
glands (0. G.). Immature ova of varying size are interspersed among the glands and 
dip down between the ripe peripheral eggs. These structures, together with irregular 
blood sinuses (Bl. 8.) and strands or nodules of muscle and connective tissue, make 
up the substance of this organ. 

The glands are folds of follicular epithelium similar in origin to that which encap- 
sules the larger ova. The long axis of the fold is parallel with the ovarian wall. The 
glandular fold consists of a structureless basement membrane and of columnar 
epithelial cells (fig. 152, plate 41). The nuclei generally lie at the deeper ends of the 
cells, the protoplasm of which is decidedly granular, and cell walls are very indis- 
tinct after the ordinary methods of treatment. Occasionally a glandular fold is seeu 
(plate 41, fig. 153) which has a very different character from the structure just 
described. It is expanded into an oval or oblong form, and its epithelial wall appears 
in a much disordered state. It is highly vesicular, containing numerous vacuoles, 
which probably represent fat globules (F. G.) ; cell walls are absolutely effaced ; nuclei, 

150 



THE AMERICAN LOBSTER. 151 

no longer spheroidal, have become shrunken and scattered about the meshes of a 
protoplasmic network. There are, besides, globules (fig. 15;3, y. s.), probably of an 
albuminous nature, which resemble spherules of yolk, and lie either in the lumen 
of the fold or are embedded in the protoplasmic reticulum. They are most abundant 
in the reticulum, where they sometimes occur as large granular masses. In tig. 
145, plate 40, a single large spherule (y. s.) of this kind is seen interpolated between 
the follicular cells. A number of nuclei surround it and, however anomalous its 
position, the appearance is not artificial. In other cases, where no degenerative 
processes are at work, the lumina of these folds are filled with a fine granular residue. 
The intimate relations which these structures bear on the one hand to the vascular 
sinuses, and on the other to the growing ova, point to their probable function, that of 
the formation of yolk. If this is the case, it is evident that the ovarian glands can 
play but a minor role in this process. The massive yolk of the ripe egg is formed for 
the most part in the protoplasmic reticulum of the egg cell from materials which are 
drawn directly from the blood. A third source of the yolk is the follicular cells 
themselves, large masses of which pass into the egg at this stage, where they undergo 
complete degeneration, as I have pointed out in another paper (93, 94), and shall 
describe more fully presently. 

THE OVARY AFTER OVULATION. 

The appearance of the ovary shortly after egg-laying is represented in plate 38, 
fig. 136. It has collapsed from its distended condition, and is now of a yellowish- white 
color, flecked with green and orange spots. The green bodies are ripe ova which failed 
to be forced out at the time of the last laying. The ducts are often full of them (com- 
pare fig. 119). The orange specks are the remains of similar eggs left over from the 
previous ovulation. While the latter have thus been in the ovary for at least two 
years, they are not yet completely absorbed. The primary membrane of the egg still 
remains, inclosing a small disorganized residue (fig. 150). 

The structure of an ovary at this period is shown in fig. 139, plate 39. The external 
eggs were in an early stage of yolk segmentation, showing that not more than thirty- 
six hours had elapsed since the last egg-laying. The ovarian lobe is now a solid mass 
of tissue, the youngest ova being disposed about the axis, the older at the periphery. 
Irregular blood sinuses penetrate to every part, between folds of follicular epithelium. 
These folds take the form of irregular pouches and represent, as Bumpus has shown 
(30), invaginations of the ovarian epithelium. This is better seen in Palinurus, or in 
the ovary of the adolescent lobster. 

The ovarian glands have now attained their greatest prominence, and their relation 
to the growiug eggs is well illustrated in fig. 139, plate 39, and figs. 151, 152, plate 41. 
In fig. 151, from a horizontal section, the eggs lie in strings, or rather tiers, between 
the double walls of the epithelial folds, which dip down vertically from the surface of 
the ovary. This is from a later stage than fig. 152, which represents a section through 
the central or terminal boundary of the fold. It is from the same ovary as fig. 139, 
where the glands are in the ascendant. The glandular cells have the form of tall 
columns, the nuclei lying at their deeper ends. Cell boundaries are very vague, the 
central ends of the cells merging into what appears as a granular reticulum. The 
columnar cells, though apparently stopping short at the sides of the egg, are directly 
continuous with the less conspicuous cells of the true follicle. This glandular co?cum 
resembles, in sectiou, a narrow bag with an egg pushed into its mouth. A thin layer 



152 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

of follicular cells, however, screens this particular egg (fig. 152) from the lumen of the 
glandular fold. In some cases, however, I have seen the glandular cells in direct 
relation with the yolk, with amoeboid cells passing into the egg along the line of 
contact (plate 40. fig. 149). At this point cells are sometimes seen completely engulfed 
in the food yolk. Their nuclei swell to a somewhat larger size, and then speedily 
degenerate. Faint ghost-like outlines can be detected for some time; then the 
chromatin becomes concentrated about the walls of a gradually dwindling vesicle 
(plate 39, fig. 142, Dg.). Finally the chromatin is reduced to very small stainable 
fragments. In other cases the chromatin probably breaks up more immediately into 
a swarm of minute particles, which remain in the interstices of the yolk spheres in 
the peripheral parts of the egg. The "plasmic vesicles" or vacuoles, which Bumpus 
(30) has described, are products of the cell degeneration just considered. 

Eggs which have been well started on the road of normal growth suddenly go into 
a decline and are probably finally absorbed into the blood, somewhat as the follicle 
cells are converted into nutriment within the eggs. (See pp. 211-213.) A number of 
such degenerating ova are seen to the right of tig. 150, plate 41. They are filled with 
refractive globules, which are undoubtedly of an albuminous nature. 

After the lapse of from ten to fifteen days after ovulation (the external eggs being 
then in the egg-nauplius stage), the ovarian glands have almost wholly disappeared. 
The walls of the follicular folds, now crowded to the extreme periphery beneath the 
ovarian wall, are shrunken and crumpled. At a still later period (attached eggs with 
eye pigment, from four to five weeks old) the glands are reduced to shriveled remnants. 
Later still, no vestige of them is seen. 

STRUCTURE OF THE OVARY AT TIME OF HATCHING OF EXTERNAL EGGS. 

When the external eggs are ready to hatch, the ovarian ova have had nearly a 
year's growth. The appearance of the ovary at this time is shown in fig. 138, plate 38, 
and its structure in fig. 147, plate 40. It has a characteristic pea-green color, and the 
largest peripheral ova (fig. 133, plate 38) have a diameter which is equal to only one- 
tenth that of the mature eggs. The ovarian wall is thinner than in previous stages, 
and in the axial portions there are the usual germogenal folds. 

Fig. 137 (plate 38) represents the ovary of a lobster taken August 21. An exami 
nation of the external eggs shows that they are about six weeks old. The ovary was 
light green, sparingly flecked with yellow. The individual eggs are greenest at the 
center, which gives the organ a finely dotted appearance. There is no trace of glands. 

The ovaries of "paper-shells" taken in July, after having produced a brood and 
molted during the current season, contain ova which measure fully half the diameter 
of the mature egg. This shows that after ovulation and again after the hatching of 
the young — that is, during the first, second, and twelfth, thirteenth, and fourteenth 
mouths after egg-extrusion — the ovarian eggs experience their most rapid growth. 
(See p. 71, and in particular the description of fig. 138, p. 246.) 

At a still later period, when the ovarian eggs have been growing for the space of 
nearly two years, ' aud the ova have attained a diameter which is from 80 to 90 per cent 
that of the ripe egg, the organ has the structure seen in fig. 140, plate 39. There may 
be considerable variation, but in the specimen from which this drawing was made 
(female, taken July 30) the ovarian wall is excessively thin and the lumen is packed full 

1 This is an estimate based upon the general facts of growth and development of the ovary, and 
not upon the observation of single individuals during this lengtli of time. 



THE AMERICAN LOBSTER. 153 

of eggs of fairly uniform size. The stroma of germogenal tissue is reduced to a minimum, 
and there is no trace of the ovarian glands which subsequently appear (tig. 141). 

The anatomy of the ovary and the slow growth of the ovarian egg, which we have 
followed from the time the new eggs were laid during a period of two years, when the 
next batch are ready for extrusion, proves conclusively, as I have pointed out in 
earlier papers (93 and 97), that the breeding season of the lobster is not an annual 
one, as had been supposed. (See pp. 70-73.) 

We have seen in the foregoing account that the massive yolk of the eggs is 
produced in three ways : (1) It is manufactured in the protoplasm of the growing ovum 

fr materials absorbed from the blood — the most fruitful source; (2) it is produced 

by the activity of the ovarian glands; (3) by the direct absorption of follicular cells. 

The fact that parts of the follicular epithelium become differentiated into glands 
at a definite period, and that these later become totally obliterated is certainly remark- 
able, but I do not see how the phenomena which have been described can receive any 
other interpretation. The yolk in Peripatus novce-zealandice is described by Lilian 
Sheldon (ISO) as arising in part from follicle cells. The latter pass into the egg 
through the tubular stalk by which this is attached to the ovary, and become converted 
into yolk. Yolk is said to originate also in the protoplasm of the ovum, as is commonly 
observed in Arthropods; also from the breaking up of a part of the germinal vesicle, 
and finally it is produced by certain parts of the ovarian tube itself. The condition 
usually found in Platyhelminthes, where there is a permanent yolk-secreting gland, 
may thus be compared with that of Peripatus and the lobster, where this function is in 
some measure performed by parts of the follicular epithelium. 

THE ORIGIN OF THE OVA. 

The ova arise from nuclei of the germinal epithelium, as I have described in detail 
in a former work (94). The origin of the primary egg membraue from the follicular 
cells (tig. 148, plate 40) is well known, but it should be remembered that this chitin-like 
envelope is not completed until after the decay of the ovarian glands. Thus, in the 
eggs shown in fig. 142, plate 39, and fig. 149, plate 40, there is no membranous boundary 
between the yolk and glandular cells. 

Cases of the apparent fusion of young ova, mentioned by Bumpus (30), are occa- 
sionally met with, but it seems to me probable that no real fusion ever occurs — the 
impingement of cell upon cell often seeming, however, to support this idea. 

THE METAMORPHOSIS OF THE GERMINAL VESICLE. 

The very young ovum has a large, rapidly growing germinal vesicle or nucleus, 
as shown in fig. 154. At this stage the cell protoplasm forms a thin peripheral zone 
having a fine granular appearance in stained sections. 

The metamorphosis of the germinal vesicle from this early stage to the perfectly 
ripe condition is illustrated by figs. 155 to 161, all of which are drawn to the same 
scale. The nucleolus is formed at a very early period (fig. 154) and is soon vesiculated 
(fig. 155). Barely two or more nucleoli are present (fig. 156); there is usually but one. 

The nucleus reaches its largest size (about ^\- mm. in diameter) at the close of 
the first year after ovulation. It is now regularly oval, its long axes being parallel 
with the long diameter of the egg (fig. 158). As at an earlier stage, the nucleolus is 
vesiculated and almost always found lying close to the nuclear membrane, as if it had 
fallen of its own weight like a shot in a bag. 



154 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



The nuclear membrane is very distinct up to the time when the ovum approaches 
maturity (figs. 159 and 160), when its outlines have become hazy. In the case illus- 
trated (fig. 140) tlie long diameter of the nucleus corresponds with the short diameter 
of the egg. The nucleolus and nuclear fluid have undergone a very marked change. 
When stained in Kleinenberg's haemotoxylon, the nucleolus has a hazy, almost 
homogeneous, appearance, and stains rather feebly, while the karyoplasm is of the 
same character, but takes the stain more feebly still. 

When the eggs are ripe and lie free within the ovary ready for extrusion (fig. 141, 
plate 39), it is difficult to And the nucleus (partly, no doubt, on account of the great 
mass of yolk and the difficulty in cutting it). In one case, where I succeeded, what 
appeared to be the metamorphosed nucleus was a somewhat eccentric island of karyo- 
plasm (tig. 160; for position in ovum, see fig. 141) without membrane or trace of a 
nucleolus. This vesicle stains uniformly, and has a very fine-grained texture. It 
has started for the surface of the egg, and in the next stage examined (fig. 161) is in 
contact with it. In this particular egg, taken from the oviduct of a female shortly 
after ovulation, the cell is dividing, or giving off a polar body; the nucleus has dimin- 
ished in size, and no membrane is distinguishable. 

THE MOVEMENTS OF THE NUCLEOLUS THROUGH THE ACTION OF GRAVITY. 

I have already pointed out the eccentric position of the nucleolus, which is always 
observed whenever the immature ovary is sectioned. This was noticed by Bumpus in 
1891, but no explanation of the fact was offered. (30, p. 225.) 

D 





Cut 19. 

Cut 18.— From transverse section of a part of ovary of lobster, hardened with ventral side uppermost, to show the 
effect of gravity upon the nucleolus. From hard-shell lobster which had recently hatched a brood. July 18, 1894. 

Cut 19. — From transverse section of a part of same ovary, hardened with dorsal side uppermost, to show the effect of 
gravity upon the nucleolus. D, dorsal surface of ovary ; nc, nucleus of ovum ; nel, nucleolus of ovum ; ow, ovarian wall ; 
V, ventral surface of ovary. 

The arrow in each cut shows the direction of the force of gravity. 

It seemed very probable that this phenomenon was due to gravity acting directly 
upon the nucleolus, which was free to move in every part of the nucleus. A few simple 
experiments immediately proved that this was the case. The ovary of a lobster which 
had recently hatched a brood was selected and cut into several pieces. These were 
then hardened in different |)Ositions, in Mayer's picro-sulphuric acid, with ventral or 



THE AMERICAN LOBSTER. 155 

dorsal side uppermost or in vertical suspension. This was repeated, and it invariably 
followed that the nucleolus fell from its own weight, to the lower side of the nucleus, 
like a shot within a tennis ball. This is well illustrated in cuts 18 and 1!). The 
latter shows in section a part of the ovary hardened in its natural position, with the 
dorsal surface uppermost ; the nucleoli are here invariably ou the lower side, in contact 
with the nuclear membrane. In 18, where the part of the ovary was turned bottom 
side up, the nucleoli are eccentric, but lie against the opposite side of the nucleus. 
Suspend the ovary and kill the tissue in any position you please, the nucleoli sink like 
shot in the karyolymph and lie against the lower side of the nucleus. This is true of 
all but the smallest ova, in which the nucleolus may or may not so readily respond. 
Such eggs sometimes possess two or more nucleoli (fig. 156). 

This pheuomeuou is a direct result of the structure of the nucleus and of the 
action of gravity, or else it is an artifact, the result of post-mortem changes. The 
nucleus consists of karyolymph, in which float granules of chromatin and other 
substances of but slightly less specific gravity, and a single large nucleolus of greater 
specific gravity than the surrounding fluids. The chromatophilous substance is 
distributed iu flocculent masses (tigs. 157, 158), which are commonly suspended in the 
nuclear fluid, but tend to "sink to the bottom" together with the nucleolus. There is 
no trace whatever of a nuclear network in the meshes of which bodies are suspended. 

The nucleolus stains very intensely, but is often highly vesiculated, in some cases 
forming a hollow shell, owing probably to the extraction of soluble matter by some of 
the reagents used. When the nuclear membrane is strongly contracted over any part 
of its area (as in fig. 152) it leaves between it and the rest of the egg a regularly 
defined space, which is partially filled with a coagulable liquid. This may come partly 
or wholly from the nucleus. 

I have never seen this phenomenon in the eggs of any other animal. If anyone 
have doubts about the facts, a very simple experiment like the one herein described 
will be convincing. The explanation which I have offered may, however, be questioned. 
1 regret that the subject of post-mortem change did not come up for consideration 
when I was at the seashore. ' 

THE RIPE OVUM. 

The ripe unfertilized ovum is illustrated by figs. 119 and 141. Those which I have 
examined have been taken from the ovary or ducts a few hours or days after ovulation. 

The nucleus was in such cases found at or very near the surface of the egg. In 
fig. 161, as already mentioned, the nucleus was in karyokinesis. The plane of section 
passed through the equatorial plate, so that the poles lie, in reality, above and below 
the plane of the paper. This is apparently the division preliminary to the formation 
of the first polar body. The rest of the egg is composed of yolk disposed in spherules 
of fairly uniform size. A coagulable liquid is usually gathered at the surface, below 
the eggshell, where the yolk spheres are here apt to be smaller. There is a single 
egg membrane (about 2x0 mm - in thickness), which is unaltered in the course of the 
passage of the egg through the oviduct. 

1 In regard to this question Professor Bumpus writes me that Bellonci found something very 
similar in the brain of Sqmlla, and that this was afterwards explained by Mayer as the result of the 
action of reagents, the nucleoli migrating from the killing fluids. Here, however, the action of gravity 
certainly plays a part. 



156 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

THE DEVELOPMENT OF THE REPRODUCTIVE ORGANS. 
GENERAL DEVELOPMENT. 

In well-advanced embryos taken in January (for stage of development, compare 
cut 38) a very minute cluster of cells can be detected on either side of the middle line 
close upon the mesodermic partition which screens the heart from the intestine. 
These cells are mesoblastic in origin; they possess oval or spherical nuclei which, 
however, are not conspicuous for their size. At the time the embryo is about to hatch 
there is less doubt in the identification of the reproductive organ (fig. 116, plate 36). 
It now consists of a small oval, somewhat flattened mass of cells, lying close upon 
the mesentery, next to the intestine. It appears to arise as a proliferation of the 
mesoblast of the mesentery, but at this time is very distinct from it. 

Later, in the first and second larval stages, the reproductive organ is a more com- 
pact, almost spherical, cell mass (about 4 \- mm. in diameter). Its position, close to the 
anterior end of the heart, but in contact with the mesentery, is well shown in fig. 174, ov, 
plate 43. It is now differentiated into two kinds of cells: (1) Central cells with large 
nuclei; (2) peripheral cells with much smaller nuclei (fig. 117, plate 36). The latter 
probably give rise to the ovarian wall, the former to the ova and follicular epithelium. 
The clearer central cells contain a distinct reticulum in which masses of chromatin 
are held. The organ is delicately suspended to the side of the mesentery by connective 
tissue. I did not distinguish the outlines of cells in any part of it. 

In as late as the sixth or seventh stages the reproductive organ is still of very 
small size and not readily seen. 

THE OVARY. 

In a female 44 mm. long (No. 2, table 32) the ovary was of the size shown in fig. 
131. I did not observe the ducts, probably because of the poor condition of the 
specimen when dissected. These were undoubtedly present, since their openings are 
visible in the eighth stage (fig. 89, plate 32 — No. 3, table 34), when the animal is less 
than an inch long. This ovary was 15 mm. long, and each lobe was about one-fourth 
mm. in diameter. The anterior lobes embrace the masticatory stomach, and one of 
the posterior lobes was branched. 

If the condition of the tissue could be trusted — it was preserved in alcohol, 
considerably diluted — the organ now consisted of a distinct connective tissue wall and 
an inclosed mass of large cells, which are the ova (fig. 146, plate 40). There was no 
plaited or folded ovarian epithelium such as we see at a later stage. 

In a young female 2|f inches long the ovary had the size and appearance shown in 
fig. 132. It is about 40 mm. long and has a diameter of 0.5 mm. It is opaque white. 

In a lobster 4f\ inches in length (No. 42, table 20) the ovary has the same appear- 
ance but is somewhat larger. Its structure is now much more complex than at any of 
the stages described. It consists of a thin connective tissue envelope and a compact 
stroma. Folds of epithelium dip down from the surface and penetrate the interior of 
the organ, thus dividing up the outer portions into radial compartments, in which the 
larger eggs are seen. These contain large nuclei, with one, two, or more nucleoli. 
The axis of the ovary lies in a stroma in which all stages in the development of 
ova can be traced. Karyokinetic figures of dividing cells are not infrequently seen. 
Blood now penetrates to the ovary by sinuses which come in from the wall along 
reentrant folds of epithelium. 



THE AMERICAN LOBSTER. 157 

THE OVIDUCT. 

The oviduct is a straight tube of nearly uniform caliber (tigs. 119, 123 od), which 
opens to the exterior in a hairy papilla on the coxopodite of the third pair of pereio- 
pods. The skin is folded in the mouth of the opening so as to form a valve which 
prevents the ingress of water. The appearance of the duct when eggs are passing 
out is shown in fig. 119. The ovary had collapsed, but these eggs failed of passage. 

The structure of the duet is the same throughout. It has a thin wall of muscular 
and connective tissue, and a characteristic epithelium of tall columnar cells. The 
latter undergo so marked a change at the period of ovulation that there can be little 
doubt that they have some important function to perform. As shown by a comparison 
of figs. 167, 108, taken respectively from a lobster just before and just after ovulation, 
these cells become very greatly elongated and vesicular. One would infer that they 
secrete a liquid which is poured out with the eggs when they are laid. Whether these 
cells take any share or not in forming the cement I do not know. 

THE SEMINAL RECEPTACLE. 

The sternal pouch of the female was noticed and roughly figured by Nicholls in 
the Philosophical Transactions of the Eoyal Society for 1731, but he entertained a 
wrong notion of its function. His interesting and unique account of this organ is as 
follows (141): 

lirtween the two last legs and the two legs above them there are two processes, which, from their 
resembling the nyrnphie of women, I shall term nymphajform processes. These processes are covered 
with hair, and unite at their bases without leaving any passage. The two processes, which 

I have termed nymph;eform, in the female make a more obtuse, angle at the union of their bases, are 
less hairy, and leave a passage, through which it is probable the ova are emitted, to be affixed to the 
appendages under the tail. 

This remarkable conclusion reached in the last paragraph is unexplained even by 
the forced comparisons which were employed. 

The observation of Nicholls was forgotten, and the structure which he imper- 
fectly described was overlooked until its true function was discovered by Bum pus 
in 1891 (30). 

The seminal receptacle lies on the under side of the female near the junction of 
the thorax with the abdomen. (For its position and general appearance see plate 7, in 
which the median slit is clearly shown, and for details, fig. 130, plate 38.) Its paired 
wing-like processes, the enlarged sterna of the seventh thoracic segment, are tinged 
with bright blue and form, with a wedge-like middle piece belonging to the sternum 
of the eighth thoracic segment, a somewhat heart-shaped body. There is a median 
slit with elastic edges, and if these are depressed, as Bumpus remarks, a grayish 
substance, the spermatic fluid, sometimes oozes out. The middle sternal piece is 
prolonged inside the chamber into a stout keel-shaped body strengthened with thick 
deposits of chitin, which have a yellowish color and horny consistency. This is sup- 
ported by a pair of irregular rods belonging to the endopbragmal system, which meet 
on the middle line. If the molted shell of a lobster is examined, in place of a solid, 
horny keel, a membranous pouch is found. The solid keel-shaped mass is probably 
absorbed before a new keel is formed. In the living animal the seminal receptacle is 
a narrow, irregular cavity. 



158 BULLETIN OF THE UNITED STATES FISH COMMISSION. 
THE DEVELOPMENT OF THE SEMINAL RECEPTACLE. 

Development of the seminal receptacle is illustrated by figs. 79, 81, 89, and 98 ; 
plates 32 and 33. Fig. 98 is drawn from the molted skin of the fifth larva. The sex 
is not determinable with certainty, but it is highly probable that this is from a male; 
the sterna of the sixth to eighth thoracic segments (marked 3-5 in figure) are clearly 
defined. The sternal processes of the seventh thoracic segment are fused on the 
middle line, where they are distinctly depressed. The unpaired middle piece is 
marked as a slight transverse ridge or forwardly directed fold. It is clearly seen 
in the sternum of the adult male, where it is not so distinctly wedge-shaped or so 
intimately united with the wing like sterna of the preceding segment. Three suc- 
cessive stages in the development of the seminal receptacle are shown in figs. 89, 79, 
and 81, plate 32; they are from young lobsters measuring 21.2 mm. (eighth stage, 
No. 3, table 34), 35 mm., and 52 mm., respectively. If these are compared with the 
condition in an adult lobster (fig. 130) we observe the following external changes: 
The sterna of the seventh segment, which are united on the middle line, diverge from 
their anterior extremities, forming a wide angle. The sternum of the eighth thoracic 
segment consists of a tongue-shaped fold (fig. 81) and a pair of backwardly diverging 
rods. The former is constricted off as a single piece, though originally paired, and 
develops into the wedge-shaped process seen in the adult organ. It grows forward 
into the narrowing angle made by the wing-like process of the preceding sterna. A 
secondary cleavage or division of the united sternal pieces of the seventh thoracic 
segment is now going on, and the cleft thus formed is the permanent opening of the 
seminal chamber. The latter is formed by the approaching walls of the wing-like 
folds of the seventh thoracic sternum and tongue-like process derived from the eighth 
thoracic sternum. 

THE MALE REPRODUCTIVE ORGANS. 

TESTIS. 

Each testis of the lobster is a grayish white sacculated tube consisting of anterior 
and posterior lobes. There is no union between the organs of opposite sides. The 
testis of the lobster was figured and described by Milne Edwards, and its structure 
has been studied by Grobben (83) and Sabatier (173). According to Grobben, it is 
made up of (a) a capsular membrane, (b) tunica propria, and (c) the spermatogenous 
epithelium. Underneath the tunica propria a delicate, structureless membrane was 
seen. The epithelium is differentiated into spermatoblasts, from which spermatozoa 
are developed, and a syncytium — the ErsatzTceim — from which new spermatoblasts are 
derived. The spermatoblast is regarded as homologous with the egg cell, the Ersatz- 
keim with the follicular epithelium. A reserve albuminous material is laid down in the 
spermatoblast for use in the development of the sperm cell. 

VAS DEFERENS. 

The vas deferens or seminal duct is shown as it appears in its natural position on 
one side of fig. 120 and when dissected out on the other side. It consists of three fairly 
distinct sections: (a) A proximal segment (Zuleitungs-Abschnitt of Grobben), which 
serves to conduct the sperm from the testis ; a very slender tube of uniform caliber, which 
curls, often in an irregular manner, over the posterior lobe of the gastric gland. This 
passes very abruptly into the enlarged (b) glandular segment, where the tube bends 
backward upon itself. It then turns forward again and, in somewhat the form of the 



THE AMERICAN LOBSTER. 1 5 ( J 

letter S, passes to the buck of the hist thoracic leg. The sperm may be traced along 
the course of the tube as a central, milk-white, linear mass of closely packed sper- 
matozoa. In the glandular segment this is surrounded by a transparent, jelly-like 
substance which is secreted by the glandular epithelial cells (spermatophoral glands) 
lining this part of the duct. This is gradually constricted into the terminal (c) muscu- 
lar segment, or ductus ejaculatorius, which ends in a valvular opening. A sphincter or 
swelling of the muscular layer is seen at the beginning of the ductus ejaculatorius, 
serving to force out the sperm. 

The two distal segments (&, c) were called the penis or "verge" by Milne Edwards 
and Brocchi, because it was supposed that they were evaginated in copulation. It 
has been already pointed out that the evagination of these parts is mechanically 
impossible, a sufficient reason for dismissing this supposition. 

The structure of the different sections of the vas deferens is illustrated by plate 
37. The planes of section are marked in fig. 120, 1 to 5. As Grobben has already 
shown (S5), the vas deferens is surrounded by a distinct membrane and is composed 
of a connective tissue wall, inclosing muscles, and a lining epithelium ; the latter gives 
rise to secretions which mingle with the sperm aud surround it with protective envel- 
opes. The connective tissue is fenestrated, abounds in blood channels, and the 
muscular tissue is disposed into an inner stratum of longitudinal fibers and an outer 
layer of circular bundles. 

At the extreme proximal end of the duct (fig. 124) the epithelium is apparently 
stratified and the wall is thin. The tube is filled with a solid mass of ripe sperm (sp) 
and a surrounding coagulable fluid, which is the direct secretion of the epithelial cells. 
As the glandular segment is approached the epithelium becomes distinctively col- 
umnar (fig. 125). The glandular segment (figs. 127, 128) is partly subdivided by the 
infolding of the epithelium (/). The spermatophores (in some cases there are two) are 
restricted to one chamber and are immediately surrounded by a yellowish secretion 
(Spr.), which is probably formed in the proximal segment and stains very feebly in 
carmine. The remainder of the spacious cavity [a and b) is filled with a less dense 
coagulable siibstance which stains freely in carmine. Bodies resembling yolk-spheres 
can sometimes be seen. 

Grobbeu says that the secretion of the glandular segment of the vas deferens 
of the crayfish appears chalky-white in reflected light and consists of small, shining 
granules. 

In the ductus ejaculatorius (fig. 126) the muscular coats are strongly developed and 
the epithelium appears to secrete an albuminous, granular substance. The height of 
the columnar or cylindrical cells varies very much, as Grobben remarks, according as 
they are squeezed more or less closely together. 

The external opening of the vas deferens is formed by an invagination of the skin, 
and according to Grobben is paved with thick cuticle. 

SPERMATOPHORES. 

The sperm is ejected from the muscular segment of the vas deferens in the form 
of spermatophores, which consist of elongated packets of sperm cells, surrounded by 
gelatinous capsules, the origin of which we have just seen. The spermatophores can 
be pressed out of the ducts when these are removed from the body. They quickly 
imbibe water and swell perceptibly when wet with it. The spermatophore is composed 
of two distinct secretions, as was first pointed out by Grobben. According to the 



160 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

same investigator, spermatopLores were first seen in Eupagurus by Schwainiuerdain 
in 1752, and were observed in tbe Brachyura also by Oavoliui in 1792. They were 
rediscovered by Kolliker in 1841. 

SPEKM CELLS. 

The sperm cells of the lobster were apparently seen for the first time by Valentin, 
in September, 1837 {192), and he gave a brief account of his discovery in the following 
year. A more accurate account by Kolliker, who also remarked on the apparent 
immobility of the " rayed cells," appeared in 1843 (109). 

The structure and genesis of tbe spermatozoa of the lobster have been studied 
with much detail by Grobben (83), Gilson (77), Hermann (89), and more recently by 
Sabatier (173). 

Each sperm cell (fig. 129, plate 37) consists of a cylindrical and partially hollow 
column or shaft, surmounted with a rounded dome, on what may be called the superior 
end. Between the capital and shaft three long, slender processes are given off, making 
an angle of 120° with each other. The processes are sharp-pointed, rigid, and very 
slender. The stiffness of the rays has led to the erroneous view that the rayed con- 
dition represented an immature stage in the maturation of the cell. The sperm cells 
withdrawn from the spermatic receptacle where they have lain weeks or months are 
still rayed, although the processes are often broken off or very limp (fig. 129, a). 
Apropos to this subject Grobben (83) says: 

The stiffness of the rays does not prove that these cells are completely immobile. Moreover, 
the observation of Owsjaunikow that the, rays sometimes draw themselves in, and certain structures 
which Ihave examined, enableme to conclude definitely that these rays are living protoplasm and that 
they represent amoeboid processes, remaining almost in a state of rest. [Compare the observation 
of Cano quoted on p. 49.] 

The genesis of the sperm cells from the spermatoblasts has been satisfactorily 
determined in most particulars, but there are some questions, which concern both this 
and the structure of the adult sperm cell, which are still undecided. The conclusion of 
Sabatier that the rayed cells become enucleated in the course of their growth can 
hardly be accepted. Sabatier has suggested that the stiff rays may serve at first to 
stick the cells together. 

Nothing is definitely known either as to how the spermatophores are conveyed to 
the seminal receptacle or how the spermatozoa reach the eggs and fertilize them. 



Chapter XL— THE HABITS OF THE LOBSTER FROM THE TIME OF HATCHING 

TO THE PERIOD OF MATURITY. 

When the lobster hatches from the egg it is scarcely a third of an inch long. It 
rises to the surface, where it leads for a number of weeks a free-swimming, larval life, 
totally unlike that of an adult. After the fifth or sixth molt, its larval locomotor organs 
having atrophied, it sinks to the bottom, and though now resembling the adult lobster 
in outward form it is scarcely more than half an inch in length. 

The free swimming habit of the lobster is characteristic of the first five or six 
stages of its existence. In Vineyard Sound and outlying waters we have taken the 
swimming stages during the summer months, the latest capture being a fifth larva on 
August 28. This period lasts from six to eight weeks, varying slightly with the 
season and greatly with the individual. It will be convenient to deal with the habits 
of the larvae more fully in describing their structure and growth. 

From the end of larval life until the later adolescent period the lobster drops out 
of sight almost completely. It is a singular fact that the habits of the young lobster, 
from 1 to 4 inches long, have never been well uuderstood. Many fishermen have never 
seen a lobster less than 2 or 3 inches in length, although they have fished the greater 
part of their lives. Lobsters under 5 inches long pass readily between the slats of the 
traps and hence are seldom caught. Rarely, however, one is found clinging to some 
part of the gear and is brought up by accident. 

Sars in the course of his studies upon the European lobster, traveled along the 
coast of Norway from Lurhavn to Bergen, June 19 to August 19, 1875, but was unable 
to obtain any young lobsters from an inch to a finger's length, and says : 

So far as I know, none are found in any museum. I consider it as certain, however, that the 
lohster keeps near the coast also during this stage of development. The reason why they can not be 
caught with the bottom scraper is partly because of their quick movements, and partly from the 
circumstance that they hide among the algas on the bottom of the sea. (176.) 

He says that young lobsters 3 to 4 inches long were the smallest known when 
he began his studies, and he has nothing to add beyond a description of the first 
three larvse. 

Spence Bate remarked in 1879 that "common as the European lobster is, it is 
very remarkable that a very young specimen has, as far as I know, never been met 
with." 1 He offered a reward for very youug lobsters, but never obtained any less 
than 3 inches long. 

Ehreubaum, whose paper was published in 1894, refers to the same uncertainty 
which has so long enveloped the history of the lobster from the close of its free- 
swimming life until it reaches a length of 4 inches (10 cm.). The smallest lobster 
which had been taken at Heligoland up to that time had attained a length of 4.1 cm. 
The next largest was 7.8 cm. long. He speaks of a collector who, in the course of 



'Report of the British Association for the Advancement of Science, London. 

F. C. B. 1895—11 161 



162 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

thirty years' experience about Heligoland, had obtained only three lobsters from 3 to 
5 cm. long. (61, p. 285.) 

It is evident that the long larval period of the lobster is an important means of 
securing a transport from the shore and wide distribution up and down the coast by 
means of the tides and ocean currents. As I shall point out in another place, this 
transportation is of the utmost importance to the larva?, since it is in the bays and 
landlocked channels, where the competition among surface-feeding animals is keenest 
and destruction of life by animate and inanimate foes by far the greatest. 

In consequence of the facts just mentioned, it must often happen that the young 
lobster settles to the bottom in depths much exceeding 100 fathoms. What does the 
little animal do on reaching its new abode? It probably begins to travel toward the 
shore, slowly at first but more rapidly when, in the course of six or eight weeks, it has 
become 1^ to li inches long. Meantime it hides in the crevices of the rocks or conceals 
itself under stones whenever danger approaches. Having reached the shore, it estab- 
lishes itself iu shallow water at the mouth of some estuary or river on the rocky sides 
of a bay. It lives under stones, or in stone piles, the tops of which are sometimes left 
bare at extremely low tides. It can then be found by turning over stones in much 
exposed situations, often where the water is not over 1 or 2 inches deep, but where 
at the flood there may be from 3 to 5 feet of water or even more. Sometimes several 
small lobsters are seen lying under one rock at the same time. While the lobster 
is very small, 1£ to 2J inches long, it crawls down deep into the piles of loose stones 
where no enemy can reach it. After attaining a greater length — of 3 or 4 inches — the 
young lobster begins to leave the rock piles and digs for itself a little cave under a 
stone. From this protection it stealthily crawls forth in search of its prey, and quickly 
returns when an enemy appears. It may take up its abode in the winding chamber of 
a deserted couch shell, or in any hole or niche which promises temporary security. 

As the lobster increases in size it grows bolder and retires farther from the shore, 
although it never loses its instinct for digging and never abandons the usual habit of 
concealing itself under stones when the necessity arises. 

Little is known about the habits of young lobsters in winter, but it is evident 
that they iriust leave the rock piles as soon as ice begins to form, perhaps as early as 
December in eastern Maine, and move out, as the adults do, into deeper water. The 
casting up of young lobsters on the beach at Woods Hole, in the latter part of January 
(seep. 165), proves that they sometimes remain in shallow water even at this season. 

The colors of the young lobsters at the time they are from 1£ to 2 inches or some- 
what more in length are very different from those of the adult. This may be seen by 
comparing figures 39 aud 22, which represent, respectively, a young male 1.8 inches 
long (see No. 22, table 33) aud an adult male 10 inches in length. In the young 
lobster the general cast of color is a russet or light reddish-brown, which is most pro- 
nounced on the sides of the body and under surface of the large claws. The borders 
of the carapace and segments of the body and legs are tinged with light Prussian blue. 
The upper parts of the body aud appendages, especially the first pair of chelipeds, are 
spattered and marbled with a dull-bluish pigment. The terga of the abdomen have 
often a fine edging of dull bluish-black. 

I am fortunate in being able to present a series of plates to illustrate the adoles- 
cent as well as the adult stages of the lobster. The original photographs 1 are in many 
cases so perfect that with the aid of a hand lens the finest details in the sculpturing 
1 These were made by the Edmondson Company, of Cleveland, Ohio. 



THE AMERICAN LOBSTER. 163 

of the exoskeleton can be seen. The adolescent forms are all from ( lasco Bay region, 
ami are described in table 32. (See also descriptions of figs. 9-18, plates 8-13.) The 
smallest (plate 8, fig. 10, No. 1, table 32) is a male, 1.0 inches long. The right cutting- 
claw happens to be much under the normal size, since it is in process of regeneration. 
It would probably have attained its normal size after the next molt. The greater 
breadth of the "tail" or pleon of the female is not noticeable until at a considerably 
later period. Other secondary characteristics, such as the seminal receptacle and 
first pair of pleopods in both sexes, are not fully developed until the animal has 
reached the length of about 2 inches. 

The most striking characteristic of these adolescent stages, in comparison with 
the adult form which they so closely resemble, is the large size of the stalked eyes 
(plates 8—12). The eye is very much compressed laterally, and in size and shape 
resembles that of Pemeus. The eyes of the adult are relatively much smaller. (See 
table 38.) It is therefore possible that the large size of the eyes in the adolescent 
stages is an ancestral character. The present lobsters have probably descended 
from the Erymoid Crustacea which inhabited the seas of the Liassic period. "In the 
latter part of the Jurassic epoch," says Huxley {103), "the Astatine type — that of the 
modern crayfishes — was already distinct from the Homariue type, though both were 
marine." Hoploparia, which is found in a fossil condition in the Cretaceous and early 
Tertiary formations, combines the characteristics of Homarus (Astacus in this work) 
and Nethrops. I have seen nothing but fragments of this genus figured, but in the 
Eryma leptodactylina of Zittel (208) the eyes are relatively quite large, as we see them 
in the adolescent lobster at the present time. 

Another characteristic of these early stages is the fringe of very long seta3 on the 
caudal fan and the matted tufts of setai about the ends and toothed edges of the 
cutting-claw. (See figs. 13-15.) 

In a female lobster measuring 3f iuclies in length (No. 22, table 32) the general 
color is a dull reddish brown. The upper parts are spotted and mottled with darker 
brown ; the tips of the claws and projecting spines are generally reddish, as in the adult. 
A suffusion of light blue is seen, as in younger forms, at the joints of the appendages 
and on the edges of the carapace and abdominal terga. This coloration closely resem- 
bled that of au adult egg-bearing female which I had at the time. A small male (No. 
23, table 32) resembled this female very closely in color. The adolescent period is a 
long one, aud the gradual development of the pigments of the adult is correspond- 
ingly slow. The history of the development of the color of the adult lobster from 
that of the larva will be discussed in another place. After this general account of the 
period of adolescence, I will now add all the notes which I have gathered that throw 
any light upon this important subject. In tables 32 and 33 the history of 63 imma- 
ture lobsters, varyiug from 1.3 to 5.6 inches, is briefly given. 

I am indebted to Mr. M. B. Spinney, of Cliffstoue, Maine, for a valuable collection 
of small lobsters from the shores of Oasco Bay and Small Point Harbor, which he has 
examined with great care. This collection embraces 36 individuals, 22 of which are 
males and 14 females. They were captured mostly in October and November. Mr. 
Spinney found young lobsters from 3£ to 4 or more inches long in considerable abun- 
dance under small stones, where at au extreme low tide there would be but 1 or 2 
inches of water; the smallest lobsters were found down among the stone piles, where 
the stones were four or five tiers deep. They crawl as far as they can into the laby- 
rinthine passages between the stones, and are here secure from every enemy. 



164 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Table 32. — Young lobsters from the vicinity of Casco Bay, Maine. 
(Length, 40.3 to 129 mm. or 1.6 to 5.1 inches.] 



No. 



Sex. 



Male... 
Female 
Male... 

....do .. 

....do .. 

. . . do . . 

Female 

Male . . . 
Female 

. ...do .. 

Male... 
....do .. 
Female 

....do .. 
Male... 
Female 
Male . . . 

....do .. 

....do .. 
....do .. 

Female 
....do .. 

Male... 
....do .. 

Female 
....do .. 

Male... 

...do .. 

Female 
....do .. 

Male... 
....do .. 
....do .. 

...do .. 
Female 
Male... 



Length 
in mm. 



Date of capture. 



Place of capture. 



40.3 

44 

48 

52.5 

58 

62 

64 

67 



68 
69 

71 
73 

74 
75 
75.6 
81.5 

83.5 

84 

85.5 

86.5 

87 

92.3 

93 

93.4 

94 

95 

101.5 

102 

102.4 

1H4. 5 

110 

112 

119.-5 

124 
129 



Oct. 9-19,1893:....! Casco Bay, Small Point, Me. 

do do 

do j do 

do do 



Remarks. 



do 

Sept. 27,1893. 



Oct. 9-19,1893. 
Sept. 27,1893.. 



Aug. 31,1893.. 
Oct. 9-19,1893. 
do 

Aug. 31,1893.. 



Sept. 26-28,1893. 
Oct. 9-19,1893... 
Sept. 26-28,1893. 
do 



Oct. 9-19,1893 do 



.do 



New Meadows River,6 miles 

north of Small Point. 
Casco Bay, Small Point 



New Meadows Biver 

Basin Bay, east side Mead- 
ows River. 

Small Point Harbor 

....do 

....do 

Small Point Harbor (inner 
harbor). 

...do 

do 

do 

do 



do do 

do do 

do do 

I Basin Bay 

Oct. 9-19, 1893 J Small Point Harbor 

Sept. 1,1893 1 do 

Sept. 26-28,1893... do 

Oct. 7, 1893 | New Meadows River,8miles 

E. of Small Point Harbor. 
.East side Casco Bay, Phipps- 

burg. Me. 

Sept. 1.1893 ! SmalfPoint Harbor 

Sept, 26-28, 1893 do 

do do 

Oct. 9-19, 1893 do 

Sept. 26-28, 1893 . . ' do I 

; Inner harbor, Small Point.. 



Small Point Harbor 

Sept. 20-28, 1893 do 

Aug. 31,1893 t Inner harbor, Small Point.. 



Found in stone piles at very low tide ; 

Do. 

Do. 

Do. 

Do. 
Found under stones at very low tide ; 

tops of stones out of water. 
Under stones and in stone piles at 
very low tide. 

Do. 

Do. 

Do. 
Do. 
Do. 
Do. 

Do. 
Do. 

Do. 
Just molted; stomach tilled with 
fragments of shells of mollusks.etc. 
Found under stones and in stone 
piles at very low tide. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 
Just molted; stomach tilled with 
fragments of shells of mollusks.etc. 
Under- stones. 

Do. 

Do. 

Do. 

Do. 

Do. 
Under stones; rostrum imperfect; 

soft shell. 
Rostrum deficient, soft shell. 



Table 33. — Young lobsters from Vineyard Sound, Massachusetts, in vicinity of IFoods Hole. 
| Length, 35 to 142.8 mm. or 1.4 to 5.6 inches.] 



No. 


e pv Length 
hex - | in mm. 


Date of capture. | Place of capture. Remarks. 


1 

2 
3 
4 
5 
6 
7 
8 
9 
10 
11 


Female . ' 36 
do M 


Hatched about 
June 20,1893. 

Jan 28 1882 


Wood s H ole 

do 


Raised from egg in hatchery of U. S. F. C. 
Station. June 27, 1894, it was 36 mm. long. 
It died early in August, 1894. 

1 
Hatched and raised at the U. S. F. C. Sta- 
tion, Woods Hole, Mass. 
Do. 
Do. 

No. 98. table 20. 

Brought up in lobster pot. (See plate 26.) 

No. 43, table 20. 

No. 42, table 20. 

No. 46, table 20. 

Dredged bv U. S. F. C. steamer Fish Hawk. 

No. 91, table 20. 


Male 

Female . 

Male 

...do.... 

...do.... 
Female . 

Male 

Female . 


40.5 

41 

48 

50 

52 

55.2 

55.5 

60 

66.4 

74.8 

75 

80.3 

83.5 

83.7 

35 

36.3 
51.8 
69.5 
74.6 
47 
92 

106.3 
107.9 
112.8 
142. 8 


do 


.. do .. 


do 

do 

do 

do 

do 

do 

do 

do 

do 


...do .. 


do 


. . do . . 


do 


.. do 


...do 


. . do 


...do 


12 i.-.do ... 

13 I Female . 

14 1 Male.... 




do 


do 


do . 


. . do . . 


.. do .. 


. . do 


16 
17 

18 
19 
20 
21 
22 
23 
24 
25 
26 
27 


Male 

Female . 

Male 

Female . 
...do.... 

... do ... . 

Male 

...do .... 

Female . 
...do.... 
...do.... 
...do.... 


.. do . 


.. do 


Preserved Dec 10. 

1886. 
do 




.. do 




June 1, 1891 

June 30,1891 

July 18 1891 




Woods Hole Harbor .. 
do 


July 22, 1890 
'do . 






do 


...do 


Aug., 1892 

July 22. 1891 


Vinevard Sound 

Woods Hole Harbor . . 



THE AMERICAN LOBSTER. 165 

When the lobsters have attained a length of 3i or 4 inches they become more 
bold, leave their burrows among the rock piles, and seek the shelter of stones, beneath 
which they excavate a shallow hole. Here they lie concealed from their enemies and 
are ready at all times to strike a blow at the smaller and weaker animals which pass 
within the reach of their claws. 

The young - lobsters enumerated in table 33 were captured in or near Vineyard Sound 
or raised in the hatchery of the station of the Fish Commission. Fifteen of these 
(Nos. 2-16) were collected by Mr. Vinal N. Edwards on Nobska Beach, in Woods Hole, 
January 28, 1S82, after a hard storm, when there had been much anchor frost. Mr. 
Edwards recorded in his journal the finding also of crabs with eggs, thrown upon 
the beach, together with isopods, holothurians, sea-anemones, and a large number of 
fish, such as dinners, tautog, hake, sculpins, smelt, flatfish, herring, toincod, and 
eels. Mr. Edwards writes that many young lobsters came ashore at the same time on 
the point of land where the Fish Commission station is now built. Several years ago, 
when small lobsters were used for bait, he used to find them in comparative abun- 
dance, from li to 3 or 4 inches in length, under stones in shallow water, near Pine 
Island, on the north side of "The Hole." Some of the stones would be out of the 
water at low tide. No small lobsters are found in this place or vicinity at the present 
time. Whether this disappearance is due to the general decrease in the number of 
lobsters brought about by overfishing or to local changes in the environment, it is dif- 
ficult to say. Both influences may be at work. It is possible that owing to warmer 
waters inshore, or to other causes operating in summer, the young lobsters are driven 
into deeper water, yet they seem to be equally scarce at all seasons. The finding of 
small lobsters cast up on the beach in the winter shows, as already pointed out, that 
they sometimes remain at this season in comparatively shallow water. 

The inspector of fisheries of Prince Edward Island says {20!)) that lobsters 2 or 3 
inches long "are occasionally washed ashore after storms and have been found alive 
clinging to the meshes of hoop traps." Lobsters not much over an inch in length are 
also said to have been taken from the stomachs of codfish. (See p. 120). 

An old lobster fisherman, Mr. Thomas Garrett, at Vinal Haven, Maine, whom I 
have already quoted, informed me that he used to see thousands of small lobsters 
in the spring, beginning about the 1st of April. He would find them in sounds in 
about 20 fathoms of water, on both rocky or sandy bottom. They would ccme up 
sticking to the lobster pots, often in considerable numbers, and would average about 
li inches long. He had never seen many lobsters 2 to 3 inches long, probably because 
they go so readily through the traps. 

I made particular inquiries about the occurrence of young lobsters in the lobster 
pound on Vinal Haven Island. The smallest lobsters caught in the pound in 1893 by 
seining were about 5 inches long. Half a dozen measuring 8 inches had also been 
taken. Small lobsters were noticed in the larger of the two lobster pounds at South- 
port, Maine, in March, 1892, and about half a dozen were found from 4 to 6 inches 
long. In July and August, 1893, thirty or more lobsters were taken, varying from 3 
to 6 inches in length. Lobsters 6 to 8 inches long could be taken in the seine. The 
smaller lobsters were discovered by turning over rocks, after partially draining the 
pond. None were seen under 2 inches in length. It is possible that some of these 
young ones were raised in the pounds, yet it is not certain that this was the case, 
since they could readily pass between the iron rods of the fence. The older lobsters, 
which are placed in the pounds in very great numbers, would tend to drive out the 
smaller ones, whether hatched in these inclosures or not. 



i66 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

An intelligent lobsterman of Eockland, Maine, said that thousands of small 
lobsters, an inch long or under, came up on the warps and pots every day while lie 
was hshiug at Hare Island in October and November. The lobsters would tumble off' 
the traps as they came up. He took one of them home and examined it with a hand 
lens, and said that it had the general form and appearance of a lobster. The bottom 
in that vicinity was muddy or rocky, and covered with seaweed. He had never seen 
a 2-inch lobster. The smallest of the young - lobsters recorded in table 32 is about an 
inch and a half long. These, as we have seen, were taken from the rock piles in the 
fall of the year, and most of the lobsters which are hatched in early summer and 
survive are more than an inch long by October. Still, this fisherman's observation 
may be correct, and the lobsters seen by him may represent that period between the 
sixth larval stage (length 16 mm.) and the smallest of those found in the rock piles. 

A small lobster, about 1 J inches long, was said to have been taken from the shell 
of a living clam in Rockland Harbor not long ago. This was evidently a case of 
accidental imprisonment, and the animal may not have been a lobster. 

A fisherman at West Jonesport said that he had seen small lobsters brought up 
on traps which were set on trawls, in deep water outside, in winter. 

Mr. Adolph Nielsen, superintendent of the fisheries of Newfoundland, says that 
small lobsters 1£ to 2 inches long can be found in shallow water among the "goose- 
grass" in the latter part of September, and that he has seen lobsters an inch long in 
the same situations in the latter part of August and first part of September. 

Very few fishermen among many whom I have consulted can give any definite 
information about the occurrence of lobsters from 1 to 3 inches long, and probably very 
few can discriminate between the young of the lobster and many other Crustacea. 
Those who have made any observations agree that such young lobsters are very 
seldom seen in winter, but are usually found at other times in shallow water, in bays, 
harbors, or the mouths of rivers, on rocky (rarely muddy) bottom, where they can be 
found by turning over stones at low tide. Mr. George E. Cushman, of Cape Elizabeth, 
Maine, says that lobsters 2 to 4 inches long are found in coves and rivers, in eelgrass, 
and on sandy bottom, in from 2 feet to 5 fathoms of water. 

Mr. Rathbun, of the United States Fish Commission, informs me that hundreds 
of lobsters 4 to 6 inches long were captured in the summer of 1880 in Narragansett Bay 
by the beam trawl. The bottom was sandy, and the water 3 to 4 fathoms in depth. 

I think it is plain from the foregoing observations that a large number of the ado- 
lescent lobsters over 1£ inches long seek protected places, such as beds of eelgrass in 
shallow water, rocky shores of bays, and the mouths of rivers, where shelter from an 
enemy is always at hand; but it is quite likely that some remain in deeper water. 

The habits of this animal are molded by its immediate environment and vary to 
some extent with the varying elements in the complex of its surroundings. 

If we examine the lengths of lobsters described in table 32 we shall find they 
form a gradually ascending series, so that when we lay off these lengths as ordinates 
upon a horizontal base line, and construct a curve, the latter forms a slightly undulating 
ascending line. This means either that the breeding season is indefinite or at least 
prolonged, or that the young are extraordinarily unequal in their development. The 
number examined is perhaps too small to enable us to draw any conclusions, but it is 
a fact, as already shown, that the hatching is not strictly confined to a definite period. 
Individual variation in size in a state of nature may, moreover, be considerable. 

The interesting question of the age of these adolescent lobsters is considered in 
the chapter on the rate of growth of this animal. 



Chapter XII.— THE HISTORY OF THE LARVAL AND EARLY ADOLESCENT 

PERIODS. 

The transition from the caterpillar to the chrysalis and from this to the winged 
butterfly or moth is apparently so sadden that it strikes every one with wonder. This 
is, however, deceptive, since changes in the internal organs go on very slowly. The 
hard supporting skin of the chrysalis masks the changes which are taking place within. 
The young crustacean, on the other hand, has a soft cuticle which is readily cast off; it 
thus changes with every molt and in most cases acquires very slowly the external form 
and habits of the adult state. It is therefore possible to follow its metamorphosis 
step by step. For convenience I shall divide the life-history into three periods — the 
larval, adolescent, and adult. The larval period will embrace the free-swimming life, 
during which the animal molts five or six times, and the adolescent state the long 
interval thereafter before sexual maturity is reached. 

The larval history of the lobster is one of exceptional interest and importance, 
and must be thoroughly understood before the problem of hatching and rearing the 
young can be intelligently discussed, much less solved. I therefore decided, at the 
beginning of this work, to devote as much attention as possible to this part of the 
subject. This seemed particularly desirable since the individual larval history had 
never been traced molt for molt; only four pelagic stages had been described, and the 
relations of these were not fully understood. Of the later adolescent period (length 
of animal £ or f inch to 2£ inches) nothing, as we have just seen, was definitely known. 

HISTORICAL NOTES. 

J. V. Thompson, who was first to establish beyond any doubt the important fact 
that the decapod Crustacea underwent a metamorphosis after hatching from the egg, 
was also the first, so far as I am able to learn, to point out that the European lobster 
was no exception to this very general rule. His letter (published in 1835) to the editor 
of the Zoological Journal is dated at Cork, December 16, 1830. A "rough sketch of 
the cheliferous member of the larva of the lobster" accompanies this letter. He says: 

With regard to the marine species, Astacus marinus or Lobster, I can aver that it actually does 
undergo a metamorphosis, but less in degree than any of the above-mentioned genera (Pagurus, Por- 
cellana, Galathea, Crangon, Palremon, etc.), consisting in a change from a cheliferous Schizopode 
to a Decapode; in its first stage being what I would call a modified Zoe with afrontal spine, spatulate 
tail, and wanting subabdomiual tins; in short, such an animal as would never be considered what it 
really is were it not obtained by hatching the spawn of the Lobster. (189.) 

Brightwell (24) gave in 1835 a very imperfect description of the young lobster 
which he dissected from the egg membranes. He was the first to notice the occur- 
rence of double monsters in this species. (See p. 216.) 

The embryo of the European lobster when ready to hatch was described by Eathke 
in 1840 (159), and a fuller account with figures of the embryo and of some of its append- 
ages appeared in 1812 (160). He found lobsters with external eggs in early stages of 
development at different times of the year — at the end of May in Christiania, in June 
and July at Molde and Christiansund, in September at Gothenburg, and in the first 
half of October in Hamburg. He therefore concluded that lobsters either laid their 
eggs at different times of the year or that their development was very slow. 

167 



168 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Kroyer also, in 1842 (110), described with drawings the first larva of the lobster. 
In the following year the paper of Erdl was published on the development of the egg of 
the lobster (62), in which some good colored drawings of the older embryos are given. 

About thirty years later, in 1874, the first circumstantial account of the meta- 
morphosis of the European lobster was published by Professor Sars (175). His studies, 
however, included only the first three larval stages, and, as he remarked, the changes 
which these early larva 3 undergo, before they reach the adult state, were still unknown. 
Some comparisons are drawn in this paper between the first larvae of the European 
and American species. (For figures of Homarus americanus, see 175, Tab. I, figs. 18-20.) 

The first description of the metamorphosis of the American lobster was given by 
Professor S. I. Smith, in 1872 (182), his fuller paper being published in the following 
year. He described and figured the first three larval stages and what appeared to be 
a fourth or fifth stage from specimens obtained in Vineyard Sound, Massachusetts, 
in the summer of 1871. At that time the United States Fish Commission did not 
possess the laboratory facilities which afterwards grew out of the labors of Professor 
Baird, but notwithstanding these drawbacks this work is so carefully done that sub- 
sequent studies will find little to correct, so far as they deal with the external anatomy 
of the larva? described. Professor Smith says that between the third stage and what 
he called an " early stage of the adult form " " there is possibly an intermediate form. 
The changes in the whole appearance of the animal have been so much greater than 
between the first and second or between the second and third larval stages that, 
although the difference in size is inconsiderable, the whole change did not perhaps 
take place in one molt." 

Professor Ryder, who published a short paper on the metamorphosis of the lobster 
in 1886 (171), supposed that the first adult-like form of Smith was preceded by four 
stages, but by only three ecdyses, the first molt (which occurs at the time of hatching, 
as Sars (175) had found to take place in the European lobster) having been overlooked. 
The fact of the case is that the lobster molts four times before reaching the stage in 
which it resembles so strikingly the adult animal. It is still essentially a larva in 
habit and structure and swims at the surface, although its earlier natatory organs are 
reduced to mere rudiments (plate 23). 

Figures of the late embryos and of the first larva or its appendages have also been 
published by Erdl (62), Couch (48), Cerbe, 1 and Faxon (67), the work of the latter con- 
taining drawings by Stimpson and Alexander Agassiz, but it is not necessary to refer 
to these in detail. 

METHODS OF STUDYING THE YOUNG. 

In the course of my studies on the metamorphosis of the lobster I have endeavored 
to follow the history of individual larvae. This seems to the inexperienced a very 
simple matter, but the task is beset with serious difficulties. We may isolate the deli- 
cate larva from its natural enemies and place it under the most favorable conditions 
which we can devise, when new foes immediately spring up or unexpected disasters 
happen. The larvae which I studied were in most cases hatched at a known period by 
the artificial methods now in use. Healthy specimens were then selected and placed, 

'The figures of Gerbc are very crude, as reproduced by Blanchard (19) and Duncan. They are 
intended to represent the embryo shortly before hatching, the young immediately after hatching, ard 
after the second molt. The original paper of Gerbe I have not seen. 



THE AMERICAN LOBSTER. 169 

usually singly, in a 4-gallou glass jar, which was covered with coarse linen scrim and 
supplied with runuiug sea water. The mesh of the cloth soon became clogged, thus 
fouling the water in the jar, which had to be cleansed daily. Under these conditions 
young lobsters have been kept alive over 100 days and carried through ten molts. 
The only food which they had beside that contained in the water was lobster eggs. 
These were rarely touched by the very young larvae, unless they were lioated. Had 
my stay at the seashore been prolonged some of the young could have been kept alive, 
1 am sure, for an indefinite period, but other duties calling me away before the close 
of summer, they usually died from lack of attention. 

There is now (August 1, 1804) alive in the hatchery of the Fish Commission sta- 
tion a lobster which was hatched from the egg in June, 1893, and which is, therefore, 
considerably over a year old. 1 The length of this lobster is only 36 mm., while three 
lobsters which were hatched and kept alive until December 10, 1886, being then between 
five and six months old, measured 35, 36.3, and 51.8 mm., respectively. 1 mention this 
fact, now, to show how variable individuals are in their molting or, what amounts to 
the same thing, in their rate of growth. It is improbable that such a marked variation 
would occur in a state of nature, yet it is likely, as I shall later show, that even here 
variation in individual growth is by no means slight. (See table 31 and p. 97.) 

Before describing the structure and habits of the larva we will glance at the 
condition of the embryo at a late period in embryonic life. 

THE EMBRYO IN LATE STAGES OF DEVELOPMENT. 

A photograph of a living lobster with, external eggs taken in Cleveland, Ohio, 
December 8, 1893, is reproduced in plate 7. A cluster of these eggs, showing how they 
are attached to one another and to the set?e of the swiinmerets, is illustrated by fig. 25. 
Drawings of the living egg and of the embryo teased from the egg capsule (figs. 
26 to 28) give us some idea of the stage of development reached, in this instance, at 
the very beginning of winter. Progressive stages of growth in the case of a lobster 
whose eggs were laid July 1, 1890, and were beginning to hatch June 1, 1891, are illus- 
trated by figures in the text. (Plates G to J.) 

At the stage shown in fig. 27 the bright green yolk occupies nearly one entire 
hemisphere of the egg. This massive store of food, at the expense of which the organs 
of the body are gradually developed, becomes reduced at the time of hatching (fig. 29, 
plate 18) to a mere remnant within the stomach of the larva, and often undergoes 
changes in color, at the last stage becoming a dull yellowish-brown. The paired com- 
pound eyes have already become most conspicuous, both on account of their size and 
color. The pigment area, which has a peculiar contour, is almost black when light is 
transmitted or when reflected, except at a certain angle. It then glistens with great 
brilliancy, owing probably to the interference of light in the thin peripheral pigment- 
layer. Bright red chromatophores are distributed in a characteristic manner on the 
appendages, particularly on their basal segments and along the sides of the carapace. 
The yolk is divided by conspicuous dorsal and lateral indentations, corresponding to 
the folds of the digestive tract and its diverticula, which gradually inclose it. 

During the course of development the ova increase considerably in size and, 
losing their original globular form, become distinctly oval or oblong. 



See No. 1, table 33. 



170 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Peculiar concretions are developed in the intestine of the embryo when 5 or (5 
weeks old, as shown in figure 233, plate 51, and persist up to the time of hatching 
(fig. 30, pi. 18). They were noticed as early as 1813 by Erdl (62). We see them to 
better advantage in a section of the intestine of a much older embryo, as in figure 
253, P. There is great variation in both the size and shape of these bodies, but they 
consist of a staiuable, apparently structureless core, surrounded by a nonstainable 
substauce. The latter has distinct concentric stria? and resembles the cyst of a para- 
site. A concretion teased from the intestine of a similar embryo is illustrated in 
figure 250. 

In the living animal they have a white lustrous appearance, and are quite conspic- 
uous, moving to and fro with the peristaltic contractions of the intestine. On the 
suspicion that they might be of a parasitic origin I submitted them to Dr. Stiles of the 
United States Bureau of Animal Industry. He has kindly examined them, and con- 
cludes, so far as it was possible to reach a conclusion from the material at command, 
that the bodies in question were nonparasitic. In this event it is probable that they 
are the faecal residue of the egg yolk which undergoes digestion in the course of 
embryonic life. The animal is entirely rid of them soon after hatching. 

THE HATCHING OF THE LARVA. 

A lobster in the act of hatching is represented in fig. 29, plate 18, and one teased 
from the egg in fig. 30. The embryo at this time is inclosed by three membranes, 
namely: (1) the outer or secondary egg membrane; (2) the primary egg membrane, 
improperly called the chorion ; (3) a larval membrane, which is seen inclosing, like 
a glove, the various appendages in fig. 30. These are better shown in a much distended 
condition in cut 20, plate F. In this case, however, the innermost cuticle is not the 
larval membrane, but an earlier embryonic molt, which is absorbed long before the 
time of hatching is reached. 

When burst by internal pressure the secondary egg membrane splits (in the ver- 
tical longitudinal plane of the embryo) into two halves like the cotyledons of a beau, 
and is drawn off in most cases over the head by the strand or stalk with which it is 
continuous. It is a thick, translucent bag of a yellowish-brown tint, slightly elastic 
and easily torn. It completely separates from the underlying membrane, except at 
one point, that beneath the stalk of attachment. Here it adheres to the primary 
membrane, which has now become reduced by distention into an exceedingly delicate 
pellicle. In this particular case (fig. 29) it was whole, until ruptured by needles (just 
above eyes), and thus completely inclosed the exposed parts of the embryo. When 
the outer membrane of attachment bursts, it contracts and usually drags the delicate 
inner cuticle away with it. The embryo thus slips out in the condition shown in 
fig. 30. 

This is a very critical period in the life of the artificially hatched lobster. If it is 
healthy it soon molts, the swimming hairs are rapidly evaginated, and it emerges into 
what may be properly called the first locomotor larval stage. If less fortunate, it lies 
on its back for hours, struggling to get clear of some part of its larval covering. The 
failure to pass this molt is the cause of death to many embryos which have been reared 
successfully up to this point in the hatching jar. 



THE AMERICAN LOBSTER. 171 

THE FIRST STAGE. 

When the lobster has successfully escaped from the egg capsule, and shaken itself 
free from its larval cuticle, it emerges as a free-swimming animal, rising to the surface, 
where it remains until its pelagic life is over. A sketch of one of these young lobsters 
is represented in plate 19, and a lateral view is given in plate 20. 

The animal is but little over a third of an inch long. The average length of 15 
specimens was 7.84 mm., the extremes being"7.50 and S.03 mm. 

The body is segmented as in the adult 'form, the most striking characteristics 
being the enormous compound eyes, the conspicuous rostral spine, the spatulate telson, 
and the biramous swimming appendages, which, from their resemblance to the perma- 
nent swimming organs of the Schizopods, have given to this and the two succeeding 
forms the name of "Schizopod larvae." Functional appendages are wanting only in 
the abdominal segments, where, however, very small buds of the adult swimmerets 
can be seen beneath the cuticle, iu the second, third, fourth, and fifth abdominal 
somites. 

The cuticle of the larval lobster is now as translucent as glass, and the organs of 
the body — the heart and blood vessels, the alimentary tract, and rudimentary gills — 
are seen with great clearness. The green food yolk has disappeared entirely, or is 
reduced to a mere remnant, now more yellow than green, in the masticatory stomach. 
Perhaps the most conspicuous internal organ is the yellowish-brown liver, or gastric 
gland, the form of which on either side of the body, resembles a cluster of grapes. 

VARIATIONS IN COLOR. 

The color of the larval lobster is produced, as we have already seen, by a blue 
pigment dissolved in the blood plasma and by chromatophores which lie in the dermal 
layer of the skin, besides the pigment cells of the eyes. The distribution of the chro- 
matophores is very characteristic aud it is to these that the brilliant colors of the 
larvae are largely due. (See plate 19.) The pigment which they secrete is of two 
kinds, bright vermilion and yellow. The red cells are the larger aud play the most 
prominent role. The expansion and contraction of the chromatophores, by which the 
animal becomes brightly colored or pale, ordinarily requires from ten to fifteen minutes 
when stimulated by pressure. The chromatophores are distributed in the region of 
the carapace, along its sides, aud in front of the cervical groove. When they are 
contracted the animal is pale blue aud very translucent; when expanded the red cells 
give it a very decided color. Larvre when struggling on the bottom to get free from 
their old cuticle or wheu crippled iu any way are usually red, a commonly recognized 
symptom of weakness. This, however, does not seem to bean infallible sign. Larvae 
which were placed in a pool out of doors on a bright day in June became red in a 
few hours while swimming at the surface in apparent vigor. (See p. 188.) 

Both the blue pigment of the blood and the yellow and red pigment of the 
chromatophores are lipochromogens, which are converted into lipochronies under the 
influence of alcohol and other reagents (see pp. 135-136). The stomach and liver are 
sometimes bright red, which recalls an observation by MacMuun (132), A\ho concluded 
from spectroscopic evidence that in the lobster (Homarxs f/ammarus) the euterochloro- 
phyllof the liver might be carried to the hypodermis and converted into a lipochrome. 



172 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

HABITS. 

The habits of young lobsters differ but little during the various "stages" of their 
free-swiinming life, which is spent near the surface. Their pugnacious instiuct is 
undoubtedly strongest immediately after hatching, when their activity in killing and 
devouring one another invariably attracts the notice of the spectator and forms an 
insurmountable barrier to raising them in small aquaria. Like the young of most 
pelagic organisms, they can not bear crowding, either in vertical or horizontal limits. 
As Weldon and Fowler (201) have remarked: 

They must, if they are to thrive, have a large superficial range, as well as a considerable depth 
of water in which they may sink when such conditions as light and heat demand it. 

In swimming the larva? use both the exopodites of the thoracic limbs, by the beating 
movements of which they are impelled upward and forward, and the abdomen, by 
the contraction of which, with its broad telson-plate, they dart rapidly backward. 
Each thoracic limb consists of a short stalk, with two diverging branches, the outer 
branch, which serves as an oar, being flattened and fringed with long feathered hairs. 
The oars or exopodites work independently of the inner branches, which are mainly 
prehensile organs, and alone give rise to the adult limb. The exopodites atrophy and 
disappear completely after the fifth stage. In the common swimming or floating 
position at the surface the thorax is usually held in a horizontal position, with bent 
abdomen. In rising the head is inclined downward, often with the "tail" uppermost. 
When too weak to keep at the surface, they vacillate over the bottom, standing on their 
head, as if probing for food, which, however, is not the case. 

The larvae appear to be quite hardy under certain conditions. Thus I have kept 
them alive, and apparently healthy, in small flat dishes of sea water, without change, 
for from one to four days at a time, or until they molted to the second stage. 

The time which elapses between two successive molts varies, as at all subsequent 
stages, with the supply of food and general condition of the animal. lu the larvae 
which I had under observation the first stage lasts from one to four or five days, the 
healthier ones molting in the shorter period. 

THE SECOND STAGE. 

All the larvae of this stage which I have examined were raised from the egg. 
The average length in forty-seven cases was 9.2mm., the extremes being 8.3 to 10.2mm. 
It is evident that some of these were undersized, and the measurement of this stage 
given by Professor Smith, 10.6, is greater than any which I have observed. His speci- 
mens were all taken by the towing net, and if the number examined was sufficiently 
large it would indicate that under natural conditions a greater size is attained. 

A profile view of the second larva is given in plate 21. This is drawn to the same 
scale as the first larva on plate 20, and illustrates the increase in size effected at 
the second molt. All parts are now much larger, excepting the swimming thoracic 
appendages, which have grown but little. The swimmerets, visible as buds below the 
cuticle of the first larva, have now grown out on the second to fifth abdominal somites, 
and the rudiments of the last pair of appendages can be seen beneath the skin at the 
proximal end of the telson plate (fig. 102, plate 34). 

The habits of the second larva differ in no respect from those of the first, and in 
color the two stages are very similar. In transparent larva', with contracted chroma- 



Tl IK AMERICAN LOBSTER. 



173 



topbores, great variety may be produced by tbe color of the gastric gland, which is 
often orange or some cast of yellow, and by the contents of the alimentary tract, which 
shows plainly through the body walls. Bright green pigment now appears for the first 
time upon the dorsal surface of the carapace and upon the tergal surfaces of the hist 
five abdominal somites. 

As in the first stage, the larvae thrive only on one another when kept in close quar. 
ters. I have often watched one of these larvae as it attacked another which appeared 
to be its equal in size and strength. The aggressive lobster usually tried to seize 
his fellow by the small of the back or between the carapace and abdomen, using for 
weapons the walking appendages, chiefly the first three pairs. He was soon astride 
the back of his victim, and dragged him to the bottom of the jar, where he began to 
devour him. 

The second larval stage lasts from two to five days. 

THE THIRD STAGE. 

The average length of the third larva in seventy-nine individuals examined was 
11.1 mm., the extremes being 10 to 12 mm. 

The third larva resembles the preceding stages very closely in habits. Struc- 
turally, it differs but little from the second larva. (Compare plates 21 and 22.) The 
outer branches of the thoracic legs are still the principal swimming organs. However, 
the last pair of abdominal appendages, which form the outer blades of the tail-fan, 
are ready for service, and the swimmerets are fringed with short seta?. The large 
claws, which were already conspicuous, are relatively much larger. 

COLOR. 

The third larva resembles the preceding stages closely in color. When the chro- 
matophores close the animal is quite pale, as was the case with one which 1 examined 
in the act of molting. As a rule, the color is enhanced by this stimulus. When this 
specimen was examined with the microscope it was seen that the red chromatophores 
were contracted so as to resemble small dots or stipple marks. The yellow pigment 
cells were more irregular. 

When this transparent, almost colorless, larva is placed in a dish with others the 
contrast is very striking. The colored form, in which the pigment cells are expanded, 
is a rich, deep brown, varied with a vivid yellowish-green. The appendages are for 
the most part reddish-brown, excepting the terminal parts of the smaller ones, such 
as the exopodites and endopodites of the pleopods and the tiagella of the antennae, 
which are bluish. The large chelae are a deep reddish-brown. The same color occurs 
sparingly on the sides of the carapace and on the lateral and ventral surfaces of the 
abdomen. The hinder parts of the carapace are touched with bright yellowish-green, 
as are the third, fourth, and fifth terga of the abdomen. These intense metallic 
colors greatly resemble those of the fourth larva. In reflected light a whitish pigment 
is seen in the lateral eye, which is strongly iridescent, as in the earlier larva?. 

One larva (10.8 mm. long) has the thorax and upper half of the abdomen greenish- 
blue; abdomen reddish below ; tail-fan reddish; red pigment cells occur on the append- 
ages and on the sides of the branchiostegites, as in the earlier stages. 

In another, examined in the act of molting, on July 3, the colors were very bright. 
Especially noticeable were the metallic green spots on the fourth and fifth abdominal 
segments. 



174 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Another larva (11 mm. long) has colors similar to the first just described: Large 
chelae reddish-brown; lower half of the abdomen, caudal fan, and sixth abdominal seg- 
ment of same color; carapace yellowish-green, rather less transparent than in earlier 
stages; bright peacock-green with yellowish tinge on the terga of the fourth and fifth 
abdominal segments; considerable blue at the joints of the appendages (probably 
because the cuticle is here thinner) and in different parts of the body. It must be 
remembered that the transparency of the larva is now determined iu an important 
degree bj^ the greater or less time which has elapsed since the last molt — that is, by the 
greater or less proximity to the ecdysis which is to follow. The old cuticle becomes 
partially opaque as soon as any lime is deposited in it, which happens at about this 
period. 

The third larval stage lasts from two to eight days. 

THE FOURTH STAGE. 

The young larva 1 emerges from its fourth molt into a form which bears such a 
striking resemblance to the adult lobster that an intervening stage between this and 
the preceding was supposed to exist; but such is not the case. A dorsal view, colored 
to life, of one of these larvae is represented by plate 23. The swimming branches of 
its thoracic legs have been abruptly shed, or rather have been reduced to functionless 
stumps (plate 31, figs. 74, 75). It still swims at the surface, with greater agility and 
speed than at any former stage, and is still virtually a larva, although it has the adult 
locomotor organs. 

It swims rapidly forward by means of the swimmerets, and darts backward 
with quick jerks of the abdomen, " frequently jumping out of the water in this way," 
as Professor Smith says, " like shrimp, which their movements in the water much 
resemble" (182). As they move forward they hold the large chela? extended straight 
in front of the head; when disturbed they raise the chelae to defend themselves like 
an adult lobster. 

It has the larval rostrum and the large antennal scale or exopodite, and the 
first abdominal somite is without trace of appendages. 

The average length of 61 larvae was 12.6 mm., or about half an inch, the extremes 
being 11 and 14 mm. 

COLOR. 

The range of variation in color is now very great. A typical color pattern is rep- 
resented in plate 23. Occasionally, even at this period, a larva is very light-colored 
and its transparency is nearly equal to that of the third larva. 

The cast of color maybe (1) yellow and red; (2) red; (3) green; (4) green and 
reddish-brown. In the first case the carapace is light yellow, translucent, and sprinkled 
with red chromatophores. The abdomen and large chelae are reddish- brown, and there 
is a quadrilateral yellowish-green area on the terga of the fourth and fifth abdominal 
segments. In the red individuals the animal is bright red, especially on the abdomen 
and large chela?. The carapace is yellowish, spotted with red, and the abdomen is 
marked in the way just described. In the green variation, the whole animal is bright 



1 The use of the word "larva" for the fourth and fifth stages is not without objection, hut it is 
perhaps better than the phrase " adult-like form.'' It is very probable, as I have shown, that the 
young lobster may remain at the surface of the ocean, even after the sixth molt. It will be most 
convenient, however, to define the larval period of the animal by the duration of its pelagic life, 
which is practically at a close by the end of the fifth stage. 



THE AMERICAN LOBSTER. 175 

green. Bright yellow-green areas are noticeable on the abdominal terga as before, and 
upon the hinder portion of the carapace. There is some brown pigment on the large 
chehe and tail Ian. In the fourth variety (fig. 36), the abdomen and chelae are rich 
reddish brown, with light peacock-green on the terga of the abdominal rings, as is 
commonly seen, and on the carapace next to the abdomen. The rest of the carapace is 
greenish brown. In this and all earlier stages the color of the carapace is partly due 
to that of the internal organs, especially to the alimentary tract and gastric glands. 

The following notes illustrate the changes which individual larvae undergo, with 
reference to molting and surrounding conditions. A fourth larva raised from the egg, 
when examined on July 13, was decidedly bluish. The whole animal was quite trans- 
lucent, the heart and yellowish "liver" showing plainly through the shell. The claws 
and body were sky-blue, due, as in the first larva, to the blood pigment. The brown 
and yellow chromatophores were contracted to such an extent as to have no appreciable 
effect upon the general color pattern. Two days later the carapace was greenish and 
the chela? dark brown. On July 17 the colors were deeper; on the 19th the general 
cast of color was dark bluish-green; reddish-brown on the abdomen and chela?. On 
July 21, when the animal was nearly ready to molt, the carapace was bluish-green, the 
abdomen and chela? brownish-red. Four days later, July 25, this animal molted to the 
fifth stage. The fifth larva was dark olive, tinged with brown on the abdomen and chehe. 

A larva which molted July 11 to the fourth stage was pale, and apparently 
almost devoid of pigment. The internal organs were plainly visible. There was a 
delicate wash of brown on the abdomen, tail-fan, and chela?. The microscope showed 
that the closed chromatophores were very small. 

Another larva, 13.1 mm. long, which was raised from the egg, had on July 6 the 
usual mixture of brown and green pigments. On July 15 the animal was very dark 
brown, excepting the carapace, which had a metallic green luster. The large chela? 
are tipped with white or cream color, and there is a large light patch ou the outer side 
of the hinder end of the exopoclite of the uropod. Fainter and smaller whitish areas 
occur on the pleura of the first abdominal ring. This larva molted about August 3 to 
the fifth stage; color, reddish-brown. 

Barely is a larva seen which is reddish-orauge, the blue and brown pigments 
being almost completely obscured. The pigments of the eye are similar to those of 
the earlier stages. 

In a larva of 14 mm. long, observed July 25, the carapace was of the usual greenish- 
brown cast, with three light-greenish spots on each side — a very small spot behind 
the eye, a smaller one below this, and a larger one farther back below the cervical 
groove. These are the first traces of very characteristic areas, which I shall call 
"tendon marks," upon the skeleton of all later stages, and mark the places where 
certain muscles are attached to the integument. The significance of these color 
changes will be considered later on. (See p. 135.) 

A fourth larva, which was caught at the surface near the Fish Commission wharf 
on a very bright day (July 25, 1891), was similar in color to some of those already 
described. The thorax was green, brightest posteriorly; the chela? and abdomen dark 
reddish-brown; a brilliant light-green area appeared on the tergum of the third and 
fourth abdominal segments. 

On August 10 I examined a number of lobsters in the fourth, fifth, and sixth 
stages, which had been kept in glass jars and fed upon meat. Many of these were so 



176 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



completely covered with foreign matter that they could hardly swim, some lying upon 
their backs on the bottom of the aquarium. Colonies of zoothamnium-like protozoa 
were clustered over all their appendages. The setae were loaded with sediment filled 
with bacteria, diatoms, and infusoria. This illustrates the fate which awaits the larvae 
of all crustacea, when crowded in small aquaria. 

The fourth larval stage lasted (in th.e average of nine individuals, which were 
raised from the egg) 13 days and varied from 10 to 19 days. 

THE FIFTH STAGE. 

In fifteen individuals known to have molted five times, the average length was 
14.2 mm., and the extremes 13.4 and 15 mm. 

There are no external marks by which the fifth stage can be distinguished from 
the fourth or even from the sixth stage with any degree of precision, at least by the 
unaided eye (fig. 31, plate 18). Neither the size nor color changes can be invariably 
relied upon. Microscopical examination, however, shows that the rudiments of the 
swimming exopodites, which could be readily detected in the fourth larva, have now 
become still more reduced, while in the sixth stage they have completely disappeared. 

The following notes illustrate the changes of color which are observed in larvae 
passing from the fourth to the fifth and sixth stages. On July 7 a fourth larva 
(No. 35, table 34) showed the typical colors, reddish-brown and various tints of green. 
When observed eight days later the color was dark maroon. The fifth molt occurred 
about July 17 (length, 14.8 mm.). The color was then greenish-brown; the large 
chehe reddish-brown, tipped with cream color, most marked upon the propodi. As 
in some fourth larvae, there is a terminal light spot on the exopodite of the uropod. 
Faint light spots are also seen on the sides of the abdominal segments. There are, 
moreover, two very prominent, white, discoidal areas on the carapace corresponding to 
the insertions of muscles, as already pointed out. 

The following measurements of this larva will give a clearer idea of the length 
of some of the parts and of their increase after the molt: 



Measurements of larva, third to fifth stages. 



Length of the fifth larva 

Distance from tip of extended chelipeds to end of telson 

Length of flagellum of second antenna 

Length of carapace in third stage 

Length of carapace in fourth stage 

Length of carapace in fifth stage 

Greatest width of carapace, fifth stage 

Length of large chelae, fourth stage 

Length of large chelae, fifth stage 




Another larva raised from the third stage (No. 12, table 34) is olive-green, with 
the characteristic white marks very faint on the carapace. The large chelae are 
yellowish-green, due to the presence of blue and yellow chromatophores. 

In the case of a fifth larva reared in an aquarium the colors resemble those of 
the sixth stage, represented in plate 25. The white spots on the carapace have the 
disposition shown in fig. 37, plate 24. The third pair of maxillipeds are tipped with 
white. 

No noticeable differentiation can be detected in the large claws unless occasioned 
by loss and subsequent growth or by injury to one of the members. It often happens 



■at stages. 



Length. 



2 
13 



14 

22 



15 



10 
21 



30 

i:; 



15.5 
16.5 



15.3 

16 

16.8 

16 
16.6 



16.5 

17 



16.3 



16 
15 



I ncrease 

in 
length. 



1.3 



1.3 



1 
1.6 



Increase. 



Per cent. 
n. i 



9.3 

14.3 



6.7 
10.7 



15.4 
13.3 



Seventh 
molt. 



Aug. 20 
July 27 



July 25 



2 14.3 

1.6 11.9 II. 



16. 12 1.58 I 11 



Length. 



18.4 
19.5 



Increase 

in 
length. 



nun. 



2.9 

3 



Increase 



Per cent. 



18.7 
18.2 



10.4 



18.60 2.53 15.76 



Eighth 
mult. 



Sept. 10 
Aug. 14 



Aug. 8 



e Sept. 22 
Aug. 13 



Length. 



21. 2 
22.6 



Increase 

in 
length. 



19. 75 
21.2 



20. 09 



4. 75 
2.7 



Increase. 



Per cent. 
15.2 



2.83 



Ninth 
molt. 



Aug. 23 
Aug. 1 



Len" 



24. 



i9, plate 32. 



3 Accurate within 0.2 to 0.9 mm. 



4 For colored sketch of this lobster in sixth sta 



Table 34. — Record of molts of larval and adolescent stages. 



New. 


i inn 

of 

hatching 


First. 

molt. 


Length. 


i uoreaai 

length. 


Increase 


Ago. 


Second 

molt. 


Lengtl). 


[ ii crease 
length, 


Increase. 


Third 
1 molt. 


Length. 


Increase 

in Inoroase. 
length. 


Age. 
Dayi, 

ia 

21 


Fourth 
molt. 


Length. 


Increase 
length. 


Increase. 


Ago. 


Fifth 
molt, 


Length. 


length. 


Increase. 


Age. 


Sixlh 

nit.lt. 


Length. 


length. 


Increase. 


Seventh 

1IM.11. 


Length. 


Inuroaae 
length. 


Increase 


Eighth 

it. 


Length. 


Inoreaae 
length. 


Increase. 


Ninth 
moll. 


l ength. 


ll.i 1. ;, ., 

in 

longl h. 


Increase. 


1 '.-.it 1 ■ 

.....It. 


Length. 


Increase 
length. 


1 in rea e 


1 

2 

'n 

'4 

:. 

6 

7 
8 
!' 
10 

11 

12 

11 
ii 
15 

Hi 
17 
l« 
18 
20 

21 

■ 

■■■■ 

20 
27 

2« 
-■' 
.in 

II 
32 
:u 

|| 
35 

:m 
• :i; 
38 
no 


18111. 

■i .■■ 

...do 




mm. 





P ( 


Day 




mm. 


iJF 


Per rent. 


Jnly 13 
July 15 


10,3 

lu. a 


mm. Per cent. 


July 18 
.July 17 
July 13 


lj' 
12.3 
13 


1.7 

2 


Pel cent. 
10.4 

19.4 


Days, 
24 
23 
48 


Aug. 1 
July 15 


13. '4 

14.2 
15 

14. G 
14 
14 
10 

15 
15 

14.3 
13. 5 
15 

12.5 

14.:. 

15 
14.8 

15.3 
14.8 

14 

13.4 

14.34 


1.4 
1.2 


Percent. 
11.7 

9.2 


Day*. 

38 


"Aug- 2 
July 13 

Julv 14 

July 22 

<li. .. 

July 15 


15.5 
10. 5 

15.3 

16 

1C.8 

10 
10.6 

16.5 

17 

16.3 

16 
15 

10.12 


1.3 


Per cent. 
9.1 


Ans;. 20 

July --'7 

.Inly 25 


18.4 

10. 5 

18 


2.9 

3 

1.7 


Percent. 

is. 7 
18.2 

10.4 


Sept. 1U 
Aug. 14 

Aug 8 

e Sept. 22 
Aug. 13 




21.2 
:2.li 

21 

10. 7.1 
21.2 

20. 119 


?.8 


Per o«l(. 
15.2 








Per <■■ 1,1 




211.5 


8.5 


Per cent. 

1;. -1 
16.7 




















































June 30 
Mn> 27 




i 












July 18 


11.0 








July 20 
July 10 


13. G 
13.5 


1.7 


14.3 




July 17 
July 13 


1.1 


8.1 




1.3 
2 
.8 

1 

1.0 

2.2 


9.3 

14.3 
5 

0.7 
10.7 

15.4 
13.3 























































:::::::::;:•::::: 

























































July 13 


14 




:::::::;:: 




...do.... 


2 


14.3 




3 


10. 7 
































„„ 












































1892 
Jnly ii 

• l.. 
.1,. 

-I :- 


.Ink 

...ilo 

ilo 


8 

- 






Jiilv 7 

jiiij a 


9 

ll.l 
9 

8.0 
8.9 
8.9 
9.5 
9.5 


1 

1.1 

1 


12.5 

13.7 
12.5 


July 13 
. . .do .... 

-Inlv 2 
.Jnly 3 
July 4 
July 
July 7 

July C 
July 4 


11.8 
10 

10.8 
Id 

11.1 
11 

10.7 

■11.0 
11.5 


l 

1.9 
1.1 
1.3 
1.5 
1.2 


24. 2 
11.1 

21.3 
12.4 
13.5 
15.8 
12.0 




July 17 
July 19 

July 8 
July 9 

July 11 

July 13 
July 6 
July 25 
.July 4 
July 8 

July 9 
July 8 
July n 

July 6 
July 15 


13 
11 

13 
12 

13 

"12.7 
13.1 
13 

12. H 

11.7 

12 

11.1 

12.8 

i;i 

13 

13.3 

12.2 
12 

12.9" 

12.5 
'12,5 

12.05 


1.7 

1 

1.2 
1.6 


15 
10 

20.4 
20 

18.2 

in. 4 

...™±. 




July 29 

Aug, a 

Aug. 

July 27 
July 22 

July 27 

July no 

j'uTy'lf 

July 1(1 

July 30 








Alii:. 10 
Aug. 21 

July 25 

'July :to 
Aug. 1U 












1.0 
.4 

2 

1.4 

1.7 

1.6 


12. G 
3 
15. 4 

12.6 

13.3 

15.4 
12 






.!„,„ 10 




























July - 










July 4 
















July 1 
Juno 30 














































































10.7 
10.5 

10 
in 

11.5 
11.8 
'11.3 

Ml. 3 
1U.0 
« 10.8 

i- ■ 

11 
11 

11". 87 








2. 1 
1.2 

2 

1.1 

1.3 

1.2 

3 1.7 

1.6 
<1.2 

■J. 1 

1.5 
1.5 

1.05 


19.0 

11.4 

20 

11 

11.3 

111.2 

15 

17.7 
15. 1 
11.1 

iit.4 " 

13.7 





■I >29 


















Jnly 3 









































































































July 2 
do 




















July 7 
















. 








































July 7 
July 8 

July 7' 


















:::::::::: :::::::::: 






Juui 20 

.1.. .. 




























July 4 


1.9 

1.5 
.9 

1.48 


14 7 

12 
7.2 

11.53 




2 
1.6 

1.58 


14.3 

11.9 

11 


\!,. _ 1 




27.3 


.1 . . 

Aug. 1:1 





























...do-.-- 


-1 . 

A i ■ . . 






-'— 









0.1 


1.03 


12.9 




1.44 1584 











18,5 

18,111) 


2.53 


15.70 


2.7 | 14.fi 
2.83 1 15.5 


ji 


3.8 


21'.. ' 1.0 
28 4 

" 


! 


■ 
Jin- Inn.' 


■'■'■■■ 1" 

.1 I ibii 


r..'.ii of 9 

iz of lobst 


ages 13.1 
rsMoi. U 


7. Of imli 

>-nc i» nnl> 


■idnalc 
appn 


. 13.80 |om 


UlLIL' NO. 


38, ninth f 


tage). 1 




1 IViii 


les. 




»F 


r cnlur.s ill 1 his lobster in si.\lli st;i£i- sen 


plate J4: Ventra 


1 view of thorax, eighth stage, 


hown 


in tig. 89, plate 32. 






3 Accurato within 0. 


J In 11. '.i mi 






1 

* For colored sketch of this lobster in s 


vih stage 


see jiluto 2 






M)ied O.i.iliir ."-. 






F. C. 15. 1895— Fore page 1711. 



INK AMERICAN LOBSTER, 177 

that the dactyl is bent upward as much as forty degrees away from the propodus, so 
that the cutting edges meet but imperfectly. 

Larva No. 36, table 34, was nearly ready to molt to the fifth stage on July 17. It 
was of an opaque greenish-brown color, the claws deep brown. The carapace had a 
dull, bluish luster when strong light was reflected from it, a well-recognized mark of 
the molting state. 

Two days later it was in the fifth stage. The carapace and upper surfaces of the 
abdomen were now greenish brown. The white tendon mark on the side of the cara- 
pace below the cervical groove was very prominent. The light areas on the first 
abdominal ring and upon the uropods were rather faint, and the chelae, as usual, were 
tipped with cream color. 

The remarkable "death-feigning habit," which I shall discuss later, was developed 
in this larva to an unusual degree. A colored drawing of this lobster after the sixth 
molt, which occurred about July 30, is represented in plate 25. 

The fifth larval stage lasted in five observed cases from 11 to 18 days. 

THE SIXTH STAGE. 

The average length of five lobsters known to have molted six times was 16 mm., 
the extremes being 15 and 17 mm. 

I have already referred to the color of this stage, which is represented in an indi- 
vidual raised from the egg on plate 25. The general cast of color of the upper parts 
is often dark green or greenish-brown, and the "tendon-marks" on the carapace have 
now become very conspicuous. Equally characteristic are the snow white pleura of 
the first abdominal ring. 

A dorsal view of another lobster of this stage is given on plate 24. The coloring 
is from the sixth stage of larva No. 3, table 34. The whole animal is of a reddish- 
chocolate color, against which the white spots contrast very sharply. In the cervical 
groove there is a narrow transverse white area, a large white spot on the distal 
extremity of the meros of the cheliped, in addition to those already mentioned and 
the flattened rostrum is conspicuous for its absence of color, being but faintly tinged 
with green. 

A young lobster captured with the tow net in Woods Hole Harbor in the day- 
time, August 23, 1890, resembles the sixth stage, already described. The length of 
the lobster was 10.5 mm. (For record of the capture of other lobsters in sixth stage, 
see table on p. 187.) 

The individual color-changes which these lobsters undergo were well illustrated in 
a specimen, 16 mm. long, captured in the net July 24, 1890. When first taken it was 
bright bluish-green, excepting a slight amount of brownish pigment visible on some 
of the appendages. This lobster was accidentally left over night in a glass dish of 
water on my work-table. In the morning it had a decided reddish-brown color and 
was very weak. One is reminded of the similar but more striking change in color 
which the remarkable little lizard Anolis princeps, of the Southern States, undergoes 
when it is suddenly stimulated. 

Larva? have also been captured in the tow, from 15 to 16 mm. long, which resembled 
more nearly the fourth stage in color, but undoubtedly belonged to the fifth and sixth 
stages. 

F. C. B. 1895—12 



178 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

A young lobster about six weeks old, raised from the egg, and probably in the 
sixth stage, was light brownish-olive on the upper surface, the chehe being more 
decidedly brown. The under surface of the body was almost colorless. The usual 
cream-colored or white spots occurred on the carapace and appendages and the ter- 
minal spines of the abdominal pleura were whitish. The large claws, which show no 
special differentiation, are held together in frout of the auimal as it swims forward. 
When suddenly disturbed, the young lobster opens its claws, spreads wide its arm- 
like chelipeds, at the same time raising itself into a threatening attitude, ready to 
receive or strike a blow. The iridescent pigment of the eyes is no longer visible. 
Some measurements of parts of this lobster are as follows: 



Measurements. 



Millime- 
ters. 



Len gth 16 

Length of thorax, including rostrum 

Greatest width of thorax j 4 

Length of antennary flagellum ! 11 

Length of propodas of large chela 5. 5 



Lobsters in the fifth stage, which are raised in aquaria, swim less at the surface 
than in preceding stages, going frequently to the bottom of the jars for their food, and it 
is during this and partly in the sixth stage that the pelagic life of the lobster comes 
to an end. It then sinks to the bottom and leads an entirely new life. Its larval 
characters have completely disappeared, and buds of the modified appendages of the 
first abdominal segment have begun to grow out. In locomotion and general habits it 
resembles the adult animal closely, but t lie final adult condition is only attained after 
a long series of molts, which require, in all probability, from four to five years. 

The sixth stage lasted (in three cases observed) 9, 14, and 18 days, respectively. 

SEVENTH STAGE. 

The seventh stage can not be distinguished by any known characteristics from 
that which immediately precedes and follows. Unless one has watched and recorded 
the molts, it is impossible to say at this or a later period through just how many 
ecdyses the animal has actually passed. The larval stages merge insensibly into 
those of the adolescent period, and these pass as gradually into those of the adult, so 
it will be more profitable to follow the history of individual lobsters from this period 
onward rather than to attempt to describe stages which have no marked distinguishing- 
characters. 

In table 34 I have recorded the molts of thirty-nine youug lobsters raised during 
the summers of 1891 and 1892. The increase at each ecdysis and the increase percent 
(that is, the ratio between the actual increase and the former length) are also given. 
Many of the adolescent lobsters, which it should be understood are the remnant of a 
much larger number which I attempted to raise, died shortly after the last recorded 
molt. Some, however, were living when I was obliged to leave Woods Hole, at the 
middle or latter part of August, and doubtless could have been reared had they 
received the necessary care. The life-history, as illustrated in table 34, has been 
followed from the time of hatching to the tenth stage or ecdysis, when the animal 
is over an inch long and about three months old. 

We have considered in detail at the close of Chapter in the bearings of these 
observations upon the rate of growth in the lobster. 



THE AMERICAN LOBSTER. 179 

DESCRIPTION OF SMALL LOBSTERS. 

The number of molts or the rapidity of growth is a question which now assumes 
special interest and, as I shall eventually show, it is subject to considerable individual 
variation. 

Two young lobsters alter the seventh molt measured 18.4 and 19.5 mm. (Nos. 1, 2, 
table 3")) and remained in this stage 21 and 18 days respectively. 

Lobster No. 1 (table 35). — The first of these was raised from the fourth stage. Its 
color in the sixth stage is represented on plate 24. The animal after the seventh molt 
was light brown, tinged with green, when observed on August 20. It exhibited the 
"death-feigning habit" in a very marked degree. This lobster molted for the eighth 
time on September 10, and died the day following, when it measured 21.2 mm. It was 
hatched about May 27, and was therefore 107 days old. 

Lobster No. 2 (table 35). — This young female lobster had just molted when first 
examined on July 13, and was theu without doubt in the sixth stage. In color it 
closely resembled fig. 37, plate 24. It molted for the seventh time on July 27, when it 
attained a length of 19.5 mm. The color at this time was but little changed, being 
a deep chocolate above, with the tendon marks on the carapace equally prominent. 

The triangular rostrum is somewhat uarrower. The " finger " of the large claw 
aud the outer branch of the tail-fan are cream-colored. The latter, as in the sixth 
stage, carries a very long fringe of seta3, which becomes characteristic of the adolescent 
period. These setae are about two-thirds the length of the uropod. The left cheliped, 
which was thrown off at the time of the sixth molt, had grown out again, so that after 
the seventh ecdysis the length of the new appendage was about seven-tenths of that 
on the opposite side. The length of the right chela was 6.5 mm.; of the left, 4.5 mm. 

The stalked eyes are now very large aud continue to grow relatively faster than 
the rest of the body until they attain great prominence in the adolescent stages, as 
already described. 

The first pair of abdominal appendages are present as small buds, aud after the 
next molt their size is not greatly increased. 

After the eighth molt (August 14, length 22.G mm.) there was but little noticeable 
chauge in color. The general cast is still brown, with a bluish -green tinge on the 
carapace. The length of the fringing set* of tail fan — 1£ mm. — nearly equals that of 
the telson. The median sternal spines are present on the second to fifth abdominal 
somites, and have a bluish color. 

Lobster No. 3 (table 35). — This young female lobster was raised from the egg and 
placed under observation when in the third stage, July 4, 1892. At this time it was 
11 mm. long. It molted to the sixth stage on August 13, and when I finally left Woods 
Hole on the 23d of this month there had been no noteworthy change. When examined 
on September 22, by Dr. E. A. Andrews, it had attained the length of 19.75 mm. It is 
therefore highly probable that only one intervening molt had occurred and that this 
happened late in August or early in the following month. It died before another 
ecdysis, on the 5th of October, when it was about 105 days old, having molted eight 
times. 

Lobster No. 4 (table 35). — When this lobster came under systematic observation, 
on the 25th of July, it was iu the sixth stage and 10.3 mm long. An account of its 
ecdyses, which were carefully watched, one occurring on that very day while in a dish 
upon my table, will be given in another place. (See p. 183.) 



180 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Before molting the animal was of a dark umber color and very sluggish. Imme- 
diately after this ecdysis (the seventh in number) the whole body was translucent, the 
general color being reddish-brown, with a slight greenish tinge on the carapace. The 
large claws were a bright terra-cotta color. There was a prominent whitish crescentic 
spot immediately behind the cervical groove and the three characteristic tendon marks 
on each side of the carapace were as prominent as in the sixth stage. (Compare plate 
24.) The pleura of the first abdominal somite were snow-white, and the uropods of the 
tail-fan were tipped with cream color. 

The lobster after the seventh molt keeps steadily upon the bottom, in walking- 
over which it uses chiefly the last three pairs of thoracic legs. The large claws and 
smaller chelate legs next to them are extended forward in front of the head, although 
the latter appendages are occasionally used for locomotion. A very slight differentia- 
tion in the large chelae is noticed, but in the eighth stage the difference is marked. 
At about the time of the seventh ecdysis the right antennary flagellum was lost; 
eight days later it appeared, in the process of regeneration, as a short spiral coil; 
this continued to grow, and after the eighth molt, which occurred on the 8th of 
August — an interval of two weeks from the last — it was about its normal size. 

At the seventh stage pigment has been deposited below the enamel layer of the 
cuticle in an amount which, though at first very slight, increases with every molt, and 
the color pattern becomes more and more complex. In the eighth stage the general 
color is deep reddish-brown, with olive tints. The characteristic tendon marks and 
cream-colored spots are present. There is a dorsal light-green median stripe on the 
carapace, very much narrower than when first seen in the fourth stage. 

This lobster had uudergone no appreciable change by the 23d of August, but 
when next examined, September 22, it measured 29.5 mm. In the interval of thirty 
days it had undoubtedly molted twice and was in the tenth stage. The first abdominal 
somite has very delicate, white appendages, which are distinctly two-jointed and raised 
from the surface to a nearly vertical position. 

Lobster No. 5 (table 35). — This lobster was hatched about May 25, and when 
isolated, on August 1, it measured 24 mm. It was probably in the ninth stage and was 
about 67 days old. The general color was dark green, touched with brown; large 
chela' olive-brown, reddening toward the extremities, with glistening white tips; the 
under side was a tint lighter. The uropods and telson are whitish, bordered with 
reddish-brown. The contents of the intestine can be seen through the slightly trans- 
lucent shell. Tendon marks on the carapace are prominent, as in the other cases 
described. 

Some measurements of this lobster are as follows: 



Measurements of lobster No. 5, in ninth stage. 



Length 

Length of carapace 

Greatest width of carapace 

Length of antennary fiagelluni. 

Length of large chela on either side... 
Greatest breadth of chela of one side. . 
Greatest breadth of chela of other side 



Millime- 
ters. 



24 
31 

5 
23 

9 

3 

2.5 



In the smaller of the two claws the extremities are nearly straight; in the larger 
the "fingers" are more bent, and each bears a large tubercle at about the middle of 
the occludent margins. 



TTITC AMERICAN LOBSTER. 



181 



The animal hides among the stones at the bottom of the aquarium, and behaves 
in most respects like an adult animal. The eyes are dull brownish-black, without 
iridescence. 

When examined again on August 13 this lobster had molted, now for the tenth 
time, and was 28 mm. long. The general color was dark brownish-green, with 
reddish-brown on the large chelipeds, as before. The white or light color of the 
pleura of the first abdominal segment and tail-fan is obscured or has disappeared. 
The shell pigments are now more abundant, and the cuticle has lost its transluceucy 
in consequence. 

The following measurements illustrate the growth of some of the parts: 



Measurements of lobster No. 5, in truth 
stage. 


Millime- 
ters. 


Measurements of lobster No. 5, in tenth 
st age. 


Millime 
ters. 




28 
13 
C.4 

34 
25 

5.5 
10.5 

3.5 

5 




11 
3 

5.7 
4 

3.3 
2 

5 
4 
2 




Greatest breadth of cutting chela 

Length of dactyl of cutting chela 


Greatest width of carapace 

Length from tips of extended cheli- 
peds to end of telson 

Length of antennary tlagellum 




Length of terminal fringe of hairs. . . . 
Greatest width of abdomen at second 


Greatest breadth of crushing chela... 
Length of dactyl of crushing chela. . . 









Lobster Xo. 6 (table 35). — This was the only survivor out of a considerable number 
of lobsters hatched early in the season of 1892, and when first examined — about the 
first week in August — measured 18.5 mm., and was probably in the seventh stage. At 
this time a slight difference in the large claws could be detected, which increased 
with subsequent molts. There is nothing noteworthy in which this young lobster 
differed from those already described. (See No. 38, table 34.) 

Lobster No. 1 (table 33). — I have referred to this young female lobster, which was 
hatched about June 20, 1893, and was alive when I left Woods Hole, August 0, 1894. 
It was therefore 412 days old, and allowing it to have attained the length of 28 mm. 
at the tenth molt — the average length of three individuals known to have reached 
this stage — it must have molted thirteen times, which I am confident is not far from the 
truth. It is probable that no molts occurred during the winter, the last two recorded 
having taken place May 21 and June 18, 1894. 

The brilliant color is now wholly due to the pigments of the shell, which is no 
longer transparent, and the color pattern is so complicated that it almost baffles descrip- 
tion. The body is light umber, freely speckled and mottled with darker shades. Tlie 
appendages are reddish-brown and slightly translucent. Small light areas or suffu- 
sions are scattered over the body. The tendon marks on the carapace corresponding 
to those seen in the fifth and sixth stages are prominent, that below the cervical groove 
being over a millimeter in diameter. The pleura of the first abdominal ring are snowy 
white. The free edges of the segments of the body and appendages are bright blue. 
The large chelae are tipped with white. The openings of the oviducts are clearly 
seen and the copulatory pouch is not yet closed. The color of the appendages on 
the under side is light reddish-brown. The tail-fan is of the same hue edged with 
deep red. The claws, which are tufted with seta3 at their tips, show remarkably 
little differentiation. The eyes have a dark-purplish pigment and have acquired the 
characteristic large size and prominence of the adolescent stages. 



182 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

The following measurements show the proportions of some of the parts : 



Measurements. 


Millime- 
ters. 


Measurements. 


Millime- 
ters. 


Length June 27 1894... 


36 
16.5 

7.9 
33 
13.5 

4 

7 


Length of left chela (propodus) 

Greatest breadth of chela (propodus) . . 


13 
3.6 

7.8 

5 

4.1 

2 

2 






ljength of anteimary flagellum 

Length of right chela (propodus) 




Length of fringing setse 

Diameter of cornea of lateral eye 







This lobster was kept in a small glass aquarium, and. fed with clams and with 
lobster and cod eggs. It was undoubtedly undersized for its age, having molted about 
tifteen times. 

The three lobsters raised in 18S6, which on December 10 measured 35,36.3, and 
51.8 mm., respectively (ISTos. 7, 8, 9, table 35), had probably molted twelve times in the 
first two instances and fifteen times in the last. 

Lobster No. 10 (table 35). — When this young lobster was brought up accidentally 
on a lobster pot in Woods Hole Harbor July 18, 1891. it measured only 47 mm. (See 
colored drawing, plate 20.) If it was hatched in the summer season it must have 
been a little over a year old, and it is very probable that in this case also there had 
been fifteen molts. 

The youngest lobsters taken in Casco Bay, Maine, October, 1893 (Nbs. 1, 2, table 
32), were doubtless hatched in the previous June, and were therefore about 16 weeks 
old. They had probably passed from thirteen to fourteen molts. 

It is, therefore, clear that the young lobster varies very considerably in its rate of 
growth, whether under artificial or natural conditions. In a state of nature the young 
lobsters hatched in June are probably from 2 to 3 inches long when 1 year old. (See 
pp. 96-99.) 

I will now add a tabular statement of the successive molts of the adolescent lob- 
sters, whose development has .just been considered. Further details of their history 
are given in table 34. 

Table 35. — Successive molts of young lobsters and their measurements in millimeters. 



No. of lobster. 


Number of molt. 


Date of 

last 
measure- 
ment. 


Age in 
days. 


1 


2 


3 


4 


5 


6 


7 


8 


9 


10 


11 


12 


13 


14 


15 


1 (No. 3, table 34).. 








13 


14.2 


15.5 
16.5 
15 
16.3 


18.4 
19.5 
2 17. 05 
18 


21. 2 
22] 6 
19.75 
21 














Sept. 11 
Aug. 14 
Oct. 5 
Sept. 22 
Aug. 13 
Sept. 22 
Dec. 10 
. do 


107 

79 

105 

94 

80 

294 

2173 

2 173 

2 173 

2 390 


2 (No. 4. table 34) . . 






















3 (No. 37, table 34). 

4 (No. 34, table 34) . 

5 (No. 39, table 34). 

6 (No 38 table 34) 






ii 


'12.5 


13.4 
















2 25 
24 
25 


29. 5 






















28 
26.6 






















18.5 


21.2 












7 (No 17, table 23) 










2 35 
2 36.3 








8 (No 18 table 23) 


i " 






















9 (No. 19, table 23). 
10 (No 22, table 23). 






















251.8 

2 47 


...do.... 
July 18 
























. 



















1 Approximate. 2 Number of molts, length, or age estimated. 

THE MOLTING OF THE EMBRYO AND LARVA. 

The first cuticular structure formed in the egg is a delicate blastodermic mem- 
brane, which appears in the later stages of yolk segmentation and has often been 
erroneously considered to belong primarily to the ovum. It becomes so firmly glued 



THE AMERICAN LOBSTER. 183 

to the primary egg-membrane that any attempt at its removal almost inevitably results 
in stripping oil' the blastoderm with it. It is, however, soon absorbed, or at least 
detached, so that in the early egg-nauplius stages the shelling of the egg is quite an 
easy matter, yet when the egg-nauplius is fully developed the inner layer of the 
capsule invariably sticks to the tips of the antennae, which are usually torn off with 
its complete removal. 

At a stage closely following the egg-nauplius the embryo is inclosed by three dis- 
tinct membranes. I think it probable that the delicate inner cuticle, which can now 
be removed by the aid of hot water without injury to the parts, is a distinct structure 
from the blastodermic membrane just mentioned. The appendages at this time are 
gloved with a cuticular molt, evidently distinct from that which comes off with the egg- 
capsule when the animal is hatched. When eye pigment is formed these envelopes 
are very easily demonstrated, as seen in cut 20, plate F, where they have been distended 
by the prolonged action of picro-sulphuric acid. Up to this time it is therefore probable 
that at least three embryonic molts have occurred. Others follow during the long embry- 
onic life, and, as I have already shown, when the animal is about to hatch it is inclosed 
in a cuticular molt which must be shed before it can enter upon its larval career. 

In the second molt, preceding the second larval stage, the delicate shell is cast 
entire, the only break being, as in the later stages, along the margins of the inner fold 
of the carapace — that is, in the epimeral region of the branchial cavities and next 
the abdomen. The shed cuticula is transparent, colorless, and flexible, and contaius 
little or no lime. The abdomen is usually withdrawn last, as is the case in adult life. 

The cast shell at the fourth molt, which precedes the fourth stage, contains a 
little lime, but no pigment. The fifth ecdysis, which ushers in the fifth stage, is 
more noteworthy. A larva of this period molted in a glass dish on my table in the 
forenoon of July 13, 1892, and was soon attacked by others in the dish and killed. The 
carapace is gradually elevated from behind, and the animal escapes through the open- 
ing thus formed. The calcareous shell, which is of a beautiful light-blue color, retains 
its shape perfectly. The carapace, as early as the fourth stage, has a characteristic 
areolation (see figs. 113 and 115, plate 35) and is covered with short setae. There is a 
wide median stripe or band of absorption which branches into the cervical groove on 
either side and widens at the rostrum. The carapace can be easily split along this 
thin unpigmented area. 

The ecdysis of a lobster in the sixth stage, the color of which has already been 
described (No. 34, table 34), was observed under similar circumstauces. On the 8th of 
August this lobster molted again while I was watching it. At about 9.30 a. in., when 
first examined, the abdomen was drawn away from the thorax, showing a distended 
pink membrane which connects these parts of the shell. Fifteen minutes later the 
carapace was elevated, the pressure of the inclosed body swelling out the mem- 
branes slowly. At 10.24 a. m. the young lobster turned over on its side and in three 
minutes was out of its shell, about an hour having elapsed from the moment when 
the process, already begun, was observed. The eyes and cephalo- thoracic appendages 
are withdrawn first, and when these are free the animal slips away from the old shell, 
the abdomen coming out last, as in the adult lobster. 

The color of the cast shell is blue, with some green and brown pigment ou the 
tergal surfaces. Pigment is now gradually deposited in the outer calcified layer of the 



184 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

shell, which soon becomes wholly responsible for the color of the animal. The dorsal 
median stripe of the carapace is much narrower than when first observed in the fourth 
stage (fig. 115), and the areas of absorption of lime salts from the lower segments 
(meros and ischium) of the large chelipeds are clearly outlined. The molting and 
growth of the adult animal are fully discussed in Chapter in. 

COLOR VARIATIONS IN THE YOUNG LOBSTER. 

In the description of the larval stages just given I have purposely dwelt upon the 
color changes which the young animal undergoes. This is intended to supplement 
the previous observations upon the color variations of the .adult. To sum up these 
detailed accounts, we find that the color of the first four larval stages is subject to 
considerable individual variation, due to the transparency of the shell and the con- 
tractility of the chromatophores which lie beneath it. In the first larva the pigment 
cells are relatively few, and respond to the slightest stimulus. With the growth of 
the animal they become very numerous, more differentiated, and so commingled that 
a very varied color pattern results. It is probable that in these stages their chief role 
is a physiological one. A transparent and almost colorless larva swimming at the 
surface of the ocean would undoubtedly be safer than a brilliantly colored one, but the 
indiscriminate destruction of these larvae is so great, both on the part of animate 1 
and inanimate foes, that such protection would count for little. That it really counts 
for nothing is shown by the fact that the fourth larva (also a pelagic animal) is almost 
invariably richly colored and is far more conspicuous at the surface than it would be if 
colorless. Again, it is not likely that larvae know any such thing as fear, and the 
chromatophores appear to expand under any unusual stimulus. 

The color variations of the larva are the expression of physical and chemical 
changes taking place in the body, as the result, for the most part, of physiological 
conditions. Some of these changes are sudden or discontinuous, and have no adaptive 
or protective significance. 

After the fourth molt pigment begins to appear in the chitinous shell and a com- 
plicated color pattern is gradually produced which, as I have already shown, has, in all 
probability, a protective value. This happens when the young animal has given up 
its pelagic life and lives upon the sea bottom, having essentially the characters of 
the fun -grown mature form. 

The color variations of the adult are discussed in Chapter vin. 

THE DEATH-FEIGNING HABIT. 

It was a matter of no little surprise to find that young lobsters in the fourth and 
fifth stages sometimes exhibit in a striking degree the remarkable phenomenon known 
as "feigning death." It is not strictly a habit, since it does not appear in all larvae. 
Some display it upon the least provocation, the greater number but seldom or not 
at all. I have observed the same thing in a lobster over a year old, but have seen no 
trace of it in the adult. 

A young lobster to which I have already referred (No. 36, table 34) when examined 
two days after the fifth molt showed this peculiarity in a typical way. When stroked 
lightly with the finger it would immediately stiffen, and lie stretched out at the bottom 



1 Such as herring, mackerel, and menhaden, which from their peculiar habits of straining water 
*br food can hardly fail to he great destroyers of crustacean larvae. (See note on nienhaden, p. 122.) 



THE AMERICAN LOBSTER. 185 

of the dish, ou its side or back, as if paralyzed. Its appearance is now, however, 
very different from that of a dead animal. The large chelipeds are stretched forward 
in front of the head, and the other thoracic legs are drawn after them and held close 
together with their tips pointing forward. It usually remained in this position from a 
quarter of a minute to a minute, when it would slowly orient itself and begin to move 
about, in a short time becoming very active. This lobster on one occasion remained 
in this stiffened, apparently paralyzed condition for the space of eight minutes, and 
would have continued in it a longer time still had it not been aroused. 

While lying at the bottom of the dish in this state, a convulsive movement 
of the swimmerets was detected and a twitching of various muscles over the body. 
The appendages sometimes quivered, as if the muscles were in tetanic contraction. The 
chelipeds and other walking legs remained perfectly rigid. When the animal finally 
recovered, the thoracic appendages were gradually relaxed and, putting itself in a 
defensive attitude, it slowly swam off. 

If water is squirted at it with a pipette it will sometimes roll over and immedi- 
ately straighten out as if dead. When disturbed and treated roughly with the finger 
or a penholder, it stiffens in the same way; the abdomen is bent up slightly; all the 
appendages are straightened out; the swimmerets are bent backward and can be seen 
to quiver ; the beating of the scaphognathite does not cease. 

I have no doubt that this phenomenon is strictly analogous to the " shamming 
death" of insects, but it is neither a habit nor an instinct. It is, perhaps, the raw 
material, so to speak, out of which useful instincts are developed in some animals. 
According to Darwin, there is great variation in the degree in which this instinct is 
manifested in insects. He observed " a most perfect series, even within the same genus 
(Ourculio and Chrysomela), from species which feign only for a second and sometimes 
imperfectly, still moving their antennae (as with some Histers), and which will not 
feign a second time however much irritated, to other species which, according to De 
Geer, maybe cruelly roasted at a slow fire, without the slightest movement — toothers, 
again, which will long remain motionless, as much as twenty-three minutes, as I find 
with Chrysomela spartiiP In seventeen different species which he observed, including 
an lulus, a Spider, and Oniscus, "both poor and first-rate shammers," he found that 
"iu no one instance was the attitude exactly the same, and iu several instances the atti- 
tudes of the feigners and of the really dead were as unlike as they possibly could be." x 

Romanes, in his Mental Evolution in Animals, has treated the subject of feigning 
death very fully, and has collected some very interesting facts. Two observations 
upon the Crustacea are quoted, one of Bingley upon the "common crab, which, when 
it apprehends danger, will lie as if dead, waiting for an opportunity to sink itself into 
the sand, keeping only its eyes above it," and one by Preyer, who is said to have made 
crayfish "stand upou their heads while in the hypnotic state"! Romanes agrees with 
Preyer in attributing the shamming death in insects to "kataplexy," or mesmeric sleep 
(in many cases the physiological effect of fear), but gives some remarkable cases among 
vertebrates in Avhich it seems almost equally probable that there is intentional purpose 
to deceive. 

The "shamming dead" in insects and Crustacea which leads simply to quiescence, 
and thus to their becoming conspicuous in the presence of their enemies, had been 



'Chapter on Instinct written for The Origin of Species. See Appendix to Mental Evolution 
in Animals, by George John Romanes, p. 364. 



186 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

intensified, as Darwin believed, through the agency of natural selection. It is evident 
that no such instinct could thus arise in pelagic animals, "where the cessation of the 
natural movements through hypnotic or other influences would lead to vertical down- 
ward motion by the action of gravity, unless such movements were of decided benefit. 
It may be significant that the phenomenon is seen for the first time in the lobster 
when it is about ready to sink to the bottom and assume the adult habits. I have not 
examined a sufficiently large number of the adolescent lobsters, from 1£ to 3 inches 
long, to say how commonly they exhibit this peculiarity. I believe, however, that it is 
in this case a sporadic phenomenon, which has not at present become a habit. It is 
not easy to see, moreover, how. in the environment of these animals, where so many 
of their enemies are scavengers or omnivorous, it could be of much service, to its 
possessor when finally established on the bottom. 

THE FOOD OF THE LARVA. 

The food of the larval lobster must necessarily consist for the most part of minute 
pelagic organisms, such as copepods and crustacean larva?. When watched in con- 
finement they may now and then be seen giving chase to copepods, sometimes larger 
than themselves, and often without success. 

The young lobster, however, shows little discrimination in its food. It seems to 
snap up almost any moving object, living or dead, which it is able to seize and swallow. 
Thus I have found in the stomachs of the older larvae vegetable fibers, the scale of a 
moth or butterfly, and fine granules of sand. 

On June 17, 1893, I examined the stomachs of a number of larvae (raised in 
aquaria) 13 to 14 mm. long, probably in the fourth and fifth stages, and found them to 
contain the following substances: (1) diatoms in abundance, chiefly Navieula and the 
long tangled ribbons of Tabelaria; (2) remains of Crustacea, probably parts of young 
lobsters; (3) bacteria in large numbers; (1) cotton and linen fibers and parts of alga?; 
(5) amorphous matter, with sand grains. The sediment of the jar contained the same 
species of diatoms in abundance, and amorphous debris similar to that found in the 
stomach and intestine. 

The stomach of a larva captured in Vineyard Sound August 12 (length 15 mm.) 
contained the following organisms: (1) parts of crnstacea; (2) diatoms; (3) shreds of 
algae. In another young lobster taken at the same time (length 17 mm.) there were 
(1) parts of Crustacea, (2) large numbers of diatoms, (3) filaments of green algae and 
thin sheets or shreds of vegetable tissue, (4) the scale of a lepidopterous insect, (5) 
bacteria, (6) amorphous matter in large masses. 

Messrs. Weldon and Fowler (201) came to the following conclusions after experi- 
menting with different kinds of food which were thought might be acceptable to the 
larvae : 

It was definitely concluded from these experiments that whatever food is used must he floating in 
the condition of small particles at a short distance below the surface, i. e., in the same position as the 
natural pelagic food of the larvaj of the sea, whether this consist of G'opepoda, other Decapod larvte, 
trochospheres, fish ova, or other members of the pelagic fauna. As to the other two forms of food tried, 
the Noctilucaj were apparently eaten, the shrimp larvae (Mysis stage) certainly were attacked, and 
from the fact that the young lobsters attack and devour each other it is prohable that Decapod larvae 
form at any rate part of the usual food. The contents of a tow net taken near the Eddystone on 
August 6, which held a young lobster, consisted chiefly of Megalops and Mysis stages of Decapoda. 



THE AMERICAN LOBSTER. 



187 



The yolk of bard-boiled eggs, crushed crab, boiled liver, tow-net material, Doctilucae, 
copepoda, and live shrimp larva', were all partially, but none absolutely, successful as 
a food supply. 

The self-destructiveness of the young lobsters when too closely crowded in aquaria 
has already been referred to. When one lobster attacks another under these con- 
ditions the pursuer usually endeavors to get astride of his victim and nip into the 
abdomen at its junction with the carapace with its sharp-pointed prehensile legs. 
When the object is too heavy to float, such as the egg or larva of the lobster, they 
frequently go to the bottom; but if the animal is healthy it will be usually seen swim- 
ming about the aquarium dragging its prey with it and feeding upon it as it goes. 

HELIOTROPISM OF LARVAL LOBSTERS. 

During the past six summers which I have spent at Woods Hole, 1S89-1894, 1 bave 
been struck with the scarcity of the larvoe of the lobster in the waters of Vineyard 
Sound. The tow net has been frequently used both by day and night, and 1 have 
made many unsuccessful trips in search of young lobsters in the season when one 
would expect them to be common. Thus, on July 11, 1891, 1 towed all around Gay 
Head, a mile beyond the Devils Bridge buoy, and in Vineyard Sound. We found 
only copepods, sagitta, young fish, and fish eggs. The day was bright and the water 
had been calm for two days. The prevailing winds had been from the northeast. At 
Menenisha we obtained one lobster with eggs hatching out, but the fishermen reported 
that very few lobsters with old eggs were then taken; that is to say, the hatching 
season was about over. 

I had a similar experience on July 1G. The water was smooth; the wind had 
been southwesterly for four or five days. There was very little surface material, a. 
few barnacles, megalops and sagittas. 

The following is a list of all the lobsters taken at the surface of the ocean during 
the six seasons mentioned — the capture was made in the daytime unless otherwise 
stated : 



Date. 



Observations. 



July 9,1889 
July 8, 1890 
July 9,1890 
July 16,1890 

July 24,1890 
July 28,1890 
Aug. 23, 1890 
July 1, 1891 

June 29, 1892 
June 29, 1892 
Aug. 15, 1892 



One lobster (fourth or fifth stage) at surface of harbor. 

One lobster, length 15 mm.; captured with tow net, in harbor, in the evening. 

Five lobsters, 15 to 16 mm. long; taken by R. P. Bigelow aboard the Grampus, at station 32.' 

Two lobsters in sixth stage, 16 niiu. long; taken with dip net close lo wharf of U. S. Fisli 

Commission Station. 
One lobster. 16 mm. long; taken with tow net in harbor. 
One lobster, 15 mm. long; taken with tow net in harbor. 
One lobster, 16.5 mm. long; taken with tow net in harbor. 
One lobster in sixth stage, 18 mm. long; taken at surface 7 miles southwest of No Man's 

Land. 
One lobster in third larval stage; taken at surface, near wharf. 
One lobster in fourth larval stage ; taken at surface near wharf. 
Young lobsters, probably in fifth and sixth stages, seen at surface of Vineyard Sound by 

Professor Libbey. 



* Location, latitude 41° N., longitude 71° 9' W. Observations made by Professor Libbey, July 12, 1890, 
10.47 a. in. Surface temperature 63.8° F. ; bottom temperature, 54.1° P. 

Larvne in the first stage have been taken in Vineyard Sound as early as June 3. 
Lobsters in the fourth stage were captured by Vinal N. Edwards, August 12, 1S87. 
Young lobsters (stages not determined) were also taken by him in Woods Hole Harbor, 
Vineyard Sound, and in the vicinity of Gay Head, in the mouth of July, 1888. 



188 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Surface towing was done at the following places in the same year without obtain- 
ing any lobsters: August 1, 17, and IS, Vineyard Sound; August 23, off Cuttyhunk; 
August 27, 30, 31, Woods Hole Harbor. 

Professor S. I. Smith says of the young lobsters which he obtained in Vineyard 
Sound in the summer of 1871, that numerous specimens "were mostly taken at the 
surface in the daytime, either with the towing or hand net" (182). Of the older pelagic 
stages he says: 

They appear to live a large part of the time at the surface, as in the earlier stages, and were often 
seen swimming ahout among the surface animals. They were frequently taken from the 8th to the 28th 
of July, and very likely occur much later. 1 

We know that lobsters are now far less abundant around the Elizabeth Islands 
than they were twenty years ago, and we should expect to find that the young had 
diminished in a proportionate degree. Millions of larvae, however, must still be 
hatched in Vineyard Sound and adjacent waters every year. What then becomes of 
them? I believe that they are eaten up by surface-feeding animals, principally fish, 
or meet their death from indiscriminate causes. The tides tend to disperse the young 
over a wide area, thus carrying them to and from the shores. Horizontal distribution 
alone would not account for the extreme scarcity of the young in Vineyard Sound at 
the present time. If, however, there were a corresponding vertical distribution, the 
conclusion which we have reached would not be warranted. It thus becomes a matter 
of much interest to determine the heliotropism of the larva?, or the law which governs 
their vertical movements in the water. 

The results of my observations and experiments with larva? lead me to conclude 
that the young, free-swimming lobster usually displays what Loeb has called positive 
heliotropism (125) — that is, it tends to swim toward the light or near the surface iu the 
daytime. The conclusion therefore which we stated above, that the absence or extreme 
scarcity of young lobsters in a region where the adults still abound is due to their destruc- 
tion, is supported by experimental testimony. The bearing of this fact upon the artificial 
propagation of lobsters I have discussed in an earlier paper (see 97). 

I will add a few notes upon the experiments which were made to test the helio- 
tropism of these larva?. 

Experiment 1. — On June 27, 1894, 1 placed about 25,000 young lobsters, in the first 
larval stage, in the observation pool at the Fish Commission Station, to watch their 
behavior. The sun was intermittently obscured by clouds during the greater part 
of the forenoon. When liberated, the larva? formed a large cluster near the surface, 
where they remained for a short time. Then all went down to a distance of from 1 
to 2 feet, some apparently reaching the bottom, a distance of 3 feet more. A lot of small 



'With reference to this subject, Professor Smith has kindly written in detail substantially as 
follows : "All the larva 1 captured in Vineyard Sound and neighborhood in 1871, on which my papers 
were based, were taken in the 'daytime.' My notes usually give only 'day,' or 'evening' for time 
of capture, but the larvae of my first and second stages, taken July 1, are marked 'forenoon.' 
Since 1871 1 have many records of first and second stages taken in the 'day' and, as far as I can find 
now, only two cases of capture in the 'evening,' and one of these cases was when the electric light 
was used in the water to attract the surface forms. The young in the adult form [equivalent to fourth 
and possibly fifth and sixth stages described in this work] were, however, often taken in the evening 
and were almost always attracted by the electric light. In my experience the young of the adult 
form were much more frequently taken at the surface than the larvae." 



THE AMERICAN LOBSTEK. 189 

cunners then made their appearance and snapped up the larvae right and left. Two 
hours later the lobsters were diffused over the whole surface of the pool, a large num- 
ber of them swimming close to the surface. The paler larva?, with chromatophores 
contracted, can not be easily distinguished at a distance of a few feet, but when one 
of their eyes is turned at the right angle it glows, like a minute electric spark, with a 
greenish light. At 1 p. in. the surface on the lee side of the pool swarmed with larva'. 
Occasionally one cotxld be seen to attack and drag another down. They swim about 
aimlessly with considerable rapidity, now rising or falling, and changing their direction 
frequently. The majority had now become quite red. Later in the afternoon nearly 
all had disappeared, having been swept out by the tide or destroyed by the dinners 
and other lish in the pool. 

Experiment 2. — On July 13, 1894, 1 placed a number of larvae, mostly in the first 
stage, in a glass dish, next to the window in the hatchery. The larva? immediately 
gathered on the side of the dish nearest the window. Turn the dish slowly through 
an angle of ISO degrees, and the lobsters invariably flock toward the source of light. 
This may be repeated indefinitely, but always with the same result. 

Experiment 3. — A box was made with blackened sides, so that when a glass jar 
was set in it vertically, with its upper end exposed, ligh could enter only from above. 
When larva? were placed in this, the stronger always rose toward the source of light 
into the illuminated zone. Some, however, apparently the weaker ones, remained below. 

Experiment 4. — A light-proof box was then constructed with sliding lid and end, 
so that a long, closed jar could be laid in it horizontally. When the lid was removed, 
the larva? swam up to the surface in different parts of the jar. When the diffused or 
direct sunlight was admitted only at the end the larva? invariably flocked toward the 
illuminated end and remained there. If any lagged behind, it was because they were 
too weak to swim. 

These simple experiments 1 seem to show conclusively that under ordinary circum- 
stances the larva? of the lobster are positively heliotropic. I made no experiments on 
the effects of changing the temperature conditions. The temperature of the water 
used was the same as that of the water running through the aquaria, or about 1° 
higher than the water temperature of the harbor (see table 2). 

The second experiment was tried in the summer of 1893 with the reverse result, 
the lobsters swimming away from the source of light, showing possibly that under 
certain conditions the larva? are negatively heliotropic (97, p. 82). This experiment is, 
however, the least trustworthy of all, since there are al ways cross lights in a room and 
the conditions are consequently changing. Professor Eyder found that under similar 
circumstances the larva? gathered on the side nearest the source of light 2 (172). 

The general conclusion reached, that larva? swim up to the surface during the day- 
time and stay there, probably sinking at night and rising again with the approach of 
light on the following day, is supported by the record of the capture of larva? which 
I have already given. The taking of larva? at night seems to be the exception; their 
capture by day the rule. 

■In the course of these experiments I had the advantage of consulting with Professor Loeb,to 
whose researches our knowledge of heliotropism in animals is very largely due. 

- He also says : "At night, or if light is shut off, the young lobsters go to the bottom of the tanks ; 
and it seems they may then be most actively engaged in feeding if food is placed within their reach." 



190 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

THE MORTALITY OF LARVAE. 

The following notes illustrate the difficulty of raising the young of the lobster 
in close quarters. Old eggs were always placed in the jars, but even when the water 
was agitated so that these were floated, the young invariably preferred to feed on one 
another. The death rate, however, is due in part to other causes besides cannibalism. 

On July 2d, 1893, 130 larvae in the second stage were placed in a 4-gallon jar and supplied with 
running water. On July 3d, 108 were alive ; on July 4th, 96 ; July 5th, 89, 3 of these in the third stage ; 
on July 6th, 63 were alive, 47 of these having molted for the third time. In the course of four days 
48 per cent had succumbed. 

On July 1st, 100 second larva; were placed in a hatching jar. On July 2d, 82 were living; July 
3d, 73; July 4th, 64, 2 of these having molted to the second stage; and on July 5th, 50 were alive, 24 
in the third stage. The third larvae, 26 in all, were left in this jar, and on July 6th 24 were alive; on 
the following day only 6. 

June 29th, 1893, 1 placed 12 lobsters in the first larval stage in four flat glass dishes (3 to a dish). 
By the 1st of July 10 were alive, 4 in the second stage; on July 5th 7 were living, all in the second 
stage, and July 6th 1 second larva only was alive. 

July 6th I placed 6 iirst larvae in two flat dishes (3 to a dish) with lobster eggs for food. Each 
lobster was 8 mm. long. On July 7th 2 in one dish were alive, both in second stage and devouring 
the remaining larva; no change in the other dish. On the 9th, at 9 a. m., 4 were alive, 3 in the third 
stage and 1 in the first. 

I placed 4 third larvae in a hatching jar on the 7th of July. All were living on the 13th, and on 
the 15th 3 were alive, having molted to the fourth stage. The smallest had been attacked by the rest 
and its thoracic legs were eaten off. I left 2 fourth larvae in the jar, both of which were in the fifth 
stage on the 27th of the month. 

THE EFFECT OF INCREASED TEMPERATURE ON THE RATE OF DEVELOPMENT 

OF THE LARViE. 

The following experiment is interesting in showing how the rate of development 
is affected by raising the temperature : 

July 1st, 1893, I placed 100 first larvae of the lobster in a hatching jar, with food, and heated the 
water by means of a block-tin coil to 74° F. The water in the aquaria at this time registered 66.9° 
and that of the harbor 66°. 

July 2d, 9 o'clock a. m., 56 were alive. Some were weak and lying on their backs at the bottom, 
an easy prey of the strong. 

July 3d, 9.30 a. m., 56 alive, not looking healthy, many with air bubbles in branchial cavities; 
temperature raised to 78°. 

July 4th, 41 alive, 28 in second stage, 13 in third stage. 

July 5th, 24 alive; left third larvae, 18 in all, in jar. 

July 6th, 7 alive; temperature of water 80°. 

July 7th, all living, another in fourth stage; left 6 third larva? in jar. 

July 8th, all alive, 3 molted to fourth stage. One fourth larva had one blind eye; the eye was 
small and pigment deficient. All left in jar. 

July 11th, all alive, 4 in fourth stage, 2 in third stage. 

July 13th, all alive; no change; temperature 79°; left 3 larva; in fourth stage in jar. 

July 15th, 2 alive. 

July 17th, both living; temperature 79°. 

July 19th, both living; temperature 78 c . 

July 21st, both living; temperature 75°. 

July 30th, one alive; temperature 78°. 

August 2d, one alive, in fifth stage (length 13 mm.) ; temperature 79°. 

August 5th, last one dead. 

We see that with a rise in temperature of from 7 to 13 degrees the third molt was 
passed in about 5 days, which is not far from the average age of these larva? reared 



THE AMERICAN LOBSTER. 191 

under the usual conditions. The fourth stage was reached when the larva was !) to 11 
days old, the average age under normal conditions being about L3 days. The only 
fifth larva reared was from 33 to 34 days old, which is nearly twice the age of this 
larva living under the usual temperature conditions. If the larva} had been less 
crowded in the early part of the experiment, and if the temperature of the water 
had been raised very gradually, without fluctuations, it is possible that the results 
might have beeu more favorable than they proved to be under the circumstances. 
This would require considerable care and close watching, but the experiment, as 
performed, seems to demonstrate the impracticability of making such attempts. 

The development of the embryo can be hastened by artificially raising the tem- 
perature, but it is not certain that any advantage would attend the practice. Bumpus 
suggests (30) that if the young were hatched by artificially raising the temperature 
of the water during the cold months of the year, aud were then liberated into the 
ocean, they would be certain to escape the attacks of many summer enemies. This is 
undoubtedly true, but it is almost equally certain that the young lobsters would 
encounter new enemies in winter and that indiscriminate destruction, which must be 
very great at any time, would then be enhanced. 

THE DEVELOPMENT AND MORPHOLOGY OF THE BODY AND APPENDAGES. 

It was my original intention to trace in detail the development of the form of the 
body and its appendages, but I have not been able to devote as much time as I had 
wished to this subject. With this in view, however, I have given a pictorial history 
of the development of the most important parts, which will be fouud chiefly on plates 
27-35. 

Professor Smith has already described the tegumentary appendages of the first 
three larva' and the "early stages of the adult form," which, as I have shown, compre- 
hend the fourth, fifth, and in some cases the sixth stages. In describing these I shall 
avoid repetition as far as possible, and pay most attention to those parts upon which 
few or no observations have been made. 

THE BODY. 

The carapace. — The carapace arises in the embryo as folds of the ectoderm, the 
lateral and posterior parts being the first to appear (cut 34 and fig. 234). In the first 
larva it has the form shown in fig. 110, plate 35. It is somewhat gibbous behind, and 
is armed in front with three downwardly directed processes, a median, slender, sharp- 
pointed rostrum, and two lateral teeth. There is also a keel-like process on the middle 
line near the base of the rostrum. The latter is nearly as long as the rest of the 
carapace. The position of the future cervical fold or groove is very faintly marked. 
In the second and third larval stages the rostrum becomes expanded horizontally into 
a thin plate with toothed margins, but increases very little in length (figs. 109, 111, 
112). 

In the fourth larva (figs. 113, 115, plate 35) the cervical groove is well developed; 
the rostrum is a thin, triangular plate, bordered with spines and plumose seta?. The 
terminal spine is usually bifid at its apex, carinate below, and turned slightly upward. 
The length of the rostrum is now but little more than one-third that of the entire cara- 
pace. The anterior lateral spines are much reduced. Tendon marks now make their 
appearance, but are more pronounced in the fifth and sixth stages (fig. 114). Areas of 
absorption, corresponding to the median longitudinal stripe, the "welt" and lateral 



192 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



bright blue areas of the carapace of the adult lobster are clearly seen. The flue trans- 
verse hair line, just above the cervical groove, behind the second antenna, can also be 
detected. The cross-shaped figure seen on the upper surface is formed by the wide 
median absorption area and the cervical groove with which it is continuous on either 
side. Besides the fringing hairs, the whole surface is covered with short setae which 
correspond in some measure at least to the hair pores of the adult carapace. In 
certain cases some of these changes, as in the relative lengths of the rostrum and 
anterior lateral spines, are far less marked. The anterior median carina is not promi- 
nent after the third stage. 

The carapace of the fifth stage is illustrated in fig. 114. The characteristic tendon 
marks, which have been described, are very conspicuous. The rostrum is narrower 
and in the sixth stage is about one-fourth the length of the entire carapace. 

In a young lobster 35 mm. long, which had molted about twelve times, the shape 
and areolation of the carapace were very similar to that of the adult. 

The abdominal segments. — In the first larva (plate 20) the abdomen has its full 
number of segments. The first is unarmed and partially covered by the carapace. 
The second, third, fourth, and fifth somites bear early a prominent median spine, which 
projects upward and backward from the posterior end of the tergum. Each of these 
segments also bears upon either side a long, sharply pointed pleural spine, which 
projects backward. 

The median spines, of which the last two are the longest, are gradually reduced 
during subsequent stages aud finally disappear at the fourth molt. Meantime the 
pleural spines become shorter, shift their position slightly, and in the fourth larva 
point downward. 

The disappearance of the median dorsal spines is, however, not uniform, but 
subject to considerable variation, as shown by the following observations upon eleven 
larvae in the second and third stages. 



Table 36. — Variation in time of disappearance of the median tergal spines of the larval abdomen. 



No. of 

larva. 


Stage of development. 


No. of abdominal somite. 


2 


3 | 4 j 5 


1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 




End. 
Eud. 





1 
Eud. 







Eud. 


1 
1 
1 
1 

1 
1 
1 
1 


1 


1 
1 
1 
1 
1 
1 
1 
1 
1 
1 
1 


1 
1 
1 

1 
1 
1 
1 
1 
1 
1 
1 


do 


...do 


do 




do 


. do 


do 


... .do 


do 


do 









rud. — spine rudimentary. 1 = spine present. 



: spine absent. 



We see by the preceding table that the median spine of the second abdominal 
segment may entirely disappear at the second molt or persist in either a rudimentary 
or perfect condition even after the third ecdysis, while the spine of the third somite, 
though usually present, is sometimes absent in the third stage. (Nos. 5, 10.) 

The sixth abdominal somite bears at its posterior margin a pair of dorsal spines 
on either side of the middle line. These curve backward over the telson, and are 
much smaller than the median spines (fig. 33, plate 20). They disappear at the fourth 
molt. 



THE AMERICAN LOBSTER. 



193 



The respiratory organs.— In the adult lobster there are twenty pairs of gills, oue 
of which, belonging to the second pair of maxillipeds, is rudimentary. There are 6 
podobranchise, 10 arthrobranchiae, and 1 pleurobranchiae, distributed according to the 
followiug table: 

Table 37. — Branchial formula. 



Thoracic segments and appendages. 


Podo- 
branclriae. 


Artbrobrancliiaj. 


Plouro- 
branckiae. 


Totals. 


Anterior. 


Posterior. 


VII, first maxilliped 


0(ep.). 

liud.(ep.). 
1 (ep.). 
1 (ep.). 
1 (ep.). 
l(ep.). 
1 (ep.). 





1 
1 
1 
1 
1 






1 
1 
1 
1 
1 









1 
1 
1 
1 


(ep.). 

1 rud. (ep.). 
3(ep.). 

3 (ep.). 
4(ep.). 
4(ep.). 
4(ep.). 
1 


VIII, second maxilliped 


IX, third maxilliped 












Total 


6 (ep.). 


5 


5 


4 


20(1 rud.). 



ep. = epipodite. 



rud. = rudimentary. 



The first larva has no rudiment of a podobranchia in the eighth somite, but all 
the other branchiae are represented. The podobranchise of the following segments are 
very small and are partially exposed, together with their reniform epipodites. In the 
second larva the podobranchia are covered by the carapace (plate 21) and the branchial 
formula is complete (fig. 101, plate 31). 

The gills are developed in the embryo as simple folds or pouches in the body 
wall. 1 They belong to the trichobranchiate type, the respiratory surface being gradu- 
ally increased by growth of the multiserial branchial filaments. 

In the fourth larva (fig. 106, plate 31) the podobranchia carries four rows of 
filaments, and the mastigobranchia, or epipodite proper, is a long, tapering, hairy 
plate. 

THE VISUAX, ORGANS AND APPENDAGES. 

The ocellus.— The median eye, which is present in the first larva, is situated at 
the apex of a prominent median papilla, between the paired eyes and anteunules. It 
is marked by a pear-shaped mass of dark pigment. It disappears in the course of 
larval life, and no trace of it can be seen in the adult. The ocellus was observed by 
Sars (175) in the first larva of Homarus gammarus. 

The paired eyes.— The compound or lateral eyes originate in the embryo as disk- 
shaped thickenings of ectoderm, and do not become lobate until a relatively late period 
(cuts. 27-34). 2 In the summer eggs eye-pigment is developed when the embryo is 
about 27 days old. It then appears as a thin line or crescent-shaped area, when seen 
from the surface. The eye-spot increases gradually in size, and its characteristic 
shape affords a convenient gauge to measure the embryonic development. (Plate J.) 

In the first larva the eye is relatively very large. It is dorso-ventrally compressed 
or flattened, as in the embryo and in all subsequent stages. The stalks are propor- 
tionally shorter than in the fourth larva, and since they nearly meet in the middle 
line in front of the brain, they are practically sessile and immobile. 



1 For an account of the development of the Decapod gill see 94, p. 392, figs. 193, 230-233. 

2 The structure and development of the compound eyes of the lobster have been carefully worked 
out by Parker (149), 



F. C. B. 1895—13 



194 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



The following measurements show the greatest diameter of the eye and the length 
of the eye-stalk, as compared with the length of the body, in the first and fourth larvae, 
in a lobster 58 mm. long (No. 5, table 32) and in an adult male: 



Table 38. 



Measurements. 



Greatest diameter of eye 

Length of eye-stalk 

Length of body 

Ratio of diameter of eye to total length 
of body 



First 


Fourth 


No. 5, 


Adult 


larva. 


larva. 


table 32. 


male. 


mm. 


mm. 


mm. 


mm. 


0.74 


0.8 


3 


7 


.92 


1.2 


3.3 


10 


8 


14.5 


58 


264 


.092 


.055 


.052 


.026 



The diameter of the eye, expressed in terms of the total length of the body, is 
much greater in the first thau in the fourth larva, but is relatively twice as great in the 
latter stage or in a lobster 2 inches long as in the adult condition. (See p. 163.) 

Labrum and metastoma. — Both the upper lip and paired metastoma have in the 
first larval stage (fig. 54, plate 28) the general form and appearance which they finally 
possess. The surfaces of the latter abound in setae. What look like setae occur also 
on the labrum, but none are present in the adult organ. (See p. 133.) 

First antenna. — The first antenna is a simple appendage up to the time of hatch- 
ing. In an embryo about four months old (fig. 107, plate 35, and fig. 27, plate 17) 
it is tipped with short setae and shows no trace of segmentation. When the embryo 
is five weeks old the first antenna has the appearance shown in figure 77. In the 
first larva this appendage is no longer simple, as described and figured by Smith (182), 
but the inner, secondary flagellum (plate 27, fig. 40) is present, though a small rudi- 
ment, and bears at its apex a single plumose seta. When the stalk is examined from 
the under side we can detect traces of segmentation into three parts, but on the upper 
surface the proximal cuticular fold only can be seen. The appendage terminates in a 
small bunch of setae, one of which is conspicuous for its leugth. It is possible that in 
some cases the flagellum is not liberated until after the second molt, as described by 
Professor Smith, but none such were observed. These appendages are immobile in 
the first larval stage. 

The superficial changes which take place in this appendage during the first five 
larval periods are illustrated in plate 27, and will not be described in detail. 

In the second larva the segmentation of the stalk into three joints is sharply 
defined and the flagella show faint constrictions. The clusters of olfactory setae, which 
increase in length and number with every molt, are developed during the first larval 
period and appear full-fledged immediately after the second molt. 

The auditory pit becomes prominent after the third stage. In the fourth larva 
(fig. 43, mi) it is a wide and shallow, -shaped depression, marked with brown pigment 
cells, bordered with short setae, and containing a few otoliths or granules of sand. In 
the fifth larva (fig. 44) the closure of the auditory sac has already begun. The j)it is 
filled with otoliths and the irregular orifice is guarded by short, feathery setae. The 
constriction of the opening continues until in the adult state it becomes a small pore, 
into which it is barely possible to insert the point of a pin. 

The first antenna of the European lobster, as represented by Sars (175, tab. I, 
fig. 4), agrees essentially with that of Homarus americanus, but the secondary flagellum 



THE AMERICAN LOBSTER. 1!)5 

is more rudimentary. The arttennular nerve was traced by Sars toward the end of 
the appendage, where it appeared to divide into two branches. 

Second antenna. — The outer antenna of the first larva (fig. 45, plate 27) consists 
of three parts, which are represented in the adult (fig. 118) — a two-jointed stalk, a 
segmented endopodite, and a scale like exopodite, terminating in a sharp tooth and 
bordered on its inner margin with long plumose hairs. 

This is the first of the naupliar appendages to become bilobed (cut 30). In an 
embryo four months old, fig. 108 (compare fig. 77), the cuticular molt shows the traces 
of only a few terminal setae on either branch. 

The progressive changes in the second antenna during the first five larval periods 
(figs. 45-49) consist mainly in the reduction of the scale and its feathered setae, in the 
rapid growth and segmentation of the slender endopodite, and differentiation of the 
latter into stalk and flagellum proper, and in changes in the stalk or protopodite. In 
the fourth larva (fig. 48) the first segment (coxa) : of the latter bears a prominent tubercle 
(already conspicuous in the third stage), on which the duct of the excretory organ 
opens, while the second segment or basis is divided by oblique constrictions into three 
parts, as in the adult lobster. The external division bears, next the articulation of 
the scale, a stout spine which grows with the gradual reduction of the exopodite until 
it finally nearly equals the latter in length. The terminal seta; of the flagellum are 
rapidly reduced and are barely recognizable in the third larva. 

The mandibles. — The jaws of the first larva (fig. 54) consist of a stout basal portion, 
with toothed, indurated, coronal surfaces, meeting on the middle line opposite the 
mouth, and of a slender, three-jointed palpus, which terminated in the specimen fig- 
ured in a single strong seta. The cutting edges are asymmetrical, and at the anterior 
angle there is a stout, variously toothed process which is separated from the rest of 
the coronal surface by a deep groove. As Professor Smith observed, this is most 
prominent on the left side. 

In the third larva the asymmetry of the coronal surfaces is even more striking, 
particularly in the toothed process on the outer side at the anterior end. On the left 
side this forms a widely overlapping fold, which carries three sharp teeth. The process 
of the right side is smaller, but had also three teeth in the specimen examined. 

In the fourth larva the mandible is deeply cleft by a wide groove, as in the adult 
(figs. 55-57), and the brush-like palpus folds over the cutting margin into the fossa. 

In the fifth stage the mandibles are still asymmetrical, and the teeth are no longer 
sharp but tubercular, the smaller being at the posterior angle. The stout-toothed 
process of the first larva remains as a blunt tubercle on the left side, where it was 
most prominent, but has disappeared from the right side. 

First maxilla. — The metamorphosis of this appendage from the larval to the adult 
condition is relatively very slight. It consists in the first larva (fig. 51) of coxa, basis, 
and a one-jointed endopodite. All are armed at their extremities with setae of various 
kinds — slender, sensory hairs on the outer segment, a double row of stout masticatory 
teeth on the basis, and a cluster of less regular, distinctly serrated, stiff bristles at 
the extremity of the coxa. 

1 The following abbreviations for the segments of the decapod limb will be used: (1) coxa = cox- 
opodite; (2) basis — basipodite; (3) iscft.iitm=iscliiopodi.te; (4) ?neros = meropodite; (5) carpus = carpo- 
dite; (6) propodus = propodite ; (7) dVictyZ = dactylopodite. 



196 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

In the iourth stage (fig. 61) tlie endopodite is two-jointed, "and is tipped with two 
nonplumose setae. A few hairs occur at the distal articulation on the inner side and 
a larger number at the base on the outer side. The other branches have more of the 
configuration and character of the adult state. 

In the fifth stage (fig. 02) the terminal segment of the endopodite is folded back 
toward the basal joint and bent somewhat as in the adult. The inner margin of the 
proximal segment has scattering setae, and those on the outer side near the base now 
form a dense bunch, most of which are feathered. The tegumental glands, which later 
are so abundant in the foliaceous parts of the maxillae, can now be distinctly seen in 
at least the basis. 

Second maxilla. — The structure of the second maxilla of the first larva is repre 
sented by fig. CO, plate 29. It consists of two biramous lobes, the coxa and basis, the 
respiratory plate or "bailer" and median endopodite. The masticatory setai are some- 
times jointed and but sparsely plumose. The long sensory seta of the endopodite is 
also marked by transverse constrictions and has a few lateral hairs, while the fringing 
seta3 of the scaphognathite are all plumose and of nearly equal length. The posterior 
lobe is the wider and somewhat spatula-shaped, and this difference is emphasized after 
the second molt. Minor changes which occur in the course of the three following molts 
concern chiefly the endopodite and the conformation of the mouth parts to the mandi- 
bles and of the scaphognathite to the branchial cavity. 

First maxillvpeds. — In the first larva these appendages have the form shown in fig. 
58, and if this is compared with the condition met with in the fourth stage (fig. 59) we 
find that the principal changes concern the two-jointed endopodite and the flagelliform 
exopodite. In the fourth larva the latter is bordered on both inner and outer margins 
with plumose hairs. The setae on both protopodite and endopodite are more numerous, 
and in the latter branch are much reduced. The respiratory epipodite is relatively a 
little larger. 

Second maxillipeds. — In passing through the first four molts the second pair of 
maxillipeds undergo but minor changes (figs. 63, 64, plate 30). The exopodite becomes 
segmented, flagelliform, and setigerous. The segments of the endopodite, particularly 
their inner margins, become more densely studded with setae, many of which are 
serrated. A rudimentary podobranchia is developed. The natural position of the 
appendages in the first three larval stages is shown in plates 20-22. 

Third maxillipeds. — In the early larval stages (plates 20-22) these appendages are 
usually directed forward and bent into nearly a right angle at the third articulation 
from the extremity. In the first larva (tig. 69) the distal ends of the three terminal 
segments (dactyl, propodus, meros) are armed with stout setae, some of which are 
serrated, while the inner margins only of the proximal divisions are setigerous. The 
exopodite reaches beyond the middle of the fifth segment, and is an important swim- 
ming organ during the first three larval stages. 

The right third maxilliped of the fourth larva is shown in its natural form and 
position in fig. 65. The appendage is still partially bent upon itself, as in the first 
larva, but the proximal half (first to fourth segments) has been twisted through an 
angle of 90°, until what were the inner and outer margins have come to lie in a 
vertical plane. The proximal joints are trihedral, and what now forms the inner, 
upper margin has developed a row of stout, rather sharp teeth, which are very 
prominent in the adult. The podobranchia, which is rudimentary in the first stage, 
is now well developed. 



THE AMERICAN LOBSTER. 197 

The pereiopods. — The general structure of the pereiopods is shown in the various 
plates illustrating the larval and adolescent history. For a considerable period before 
the time of hatching the great chelipeds can be distinguished by their size. At the 
time of hatching all have prominent podobranehke and long exopodites. After the first 
molt the swimming hairs and seta' which garnish the endopodites are rapidly ev agin ated. 
The first three pairs of pereiopods are subchelate. After the fourth molt (fig. 67, plate 
30) the exopodites are reduced to rudiments and leave no trace in the sixth stage. 

The first pereiopods. — In the first larva (fig. 6G) the first pair of pereiopods or large 
cbelipeds are nouprehensile, armed with stout, scattering seta;, of which those seen on 
the inner margins of the meros and ischium are the representatives of stout spurs 
which are developed in the fourth larva. Both propodus and dactyl end in a strong, 
nearly straight spine, which in the latter joint is conspicuous for its length. 

Autotomy of the large chelipeds occurs in the fourth larva, but fusion of the basis 
and ischium is not effected until at least after the fifth stage (plate 33, fig. 96, and 
plate 30, fig. 67). 

In the second, third, and fourth stages the prehensile claw is gradually developed 
(plates 20-23). In the third and fourth larvse the opposed margins of the large claws 
are distinctly toothed, and the latter end iu incurved, horny tips. 

There is usually but very little or no difference in the size of the large chelre until 
after the seventh molt. In the sixth stage the extremities are already provided with 
numerous tufts of sensory seta? (compare plates 23-25). In the later adolescent stages, 
when the differentiation of the large claws is complete, these tufts are mostly confined 
to the cutting claws, where they form a dense mat over the toothed margins and 
extremity of the propodus (plates 10-12). 

The differentiation of the chela3 for crushing and cutting is a gradual process, but 
is fairly well established in a young lobster 30 to 40mm. in length (plate 8). It rarely 
happens that both claws are simdar in the adult stages (see Chapter ix). 

Second and third pereiopods. — The structure of these appendages, which agree, 
except in size, is illustrated by fig. 73. In the fourth larva (fig. 74) the chelate struc- 
ture is pronounced and the exopodite is a rudiment. 

Fourth and fifth pereiopods. — The dactyl of these appendages in the first larva 
(fig. 70, plate 31) ends in a very long, nearly straight spine, while the propodus bears 
a characteristic cluster of setre close to its articulation Avith the dactyl. 

In later stages (fig. 76, plate 31) the terminal spine becomes reduced and the 
terminal cluster of serrated set?e on the propodus is then very conspicuous. In the 
fifth larva the constriction at the proximal end of the ischium is clearly defined and 
the exopodite has disappeared except as a microscopic rudiment (not shown in fig. 76). 

The pleopods. — The second, third, fourth, and fifth pairs of abdominal limbs are 
visible as buds beneath the cuticle of the first larva and emerge after the second molt 
(plates 20, 21). 

The sixth pair of pleopods, which form with the telson the tail-fan, are seen as 
rudiments through the cuticula of the second larva and are released with the third 
molt. 

THE DEVELOPMENT OF THE FIRST PAIR OF PLEOPODS. 

No accurate observations have been made upon the development of the first pair 
of abdominal limbs, which are specially modified in the two sexes. They are the last 
appendages to appear, and their growth and differentiation are very gradual. In the 



198 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

fifth stage they are represented by small rounded tubercles (fig. 78, plate 32). At this 
time there are no external characters by which the sex of the individual can be deter- 
mined with certainty. 

In the sixth stage (fig. 95, plate 33 ; lobster No. in, table 39) this appendage 
consisted of a small bud (0.1 mm. long) ; after the seventh molt (larva 18 mm. long) 
its length was doubled (tig. 83). 

In lobster No. VI (table 39) this appendage in the eighth stage (larva 19.75 mm. 
long) was a simple bud of about the same dimensions (fig. 80). 

In another young lobster, probably a male in the eighth stage (length, 19.3 mm., 
fig. 90), the appendages of the first abdomiDal somite are similar to those of the seventh 
and eighth stages just referred to. 

In another case, that of a lobster in sixth stage (No. n, table 39, fig. 84, plate 32, 
length of lobster 16 mm.), this appendage was about equal in size to those just 
described. In still another lobster (No. vi, table 39), which was followed from the 
fourth stage onward through four molts, this appendage is a little larger and is 
partially segmented (fig. 85, plate 32) in the eighth stage. The under surface of the 
thorax of this lobster is shown in fig. 89, plate 32, where the openings of the oviducts 
are clearly seen, thus determining the sex. 

In a young female 35 mm. long (No. x, table 39) this appendage measures 2 mm. 
and is composed of two joints (with possibly a small coxal segment) of about equal 
length (fig. 86). The distal joint is constricted into a number of smaller segments and 
bears a few very minute seta?. When the female is 2 inches long the first pair of 
abdominal limbs have attained the length of only 3 mm. (fig. 88, plate 32). The 
appendage is exceedingly slender and, as in earlier stages, is devoid of pigment. The 
peripheral segment is multiarticulate and is fringed with fine, short hairs. 

In a male 36.3 mm. long (No. xi, table 39) the appendage, though very minute 
(2.3 mm. in length), has the same shape as in the adult. It consists of a two-jointed 
protopodite, a minute coxa and long basis, and a grooved distal segment (fig. 87). In 
a lobster but little larger (No. xn, table 39), length 40.3 mm., the appendages of the 
first abdominal somite are similar, bat a trifle longer. As shown in the drawing of 
the under side of the thorax of this lobster (fig. 91, plate 32), they nearly meet on the 
middle line. 

We see that the appendage of the first abdominal ring may assert itself either in 
the sixth, seventh, or eighth stages. The buds are developed on the posterior margin 
of the sternum of the first abdominal somite, and in the early period of their growth lie 
facing each other, transverse to the long axis of the animal (fig. 95, plate 33). These 
minute delicate appendages do not at first show any trace of pigment. After seg- 
menting into two joints the appendage becomes elevated from the surface of the somite 
into a nearly vertical position. 

The sex can be determined as early as the eighth stage, but not, as Professor Ryder 
supposed, by the appearance of the appendages of the first abdominal ring. At this 
stage these vary from 0.20 to 0.27 mm. in length, and may or may not be segmented into 
two joints (figs. SO, 85, 90). It is only by the openings of the sexual ducts that the sex can 
be distinguished at the eighth stage. The under surface of a female in the eighth stage 
(21.2 mm. long, No. vn, table 39) is shown in fig. 89, plate 32. The openings of the 
oviducts were discernible, and the development of the sterna of the last and penulti- 
mate thoracic segments which enter into the formation of the seminal receptacle is 
slightly different from the conditions seen in the male. 



THE AMERICAN LOBSTER. 



199 



The sex can not be determined by the abdominal appendages alone until after the tenth 
nolt. In two lobsters, 35 and 36.3 mm. long respectively (Nos. x, xi, table 39), which 
Lad probably molted twelve times, we have no difficulty in deciding from the structure 
of the abdominal appendages (represented by figs. 80, 87) that the first is a female, 
the last a male. 

The gradual growth of the appendages of the first abdominal somite is illustrated 
in table 39. In a lobster 2 inches long (51.8 mm.) these have a length of about an 
eighth of an inch (or 3 mm.). 

TABLE 39. — ■ Progressive stages in the development of the appendages of the first abdominal somite. 



No. 


Number in tables. 


No. of 
molt. 


Length 
of lob- 
ster. 


Length of 
first ab- 
dominal 

appendage. 


Sex. 


Remarks. 


I 

11 

III 


(36, table 34) 

(36, table 34) 

13.1 mlilo 34l 


5 
6 
6 

7 
8 
8 
8 
10 
10 
3 12 
3 12 


mm. 
14 
16 

16.3 
18 

19.3 
19.75 
21.2 
26.6 
29.50 
35 
36.3 
• 40.3 
51.8 


mm. 
•0.11 
.27 
2 .10 
.2 
.27 
.2 
.25 
3 1.5 
3 2 
2 

2.30 
2.60 
3.04 


i 


See fig. 78, plate 32. 

See fig. 84, plate 32. 

See fig. 82, plate 32. 

See fig. 83, plate 32 (bud without joints) . 

See fig. 90, plate 32. 

See fig. 80, plate 32. 

See figs. 85 and 89, plate 32. 

Appendage not segmented. 

Appendage consists of two minute joints. 

See fig. 86; plate 32. 

See fig. 87, plate 32. 

See fig. 91, plate 32. 

See fig. 88, plate 32. 


t 


j 


V (34 fabln 341 


t 


IV 




Male.... 
Female . 
Female . 
i 


VI 
VII 

VIII 

IX 

X 

XI 

XII 

XIII 


(37, table 34) 

(3, table 34) 

(38, table 34) 

(34, table 34) 

(17, table 33) 

(18, table 33) 

(1 table 32) 


i 


Female . 

Male 

...do .... 

Female . 


(19 table 33) 









1 Tubercle. 



2 Bud. 



' Not accurately determined. 



Second, third, fourth, and fifth pleopods. — The condition of these appendages in the 
second, third, and fourth larval stages is illustrated by figs. 93, 94 and 97, plate 33. Each 
appendage consists iu the second larva of a stalk with the blade-like endopodite and 
exopodite. Eudimentary fringing setae are developed after the third molt, but the 
appendage is but little longer and otherwise unchanged. In the fourth larva (fig. 97) 
the natatory appendages come immediately into use. The long fringing setae grow 
out and the limb itself is almost double its former size. 

The telson and " tail-fanP — The flat telson of the older embryos is deeply cleft 
into two lobes (fig. 72), which bear on their free terminal edges short interlocking 
setae. The bifurcate condition of the embryonic telson, which recalls very forcibly that 
of a protozoea and is probably the remnant of a former larval condition, is retained up 
to the time of hatching and is lost only with the molt preceding the first larval stage. 

After the first molt the telson appears as a broad, triangular plate (plate 19, and 
plate 34, fig. 103) joined immovably to the abdomen and admirably adapted for 
swimming. By the aid of this paddle the animal darts rapidly backward with every 
flexion of the abdomen. The dorsal surface of the plate is convex, and its posterior 
margin is incurved and armed with spines and stout plumose setae, as shown in the 
drawing. 

The sixth pair of abdominal appendages, which, as already mentioned, are clearly 
outlined beneath the cuticle of the second larva (fig. 102,, become broad lamellar pad- 
dles in the third stage (fig. 104), and in the fourth larva nearly equal the telson in length 
(fig. 105). The outer lamella is jointed at its posterior end and bears on its upper 
surface, near the line of the articulation, a short median tooth, as in the adult state. 
After the fourth molt the caudal-fan is very similar to that of the adult. The telson is 



200 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

a quadrangular plate, about two-thirds as broad as long, with an even convex margin 
bordered with long fringing setae at its hinder end. The median spine has disappeared 
and the long lateral spines are reduced to short, stout teeth. 

In the later adolescent stages the fringing setae of the caudal-fan become greatly 
elongated until they nearly equal the telson in length. The adult telson is somewhat 
spatula-shaped and about as broad as long at its base. 

THE METAMORPHOSIS OF HOMARUS GAMMARUS. 

Sars studied the first three larval stages of the European lobster in specimens 
which he collected at the surface of the ocean. He saw enough to convince him that 
they were at this time an easy prey to fish, swimming birds, and to ocean currents 
which swept them into unfavorable places (175). 

At Espevaer, a fishing-place on the coast of Norway, his attention was directed to 
large numbers of lobster larva?, which were there "packed together with an enormous 
mass of Calanides (a kind of herring) and other species of pelagic animals, upon which 
swarms of herring and birds were feeding." 

The abbreviation of the metamorphosis has been carried a little further in Romarus 
gammarus than in the American species. The young of the two forms apparently agree 
in color, but are very dissimilar in size. According to Sars, the first three larvae of 
the European lobster measure 10, 14, and 17 to 18 mm., respectively. If these meas- 
urements are representative, the first larva of this species is larger than the second 
larva of Romarus americanus, and the third larva larger than the sixth stage. (See 
table 25.) 

The color of the third larva, according to Sars, is a mixture of yellow-red or brown 
and blue-green, and at this stage the integument has lost much of its transparency. 

The carapace, the large chelipeds, and abdomen in the first larva of the European 
species have reached a stage of development which corresponds very nearly to the 
second larval stage of the American form. This is best illustrated by the rostrum, 
large chelae, and telson. The second somite of the abdomen is devoid of the median 
spine, which, as we have seen (table 36), usually disappears in the American form 
with the second molt. Sars says that even in the first stage the anlage of the uropods 
can be discerned beneath the cuticle. These appendages, however, are not released 
until after the third molt, as in our lobster. 

THE SHORTENING OF THE METAMORPHOSIS IN THE LOBSTER. 

I have discussed in my work on the development of Alpheus (94, p. 380) the 
abbreviation of the larval period in Crustacea, and described the remarkable exam- 
ples of this phenomenon which the study of the Alphei revealed. We will now consider 
the case of the lobster a little more closely than it was possible to do at that time. 
What is the cause of the suppression of the zoea stage in the metamorphosis of this 
animal % 

We can not doubt that this is a secondary phenomenon which has appeared in 
comparatively recent times, and that some of the immediate ancestors of the lobster 
went through the long metamorphosis after hatching, as the majority of Decapods do 
to-day. It is equally certain that something in the environment of these animals has 
called forth this change. Why should the lobster be better off with a short metamor- 



THE AMERICAN LOBSTER. 201 

pilosis than the common bine crab (Oallinectes hastitt its) or common shrimp ( Crangon 
vulgaris) in bol li of which the larval life is prolonged ? The only clew to an answer lies 
in the study of the habits and economy of these animals. The course Avhich the larval 
development finally assumes in any species is a compromise between several conflict- 
ing paths. A wide surface distribution is necessary for the continuance of certain 
animals, but in order to secure this the larval period must be extended. On the other 
hand, a long life at the surface would be death to many species. 

Natural selection is operative at all stages of development, and is effective in 
increasing the chances of survival mainly in two distinct ways: (1) Either by increasing 
the number of ova or young produced, or (2) by shortening the path of development. 
In the latter case the number of eggs is diminished and the size of the egg increased. 

The crab and shrimp have adopted the former course and the lobster has followed 
the latter. A lobster 10J inches long lays, upon the average, 11,000 eggs, each of 
winch is about 1.9 mm. in diameter, while Calliuectes produces, according to S. I. 
Smith (/Si), 4,500,000 eggs, each having a diameter of only 0.28 mm. Thus the crab, 
though much the smaller animal, lays over four hundred times as many eggs. With 
the same number of eggs as the lobster and a long larval life, the crab could not 
survive. The lobster lives in deeper water than the crab and is probably more sensi- 
tive to changes in temperature. The larval period lasts from 5 to 8 weeks; that of 
Calliuectes probably longer, but this is not known. Any further shortening of the 
development of the lobster would lead to a considerable reduction in the number of 
eggs, and if the metamorphosis were lost completely so that the animal left the egg in 
what now corresponds to its sixth or seventh stage the conditions of life would 
be very unfavorable for the young, on account of the sedentary habits of the adults. 
The adolescent lobsters (being thus concentrated in a relatively small area) would 
fall in vast numbers the prey of fish and Crustacea, especially to members of their 
own species, before they could establish themselves securely in their retreats along 
the rocky shores. (See Chapter xi). 

The advantage of a larval life lies in securing distribution, in this case an absolute 
necessity, over wide areas top and down the coast, and at the same time in the immediate 
transportation of the young from the shore out of reach of many enemies. This being- 
true, why, it may be asked, has the larval development been shortened at all? This 
has been brought about, in all probability, because of the general slowness which 
characterizes the whole period of development and because of the great destruction 
which is wrought upon the pelagic larvae even under the most favorable conditions. 

It is very interesting to notice, as I have already mentioned (p. 200), that abbre- 
viation in development is carried a step farther in the European species. 

It is a well-known law that a fresh-water life tends to shorten the development of 
animals, and this may be due to the fact that the seasonal changes of temperature are 
far greater and more abrupt in inland waters than in the ocean. 

A life in deep water tends also to shorten development and eliminate the larval 
period. Where deep-water forms at the present day have an indirect development, it 
is possible that the problem is complicated by other conditions or that the bathic 
habit has been acquired in comparatively recent times. 



Chapter XIII.— THE EMBRYOLOGY OF THE LOBSTER. 

I shall not attempt to give a detailed account of the embryonic history of the 
lobster, although for several seasons I have spent much time both in collecting and 
preparing material for this purpose. I will offer only a few notes on the early 
phases of development, and, to lend continuity to the whole, will sketch briefly the 
changes in external form which the embryo undergoes. 

Early embryo] ogists, Eathke in particular, to whom reference has already been 
made (160), examined the older embryos of the lobster or dissected them from the 
egg membranes, but the only paper of this period which attempts to deal directly with 
the embryology of the animal is that of Erdl (62), published in 1843. Erdl treats 
of the laying of the eggs and the fastening of them to the appendages of the 
mother; of the nature of the laid egg and of the external anatomy of the older 
embryos; but his work was done before the modern methods of microscopical research 
had been discovered. This pioneer observer was thus greatly handicapped and his 
results are now of but little value. 

Smith figured and described the external anatomy of a well-advanced embryo from 
a lobster captured May 2, 1872, at New London, Connecticut (182). This stage nearly 
corresponds to that shown in cut 38. 

In September, 1891, a paper on the Embryology of the Lobster, by Bumpus, 
appeared, in which the early stages, to the close of the egg nauplius period, are care- 
fully described and illustrated by very accurate and beautiful drawings (30). 

A short account of my earliest studies appeared in 1890 (91), and this was followed 
by additional notes in May, 1891 (92), in 1893 (96), 1894 (97), and 1895 (100). 

NORMAL DEVELOPMENT. 
THE MATURATION AND SEGMENTATION OP THE EGG. 

In the section on the growth of the germinal vesicle I have described the only 
stage in the maturation of the egg which has been directly observed (p. 154, plate 42, fig. 
161), where the germinal vesicle has approached the surface and is undergoing indirect 
division, being overtaken in the metakinetic stage. As already stated, it is evident 
that in this particular egg the germinal vesicle was about to give off a polar body. 

Bumpus, who was the first to detect polar bodies in the egg of the lobster, gives 
the following account of them : 

They are present in many eggs, and appear to be attached at no special point of the vitellus, so 
far as the flattened area is concerned, being sometimes within it and sometimes without. It may be, 
however, that I have only seen them in secondary positions ; for in some cases they seemed to move 
freely about within the egg membrane. They were not observed in process of formation, nor were 
they invariably present. Before the blastula is formed they disappear. (SO) 

I was unable to satisfy myself that the polar cells could be distinguished with 
certainty, and so have not figured them. It is difficult to detect such minute bodies 
in so large and so opaque an object as the egg of the lobster, and owing to mechanical 
causes, possibly through the emission of the polar bodies themselves, minute spherical 
globules of food yolk are set free and float in the fluid which underlies the eggshell. A 

202 



THE AMERICAN LOBSTER. 203 

single globule of yolk is practically colorless, and as I have never detected the polar 
bodies in stained sections I can not affirm that the small particles which seemed to 
answer to their assumed appearance were not detached globules of yolk. In ovarian 
eggs which had failed to pass out of the body at the time of ovulation I have seen 
what looked like polar corpuscles, but here, although the nucleus of the ovum was 
at the surface, the observation could not be confirmed by histological analysis. The 
position of the nucleus in such cases seems to point to the extrusion of the polar cells 
under normal conditions, while the eggs are within the ovary or its ducts. 

I have already described and figured the egg of the shrimp, Stenopus hispidus, 
iu which two cells and a single polar body can be distinguished in sections (95, fig. 
1, plate G). One cell lies at the surface, and very near it in the space beneath the yolk 
and shell a spherical mass of deeply staining chromatin, corresponding in size with 
the nucleus of the superficial cell. It is probable that the latter represents the ger- 
minal vesicle after one division, and that the deeper lying cell is the male pronucleus. 
(Compare 94, description of plate, p. 474.) 

THE EXTERNAL PHENOMENA OF SEGMENTATION. 

A colored sketch of the fresh eggs of the lobster is given in fig. 24, plate 17. These 
were laid in an aquarium, and when examined August 11, 1893, were closely adherent 
and could be separated only with difficulty. The fresh egg is spherical, oblong, or 
somewhat irregular iu form, and measures about -£■ inch in diameter. (See p. 55.) It 
has in appearance a fine granular texture all over, owing to the uniform distribution 
and character of the yolk spherules, and the shell hugs the egg closely in all its parts. 

An early sign of development is the flattening of a part of the surface of the 
yolk and the consequent elevation of the shell over this area. A liquid, in which a 
granular substance is sometimes feebly developed while the egg is still fresh, is 
pressed out of the yolk and fills the free space between it and the shell. This flat- 
tened area marks the animal pole of the egg and is very characteristic. The surface 
of the ovum is often flecked with light spots due to the irregular grouping and per- 
haps looser arrangement of the yolk spherules. Light flecks, three to four iu number, 
but of different character, now appear in the depressed area (fig. 215). These are cells 
which are approaching the surface, and their nuclei can now be seen shimmering 
through the green yolk. 

The phases which immediately follow are represented in figs. 216, 217, and 218, 
which were drawn from the same egg at successive stages of development. The cells 
approach nearer to the surface, multiply by indirect division, diffuse about the animal 
pole, and bring on the superficial segmentation of the yolk into hillocks as seen in profile 
in fig. 218. The drawing shown in fig. 216 was made at 10.30 a. m. At the animal pole 
there are seen two double rows of cells, 8 in each double row, or 16 in all. These are 
arranged in pairs — four pairs of daughter cells in each double row — the products of 
recent division. This egg appears in profile iu fig. 218. The yolk is now in contact 
with the shell over less than half its area, but the yolk hillocks appear about the 
animal pole only. At 10.55 a. m., 25 minutes later, 20 cells could be detected. At 12 
m., or 65 minutes later, this egg had the appearance shown in fig. 217. The segments 
or yolk hillocks were then farther apart. This process continued until the entire 
surface of the yolk was segmented. 

Opposite sides of the same egg in which that condition was already realized are 
represented in figs. 219 and 220. The former shows the animal pole, the latter the 



204 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

vegetative. At about 9.30 p. m., when I began these drawings, the nuclei were in kary- 
okinesis ; at 10 p. m. nearly all were in the diaster stage (as represented here) ; at 10.10 
p. m. superficial furrows began to appear, separating the daughter cells in the region of 
the animal pole. At 10.15 p. m. cell cleavage was completed. The cells on the opposite 
side of the egg lagged somewhat behind the others, the cleavage furrows in that 
region being completed about 5 minutes later. The yolk segments, both before and 
after division, were wedged rather closely together and were now polygonal in outline 
over the greater part of the egg. At 11 p. in. this egg had the appearance represented 
in fig. 221, when seen from the animal pole. The yolk segments or hillocks now 
protruded, becoming very convex, and the whole egg took on a beautiful mulberry-like 
appearance, the segments which were visible to the naked eye being dark green with 
whitish protoplasmic caps or centers. At 1 a. m., or 2f hours after the last cleavage 
period was completed, the segments flattened down, and by mutual pressure assumed 
a polygonal form, the energy which had been stored up during the interval being now 
directed to do the work of the next cleavage. 

A similar phase is illustrated by cuts 23, 24, plate G, the former showing the 
vegetative pole. When these drawings were made, at 12.55 p. m., the nuclei were 
mostly in the diaster stage of division, and in 70 minutes cleavage furrows were 
beginning to appear. 

An egg in a stage quite similar to that seen in fig. 221 is represented in fig. 222. 
When first observed, at 10 a. m., from thirty-six to forty segments were visible over 
that half of the egg corresponding to the animal pole. At 10.55 the nuclei were in 
active division. At 11.30, when the drawing was completed, cell-cleavage furrows 
were beginning to appear, and in 20 minutes the segmentation was completed over 
the greater part of the surface. At 12 m. (30 minutes from the time cell-cleavage 
became visible, and 65 minutes from the beginning of karyokinesis) the process was 
complete and the segments had begun to swell. The egg in this phase is represented 
by fig. 223. At 2.45 p. m. active karyokinesis again began, and at 6.25, or in less 
than 4 hours, division of the segments was again completed. This phase of the 
segmentation lasted nearly four times as long as the former period. The drawing of 
it (fig. 224) was made at 9 p. m., and represents the side including the vegetative 
pole. (See figs. 218, 219, and 220.) The polygonal cells, near the central part of the 
area represented, were the last products of this segmentation. 

The time occupied in cell division is illustrated by another egg, which was under 
observation 7 J hours (10.55 a. m. to 6.25 p. m.). It was of about the same age as the 
egg shown in fig. 222. At 10.55 a. m. the nuclei were in the diaster or metakinetic 
stage of division. At 11.40 a. in., or 45 minutes later, cell division or segmentation was 
completed. At 1 p. m., 80 minutes later, the superficial furrows were very definite and 
the protoplasmic cap of each segment was more distinct when examined in reflected 
light. At 2.45 i). m., 105 minutes later, or nearly 4 hours from the beginning of the 
last period of segmentation, the segments were closely crowded and nuclei were again 
in active division. (Stage of the equatorial plate.) At 4.15 p. m., 1J hours later, 
cleavage amphiasters were formed, but no furrows. At 6.25 p. m., 2 hours and 10 
minutes later, or 3 hours and 40 minutes from the time of appearance of the equatorial 
plate, segmentation was completed. Here the total segmentation period lasted about 
6 hours and 45 minutes, of which 2 hours and 20 minutes were spent in quiescence 
and 4 hours and 25 minutes in activity. 



Bull. U. S. F. C. 1895. The American Lobster. (To face page 205.) 



Plate F. 



h 1 




b 3 



Cot 20.— Egg embryo, showing membranes abnormally distended after 
prolonged immersion in picro-nitric acid. 29 diameters. 

mb', primary egg-membrane, formed in ovary. m& a , secondary egg- 
membrane, prolonged into tbe stalk of attachment, formed by the 
cement glands, nib 3 , cuticular molt of embryo. 





Cut 21. — Projection of an egg with 15 yolk-cells, 
all near the surface or approaching it. 



Cot 22. — Projection of an egg with 28 yolk-cells, 3 in 

karyokinesis — mostly near the surface. 
In these cuts the yolk-cells only are shown. Sections 

are represented by dotted lines in cut 22. 



Drawn by F. H. Htrrick. 



THE AMERICAN LOBSTER. 205 

About 110 cells are present iu the egg shown in fig. 223, and not far from 220 in 
the next phase (fig. 221). The lack of uniformity in cell division which was present 
iu the earlier stages now entirely disappears. In other words, the individual rhythms 
of the component cells of the embryo appear to be in harmony. 

At the next and following divisions (fig. 225) the protoplasm approaches nearer 
and nearer the surface, and the animal and vegetative poles are no longer distin- 
guishable. A surface view of an egg intermediate between the stages shown in figs. 
221 and 225 is represented in fig. 211, plate 52. The invagination stage soon follows. 

INTERNAL, CHANGES IN SEGMENTATION. 

The histological changes which take place in development up to the beginning of 
the invagination stage will now be considered. 

The segmentation nucleus in a single egg, from a batch which I obtained on 
August 1, was very eccentric in position, and in appearance resembled the germinal 
vesicle of the uuextruded egg. The nucleus was spherical and lay in a spherical 
island of granular protoplasm. The nuclear membrane was very delicate, and could 
hardly be demonstrated in sections, while the chromatin had a rather coarse granular 
appearance. 

The first division takes place near the center of the egg, and the products move 
away from each other. In two eggs examined, each of which contained two nuclei 
(possibly the pronuclei), one nucleus iu each case lay nearer the center and the other 
nearer the surface. The nuclei are relatively small, and after a few divisions become 
very much smaller. Each is surrounded by a rayed body of protoplasm, in some 
cases (as in fig. 219) the rays being exceedingly numerous and delicate, reaching far 
out among the yolk-spheres. In an egg which was cut into 56 sections, the first two 
cells appeared iu the twenty-fourth and thirtieth sections, respectively. In each case 
the nucleus was spherical, and the cell protoplasm formed a compact oval island, giving 
off no long characteristic pseudopodia, as are seen in fig. 238. In another case, where 
the egg was cut into 01 sections, one cell appeared in the thirty-first and its sister 
cell in the thirty-ninth section of the series, the latter being in process of division. 

In the second and third segmentations which follow, producing four and eight 
cells, the products separate and migrate toward the surface. The greater number 
tend to move toward the side of the egg corresponding to the animal pole, where the 
yolk is first segmented (figs. 215-218, plate 50). 

In an egg containing nineteen cells, with yolk undivided, eight were in various 
stages of karyokinesis. Some cells were nearer, others farther from the surface, the 
majority being about midway between the center and periphery, in different parts of 
the egg. 

In another egg, where the segmentation of the superficial yolk was completed, 
just thirty cells or yolk pyramids were present. (See figs. 21 ( J and 220; a section of 
the egg is represented in fig. 212.) The constrictions of the yolk are not simply 
superficial, but cleavage planes often reach halfway down to the center of the egg. 
The nucleus with its rayed protoplasm lies toward the center of the convex face of 
each segment, but is still separated from the surface of the egg by a considerable layer 
of yolk. The entire protoplasm is thus distributed among the yolk segments, none of 
it remaining in the undivided yolk mass. In surface views the nuclei can be seen 
shining through the thin stratum of yolk which lies between them and the surface. 
Sometimes a segment is partly overgrown by the surrounding cells and squeezed below 



206 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

the surface, as in fig. 238, but this must not be mistaken for one of the phagocytes or 
yolk cells, which are formed, in an entirely different manner. 

Karyokinetic figures, which are clearly seen in all dividing nuclei, show that up 
to this time the plane of cell division is radial, for all cells at least which have 
approached as near the surface as those shown in fig. 242. A little later than this, fig. 
224, plate 50, and fig. 244, plate 52, when over 200 cells were present, phagocytes or 
yolk cells suddenly appear. One egg showed, when sectioned, the following condition : 

Number of cells at surface 219 

Number of yolk cells 11 

Total number of cells iu egg 230 

Number of cells in active karyokinesis: 

Radial division 15 

Tangential division . . 2 



I » 



The yolk cells are in various stages of migration from the surface to the depths 
of the egg. Four have reached points about midway between the surface and center, 
and one of these is in the metakinetic stage of division. They originate by the 
tangential division of a certain number of the peripheral cells and by the multiplication 
of yolk cells thus formed. The peripheral cells at this time are not quite in contact 
with the surface of the egg, but are separated i'rom it by a thin layer of yolk spherules. 
When a peripheral cell divides in a horizontal or tangential plane, the central daughter 
cell migrates into the great yolk mass, filling the egg, while the other remains at the 
surface and forms a part of the primitive blastoderm. The process is illustrated in 
figs. 236 and 243, the latter showing the formation of a yolk cell near the surface, and 
also the division of a yolk cell already formed. 

THE INVAGINATION STAGE. 

After a stage similar to that shown in fig. 225 is reached the peripheral cells continue 
to divide in radial planes, and their protoplasm soon bounds the surface of the egg. 
Cell division becomes more rapid over one side of the egg, possibly that corresponding 
to the animal pole, but this was not finally determined. An area of rapid proliferation 
is thus distinctly marked off, and in the midst an invagination of superficial cells 
occurs. This begins by the in-wandering of a few cells, which is followed by the multi- 
plication of those thus immersed in the common food stock, and by the sinking in of a 
small area of the blastoderm about this point. In an ovate egg, like that shown in 
fig. 227, the invaginate area lies toward one of the poles. 

The depression is at first very shallow, but increases considerably in depth and 
becomes a well-defined circular pit. Later it elongates transversely (cut 26), and in 
abnormal cases a deep gutter is formed. The character of this depression is indeed 
subject to great variation. The pit at the surface lasts from four to five days, when, 
after becoming elongated into a slightly triangular slit, by the ingrowth of the sides, 
it completely disappears. 

In an egg in which there is a distinct patch of cells marking the area of invagina- 
tion, but where the depression is very slight or has entirely disappeared, the embry- 
onic area which lies in front of the point of invagination is marked by a wonderful 
activity among the superficial cells. This is illustrated in fig. 252, plate 54. About 
the point of invagination there is a mass of several hundred cells, from which migra- 
tion into the yolk has taken place. Many of the cells, both at and below the surface, 



Bull. U. S. F. C. 1895. The American Lobster. (To face pajje 206.) 



Plate G 





Cdt23. — Egg willi about 32 yolk segments present, seen 
from vegetative pole. About twenty-eight hours after 
fertilization. At 12.05 p. m. the nuclei were dividing, 
and at 2.05 p. in. corresponding segmentation furrows 
in the yolk had appeared. 29 diameters. 



Cut 24. — Reverse side of same egg, showing divided 
nuclei at the animal pole. Drawings from living egg. 
29 diameters. 





Cut 25.— Surface view of embryo 8 days old in invagina- 
tion stage, showing pit at surface, embryonic area, and 
mass of in-wandering cells which penetrate deeply into 
the yolk. These appear now as a dense pear-shaped 
(hmd when seen through the superficial parts. 29 di- 
ameters. From No. 3 (1), table 18, July 9, 1890. 



Out 26. — Surface view of egg in invagination stage. Pit 
very distinct, transversely elongated, showing tendency 
to become horseshoe-shaped. 29 diameters. Embryo 
about 8 days old. August 12, 1892. 



Drawn hij F. H. Herrick. 



THE AMERICAN LOBSTER. 207 

are in various stages of division, as shown by the clearly defined karyokinetic figures. 
The surface of the egg at the sides, but particularly in front of this area, presents a 
striking, and, for a transitory period, a very characteristic appearance. The nuclei 
are grouped in pairs, in short strings, or in clusters or nests of a dozen or more. In 
many cases these nuclei are breaking down and giving rise to the "plasma vesicles" 
and "chromatin nebula'" of Bumpus (30). The degenerating chromatin of these 
disrupted cells still reacts vigorously upon the staining fluids, and appears as a 
clouded mass of tine particles (fig. 237, Dg.) which in time becomes more diffused and 
scattered amid the adjacent yolk granules (fig. 241). The pairs or chains of cells 
arise by the usual process of indirect division in radial planes. 

The cell nests, as illustrated in fig. 245, plate 52, are the result of a multiple karyo- 
kinesis, and are formed immediately by either one or two divisions from a single cell 
(yn x ). Since the active phase of this process lasts but a brief interval, it is not surprising 
that it usually escapes attention. In this egg, nests of nuclei are very abundant at the 
sides and immediately behind the region of ingrowth, and occur, as is well shown in 
fig. 245, both at the immediate surface (en) and below it. In most cases a yolk ball is 
formed with very definite outlines, its size depending upon the amount of protoplasm 
which it contains. The yolk ball is strictly analogous to the superficial yolk-bearing 
cell and to the yolk pyramid. The superficial cell, which is a direct descendant of the 
enormous yolk segment or pyramid, has this peculiarity in the lobster: By the time 
a distinct blastodermic envelope is formed it tends to become distinctly separated 
from the rest of the egg. A definite stratum of cells is thus formed consisting of yolk- 
laden discoidal or columnar cells. (See figs. 251 and 255, ec.) 

The appearance of the cell nest or cluster in a resting condition is shown in figs. 245 
and 247. The yolk immediately surrounding it is usually, but not always, segmented 
into spherical masses. Upon the side of the egg, opposite the embryo nuclei are far 
less numerous and very uniformly distributed. jSTo cell nests or evidence of active 
division are seen. 

It will probably be found that, whenever clusters or nests of nuclei appear in 
the blastoderm or other parts of the embryo of Arthropods, they are the result of 
multiple cell division. Some time ago I suggested (94, p. 427) that this would account 
for the nuclear clusters which Reichenbach has figured in the large endodermal cells 
which form the lining of the mesenteron in Astacus, and which he supposed were due 
to a process of direct division (163). Both in this case and in the lobster the division 
is attended by the dissolution of some of the chromatin. 

The histology of the embryo during the invagination period is illustrated by figs. 
246, 251, 254. At a very early stage a few cells break with the surface and migrate a 
short way into the egg. A depression about the point of ingrowth soon appears, and 
the cells, being bathed with nutriment, multiply rapidly until the condition illustrated in 
fig. 251 is reached. They here form at the surface a definite layer of prismatic elements, 
each containing a quantity of yolk with definite boundaries. It should be noticed also 
that the nuclei of the in-wandering cells are often inclosed in spherical masses of yolk. 

The histological processes which occur at this period vary considerably in different 
embryos. Thus in fig. 240 we see a stage of development very similar to that of 
fig. 252, but a little earlier. In the former (fig. 240) the cells about the area of 
invagination have multiplied until they form a large cluster at the bottom of the pit. 
A syncytium is formed, and the protoplasm of the outermost cells lies at the surface, 
while the neighboring yolk is thrown into long, tapering segments. Some of these 



208 BULLETIN OF THE UNITED STATES PISH COMMISSION. 

invaginated cells have wandered a short way only into the egg. Now, if we examine 
the peripheral cell envelope, we find abundant evidence of cell division over the side 
of the egg where the embryo proper is soon to be built up. Nests of nuclei, often sur- 
prisingly large and numerous, are now and then seen in the midst of a spherical mass 
of yolk either at the surface or just below it. Isolated cells, though few in number, 
also occur, scattered through the peripheral parts of the yolk at this stage. What 
is their origin? They can not be referred to invaginate cells, since none of these 
have yet wandered to remote parts. Furthermore, these cells tend, not to scatter, 
but to migrate in a body. They may be the descendants of the primary yolk cells or 
migrants from the peripheral cell envelope, or may originate in both these ways. 

At the time of invagination the egg of Alpheus is very similar to that of the lob- 
ster in its histological relations. The main difference which is apparent to the eye 
is in the larger size or greater amount of food yolk in the latter. I have described 
and figured the invagination stage of Alpheus in some detail in my work on the 
embryology of this crustacean (94, p. 400, plate xxxi). In this species the primary 
yolk cells persist and mingle with the wandering cells derived from the invagination. 
An egg of Alpheus saulcyi in the invagination stage contains about 460 cells, of which 8 
per cent — exactly 37 were found in two separate eggs — are primary yolk cells (94, p. 
432, table 1). These yolk cells do not appear to be much more numerous in the larger 
egg of the lobster (see cuts 21 and 22, showing eggs with 15 and 28 yolk cells respect- 
ively), but in this animal they degenerate faster than in Alpheus, so that at the 
invagination period very few are left. On the other hand the occurrence in the lobster at 
this time of nests of nuclei within the yolk ball, which lies j ust below the surface or some 
times almost in contact with it, points to migration of cells from the surface after the 
invagination stage. In any case most, if not all, such cells degenerate and disappear. 

In an older embryo, represented in fig. 254, the pit in the invagination area is 
considerably enlarged, and below this a solid wedge-shaped column of cells is seen 
advancing straight down into the yolk or bending slightly toward the hinder end of 
the embryo. This mass of cells forms what has been called the thoracic-abdominal 
plate. It here gives rise in part to a mass of cells which migrate into the yolk and 
eventually form mesodermic and endoderinic structures. I shall call this cell-mass the 
mesendoderm. Regarding these cells we notice in particular the peculiar association of 
the cytoplasm with the yolk, the pseudopodia by which they worm their way among 
the yolk spherules like so many amoeba, the evidence of cell multiplication and of the 
degeneration or breaking down of cells. 

Signs of cell degeneration are also present in a striking degree over the embryonic 
area of the egg. The surface cells form a single tier of short prismatic elements 
loaded with yolk, while beneath them we see a thin cloud of fine chromatin particles. 
These are mostly the remains of cells which have migrated thither from the mesendo- 
dermic mass, and possibly in part also of cells which have wandered from the surface. 

The embryo at a little later period has the appearance shown in plate 53. The 
ingrowing plug of cells has a rounded, somewhat pear-shaped outline when seen from 
above, the stem end of the pear pointing backward and downward into the yolk. 
The embryonic area of the egg presents a beautiful mosaic of cells, among which 
karyokinetic figures are abundant. The dividing planes of these cells are always 
radial — that is, parallel with a radius drawn from the center to the surface of the 
egg, but make any angle with a line drawn upon the surface of the egg, such as that 



Bull II S F. C. 1895. The American Lobster. (To face page 208 ) 



Plate H. 





Cut 27. — Surface view of embryo, show- 
ing buds of first pair of antenna? and 
clouds of in-wandering cells. Tbe lat- 
ter extend in great cumulus-like folds 
and surround large masses of yolk with 
tbin layers of cells. Embryo about 9 
days old. August 6, 1891. 29 diameters. 
In cuts 25-33 tbe eggs were fixed with 
hot water and Mayer's picro-sulpburic 
acid, and stained in Kleinenberg's hsemo- 
loxylon or Grenadier's borax-carmine. 



Cut 28. — Surface view of embryo, show- 
ing buds of first pair of antennas and 
of mandibles. Tbe stomodaeum is 
present in form of a small transverse 
pit, on tbe level of a line drawn 
through tbe posterior margins of the 
antennary buds. Tbe outlines of the 
masses of yolk-cells appear much 
more circumscribed than in the earlier 
stage shown in cut 27. Embryo 9 to 
10 days old. August 5, 1891. 29 dia- 
meters. 













Cut 29. — Surface view of early egg- 
nauplius embryo, showing buds of 
the first and second antenna? and 
the mandibles. Mouth or opening 
of stomodaeum distinct; in-wandering 
cells beneath the thoracic abdominal 
plate shaded dark. The yolk-cells are 
still further circumscribed to outward 
appearance, having wandered far into 
the egg. Optic disks more clearly de- 
fined. Embryo about 10 days old. 29 
diameters. 



Cut 30. — Surface view of egg nauplius, 
slightly older than that shown in cut 29; 
second antenna? bifid; labrum and tho- 
racic abdominal fold present; embryo 
about 11 days old. July 12. 29 diame- 
ters. 

In cuts 25-30 surface-cells are roughly 
indicated only in the immediate region 
of the embryo. 



Drawn by F. H. Herrick. 



jll. U.S. F.C. 



The American Lobster. (To face page 209.) 



Plate I. 





Cdt 31. — Surface view of egg nauplius, 
showing thoracic abdominal fold. The 
mouth, as in cut 30, is screened by the lab 
rum, and the optic disks are more sharply 
defined; second antenna? forked; embryo 
about 12 days old. 29 diameters. 



Cut 32. — Surface view of egg nauplius, 
showing parts much more concentrated 
than in earlier stages. Antenna? exhibit 
traces of segmentation, and the second 
antenna? have a slender inner branch. 
The abdomen is bifid at its extremity, 
which nearly touches the labrum ; optic 
disk lobular; embryo 14 to 10 days old. 
August 14. 29 diameters. 





Cut 33. — Surface view of embryo with first 
maxilla; budded; embryo 16 to 18 days 
old. August 5. 29 diameters. 

In cuts 31-38 there is little attempt to 
show more than the form of the embryo. 
The series G to J represents the progres- 
sive development of the summer eggs. 
Compai'e the Eate of Development, pp. 
55 to 57, and table 18. 



Cut 34. — Surface view of embryo, showing 
5 pairs of post-mandibular appendages. 
The antennae have grown obliquely back- 
ward until they come to lie nearly paral- 
lel with the abdomen. The telson. which 
is now distinctly forked, partially over- 
laps the brain. Eye-pigment not yet 
apparent. Nearly same stage as 3 (5), 
table 18; about 21 days old. From egg 
killed in Perenyi fluid, August 15, 1893. 
29 diameters. 



Drawn by F. H. Herrick. 



THE AMERICAN LOBSTER. 209 

through tlic Longitudinal median axis. There is no tendency to form radial strings 
or concentric, circles of cells with reference to a given center at the surface, such as 
Reichenbach (163) has described in the crayfish, a fact already noticed by Bumpus (30). 
Diffused clouds or islands of chromatin particles, the wrecks of cell colonies, lie strewn 
over the embryonic area, particularly in its forward part. These are for the most part 
immediately below the ectoderm. The opposite side of this egg shows nothing par- 
ticularly noteworthy and has not been figured. The nuclei are more scattered, cell 
division is less frequent, and clouds of chromatin granules are much less extensive. 

The internal structure of a little older embryo is illustrated by fig. 255, plate 54. 
The most noticeable changes are the great spread of the inesendoderm which, like a 
cloud of dense smoke from an engine, rises up and trails backward into the depths of 
the yolk with many rounded summits ; the columnar form of the ectodermic cells — most 
pronounced in the region of the optic disks — and the swarm of degenerating par- 
ticles which underlie these regions. Sticking to the basal ends of the prismatic cells, 
numerous amoeboid elements can also be seen. How do they originate! They must 
come either from the mesendoderm or from the ectoderm. That some of them migrate 
forward from the region of the thoracic-abdominal plate there can be no doubt, and it 
seems almost equally certain that some come from the surface cells. The position of 
the nuclei of the peripheral cells frequently points to the theory that some of them are 
crowded below the surface by mutual pressure. Ou the other hand it is sometimes, but 
not always, the case that the boundaries of the ectodermic cells are clearly defined. 
The ectoderm still consists of a single cell stratum. The ectodermic nucleus is sus- 
pended in the middle of the cell, cytoplasm filling the peripheral and deutoplasm 
the central ends. Mesendoderm cells also travel backward and sideways from the 
thoracic-abdominal plate and settle down upon the ectoderm. The cells which migrate 
into the depths of the egg and form the cumulus-like mass have this peculiarity — 
they form a connected syncytial mass; their nuclei are small and of irregular shapes. 
On the other hand amoeboid cells below the embryonic area frequently possess large 
spherical nuclei. 

LATER STAGES IN EMBRYONIC DEVELOPMENT. 

The development of the external form of the embryo is illustrated by cuts 27 to 
38 and by plate 51. The mesendoderm cells play an important role at the time the 
appendages are budding. In surface views they become less and less conspicuous, 
until in the late egg nauplius (cuts 31, 32) they have passed out of sight into the 
deeper parts of the egg. 

The appendages make their appearance in the following order: (1) First antenna?, 
(2) mandibles, (3) second antennas, (4) first maxilla?, and the remaining thoracic 
appendages in regular succession. They are all formed by the folding of the body 
wall or ectoderm, and contain solid yolk cores, until these are absorbed and replaced in 
part by the mesodermic cells which migrate into them. The second antenna soon 
becomes bifid and bilobed at its apex (cuts 30-32), the inner branch representing the 
future long flageilum of this appendage. The first antenna? remain single until just 
before the time of hatching, when the inner branch or flageilum begins to grow out 
from the inner lower surface of the primary stalk. The optic disks are flat areas of 
rapid cell division. 

F. C. B. 1895—14 



210 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

The relative position of the mouth and antennae is illustrated by cuts 28 and 29. 
I will add the account given in my paper on the development of Alpheus, where the 
lobster was also included, since it applies to the higher Crustacea generally : 

Before the first antenme are folded, when they are distinguished as dense patches of cells, some 
eggs show the primitive mouth as a minute circular pit, lying uearly on a line drawn between the 
centers of these proliferating cell areas, hut, so far as my observation goes, never distinctly in front of 
them. The relative positions of the mouth and first pair of antenna shift very rapidly during the early 
period of their growth, before the fully developed egg-nauplius stage. The pit elongates and becomes 
a transverse furrow, and by the time the first pair of antennae are clearly marked off as rounded buds, 
and before the second pair are raised into folds, the mouth is on a line with the first of these append- 
ages. When the second antennse are elevated into folds the mouth is behind the buds of the first j>air, 
or on a line drawn between their posterior margins (94, p. 442). 

At a stage before the appearance of eye pigment, represented in fig. 232, plate 51, a 
diffuse but conspicuous patch of ectodermic cells is developed, similar to what I have 
already described in Alpheus (94, p. 114). In case the egg is oblong this patch lies 
at one pole about 90° behind the embryo. 

A stage just previous to the appearance of eye-pigmeut is seen in fig. 234. The 
forked telson now covers the labrum and is reaching up in front of the brain. 

The relation between the age and size of the embryo under normal conditions — 
the eggs having been laid in summer — may be seen by comparing cuts 23-38 with 
table 18. Most of these are from the same batch of eggs. 

Eye pigment is developed in about four weeks, and the rate of growth of the 
embryo can thenceforward be gauged by the increase of the pigmented area (cuts 
35-38). 

At a stage before the concentration of the embryo has begun, a little earlier than 
that shown in cut 29, Bumpus (30) has described and figured what has the appearance 
of a rudimentary pair of preoral appendages. These are elongated folds lying parallel 
with the convex border of the optic lobe, and separated from it by a slight furrow only. 
They are very transitory, disappearing completely after a brief interval. They can 
be seen in some of my preparations, but are not shown in the drawings. 

HISTORY OF THE YOLK CELLS. 

In my paper on the development of Alpheus I have devoted a chapter to the 
"Origin and history of wandering cells in Alpheus," and I have little doubt that what 
is said there of Alpheus is generally true of the lobster and of most decapoda. 

In Alpheus, as in the lobster, a certain number of cells, 30 to 40, are budded off 
from the blastosphere, and form what I have called the primary yolk cells. Wander- 
ing cells, or those which enter the yolk and move about in it, have a triple origin, 
namely, from the blastoderm, the invaginated cells, aud the ventral plate. It should also 
be added that both the process of multiplication by indirect cell division and that of 
dissolution or degeneration of protoplasm take place simultaneously in the wandering 
cells. 

During the egg-nauplius period there is a rapid diminution of the wandering cells, due to cell 
disintegration and emigration to those parts of the embryo where mesoblastic organs are being laid 
down. The history of the wandering cells in Alpheus is largely the history of the early develop- 
ment of the mesoblast and entoblast. The endoderm makes its appearance as a distinct cell layer 
during the egg-nauplius period, and takes the form of a narrow sheet of rather large cells, between 
the yolk and the rudimentary heart, near the body wall. In the space corresponding to the heart, 
blood corpuscles can already be detected, besides scattered mesoblast cells. Both the latter and the 
entoblast are derived from the wandering cells which come out of the yolk (94, p. 408). 



Bull. U S F. C. 1895. The American Lobster (To face page ?! ) 



Plate J. 





Out 35. — Surface view of embryo with eye-pigment in form 
of crescent, as seen from the surface. Telson overlaps 
brain. Embryo about 2G (lays old. From series No. 3, 
table 18, July 26, 12 m. Cuts 35-38 drawn from eggs 



fixed with picro-sulphurie acid, 
under size. 29 diameters. 



( hitline of eg"' a little 



Cut 36. — Embryo 61 daysold. Area of eye-pigment semi 
circular. Telson behind brain, from No. 3 (11), table 
18, September 1. 211 diameters. 





Cut 37.— Embryo 122 days old. Area of eye-piginenti 
rounded or irregularly oval in outline. From No. 3 (13) . 
table 18, November 1. 20 diameters. 



CUT 38. — Embryo 211 days old. Area of eye-pigment 
irregular, somewhat oval or rounded in outline. From 
No. 3 (16), table 18, February 1. 2!» diameters. 



Drain hy F. H. Herriclc. 



THE AMERICAN LOBSTER. 211 

Iu the lobster there appears to be this difference, in that the primary yolk cells 
are for the most part, if not wholly, disintegrated before invagination occurs, and 
take no part in development. This can not be shown to be the case in Alpheus. 

I have spoken of the formation of the primary yolk cells by tangential division, in 
Alpheus and other forms, as a process of delamination, on the ground that they repre- 
sented a primitive endoderm, and that the egg with primary yolk cells corresponds to 
the planula stage of coelenterates. I first called attention to this mode of origin of 
yolk cells in decapod Crustacea in my paper on Alpheus (94, p. 400), and found that 
in the lobster they arose by transverse division from the blastospheric cells or from the 
peripheral cell layer (since there is no true blastosphere in this egg). The budding of 
these cells, moreover, begins before the outwardly migrating cells have reached the 
surface and completely surrounded the yolk. The regularity with which this process 
occurs " in such typical forms as Alpheus and Homarus argues," as I remarked in an 
earlier paper, " for its presence in allied species where it has possibly been overlooked." 
A precisely similar origin and speedy dissolution of yolk cells has been recently 
described in Gebia by Butschinsky (31). It seems that there can be no doubt that the 
formation of yolk cells at this early period is thelast trace of a process which was once 
of importance, but the role which they play now must be an exceedingly minor one. I 
have never found more than 28 of these cells in the large egg of the lobster (cut 22). 
Here, while it may be admitted that they are phagocytes or yolk digesters, the impres- 
sion which they make upon this large mass of material is insignificant, and they are 
themselves soon disintegrated and become a part of the general food stock. It is pos- 
sible that they are the remains of a primitive hypoblast, that they once played a more 
important part as digesters of the yolk than they do at present, and that this function 
was usurped by the mesendoderm formed at the time of invagination. The term trans- 
verse fission instead of delamination should, however, be used in speaking of this process 
(94, see pp. 400 and 419), since no true delamination occurs and nothing certain is 
known about the origin and meaning of this process in the decapod Crustacea. 

DEGENERATION OF CELLS. 

I have discussed the subject of cell degeneration in my paper on Alpheus (94, pp. 
425-431) and need not refer to the facts again in detail (see figs. 237, 240, 241, plate 52). 
The degeneration of cells in the ovary has already been mentioned (p. 152). In the 
embryo this breaking down and absorption of cells into the common yolk mass is first 
seen in the primary yolk cells, and afterwards in the mesendoderm, where it soon 
becomes one of the most striking, and at the same time most puzzling, of all the 
varied phenomena presented by the developing embryo. If we examine a longitudinal 
section of the egg nauplius of the lobster, we find not a few chromatin balls, but a 
meteoric swarm of granulated bodies and naked chromatin grains coextensive with 
the embryo and reaching a considerable distance into the yolk amid the scattered 
mesodermic cells, but perhaps most abundant, as in Alpheus, in the neighborhood of 
the stoinodreum. A long, nebulous train of yolk spherules and granules extends 
forward a considerable distance in front of the mouth and is especially marked in the 
region of the optic disks. The labrum and the folds of the appendages which contain 
solid yolk cores abound also in these peculiar granulated bodies. They occur in less 
numbers in connection with the mesendoderm cells, which have at this stage traveled 
through the greater part of the egg and form a series of irregular sacs filled with yolk. 
These yolk masses, with their surrounding sheet or advancing column of cells, corre- 



212 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

spond to tlie endoderm sac of the crayfish. In the latter the peculiar cell fragments 
also occur. 

If one now examines very thin sections under high powers, he finds that the 
granules and the granulated bodies correspond in general to the structures found in 
Alpheus. The chromatin grains appear sometimes as naked masses in the yolk, and 
stain either very intensely or faintly. They are often vesiculated — that is, they appear 
as hollow shells (fig. 241). Under favorable conditions it is easy to demonstrate the 
fact that these bodies surround particles of yolk, and occasionally they have a cres- 
centic shape, when they seem to be enwrapping a yolk spherule (fig. 210, plate 52) 
(94, p. 127). I have shown that the "secondary mesoderm cells" described in the 
crayfish by Reichenbach (163) are undoubtedly products of degeneration which are 
afterwards absorbed in the yolk. In this species the eudodermic cells which are 
loaded with yolk probably divide by multiple karyokinesis, producing nuclear nests or 
clusters, some of which in time undergo degeneration. The naked balls of chromatin 
which are found in these cells are probably formed in situ, though they unquestion- 
ably shift their position in the egg. 

In a species of Cambarus, which I studied at a stage when five pairs of appendages 
were present, the endodermal nucleus was surrounded by a thin layer of protoplasm, 
which worked its way amid the yolk so as to practically surround a pyramidal mass. 
This strongly recalls the serpentine manner in which the cells creep through the yolk 
in the egg of the lobster. 

Later, when nine pairs of appendages are represented, the endodermal cells have 
nearly reached the ectoderm. The yolk within the confines of the ectoderm has an 
irregular, pyramidal, or radial cleavage. Centrally it blends with a serum-like fluid, 
in which occasional granules or balls of chromatin are suspended. Small spherical 
bodies containing a single chromatin ball, or several balls, occur not only in the yolk 
underneath the ectoderm and in the vicinity of the endodermal nuclei, but also in the 
central yollc of the endoderm sac at various levels below the endodermal nuclei. This is 
a point of some interest in connection with the fate of these bodies. They wander not 
only peripherally but centrally. 1 Earely we meet one which is three or four times the 
average size, having a small chromatin spherule in its center. These latter become 
absorbed and gradually disappear (94, p. 128). 

As 1 have already shown, the plasmic vesicles described by Bumpus (30) in the 
ovarian egg are mesodermic cells in the process of degeneration. (For the origin and 
history of these bodies see p. 152.) 

Later, according to Bumpus, the plasmic vacuoles are represented by chromatin 
granules scattered about in the peripheral parts of the yolk. 

In the early cleavage stages Bumpus says that the plasma cells are still represented 
by chromatin grains, which "are no longer confined to the periphery, however, but 
have advanced toward the center and formed an indefinite ring" (30). In the speci- 
mens of eggs in the early cleavage stages w r hich I have studied — stained chiefly in 
Kleinenberg's hajmatoxylon solution — I have never been able to detect any degenera- 
tive products whatever. They appear to have been completely absorbed or converted 
into yolk before this time. 

In a still later period, when the y-shaped embryonic area is differentiated, "the 
plasma vacuoles," according to Bumpus, "are represented by chromatin nebula}, which 

1 The movement of these bodies is probably due wholly to extraneous mechanical causes 



THE AMERICAN LOBSTER. 213 

generally underlie the triangular and U-shaped areas" and are "found as small clouds 
between and also outside the limits of the embryonal tract." He says further that 
"chromatin grains, as was seen in the surface view, are mosc abundant where ecto- 
dermal cells are most numerous." No inference is drawn from this, but plainly the 
true one is not that the larger collection of endoderm cells are centers of cell degener- 
ation, but that the mesoblastic cells attach themselves to those parts of the embryonic 
ectoblast which are growing the fastest, and by their own dissolution give rise to the 
"chromatin nebulae." 

Bumpus does not explain the origin and fate of the chromatin particles which he 
accurately figures, but remarks that " structures comparable with the chromatin grains 
of the plasma cells are neither mentioned nor figured by Reichenbach, though the 
so-called 'serum' may represent the region of their activity." Further on it is said 
that "future comparison may prove these," the " secondary mesoderm cells," of Eeich- 
enbach "to be the same as the plasma vacuoles and their chromatin grains;" and 
again, "I have been unable to find in Homarus preparations that throw any direct 
light on the so-called 'secondary mesoderm.'" 

I have shown (94) that the "secondary mesoderm cells" are not cells at all, but 
the products of cell degeneration, aud that in their origin and final destiny they bear 
the closest resemblance to the "chromatin nebulae" of the lobster. 

ABNORMAL DEVELOPMENT. 
SEGMENTATION OP THE EGG. 

In every batch of segmenting lobster eggs one is sure to meet with many irregu- 
lar forms, and in some cases the greater number appear to be abnormal. Nuclei can 
be detected at the surface of many of the segments, and if the egg is treated with 
Perenyi's fluid or with an acid the dark-green segments and their nuclei contrast very 
strongly with a milk-white coagulable substance in which they seem to be embedded. 
Some eggs, which were laid by a lobster on August 23, after a captivity of eight weeks 
in a small aquarium, were light-colored, but were normally fixed to the abdomen, and 
were fertile, although the segmentation was exceptionally irregular. Sections of these 
eggs showed an irregular distribution of cells both at the surface and throughout the 
yolk. In some places cells appear to have been carried below the surface by over- 
growth, and afterwards to have multiplied in the yolk. 

Eggs which are otherwise regularly segmented may contain a large superficial 
mass of undivided yolk, as in fig. 220, plate 50. Here is a very large mass of yolk about 
the pole of the egg — a similar one lay near it on the opposite side — and a considerable 
number of smaller segments. When this egg is sectioned it is found that the large 
yolk masses are nearly devoid of protoplasm, while the smaller segments contain each 
a nucleus which shows traces of degeneration. There is no nuclear membrane, aud 
the chromatin has assumed a very irregular form. 

It is common to find eggs with yolk uusegmented with the exception of one or more 
small balls at the surface. Sometimes a single large segment is seen, looking as if it 
had been pinched off, and in this and in many other cases it is evident that the egg 
has in some way received harsh treatment. 

In one egg, rather more anomalous than usual, there was a single small spherical 
segment at one of the poles of the elongated egg, while the remainder of the yolk was 



214 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

undivided. A single nucleus was visible in the small segment, but the egg in reality 
contained six cells, five lying in the unsegmented yolk. 

It would be interesting to know how many of the irregularly segmented cells 
eventually attain a normal condition. It seems probable that very many of them do, 
judging from the fact that the number of abnormal eggs which later appear when the 
nauplius stage is reached is much smaller, yet there is no evidence that any of the 
eggs are lost. 

THE INVAGINATION AND EGG-NAUPLIUS STAGES. 

I will now speak of some interesting variations which occur during the invagina- 
tion period and immediately after it. 

Instead of the normal ingrowth of cells from the surface into the yolk and the 
sinking in of others to form a small circular pit, there is what appears at the surface as 
a deep transverse invagination. This is sometimes a long crescent-shaped or irregular 
transverse fissure, as in the egg of which cut 40 represents a median longitudinal 
section. 

In other cases, in which the processes of development have gone further, there is 
formed an irregular, oval, or circular disk of cells in connection with the invagination, 
as shown in fig. 229, plate 51. Here there is a well-defined rim on one side, while upon 
the other the structure seems to blend with the yolk. In a further-developed stage in 
the same process I find that the egg has often a well-defined, sometimes round, and 
very irregular circumvallate disk of cells. The cells within the vallum are densely 
crowded, and the presence of numerous karyokinetic figures shows that at times cell 
division may become rapid. Below the surface, both within and without the vallum, 
the granular masses of chromatin bear abundant testimony to the degeneration of living 
protoplasm which is taking place in the yolk. The columnar aspect of the marginal 
cells of the disk can be plainly seen. The way in which this condition is reached is 
illustrated by cuts 39 and 40. By the ingrowth (or infolding in consequence of unequal 
growth) of some of the superficial or ectoblastic cells into the massive ball of yolk, a 
tongue-shaped or island-like patch of cells is formed, on which the embryo proper is 
subsequently marked off (figs. 228 to 231). 

The egg-nauplius may arise in a depressed central part of the disk, as in fig. 231, 
or upon its margins, figs. 228, 230. 

We will now glance at the histology of some of the abnormal embryos. Out 40 
shows a median longitudinal section through one of the earlier stages described. 
When the egg was examined from the surface a transverse irregular fissure was seen, 
corresponding to the pit {Pit) where the sheet of cells dips below the surface. We see 
from a study of this egg that a considerable stratum of cells, including the invaginate 
area, has grown into the yolk, and that its edges are folded upon themselves. In this 
case one side of the disk, corresponding to the anterior end of the embryo, is at the 
surface, while the opposite side is deeply embedded in the yolk. Numerous cells have 
budded off from this cell plate, particularly at its posterior end, where they multiply 
rapidly and move about freely in the yolk, like the normal mesendodermic cells. Like 
the latter, they move chiefly in a posterior direction into the deeper parts of the yolk. 
Many of these wandering cells are moreover already in process of degeneration. It 
looks as if there was a migration of cells from the surface behind the cell plate, but 
the appearances may be in this respect deceptive. The yolk flows over the engulfed 
cells, but I find in my preparations no new superficial layer of ectoderm established. 



THE AMERICAN LOBSTER. 



215 



Cut 39 represents a median longitudinal section through the embryo shown in 
fig - . 230, plate 51. Here the entire embryo is immersed in the yolk or in a thin coagulablo 
fluid derived from it, through 'which it can be seen, while the cell plate touches the 
surface in a narrow, bow-shaped area, but dips below again at its peripheral margin. 
The cell plate beyond the confines of the thoracic-abdominal process and appendages 
of the embryo consists of a single layer of very large cubical or columnar elements 
gorged with yolk. In front and behind, the edges of this sheet unite to form a cul-de- 
sac, so that the whole structure resembles iu form a flattened bag, which is partially 
buried in the yolk, with which it communicates by the opening or mouth of the sac 
below. The edges of the plate are curled over in the yolk, like one of the limbs of 





Cut 39. — Median longitudinal section through ab- 
normal embryo shown in fig. 230, plate 51. Fixed 
with picro-sulphuric acid, stained in Kleinenberg's 
hsematoxylon, August 9, 1892. 



Cot 40. — Sagittal section through abnormal em- 
bryo in early stage of development. Fixed in 
piero-sulphuric acid, stained in Kleinenberg's 
hseinatoxylon, August 9, 1892. 



AbT, thoracic-abdominal process. Deg., egenerating cells. ep.f., ingrowing fold of surface-epithelium. Mo, mouth 
of stomodreum. Pit, pit formed by ingrowing fold, r, outward fold of surfacs epithelium, y.c, scattered cells in yolk. 
y., food-yolk, abnormall3' covering embryo in cut 39. 



the letter S. Iu other respects the histology of this egg-nauplius embryo resembles 
that of a normal form, except iu perhaps a great preponderance of degenerating cells. 
In the embryo, the surface view of which is shown in fig. 228, plate 51, essentially the 
same conditions are seen. These abnormal embryos which have just been described 
are due in all probability to a disturbance of the normal mechanical conditions under 
which the egg usually develops. It is quite probable that they could be artificially 
produced, but no experiments have yet been made in this direction. 

I have noticed another interesting abnormal variation in the invagination stage. 
(See 91). At a period nearly corresponding to that shown in fig. 255, plate 54, there 
is a large irregular cavity or several communicating cavities in the depths of the egg. 
This chamber contains very little yolk, and its wall is composed of cells which grasp the 



216 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

yolk by long pseudopodia. The surface of the wall next the cavity is densely studded 
with nuclei. This irregular cavity is undoubtedly formed by a folding of the embryonic 
area, brought about by unequal growth, like the cases already described, and morpho- 
logically lies outside the embryo. This is probably the same as the structure referred 
to by Bumpus (30, p. 238). It has nothing to do primarily with either the endoderm 
or the alimentary tract. 

It seems quite probable that many of the abnormal stages already described may 
eventually attain to a normal growth and development, but this is not certain. 

DOUBLE MONSTERS IN OVUM AND LARVA. 

Brightwell, who gave a descrbption of the young of the European lobster (Romarus 
gammarus), in 1835, was the first to notice double monsters in this species. He says: 
"Two specimens of the young which appeared double were found, being strongly 
united in the head " (24). In 1886 the first particular account of these monstrosities 
was given by Ryder (171), who describes four types of fusion among the free-swimming 
stages. It is to his kindness that I am indebted for the opportunity of examining the 
six abnormal larvse which he described, two of which I have figured. 

It seemed worth while to trace, if possible, the history of these abnormal larv® 
back to their early embryonic stages, but although I examined many eggs from many 
individuals, I found only three monstrosities of this kind. The earliest is in the 
invagination stage, corresponding to that shown on plate 53. It has the appearance of 
a normal egg, except that instead of a single invagination there are two areas of 
ingrowth. The axes of these two embryos appeared to be inclined to each other at 
an angle of about 135°, and they were separated by considerably more than one-third 
the circumference of the egg. The posterior ends of these embryos are the nearest 
together, as with the others which I have observed. There is no cellular union of the 
embryos in the yolk, but they meet in a common peripheral layer of cells, the nuclei 
of which are now widely scattered, except in the immediate embryonic areas. 

The next youngest stage obtained was the egg-nauplius, which I have repro- 
duced in fig. 235, plate 51. The two embryos are similar in every respect and lie almost 
exactly opposite each other. The thoracic-abdominal plate of one embryo is joined to 
that of the other by a long train of cells which extends through the yolk just below 
the surface. These have the general character of migrating mesendodermic cells, 
and some have already passed into the depths of the egg. 

In a little older double egg-nauplius the long axes of the two embryos make an 
angle of about 160° with each other. Their posterior extremities are apposed and, 
as in the first instance, separated by about one-third the circumference of the egg. 
It is probable that had the two latter monsters been allowed to develop they would 
have appeared, when ready to hatch, as if fused, back to back, like the fourth type 
described by Ryder, in which four eyes were developed, two to each embryo, two 
distinct sets of mouth parts, and biramous locomotor appendages. As Ryder remarks : 
"This relation of two perfectly formed embryos in the same lobster egg is exactly the 
reverse of that which is observed in vertebrates" (171). 

In the first type of larva described by Ryder there are no eyes; the cephalo- 
thoraces are fused completely, both laterally and anteriorly, and the separate abdo- 
mens diverge at a wide angle. In his second type (fig. 200) there is a single median 
eye on the line of fusion of the cephalo-thoraces. The abdomens diverge at a very 
wide angle, and, as seen in the drawing, there is a fusion of the first pair of antennae. 



THE AMERICAN LOBSTER. 217 

This shows that parts of the embryo ou the middle line, including the ocellus, have 
disappeared, and that the large median pigment spot is beyond question the last trace 
of the fused compound eyes. 

In fig. 199, which illustrates the third type described by Eyder, the cephalo- 
thoraces are fused laterally and anteriorly; there is no median eye, but a pair of 
compound eyes, the right of which is the right eye of the right embryo and the left 
the left eye of the left. The stomachs are fused on the middle line, but there is no 
apparent union of the antenna? or mouth parts. Behind the stomach the parts are 
all double. 

It is evident that the causes which have produced the monsters with a single 
pair of compound eyes (fig. 199) are of exactly the same nature as those which have 
produced the monster with a single median pigment spot. In the latter case their 
action has been more prolonged. It is also evident that these abnormal larva? have 
been derived from embryos like those which I have described. There is, however, 
this noticeable distinction : In the abnormal embryos the posterior ends of the bodies 
are apposed and united, while in the larva? the anterior ends are united, the posterior 
parts being widely divergent. It seems to me probable that the apposition and union 
of the tail ends of the embryo do not last long, and never involve anything more than 
the cells in the yolk; that two distinct thoracic-abdominal processes and two distinct 
tail folds are formed, which begin to diverge at an early period. Along with these 
changes a process of fusion apparently takes place between the anterior parts of the 
two embryos, which are at first entirely separate and distinct, excepting for the yolk 
and peripheral cells (ectoderm) which unite them. 

The fusion of parts does not take "place coincidently with the process of gastrula- 
tion," as Ryder suggested, and does not begin to show practical results until after the 
egg-nauplius stage. In regard to the way in which the different degrees of fusion 
have been brought about, Eyder applies the rule adopted by Eauber for the interpre- 
tation of fish embryos — that the degree and manner of fusion is "determined by the 
width of the angle at which the embryonic axes were primarily inclined to each other." 
This principle probably applies to the double monsters produced from the lobster's 
egg, but the process of fusion seems to me to be something entirely distinct from the 
concrescence seen in the parts of the normal embryo. We have to do here with the 
fusion of two embryos which are practically distinct from the first. 

NOTE ON THE DEVELOPMENT OF CAMBARUS. 

I received through the kindness of Professor J. E. Eeighard, in the fall of 1893, a 
large number of crayfish of the species Cambarus immunis. They were taken from a 
pond in Ann Arbor, Michigan, on the 16th of November, when ice was just beginning 
to form. Many of the females.were already " in berry," and most of the eggs were in a 
very early stage of development, some, without segmentation of the yolk, having been 
recently laid. Several were in the egg-nauplius stage, and the oldest which I ex- 
amined corresponded to Stage H of Eeichenbach (163), having all the thoracic append- 
ages, and the folded abdomen had grown forward so that it nearly touched the labrum. 

The eggs carried by each female are relatively very large (1.5 mm. in diameter) 
and few in number. They are of a light or sometimes rather dark coffee-brown, and 
appear to be insecurely fixed to the swimmerets, being liable to drop off or become 
detached, especially when several animals are kept together. The species is hardy 



218 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

and will thrive in confinement, althou gh, as Professor Reighard remarks, the eggs 
do not fare so well. 

The early phases of segmentation of the protoplasm and yolk correspond very 
closely to what has been described in the lobster. The protoplasm divides, and its 
products migrate toward a limited area of the surface of the egg, which becomes the 
animal pole. This lies usually, if not always, somewhere between the stalk of attach- 
ment and the opposite surface of the egg. 

In one egg which I studied three small whitish spots could be seen glistening 
through the brown yolk. These, which were some distance apart, marked the first 
cells to reach the surface and initiate the segmentation of the yolk. In another egg, 
which had 27 cells visible at the surface, the shell was raised or distended over that 
hemisphere containing the animal pole. This distention of the membrane is not, 
however, so uniformly restricted to this part of the egg as is the case with the lobster, 
nor were the large yolk hillocks, so characteristic of the latter, discernible here. The 
cells are now visible to the naked eye as white dots. 

Other eggs are seen in which 40 or more cells could be detected lying rather near 
together and covering nearly half the egg, while the rest of the surface is without 
trace of protoplasm. 

The process of migration from depths of the yolk and division of those cells which 
have reached or nearly reached the surface continues until the whole superficies of the 
egg is dotted with cells, 80 or more in number. What corresponds to the animal pole 
can now be faintly distinguished where the cells are somewhat thicker or closer 
together. No segmentation of the superficial yolk has yet taken place, although the 
latter is apparently raised slightly about each cell. 

As cell division proceeds, the number of surface cells becomes very greatly 
increased until 400 or more are visible. The egg then appears to be very nearly 
uniformly segmented at the surface, and in certain phases of "rest" has the usual 
beaded appearance. This is a late " yolk- pyramid " stage. 

The invagination stage soon follows, and a very distinct round pit appears at the 
surface, very much in external appearance like the corresponding phase of the lobster's 
egg, excepting that the invaginate cavity is larger. 

An invagination of a different character sometimes occurs which is probably 
abnormal. A round, very symmetrical depression is seen in the midst of the cells 
corresponding to the animal pole. The depression is shallow, and at its bottom three 
or more cells can be seen looking as if they had been pushed below the surface at this 
point. The cells bordering this depression are sometimes arranged very uniformly. 
A similar pit was seen in the midst of the cells of the animal pole before they had 
spread over the entire yolk. In this case it was plainly abnormal. 

I have not yet studied all the phases of the external segmentation of Cambarus 
by means of sections, but from what has already been seen it is clear that it follows 
in all essential details the course of events which have been described in the lobster. 



Chapter XIV.— SUMMARY OF OBSERVATIONS. 

GENERAL REVIEW OF THE LIFE-HISTORY OF THE LOBSTER. 

1 will now give a brief summary of the most important observations which have 
been detailed in this work, emphasizing in particular those facts which bear upon the 
problem of the artificial propagation of the lobster. 

(1) Distribution. — The geographical range of the lobster covers about 20 degrees of 
north latitude, from the thirty-fifth to the fifty-second parallel, and includes a strip 
of the Atlantic Ocean 1,300 miles long and from 30 to 50 miles wide. Its vertical dis- 
tribution varies from 1 to upward of 100 fathoms. The most northern point at which 
its capture has been recorded is Henley Harbor, Labrador ; the most southern point, the 
coast of North Carolina. The fishery was begun on the coast of Massachusetts and 
gradually extended northward. Consequently, at present the lobster is most abundant 
and attains the greatest size in the northerly part of its range, in eastern Maine, and 
in the northern maritime provinces of Canada. 

(2) There is great diversity in the character of the environment which explains 
in some measure the many variations which occur in the habits of the animal, as in 
the time and frequency of molting, in egg-laying, in the hatching of the young, and 
in the rate of growth. 

(3) The lobster displays a considerable degree of intelligence and possesses organs 
to which the various senses of the higher animals have been ascribed. The tactile 
sense is diffused over the whole body, and the dead shell is perforated by innumerable 
minute pores which are capable of transmitting stimuli to sensitive cells lying in the 
delicate skin below. It has the sense of smell and of taste, but it is doubtful if the 
so-called auditory organs are really ears. 

(4) The sea-bottom is the natural abode of the lobster in the adult state, and it 
never leaves it and never forsakes the water unless obliged to do so. 

(5) Migrations. — No coastwise migrations are known to occur, but large numbers 
of lobsters move to and from deep water in fall and spring. This bathic migration 
varies in accordance with the character of the coast and nature of the bottom. It is 
influenced by the temperature of the ocean, by the abundance of food, and to some 
extent by the molting and breeding habits. 

(6) Many lobsters remain in the relatively shallow and cold waters of harbors 
throughout the winter, but at this season they are found only upon rocky bottoms, 
where food is most abundant. One may search for them in other situations, as on a 
weedy or muddy bottom, during the winter season in vain. 

(7) Influence of temperature. — The optimum temperature of the lobster is about 
55° F. When the temperature of the sea marks 50° to 55° in spring (May at Woods 
Hole) large numbers of lobsters begin to creep nearer the shores, and when again in 
the fall (October at Woods Hole) the temperature is near this point, they have already 
begun the outward movement. 

(8) In severe winters lobsters are either driven into deeper water or, if living in 
harbors, seek protection by burrowing in the mud when this is available. This some- 
times happens when a sudden lowering of the temperature arises from any cause, and 
always when the animals are confined in pounds. In such cases a prolonged cold spell 
may prove fatal (see p. 26). The lobster is practically excluded from the coast of 
Labrador east of the Straits of Belle Isle by the Arctic current and lingering ice. 

219 



220 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

(9) The adult lobster is essentially a nocturnal animal, being far more active by 
night than in the day. The reverse is true in the larval period, when the habits are 
entirely different. 

(10) Bxirroiving habits. — The lobster is a great burrower in the sea-bottom. This 
habit is developed to an extraordinary degree in pounds or inclosures, at all seasons, 
and is practiced, though less regularly, under other circumstances; (Compare para- 
graph 8.) The holes, some of which are 2 to 3 feet long, are solely for protection and 
are never used while the animal is molting. In the construction of the holes the large 
claws are used, and possibly the tail-fan. The lobster almost always enters its burrow 
tail first. 

(11) Food. — The adult lobster feeds chiefly upon fish, dead or alive, and upon inver- 
tebrates. It also takes a small quantity of vegetable food, such as algae and eel grass. 
Fragments of dead shells, coarse sand, and small gravelstones are also swallowed. 
The former yield lime, which is absorbed and finally laid down in the skeleton. Many 
small fish which inhabit the bottom fall a prey to the sharp cutting-claw of the lobster, 
which it uses with great skill and dispatch. The larger lobsters prey invariably upon 
the smaller or weaker ones when they can. 

(12) The food is seized, torn, and crushed by the large claws, and then taken up by 
the appendages about the mouth (maxillipeds, maxillae, and mandibles), by which it 
is successively torn and chopped fine, when this is possible. While the animal is 
eating, a stream of fine particles is passed into the mouth, thence to the gastric mill 
or masticatory stomach. Here the food is ground and the fluid or digestible parts 
are strained into the small delicate intestine from which they are absorbed. The 
indigestible refuse is regurgitated from the stomach-bag. 

(13) Impregnation. — In copulation the female receives the sperm from the male in 
packets or spermatophores, which are deposited in an external chamber, the seminal 
receptacle. This is a blue, heart-shaped structure, situated on the under side of the 
body, between the bases of the fourth pair of legs counting from the large claw-bearing 
appendages. It opens to the exterior by a median slit with elastic edges, which can 
be easily pressed apart. 

(14) The male does not discriminate the sexual condition of the female, which may 
be impregnated at any time. It is, however, probable that copulation takes place most 
commonly in spring. The sperm retains its vitality for a long time, in some cases 
for at least several months before it is used. 

(15) Egg laying. — Much confusion has existed concerning the time when the eggs 
are laid. This has resulted chiefly from the fact that the eggs are carried by the 
females for the space of from ten to eleven months before they are hatched. About 
80 per cent of the spawning females lay their eggs at a definite season in the summer 
months, chiefly July and August. The remainder, about 20 per cent of the whole 
number, extrude eggs at other seasons — in the fall and winter certainly, and possibly 
also in the spring. 

(16) In the western end of Vineyard Sound and the region about Woods Hole the 
greater number of eggs are extruded during the latter part of July and the first half 
of August. The summer spawning of each year lasts about six weeks, and fluctuates 
from year to year backward and forward through an interval of about a fortnight. 

(17) This variation in the time of the production of the eggs is due to the fact that 
the ovarian ova require at least two years of growth before they are ready for 



THE AMERICAN LOBSTER. 221 

extrusion. Anything which affects the vital condition of the adult female will thus 
affect the time of spawning. 

(18) The spawning season in the middle and eastern districts of Maine is about two 
weeks later than in Vineyard Sound. In 1893, 71 per cent of the eggs which were 
examined from the coast of Maine were extruded during the first half of August. 

(19) At Woods Hole, Massachusetts, 168 egg-bearing lobsters were captured from 
December 1, 1893, to June 30, 1894. Out of this number 44, or 25.6 per cent, bore eggs 
which had been laid outside of the summer months, chiefly in the fall. A lobster cap- 
tured at Matinicus Island, Maine, February 4, 1893, with the yolk uusegmented, and 
therefore in a very early stage, is mentioned in table 13, No. 20. Similar captures 
recorded in tables 12 and 13 show that the laying of eggs in fall and winter is not rare. 

(20) Lobsters laid eggs in confinement only twice during the six summers which I 
spent at Woods Hole, although ripe females were frequently placed in the aquaria. 
When kept under these conditions, or even in floating-boxes outside, the eggs are 
usually not laid, but are absorbed directly from the ovary. 

(21) Law of production of eggs. — The law of the production of eggs may be 
expressed arithmetically as follows: The numbers of eggs produced at each reproductive 
period vary in a geometrical series, while the lengths of the lobsters producing these eggs 
vary in an arithmetical series. A lobster 8 inches long produces about 5,000 eggs. 
According to this law, a lobster 10 inches long would produce 10,000, a 12-inch lobster 
20,000, a 14-inch lobster 40,000. An examination of table 15, in which the number of 
eggs borne by over 4,000 lobsters is tabulated, shows that this law holds good up to 
the fourth term. When a lobster attaius a length of 14 to 16 inches this high standard 
of production ceases to be maintained. A 17-inch lobster produces about 63,000 eggs. 

(22) The largest number of eggs recorded for a single lobster is 97,440. In one 
case the lobster was 15 inches long and in another 16 inches. In neither was the 
animal able to fold its tail on account of the large number of its eggs. This suggests 
that the rudimentary condition of the swimmerets on the first abdominal somite in the 
female is necessary for the protection of the eggs. The egg-bearing female goes about 
with the tail folded. This would be impossible if these appendages were of the usual 
size and carried the usual number of eggs. 

(23) The average weight of a lOJ-inch female lobster with eggs is 1| pounds, the 
eggs weighing about 2 ounces. A 15-inch lobster, which weighs upward of 4 pounds, 
sometimes carries a burden of a pound of eggs. The number of fresh eggs in a fluid- 
ounce is about 6,440, and they weigh about 1 ounce avoirdupois. 

(24) Incubation period. — The period of incubation for the summer eggs at Woods 
Hole is from 10 to 11 months, in one case lasting 335 days, from July 1, 1890, to June 
1, 1891, when the young were just beginning to hatch out. 

(25) The general range of the hatching period of summer eggs at Woods Hole is 
from May 15 to July 15. The greater number are hatched in June. 

(26) The hatching of a single brood lasts in some cases over a week, owing to the 
slightly unequal rate of development of individual eggs. 

(27) The period of incubation of the summer eggs varies with the temperature of 
the water. In Newfoundland the hatching period is said to be from three to six weeks 
later than at Woods Hole (15th or 20th of July to the 20th of August). 

(28) The hatching period also varies with the time of egg-layiug. Thus the 
hatching of young lobsters has been observed in November in Newfoundland and 
Woods Hole, and in February at Gloucester, Massachusetts. 



222 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

(29) Time of sexual maturity. — Female lobsters become sexually mature when from 
8 to 12 inches long. The majority of all lO^-inch female lobsters are mature. In 100 
dissections recorded in table 20, 25 females were found, from 9f 6 to 12 inches long, 
which had never laid eggs, but in 8 of these the ovaries were nearly ripe. Of the 17 
immature, 6 were lOi inches or over in length, and in most cases the ovaries would 
not have become mature for two years. 

(30) Frequency of spawning. — The lobster does not spawn oftener than once in two 
years. The spawniug interval is probably a biennial one, one set of eggs (summer 
eggs) being laid in July or August (at Woods Hole), and the following set in two years 
from that time. One has only to examine the ovary of a lobster (see fig. 138, plate 38) 
which has just hatched a brood — that is, one year from the time of the last spawning — to 
be convinced that annual spawning is an anatomical impossibility. The conclusion 
reached from a study of the growth of the eggs is confirmed by the percentage of 
egg-bearing females captured during the fall and winter. I have shown that conclusions 
deduced from statistics of this kind are often erroneous, especially when observations 
have been made in a single locality. When the results of the catch in the harbor of 
Woods Hole and off No Mans Land were averaged it was found that about one-half 
of the adult females had external eggs, which accords with the view that the spawning 
interval is a biennial one. 

(31) Relative abundance of the sexes. — The relative number of males and females' 
varies considerably in certain localities, as at No Mans Land, May, 1894 (table 22), 
especially in places affected by the inshore migrations, where the males seem to take 
the lead. In other places the number of the sexes is about equally divided ; this would 
always be true if our observations were extended over a sufficient period and area. 

(32) Molting. — By far the greater number of lobsters molt during the months of 
June, July, August, and September, but there is no month in which soft lobsters may 
not be caught. The male probably molts oftener than the female, which would accord 
with the larger proportion of soft male lobsters captured aud with the greater size 
attained by the male. 

(33) Molting lobsters are more often taken on sandy or weedy than on rocky 
bottoms. 

(34) In preparation for the molt organic matter is absorbed from the shell, makingit 
very brittle. Mineral salts are also extracted from certain definite areas of the carapace 
and chelipeds, an essential condition for the safe passage of the molt. 

(35) In molting, the carapace is raised up behind and the body is drawn out through 
the opening thus made between carapace and abdomen. Normally, the shell comes off 
entire, and there is no break in any of the membranes except that between the carapace 
and the rest of the body. The flesh of the large claws is drawn through the narrow 
openings of the joints of the limb by the elasticity of the muscles and previous removal 
of blood from the extremity. This difficult process is also aided by the absorption of 
lime from certain joints of the old shell. 

(36) The lining of the alimentary tract is molted, and the gastroliths which are left 
in the stomach are eventually dissolved. Thegastrolith is a specialized part of the lining 
of the stomach. It is formed in a gastrolithic sac, which is an organ of excretion. It 
agrees in chemical composition with the rest of the shell, excepting in the greater 
proportion of calcium salts. The view that the function of the gastroliths is to supply 
the molting lobster with an immediate supply of lime for the hardening of its soft shell 
must be abandoned. The gastroliths more probably represent a mass of lime which 



THE AMERICAN LOBSTER. 223 

has been excreted in the course of absorption of mineral salts from certain areas of 
the shell. The subsequent assimilation of these bodies thus becomes of secondary 
importance. It was found that small lobsters (3 to 4£ inches long) filled their stomachs 
with fragments of dead shells of mollusks and Crustacea, probably for the purpose of 
obtaining an immediate and abundant supply of lime for hardening the skeleton. 

(37) Hardening of the new shell. — From six to eight weeks are necessary under 
ordinary conditions to produce a shell which is as hard as the one cast off, and lobsters 
destined for the market are in better condition in from ten to twelve weeks after 
molting. 

(38) Rate of growth. — From the data at hand we conclude that the rate of growth 
varies considerably with the individual and its surroundings. The length of the 
young lobster when it hatches from the egg is about 7.84 mm., and the increase in 
length at each molt is about 15.3 per cent. The lobster molts from 14 to 17 times 
during the first year. A lOi-inch lobster has molted from 25 to 26 times, and is about 
5 years old. 

(3.)) Regeneration of parts. — All the appendages are capable of regeneration, the 
time required for this process depending upon the time of the accident with respect 
to the molting period and on the temperature of the water and the abundance of food. 
Defensive mutilation or autotomy is perfectly developed only in the large chelipeds. 

(40) Size. — The greatest size attained by lobsters is about 25 pounds. This con- 
clusion is reached after the examination of skeletons of large lobsters in museums and 
comparing them with the measurements of large lobsters of known weight. Most 
accounts of the weights of these animals are unreliable. 

(41) The weight does not bear a constant relation to the length, owing to the occa- 
sional loss of the appendages. The large chelipeds alone contribute from one-quarter 
to one-half the weight of the entire animal, and in giants like the Belfast lobster the 
weight of the large chelipeds is more than two-thirds that of the entire body. The 
weight is also subject to great variation in consequence of the molt, when a heavy 
shell is exchanged for a much lighter one. 

(42) The adult male is as a rule heavier thau the adult female of the same length, 
and this difference increases with age in favor of the male. 

(43) The egg-bearing females with eggs removed weigh less than the female lobster 
of the same length without external eggs. 

(44) Enemies. — Every predaceous fish which feeds upon the bottom may be an 
enemy of the lobster. The cod is one of the most destructive to small lobsters, after 
the larval stages are passed. 

(45) Tegumental glands. — Besides the hair pores, the shell is perforated by innu- 
merable minute pore canals which lead into tegumental glands situated in the soft skin. 
Each gland has a capillary duct of its own which opens by a pore canal at the surface 
of the shell, and each has one or two peculiar cells which resemble nerve or ganglion 
cells. These organs are found widely diffused over the surface of the body, and they 
also occur iu the walls of the oesophagus and intestine. It is probable that those in 
the swimmerets of the female secrete the cement by which the eggs are glued to the 
body, and that in some parts of the body, as in the labrum, they have a secondary sen- 
sory function, and are the organs of taste, but this is uncertain. 

(46) Color. — The color variations of the lobster, some of which, like the red, blue, 
and cream colored types, are nonadaptive, and this is also true of the remarkable color 



224 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

variations in the larvae and older stages. The normal coloration of the lobster has, 
however, a protective significance. 

(47) Abnormal variations. — Normally the large claws are differentiated for either 
catting or crushing the food, but a rare variation occurs in which the same type of claw 
is developed on both sides of the body. The large crushing-claw may be either upon 
the right or left side of the body, but this is a question of heredity, and it is probable 
that all the young of a brood have the larger claw developed on the same side. 

(48) Repetition of parts. — The large chelipeds of the lobster are especially liable to 
secondary outgrowths, which undergo a peculiar fission, giving rise to what appears at 
first sight as a double claw. It is usually a double part rather than a double append- 
age, although duplicate limbs occasionally occur. 

(49) Structure of ovary. — When the ovary is ripe it is of a dark-green color and 
can be dimly seen through the membrane between the carapace and "tail." If the 
wall of such an ovary is cut the eggs immediately flow out in a stream. The eggs if 
immature invariably adhere together or to the substance of the ovary. 

(50) After ovulation the ovary is collapsed, of an opaque white color flecked with 
green spots, ripe eggs which were left behind — or yellow spots, the remains of similar 
eggs from the last reproductive period. The presence of degenerate eggs thus proves 
that the animal has already become sexually mature and has previously laid eggs. 
The ovaries of lobsters which have never before produced eggs have a uniform tint — 
yellow, pink, gray, or green — and are unmistakable. (For histology of the organs, 
see Chapter x.) 

(51) Development of ova. — The eggs are developed from mesodermic cells of the 
ovarian stoma, and the massive food yolk is derived from three sources: (1) From the 
protoplasm of the cells destined to become eggs; (2) from the degeneration of follicle 
cells, and (3) from the ovarian glands. 

(52) When the lobster hatches, its reproductive organ is a minute cluster of 
cells -£j mm. in diameter, and in the case of the female it takes from four to five years 
for the organ to reach maturity. 

(53) The sperm cells are probably motile in the final stage of their history, but 
nothing is known either as to how the spermatophores are conveyed to the seminal 
receptacles or how the spermatozoa reach the eggs and fertilize them. 

(54) Young. — The lobster hatches from the egg as a pelagic free-swimming larva. 
It lives at the surface of the ocean from six to eight weeks, when, after having molted 
five or six times, it goes to the bottom and appears iu habit and general structure like 
a very small adult animal. After reaching the bottom it travels toward the shore and 
establishes itself in rock piles in harbors and at the mouths of rivers, where it remains 
until driven out by ice. At very low tide they can be found by digging away the 
loose stones. The smallest, from 1 to 3 inches long, go down deep among the loose 
stones, where they are secure from every enemy. When they reach the length of 3J 
to 4 inches they become bolder, leave their burrows in the rock piles, and seek the 
shelter of stones, beneath which they excavate a shallow hole. Young lobsters are 
also found in eelgrass and on sandy bottom in shallow water. 

(55) At the time of hatching, the egg membranes burst into two halves and are- 
drawn off over the head. At about the same time the little lobster sheds its entire 
cuticle; the plumose hairs which garnish its appendages are evaginated and, leaving its 
mother, it swims up to the surface. The first larva has long rowing exopodites on its 
thoracic appendages, and a six-jointed abdomen with spatulate telson. At the second 



THE AMERICAN LOBSTER. 225 

molt rudimentary abdominal appendages appear on the second to fifth abdominal 
somites, inclusive, and the branchial formula is completed. 

(5(5) At the fourth molt it loses the use of its larval swimming organs, but still 
remains at the surface, propelling itself forward by its swimmerets and backward by 
flexion of the abdomen. It is now from three to four weeks old, is half an inch long, 
and has characteristic colors. 

(57) After the fifth molt is passed the young lobster still swims at the surface, 
though it is possible that some leave it during this stage. When the sixth stage is 
reached, age five to six or eight weeks, length about three-fourths of an inch, it remains 
at the surface for a time at least, but goes to the bottom to stay before the seventh 
molt is passed. At the sixth molt all trace of the larval swimming organs is lost. 

(58) The molts follow each other at rather short intervals, and during the first 
year of life, supposing the animal to have been hatched in June, the lobster molts 
from fourteen to seventeen times and attains a length of from 2 to 3 inches. The 
main facts of the subsequent life-history need not be repeated. 

(59) The problem of artificial propagation of the lobster will be solved when 
means are devised by which the larva? after hatching can be reared in large inclosures 
until the fifth or sixth stage, when they are able to take care of themselves. 

(60) Food of larva;. — The food of the larval lobster consists of minute pelagic 
organisms of all kinds. They show little discrimination at this time, snapping up any 
floating objects not too large for them to manage. 

(61) Heliotropism of larva;. — In the pelagic stages the young lobsters are positively 
heliotropic, rising to the surface in the daytime and staying there, and going down at 
night. This habit is not invariable, but the capture of the young by day is the rule, 
by night the exception. 

(62) Survival of larvw. — Great destruction is wrought upon the free-swimming 
stages by both animate and inanimate enemies. A survival of 2 in every 10,000 
larvae hatched would maintain the species at an equilibrium, and the destruction of 
the young under the present conditions of the fishery is probably even greater than 
this implies. (For a discussion of this subject see No. 97 of Bibliography.) 

(63) The general scarcity of the young in the hatching season in places known to 
abound in lobsters is due (1) to their wide horizontal distribution, and (2) to their 
destruction. 

(64) The whole course of development and later growth is slow. The slow larval 
development secures the necessary transportation from the shores and wide horizontal 
distribution, which is absolutely necessary for the life of the species. An abbreviated 
metamorphosis such as is found in this animal appears to be a compromise between a 
still longer development which the animal would have to go through if the egg 
possessed less yolk, and the limitations to protoplasmic activity which are imposed by 
the temperature of the North Atlantic Ocean. 

For the facts pertaining to the development of the embryo the reader must refer 
to Chapter xiii, and for details and the discussion of general questions to the body 
of the work. 

F. C. B. 1895—15 



Appendix I.— PREPARATION OF THE EGGS. 

The eggs of the lobster may be easily prepared for the study of the external surface 
in the following way : The fresh eggs are to be placed in either fresh or salt water, which 
is heated to near the boiling point, until the green pigment coloring the yolk is perma- 
nently converted into bright red lipochrome (see p. 137). They should then be trans- 
ferred to cold water and shelled under the dissecting microscope. The eggshell when 
distended slightly with water may be removed by means of very fine-pointed forceps, 
nipping the shell and holding it with one pair of forceps while the shell is ruptured 
and the egg carefully released with the other pair. 

There are two periods in the course of development when it is difficult to remove 
the shell without injury to the embryo. These are at the close of segmentation, when 
the blastoderm secretes a fine membrane, which becomes soldered to the shell so that 
when the latter is removed the blastoderm itself is torn away; and, secondly, either 
during the egg-nauplius stage or shortly after it. In the early egg-nauplius two 
membranes can be removed, an outer thick one, the eggshell (composed of the primary 
and secondary egg membranes), and an inner cuticle, the secreted product of the 
embryo. This last usually sticks to the tips of the antenna?, the second pair in par- 
ticular, and carries them with it when it is removed. It sometimes happens that the 
entire embryo is thus stripped off. 

After shelling, the eggs should be placed at once in Mayer's concentrated picro- 
sulphuric acid, and left from two to three hours. They may be then transferred to 
70 per cent and finally to 80 per cent alcohol, aud the latter should of course be 
changed until all trace of the yellow salt is removed. 

I have frequently made use of 70 per cent alcohol instead of water in making up 
the picro-sulphuric acid solution, and it is usually successful. I used it with excellent 
results ten years ago in studying the eggs of Alpheus, but the aqueous solution is 
perhaps better on the whole. I have tried a great variety of killing and fixing 
reagents, but none are to be compared for reliability with picro-sulphuric acid in the 
concentrated form. 

The eggs are stained by placing them in a vial of borax- carmine for the space of 
two to three minutes or longer, just long enough to stain the surface cells only. The 
diffuse stain must then be thoroughly removed by acidulated alcohol until the eggs 
have a light-yellow color, the nuclei of surface cells only being stained red. Turpen- 
tine is one of the best clearing reagents, none of the essential oils in common use — oil 
of cloves, origanum, thyme, or bergamot — offering any appreciable advantage over it. 

Clearing requires but a few minutes, and while it is in progress the eggs should 
be placed in a solid watch glass with turpentine, and examined under a dissecting 
microscope. With a very small and thin knife they may be cut into halves in any 
desired plane. It is better to roll the egg under the knife edge, and thus cut into the 
surface all the way round before pressing the knife through the egg. The eggs cut 
like cheese at first, but later become brittle and are very apt to break if left in tur- 
pentine for too long a time. It is thus best to place a few at a time in the clearing 
fluid, aud cut them at once. 

226 



THE AMERICAN LOBSTER. 227 

In the treatment of these eggs I have profited by the experience and advice of 
my friend Dr. William. Patten, whose method of mounting the ova of Arthropods, 1 and 
orienting them for the microtome, which I have essentially followed, leaves little to be 
desired. A cell is made of strips of cardboard of the desired thickness, and the 
respective hemispheres of each egg are fixed in place by a small drop of concentrated 
Schallibaum's fixative. The cell may be flooded with turpentine while tlie process of 
fixation is going ou, and when drained thick balsam is added and the cover glass is 
afterwards applied. In this way the most perfect and beautiful preparations can be 
made. 

Eggs are hardened in the same way, when the object is to cut them into sections. 
They may be successfully embedded in either paraffin or celloidin. Bumpus has 
described his successful use of the latter reagent, which he heartily recommends. 2 
This method is undoubtedly the surest although the most laborious to pursue. I have 
obtained excellent sections of the early and late stages of development by the paraffin 
method, and for the older embryos it is certainly preferable. Turpentine and all the 
essential oils soon harden the yolk so that it firmly resists the knife. The eggs should 
therefore be allowed to remain in the clearing fluid for the shortest possible time ouly, 
and then thoroughly saturated with paraffin. The method which Patten has given 
for orientation can hardly fail to meet with success. 



Appendix II.— COMPOSITION OF THE SHELL AND GASTROLITHS OF THE 

LOBSTER. 

[By Albert W. Smith, Ph. D., Associate Professor of Chemistry in the Case School of 'Applied Science.'] 

The analyses of the shell of the lobster were made from four distinct individuals, 
taken at Woods Hole, Massachusetts (Xos. 1 to 4 in the table below), and were selected 
with reference to the molting period. The description of the shells and lobsters from 
which they were taken is as follows : 

No. 1. Hard-shell female with external eggs, August 3, 1894. 

No. 2. A hard-shell female lobster near the point of egg-laying; length, 11 inches; July 16, 1894. The 

ovarian eggs of this lobster were mostly absorbed. (See p. 48.) 
No. 3. From a female near the point of molting; length, 10 inches; August 2, 1894. (The gastroliths 

of this "shedder" are described on p. 89, and their chemical analysis is given in No. 3a of 

the following table.) 
No. 4. The molted shell of a male 11 inches long. (See No. 2, table 24, and p. 89.) 

The gastroliths subjected to analysis have the following history: 

No. Qa is taken fresh from the gastrolithic sac of a "shedder." (For drawing of this gastrolith sepa- 
rated into its constituent spicules see fig. 165, plate 42.) 

No. 3a is from lobster No. 3 of this table, taken fresh from the gastrolithic sac of the animal shortly 
before it was ready to molt. 

No. 4a is from the lobster which cast off shell No. 4 of this table, taken from the stomach of the animal 
when soft and preserved in alcohol. (For drawings of this gastrolith see cut 8, plate C; for 
description of lobster No. 2, table 24.) 



1 Orienting Small Objects for Sectioning, and " Fixing " them, when Mounted in Cells. (Ameri- 
can Naturalist, vol. 28, pp. 360-362, 1894. ) 

2 American Naturalist, vol. 26, pp. 80-81, 1892. 



228 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



Table showing composition of the shell and gastroliths of the lobster. 



Composition— air dried. 



Weight in grams 

Calculated as calcium oxide — CaO 

Magnesium oxide— MgO 

Aluminum oxide — Al 2 O3 — (Fe. 2 3 ) 

Sodi um oxide — N a 2 

Silica— Si0 2 

Phosphoric anhydride — P 2 5 

Sulphuric anhy dride — S0 3 

Carbonic dioxide — C0 2 

Water at 100° C— H 2 

Calculated as calcium carbonate — CaC0 3 . - 

Calcium phosphate— Ca 3 (P04) 2 

Calcium sulphate— CaSOj 

Magnesium carbonate — MgC0 3 

Sodium carbonate — Na 2 C0 3 

Alumina, A1 2 3 - (Fe 2 3 ) 

Silica— Si0 2 

Organic matter and water, by differ- 
ence 



Carapace. 



11.87 
22.87 
3.18 
0.68 
0.89 
0.14 
3.53 
0.34 
21.20 



43.68 
7.70 
0.58 
3.50 
1.51 
0.68 
0.14 

42.21 



21.51 

23.11 
1.14 
2.04 
1.06 
0.29 
3.81 
0.31 

17.05 
7.40 

32.83 
8.32 
0.53 
2.39 
1.80 
2.04 
0.29 

51.80 



8.48 
24.94 
1.61 
1.04 
1.35 
0.08 
5.12 
0.58 
17.70 



32.93 
11.18 
0.99 
3.38 
2.31 
1.04 
0.08 

48.09 



9.12 
30.41 
1.30 
1.36 
1.67 
0.46 
4.36 
0.40 
23.00 



44.60 
9.52 
0. 68 
2.73 
2.85 
1.36 
0.46 

37.80 



Gastroliths. 



0a. 



1.37 
45.85 
0.30 
0.20 
1.09 
0.10 
4.43 
0.07 
37.00 



72.44 
9.67 
0.12 
0.63 
1.87 
0.20 
0.10 

14.97 



3d. 



49.14 
0.40 
0.04 
1.34 
0.06 
4.16 
0.08 

37.10 



78.87 
9.08 
0.14 
0.84 
2.28 
0.04 
0.06 

8.69 



4a. 



3.96 

50.82 

0.48 

0.06 

0.55 

0.08 

5.12 

0.35 

35. 00 

3.50 

78.46 

11.18 

0.59 

1.01 

0.93 

0.06 

0.08 



As will be seen by reference to the table the principal part of the mineral structure 
in the carapace is made up of carbonate of calcium, with some considerable proportion 
of calcium phosphate and of magnesium compounds. The gastroliths differ in being 
mucb more largely mineral, and in consisting almost entirely of carbonate and phos- 
phate of calcium. All of the specimens contained iron, its quantity being so small 
that it was not thought advisable to make a separation of it from the aluminum. A 
minute proportion of potassium also was present in every case, but its quantity was 
so small that it was detected with difficulty by the spectroscope in the separated 
alkali salts. 

No successful determination of the quantity of chitin in the carapace was attained, 
and no separation of any of the other organic constituents was attempted. The total 
quantity of organic matter and water is reported as the difference between the sum of 
the calculated percentages of inorganic salts and 100. 

The portion of the shell subjected to analysis was taken in each case from the 
carapace, from the part bounded by the cervical groove in front and the branchio- 
cardiac groove above. 



Appendix III.— BIBLIOGRAPHY. 

In the following - bibliography the literature of the lobster, especially that relating 
to its habits aud development, will be found to be fairly complete. All papers possess- 
ing scientific or historical interest to which reference is made, though some of them 
are of minor importance, have been included. 

Since, in my chapter on the embryology of this species, I have not entered into 
the comparative development of the Crustacea, it has been necessary to refer to but few 
general works, and all physiological papers have been omitted when not in the direc- 
tion of my studies. 

1. Abbott, C. C. Are the "chimneys" of burrowing crayfish designed ? Amer. Nat., vol. xvm, pp. 

1157-1158. Phila., 1884. 

2. Aldrovandi, Ulyssis. A. U. philosophi et medici Bononiensis; de reliquis animalibus exsan- 

guibus libri quatuor, post mortem eius editi: Nempe de mollibns, crustaceis, testaceis, et 
zoophytis. De astaco. Cap. in, p. 108. 1st ed., fol. Bononi;e, 1606. 

3. Andrews, E. A. Autotomy in the crab. American Naturalist, vol. 24, pp. 138-142, figs. 1-4 (pi. 

vi). Philadelphia, 1890. 

4. Aristotle. On the parts of animals. Transl. by W. Ogle. London, 1882. 

5. Atwood, N. E. On the habits and geographical distribution of the common lobster. Proc. Bost. 

Soc. Nat. Hist., vol. x, pp. 11-12. Boston, 1866. 

6. v. Baer, K. E. Ueber die sogenannte Erneuerung des Mageus der Krebse u. die Bedeutung der 

Krebssteine. Archiv f. Anat., Physiol., etc. Ed. by Johannes Miiller. Pp. 510-523. Berlin, 
1834. 

7. Baker, H. A letter from Mr. Baker to the president, concerning the stones called crab's eyes, etc. 

Phil. Trans. Eoy. Soc. (abridged), vol. x, part in, pp. 876-879, for year 1750. London, 1756. 

8. Baster, J. Opuscula subseciva. De astacis, torn, n, lib. 1, tab. 1. Harlemi, 1762. 

9. Bate, C. Spence. Notes on Crustacea. Ann. and Mag. of Nat. Hist., 2d ser., vol. vn, pp. 297-300, 

1 pi. 1849. 

10. Bate, C. Spence. Report of the committee api>ointed to explore the marine fauna and flora of 

the south coast of Devon and Cornwall. No. 2. Kept. Brit. Ass. Adv. Sci., 1867, pp. 275-287, 
pis. i-iii. London, 1868. 

11. Bate, C. Spence. Report on the present state of our knowledge of the Crustacea. Part in. 

Rept. Brit. Ass. Adv. Sci., 1877, pp. 36-55. London, 1878. 

12. Bate, C. Spence. Report on the present state of our knowledge of the Crustacea. Rept. Brit. 

Ass. Adv. Sci., pp. 193-209, pis. v-vn. London, 1879. 

13. Bate, C. Spence. Report on the present state of our knowledge of the Crustacea. Part v. 

Rept. Brit. Ass. Adv. Sci., 1880, pp. 230-242. London, 1880. 

14. Bell, Thomas. A history of the British Stalk-eyed Crustacea. Pp. i-LXVi-f- 1-386. London, 1853. 

15. Belon. De aquatilibus. 1553. 

16. Bergh, R. S. Beitriige zur Embryologie der Crustaceen. I. Zur Bildungsgeschichte des Keim- 

streifens von Mysis. Zool. Jahrb., Bd. vi, pp. 491-528, Taf. 26-29. Jena, 1893. 

17. Berniz, Martinus Bernhardus. Chela astaci mariui inonstrosa. Miscellanea curiosa medico- 

physica Academhe naturae curiosorum, annus secundus, Observatio C, p. 174 (fig.). 1671. 

18. Lo Bianco, Salvatore. Notizie biologische riguardanti specialmente il periodo di maturita ses- 

suale degli animali del golfo di Napoli. Mitth. zool. Stat, zu Neapel, Bd. viu, pp. 385-440. 

1888. 

229 



230 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

19. Blanchard, Emile. Metamorphoses, moeurs et instincts des insectes. Paris, 1868. The trans- 

formations of insects, by Martin P. Duncan (London and New York, 1870) is essentially a 
translation of this work. 

20. Boeck, Axel. Om det norske Hurninerfiske og dets Historie. Tidsskrift for Fiskeri, 3die Aar- 

gangs. Kjobenkavn, 1868-1869. Transl. in Rept. of U. S. Com. of Fish and Fisheries, part ill, 
1873-1875, pp. 223-258. Washington, 1876. 

21. Bouchard- Ckantraux. CrustacEs du Boulonnais. 1833. 

22. Braun, Max. Ueber die histologischen Vorgange bei derHautung von Astacus fluviatilis. Arbeit. 

ans dem zoologisch-zootomischen Inst, in Wiirzburg, Bd. u, pp. 121-166, Taf. viii-ix. 1875. 

23. Braun, Max. Zur Kenntniss des Vorkommens der Speichel- und Kittdriisen bei den Decapoden. 

Arbeit, aus dem zoologisch-zootomischen Inst, in Wiirzburg, Bd. in, pp. 472-479, Taf. 21. 
1876-77. 

24. Brightwell, T. Description of the young of the common lobster, with observations relative to 

the questions of the occurrence and non-occurrence of transformations in crustaceous animals. 
Loudon's Mag. Nat. Hist., etc., first series, vol. vm, pp. 482-486. 1835. 

25. Brocchi, P. Recherches sur les organes gEnitaux males des crustace's dEcapodes. Reprinted 

from Ann. des sci. nat., 6 e serie, pp. 1-132, pis. 13-19. Paris, 1875. 

26. Brook, George. Notes on the reproduction of lost parts in the lobster (Homarus vulgaris). Proc. 

Roy. Physical Soc, session cxvi, pp. 370-385, pi. xvn (figs. 1-5). 1887. 
26+. Brooks, W. K. The habits and metamorphosis of Gonodactylus chiragra. (Being chap. Ill of 
the fourth memoir of vol. V of the Proceedings of the Nat. Acad, of Sciences, entitled "The 
Embryology and Metamorphosis of the Macroura," by W. K. Brooks and F. H. Herrick.) 
Pp. 353-360, with 4 plates. Washington, 1892. 

27. Brown, Patrick. The civil and natural history of Jamaica. Fol., copper pis. London, 1789. 

28. Buckland, Frank; Walpole, Spencer, et al. Reports on the crab and lobster fisheries of Eng- 

land and Wales, of Scotland and Ireland. Pp. i-xxn-f-i-xxvi-f-i-iv+1-80, with appendices, 
pis. 1-8. London, 1877. 

29. Buckland, Frank. Report on the fisheries of Norfolk, especially crabs, lobsters, herrings, and 

broads. Presented by Her Majesty's command. Ordered by the House of Commons to be 
printed. Aug. 11, 1875. 

30. Bumpus, Hermon Carey. The embryology of the American lobster. Jour, of Morph., vol. v, 

pp. 215-262, pis. xiv-xix. 1891. 

31. Butschinsky, P. Zur Entwicklungsgeschichte von Gebia litoralis. Zool. Anz., 17. Jhg., No. 452, 

pp. 253-256. July 16, 1894. Translated in Ann. Nat. Hist., (6), vol. xv, pp. 677-678. 

32. Cano, G. Morfologia dell' apparecchio sessuale femminile, glandole del cemento e fecondazione 

nei crostacei decapodi. Mittheil. Zool. Stn. Neapel, Bd. ix, pp. 503-532, Taf. 17. 1891. 

33. Cano, G. Sviluppo dei portunidi. Morfologia dei portunidi e corystoidei. Memoria estratta del 

torn, vni, serie 3 a , No. 6, della Societa italiana delle scienze, pp. 1-30, tav. i-iii. Napoli, 1893. 

34. Carpenter, William. Report on the microscopic structure of shells. Part II, Rept. Brit. Ass. for 

Adv. Sci., 1847, pp. 93-134, pis. i-xx. London, 1848. 

35. Carrington, John T., and Lovett, Edward. Notes and observations ou British Stalk-eyed Crus- 

tacea. The Zoologist, third series, vol. VI, pp. 9-15 (continued). London, 1882. 

36. Cavolini. Memoria sulla generazione dei pesci e dei granchi. Napoli, 1787. 

37. Chantran, S. Observations sur l'histoire naturelle des Ecrevisses. Compt. Rend., t. 69, pp. 43-45. 

Paris, 1870. 

38. Chantran, S. Nouvelles observations sur le developpement des ecrevisses. Compt. Rend., t. 73, 

pp. 220-221. Paris, 1871. 

39. Chantran, S. Sur la fecondation des Ecrevisses. Compt. Rend., t. 74, pp. 201-202. Paris, 1872. 

40. Chantran, S. Experiences sur la regEnEratiou des yeux chez les Ecrevisses. Compt. Rend., t. 76, 

pp. 240-241. Paris, 1873. 

41. Chantran, S. Observations sur la formation des pierres chez les Ecrevisses. Compt. Rend., t. 

78, pp. 655-657. Paris, 1874. 

42. Chantran, S. Sur le mEcauisme de la dissolution intra-stomacale.des concretions gastriques des 

Ecrevisses. Compt. Rend., t. 79, pp. 1230-1231. Paris, 1874. 

43. Coste. (Report of work of Gerbe.) Faits pour servir a l'histoire de la fEcondation chez les 

crustacEs. Compt. Rend., t. 56, p. 432. Paris, 1858. 

44. Coste. Etude sur les mceurs et sur la gEnEration d'un certain nombre d'anirnaux marins. Compt. 

Rend., t. 47, pp. 45-50. Paris, 1858. 



THE AMERICAN LOBSTER. 231 

45. Couch, Jonathan. Observations on some circumstances attending the process of exuviation in 

shrimps and lobsters. Mag. Zool. and Bot., vol, i, pp. 170-171!. ls:!7. 
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f. Naturgescli. von Wiegmann, Jahrg, 4, Bd. i, pp. 337-342. 1838. 

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Polytechnic Society, 1843, pp. 1-15. Loudon, 1843. 

47. Couch, Jonathan. A particular description of some circumstances hitherto little known con- 

nected \\ it I. the process of exuviation in the common edible crab. (With plates.) Ann. Report, 
Royal Cornwall Polytechnic Society, 1858, pp. 3£M5, pis. 1-3. London, 1858. 

48. Couch, R. Q. On the metamorphosis of the Decapod Crustaceans. Eleventh Annual Report of 

the Royal Cornwall Polytechnic Society, 1843, pp. 28-43, pi. i. London, 1843. 

49. Coues, Elliott. Notes on the natural history of Fort Macon, North Carolina, and vicinity. (No. 2.) 

Proc. Acad. Nat. Sci. Phila., 1871, pp. 120-148. Philadelphia, 1871. 

50. Dalyell, John Graham. The powers of the Creator displayed in the Creation. London, 1827. 

51. De Kay, James E. Zoology of New York, or the New York fauna. Part vi, Crustacea, pp. 

23-25, pi. xn, figs. 52, 53. Albany, 1844. 

52. Desmarest, Anselme G-. Considerations gen6rales sur la classe des crustaces. 1825. 

53. Dulk. Chemische Untersuchungen eiues Mageninhalts von Krebsen, die sich eben gehaiitet 

haben. Archiv f. Anat., Physiol., etc., J. Miiller, Jahrg. 1834, pp. 523-527. Berlin, 1834. 

54. Dulk. Chemische Untersuchungen der Krebssteine. Archiv fiir Anat., Physiol., etc., ed. by 

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55. Du Tertre, Jean Baptiste. Histoire Generale des Antilles habitudes par les Francois. T. 

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56. Duvar, J. H. Report on lobster fishery of Prince Edward Island, in annual report of the depart- 

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58. Edwards, H. Milne. Histoire naturelle des crustaces. Vols. 1-3, with atlas. Paris, 1834;-1840. 

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205. Williamson, W. C. On some histological features in the shells of the Crustacea. Quart. Journ. 

Mic. Sci., vol. 8, pp. 35-47, pi. in, 1860. 

206. Wilson, E. B. Amphioxus and the Mosaic theory of development. Jour, of Morjihol., vol. 

vm, pp. 579-638, pis. xxix-xxxvm. Boston, 1893. 

207. Wood, W. M. Transplanting lobsters to the Chesapeake — Experiments upon the temperature 

they can endure. Bull. U. S. Fish Comm., 1885, vol. v, pp. 31-32. Washington, 1885. 

208. Zittel, Karl A. Handbuch der Palaeontologie. 1 Abth. n Bd. Mollusca u. Arthropoda. 

Miinchen u. Leipzig, 1881-1885. 

209. Fisheries statements, 1880. Supplement No. 2 to eleventh annual report to minister of marine 

and fisheries. Appendix No. n, report of J. H. Duvar, inspector of fisheries for the Province of 
Prince Edward Island, for 1880. Lobsters, p. 231. Ottawa, 1881. 

210. Fisheries statements for the year 1882. Supplement No. 2 to the fifteenth annual report of the 

department of marine and fisheries for the year 1882. Ottawa, 1883. 

211. Annual report of the department of fisheries, Dominion of Canada, for 1888. Ottawa, 1889. 

212. The cultivation of lobsters. Practical Magazine, vol. 2, pp. 258-259. London, 1873. 

213. Review of the reports by Buckland and Spencer on the lobster, crab, and oyster fisheries of Great 

Britain. Quarterly Review, vol. 144, art. VI, pp. 249-262. 1877. 



Appendix IV.— DESCRIPTION OF PLATES. 



Plate 1. 



Fig. 1. The Belfast lobster. Dorsal view of male lobster, captured at Belfast, Maine, May 6, 1891. 
Living weight a little over 23 pounds. From photograph of skeleton. Original in pos- 
session of the author. For detailed measurements see table 30, No. 1. A little less than 
one-fourth natural size. 

Plate 2. 

Fig. 2. Ventral view of large lobster shown in plate 1. 

Fig. 3. Ventral view of small lobster for comparison with fig. 2. Egg-bearing female ; length 9| inches; 
weight about 1^ pounds. Most of the eggs which were attached to the abdomen have 
been removed. 
Both figures reproduced from photograph. About one-fourth natural size. 

Plate 3. 

Fig. 4. Profile view of living red lobster. Female, length llf inches ; weight about 2 pounds. Cap- 
tured near Mount Desert, Maine. From photograph from life, April 10, 1894. For colored 
drawing of this lobster see plate 16, fig. 21. A little over one-half natural size. 

Plate 4. 

Fig. 5. Adult male lobster, dorsal view. Length 12-^ inches ; weight 2 pounds 14 ounces. From 
photograph from life, December 8, 1893. A little under one-half natural size. Membrane 
between thorax and abdomen unnaturally distended. 
This lobster, with those represented by the three following plates, figs. 5-8, was captured at Woods 
Hole, Massachusetts, December, 1893, and sent alive to Cleveland, Ohio. 

Plate 5. 

Fig. 6. Adult male. Ventral view of lobster shown in plate 4. From photograph from life. A little 
under one-half natural size. 

Plate 6. 

Fig. 7. Adult female lobster with external eggs, dorsal view. Length 11-& inches; weight 1 pound 13 
ounces. From photograph from life. A little over one-half natural size. 

Plate 7. 

Fig. 8. Adult female. Ventral view of lobster shown in plate 6. The dark-green eggs attached to the 
swimmerets under the tail are very clearly seen. A colored sketch of one of these eggs, 
showing the contained embryo, and a cluster of eggs from the swimmerets are represented 
by figs. 25, 26, plate 17. One-half natural size. 
A lobster of this size produces on the average about 19,000 eggs. The seminal receptacle is seen 
between the bases of the third and fourth pairs of walking legs. Compare this with the 
organ as it appears in the immature lobster shown in plate 11. 
238 



THE AMERICAN LOBSTER. 239 

Plate 8. 

Fig. 9. Immature female lobster, dorsal view ; length 44 mm. (1.73 inchos). From photograph, life-* 
size. Casco Bay, Maine, October, 1893. See table 32, No. 2, for further details. 
This and the immature or adolescent lobsters represented by plates 8-13, figs. 9-18, were collected 
in Casco Bay, Maine, in Small Point Harbor aiul vicinity, from August 31 to October 19,1893. 
The photographs were all made from the alcoholic specimens. They are described in table 
32, pp. 163-165. All are life-size. 

Fig. 10. Immature male lobster; length 10.3 mm. (1.59 inches). See No. 1, table 32. The right cutting- 
claw is smaller than is normal, due to the fact that it has been recently cast off and is 
now only partially restored. (See Chapter IV.) 

Fig. 11. Immature female lobster; length 64 mm. (2.5 inches). No. 7, table 32. 

Fig. 12. Immature malo lobster; length 58 mm. (2.28 inches). No. 5, table 32. 

Plate 9. 

Fig. 13. Immature female lobster; length 75.6 mm. (2.98 inches). No. 16, table 32. The right cutting- 
claw is smaller than normal. See fig. 10, pi. 8, with description given above. From 
photograph ; life-size. 

Fig. 14. Immature male lobster; length 67 mm. (2.64 inches). No. 8, table 32. From photograph; 

life-size. 

Plate 10. 

Fig. 15. Immature female lobster; dorsal view; length 86.5 mm. (3.41 inches). No. 21, table 32. From 
photograph ; life-size. 

Plate 11. 

Fig. 16. Ventral view of immature female lobster shown in plate 10. Length 86.5 mm. (3.41 inches). 
No. 21, table 32. From photograph ; life-size. The seminal receptacle is seen between the 
third pair of walking legs. The normal rudimentary condition of the first pair of swim- 
merets is also well shown. Compare with plate 7. 

Plate 12. 

Fig. 17. Immature male lobster; length 92.3 mm. (3.64 inches). No. 23, table 32. From photograph ; 
life-size. 

Plate 13. 

Fig. 18. Immature male lobster ; length 110 mm. (4.34 inches). No. 32, table 32. From photograph; 
life-size. 

Plate 14. 

Fig. 19. Male lobster showing abnormal, symmetrical development in large claws. Instead of the 
usual differentiation of the great claws, one for crushing, the other for cutting (well 
shown in fig. 6, pi. 5), both are here similar and belong to the cutting type. Length 10 
inches ; taken at Woods Hole, Massachusetts. Seep. 144. From photograph from alcoholic 
specimen ; abont four-fifths life size. 

Plate 15. 

Fig. 20. Right crushing-claw of lobster, probably a male, preserved in the museum of the Peabody 
Academy of Science, Salem, Massachusetts : Estimated weight of live lobster, about 25 
pounds; weight of skeleton of claw (including the fifth joint or carpus), the parts shown 
in the drawing, 16f ounces. Natural size. 

Fig. 20a. Right crushing-claw of female lobster, of about average size; length 11 inches; weight li 
pounds ; shell fairly hard. Captured at Woods Hole, Massachusetts, July 24, 1894. Natural 
size. 
This drawing of the claw of a lobster of average size, placed by the side of the mammoth speci- 
men for the sake of comparison, shows more forcibly than words or figures can the great 
difference in size which may exist between adults of the same species. Both drawings 
are life-size, and to insure accuracy their outlines were carefully traced from the objects 
themselves. The living weight of the smaller claw (including the entire limb) was about 
10 ounces, that of the larger about 10 pounds. (See p. 115.) 



240 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Plate 16. 

tFig. 21. Red female lobster, colored from life. Length llf inches; weight about 2 pounds. Captured 
in the vicinity of Mount Desert, Maine, April, 1894. An examination of the reproductive 
organs showed that the lobster had not yet reached sexual maturity. For photograph of 
this lobster see plate 3. A trifle under one-half life-size. 
Fig. 22. Adult male lobster, colored from life. Length 10 inches ; weight about Impounds; shell mod- 
erately hard. Woods Hole, Massachusetts, August 14, 1891. About two-thirds life-size. 

Plate 17. 

Fig. 23. Eggs of lobster showing an unusual color variation. Drawn from life. The embryo was 
somewhat past the egg-nauplius stage. The lobster, which was 12£ inches long and 
weighed 2 pounds 5 ounces, was captured at Woods Hole, Massachusetts, December 4, 
1893, and sent to me alive. These eggs turned a very light salmon-color when boiled. Six 
times natural size. 

Fig. 24. Cluster of fresh eggs of lobster, colored from life. Laid in aquarium at the United States 
Fish Commission station, Woods Hole, Massachusetts. Drawn August 11, 1893. When 
first examined the eggs were closely adherent, and the glue which bound them together 
was very soft. The ovary of the lobster was examined on August 17; it was of small size, 
and contained but few unextruded eggs, which were partially absorbed. About 6 times 
natural size. 

Fig. 25. Cluster of egg embryos from swimmerets of female shown in plate 7. Drawn from life 
December 7, 1893 The entire mass of eggs are attached to each other and to the seta 1 , or 
hairs of the swimming feet, as shown in the drawing. A single detached seta with a 
number of eggs glued to it is here represented. About 13 times natural size. 

Fig. 26. Profile view of embryo released from eggshell; taken from a cluster like that in fig. 25. 
Drawing made December 12, 1893, after killing the embryos with hot water. Embryos 
from the same lobster (see fig. 8) lived eight days in damp seaweed, in a cool room, and 
could apparently have been kept alive under the same conditions for a much longer time. 
Enlarged 33 times. 

Fig. 27. Side view of embryo, as seen through the transparent shell. Drawn and colored from life. 
Eggs from same batch as those shown in fig. 25; female represented by plate 7. The 
conspicuous green yolk, which is restricted to the upper half of the egg, fills the cavity 
of the mid-gut. This eventually forms the "liver" or gastric glands, the anterior lobes 
of which are clearly seen in fig. 28. The clear space to the right (on the lower side in 
fig. 28) represents the heart. Below it the intestine joins tne mid-gut. The eye is shown 
as it appears in reflected light in fig. 27, as in transmitted light in fig. 28. (See p. 169.) 
Enlarged 33 times. 

Fig. 28. Dorsal view of embryo shown in fig. 27. Enlarged 33 times. 

Plate 18. 

Fig. 29. Lobster hatching. Drawn from life July 5, 1891. The membrane of attachment (secondary 
egg membrane) has split along the middle line and is being drawn off over the head. The 
inner part of the shell (primary egg membrane or "chorion") invested the embryo as an 
exceedingly delicate, transparent membrane, and was ruptured (above the eyes) by needles 
in order to show it. When the outer membrane is borne away it usually drags the deli- 
cate inner one with it. Enlarged 33 times. 

Fig. 30. Lateral view of a lobster, teased from an egg which was about ready to hatch, to show the 
embryonic cuticle which must be shed before the first swimming larval stage is reached. 
The healthy embryo sheds this skin either at the time of its escape from the eggshell or 
very soon after it. The intestinal concretions are clearly seen in both this and the pre- 
ceding figures. The pigment cells of the skin and other details are purposely omitted. 
Drawn from life. Enlarged about 33 times. 

Fig. 31. Profile view of lobster in fifth stage. General color reddish-brown. Pigmentation of skin 
not represented. Rudimentary exopodites of thoracic appendages present. Length 
16 mm. July 2, 1891. Enlarged 9 times. 



THE AMERICAN LOBSTER. 241 

Plate 19. 

Fig. 32. First swimming stage of the lobster, usually called tho first larva or the first schizopod 
stago. Dorsal view. Drawn from life July 3, 1890. The bright vermilion pigment cells 
or chromatophores of tho skin are here expanded under stimulation. Under some condi- 
tions they contract, and the animal becomes very pale-blue, in consequence of the blood 
pigment. The stomach-bag on tho middle lino behind the eyes, the lobes of the yellow 
''liver" on either side of this, the heart behind the stomach, and the intestine passing 
beneath this from the stomach to the hinder end of the body, are clearly discerned through 
the transparent shell. The yellow cast of color is rather too pronounced, especially in the 
abdomen. For color of eyes, see p. 169, and fig. 27. Length about 7.8 mm. (-$j inch). 
Enlarged 22 times. 

Plate 20. 

Fig. 33. Profile view of the first larva of the lobster. Length about 8 mm. July 22, 1891. The trans- 
parency of these larvae is often very great, and many of the organs, such as the heart, 
gills, and alimentary tract, are seen with great clearness through the shell. (Compare 
fig. 32.) The "liver" or gastric gland, usually of a golden-yellow color and resembling a 
cluster of grapes, is the most voluminous and conspicuous of the internal organs. The 
shading by stipple in this and the two following plates is purely couventional, no attempt 
being made to represent the pigmented skin. Enlarged 30 times. 

Plate 21. 

Fig. 34. Second larva; profile view; drawn to the same scale as fig. 33. The second larval stage is 
preceded by the second molt. Beside the striking increase in size in all the. parts of the 
body, the most important changes are the growth of the antenna? and the appearance of 
rudimentary legs or swimmerets on the under side of the abdomen — upon the second 
to fifth somites, inclusive. Length about 9 mm. (0.35 inch). Enlarged 30 times. 

Plate 22. 

Fig. 35. Third larva; lateral view. Drawn July 15, 1891. The principal changes which are empha- 
sized at the third molt concern the antennae, the growth of the thoracic appendages, chiefly 
seen in the large claws, and the acquisition of the last pair of abdominal appendages, 
which, with the telson, constitute a very important locomotor organ, the propeller or 
tail fan. Length 11.1 mm. (0.41 inch). Enlarged 22 times. 

Plate 23. 

Fig. 36. Fourth larva; dorsal view. Length 14.6 mm. Drawn and colored from life August 7, 1891. 
This represents the average normal color of this stage, yet, as will be seen in Chapter 
XII, this is subject to considerable variation. The brilliant peacock-green or intense 
yellow-green spots upon the carapace and abdominal segments are characteristic of this 
period, but it is difficult to represent these pigments in their natural glow and purity. 
Enlarged 10| times. 

Plate 24. 

Fig. 37. Sixth stage; dorsal view. Outline from a young lobster 15.3 mm. iong, July 14, 1891; color- 
ing from lobster No. 3, table 34, in sixth stage raised from fourth larva; length 15.5 mm. 
Enlarged 8W times. 

Plate 25. 

Fig. 38. Young lobster in sixth stage; profile view. Raised from the egg; lobster No. 36, table 34. 
Length 16 mm. Drawn and colored from life July 30, 1892. The white spots or tendon- 
marks on the carapace are very characteristic of this period. They are somewhat less 
prominent in the fifth stage. The fifth stage usually resembles the sixth very closely, 
particularly in color. Enlarged 11| times. 

F. C. B. 1895-16 



242 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Plate 26. 

Fig. 39. Young, immature lobster; male. Length 47 mm. Drawn and colored from nature July 18, 
1891. This animal was injured and brought up by accident in a lobster pot in Woods 
Hole Harbor. (No. 22, table 33.) Enlarged 2f times. 

Plate 27. 

[The stage or molt to which each drawing belongs is shown by roman numerals on plates 27 to 35.] 

Fig. 40. Right first antenna of first larva, from below. The inner branch or flagellum of this append- 
age is now present as a very small unsegmented rudiment, which grows out of the pri- 
mary stalk from its under side toward the middle line. 36 times natural size. 

Fig. 41. Left first antenna of second larva, from below. Segmentation of flagellum of exopodite not 
yet visible, or but faintly marked; endopodite tipped with one long and one or two short 
seta?; shows slight traces of segmentation. Nine bunches of olfactory seta? present, 4 to 
6 in a bunch, distributed in two longitudinal rows. 36 times natural size. 

Fig. 42. Left first antenna of third larva, from below. Segmentation of flageila more marked. Outer 
and inner branches separated by pressure. 36 times natural size. 

Fig. 43. Left first antenna of fourth larva, from above. Masses of brown pigment are seen in the 
auditory chamber. Segmentation of parts very distinct, au, auditory organ. 36 times 
natural size. 

Fig. 44. Left first antenna of fifth stage, from below. Lobster No. 3, table 34. Parts shown in 
natural position. 36 times natural size. 

Fig. 45. Right first and second antenna? of first larva, from above. Inner edge of exopodite of first 
antenna bears a fringe of 22 to 23 plumose seta?. 36 times natural size. 

Fig. 46. Right second antenna of second larva, from above. 36 times natural size. 

Fig. 47. Left second antenna of third larva, from above. 36 times natural size. 

Fig. 48. Left second antenna of fourth larva, from below. Flagellum divided into 40 segments. 36 
times natural size. 

Fig. 49. Proximal portion of left first and second antenna? of lobster in fifth stage, seen from below. 
Lobster No. 28, table 34. Drawn without pressure, gr, papilla on which green gland 
opens. 36 times natural size. 

Plate 28. 

Fig. 50. Left first and second antenna? of fifth larva, as seen from above. From lobster No. 28, table 34. 

36 times natural size. 
Fig. 51. Right first maxilla of first larva, from anterior face. 153 times natural size. 
Fig. 52. Terminal joint of left fifth pereiopod of first larva from anterior side. 50 times natural size. 
Fig. 53. Tip of endopodite of first maxilla of first larva. 45 times natural size. 
Fig. 54. Front view of mouth and surrounding parts — labrum, metastoma, and mandibles — of first 

larva. Dark-red chrornatophores occur on the mandibles and labrum. The mandibular 

palp sometimes carries two seta? at its tip. 154 times natural size. 
Fig. 55. Right mandible of fourth larva, from behind, showing groove and cutting edge. 36 times 

natural size. 
Fig. 56. Left mandible of fourth larva, from outer side. Hard, chitinous part next to cutting edges, 

bluish steel color. 50 times natural size. 
Fig. 57. Mandibles of fifth larva, from anterior side. Drawn from the molted shell of lobster No. 

23, table. 34, August 10, 1892. Length of larva before molt 13 mm. 36 times natural 

size. 

Plate 29. 

Fig. 58. Left first maxilliped of first larva, from the inner side. 125 times natural size. 

Fig. 59. Left first maxilliped of fourth larva, from outer side, showing tegumental glands in second 

segment (basis). 52 times natural size. 
Fig. 60. Right second maxilla of first larva, from outer side. 153 times natural size. 
Fig. 61. Right first maxilla of fourth larva, from inner side. 52 times natural size. 
Fig. 62. Right first maxilla of fifth larva, from outer side, showing tegumental glands in second 

segment (basis). Drawn without pressure. From lobster No. 27, table 34. 50 times 

natural size. 



THE AMERICAN LOBSTER. 243 

Plate 30. 

Fig} 63. Left second maxilliped of first larva, from anterior face. Epipodito is developed on basis; 
no distinct podobranchia. 50 times natural size. 

Fig. til. Left second maxilliped of fourth larva, from anterior face. Podobranchia present, but rudi- 
mentary as in the adult. 31? times natural size. 

Fig. 65. Right third maxilliped of fourth larva, from dorsal surface, natural position. 22 times 
natural size. 

Fig. t>l>. Left first pereiopod of first larva, from below. The arthrobranchise which issue from the 
membranes between the body and appendage, and are sometimes torn off with the latter, 
are also shown in tig. 65. 52 times natural size. 

Fig. 67. Left first pereiopod of fourth larva, from below. The small tubercles of the chelaj are 
scarcely visible in this position. The exopodite (compare fig. 66), now a short rudiment at 
the base of the appendage, does not entirely disappear until the fifth molt. 22 times 
natural size. 

Fig. 68. Part of left third maxilliped of fourth larva, from below, showing serrated inner margin of 
third segment. 22 times natural size. 

Fig. 69. Left third maxilliped of first larva, from above. 50 times natural size. 

Plate 31. 

Left fourth pereiopod of first larva, from above. 50 times natural size. 

Serrated spine from propodus of left second pereiopod of fourth larva. 153 times natural size. 

Telson of embryo with eye pigment, July 26. Picro-sulphuric acid preparation ; teased from 

egg in glycerin. 22 times natural size. 
Right second pereiopod of first larva, from the side. 50 times natural size. 
Left second pereiopod of fourth larva, from above. 22 times natural size. 
Left fifth pereiopod of fourth larva, from above. 22 times natural size. 
Left fourth pereiopod of fifth larva, from above. The podobranchia with epipodite, the arthro- 

branchius and the pleurobranchia are here shown. 30 times natural size. 
Fig. 77. Antenme of embryo, the telson of which is shown in fig. 72. 22 times natural size. 

Plate 32. 

Fig. 78. Bud of first left abdominal appendage of fifth larva; length of larva 14 mm. Drawn from 

molted shell of lobster No. 36, table 34. July 30, 1892. 63 times natural size. 
Fig. 79. Seminal receptacle of female. Lobster No. 17, table 33. Length of lobster 35 mm. 14 times 

natural size. 
Fig. 80. Left first abdominal appendage of lobster No. 37, table 34; eighth stage; length 19.75 mm. 

(0.78 inch); raised from egg. 63 times natural size. 
Fig. 81. Ventral view of young female lobster; length 51.8 mm. (2.04 inches); No. 19, table 33. The 

seminal receptacle is here shown in process of development. Compare with plate 11. 5.3 

times natural size. 
Fig. 82. Left first abdominal appendage of the sixth stage of development. From lobster No. 34, 

table 34. Drawn from molted shell. Length of lobster in sixth stage 16.3 mm. 63 times 

natural size. 
Fig. 83. Left first abdominal appendage of lobster No. 34, table 34, in seventh stage. Length of lob- 
ster 18 mm. (0.71 inch). 63 times natural size. 
Fig. 84. Left first abdominal appendage of lobster in sixth stage. No. 36, table 34; length of lobster 

16 mm. 63 times natural size. 
Fig. 85. Left first abdominal appendage of female in eighth stage. Lobster No. 3, table 34. Length 

of lobster 21.2 mm. Appendage segmented into two parts. For ventral view of thorax of 

this lobster see fig. 89. 63 times natural size. 
Fig. 86. Left first abdominal appendage of female. Lobster No. 17, table 33. Length of lobster 35 

mm. (1.39 inches). 14 times natural size. 
Fig. 87. Left first abdominal appendage of male. No. 18, table 33. Length of lobster 36.3 mm. (1.43 

inches). 14 times natural size. 
Fig. 88. Left first abdominal appendage of female. No. 19, table 33. Length of lobster 51.8 mm. 

(2.03 inches). For seminal receptacle of this lobster see fig. 81. 14 times natural size. 



Fig. 


70. 


Fig. 


71. 


Fig. 


72. 


Fig. 


73, 


Fig. 


74. 


Fig. 


75, 


Fig. 


76, 



244 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Fig. 89. Ventral view of female lobster in eighth stage. From lobster No. 3, table 34. Length of lobster 

21.2 mm. (0.83 inch). For first abdominal appendage of this lobster, see fig. 85; for color 

in sixth stage, see pi. 24. 5.3 times natural size. 
Fig. 90. Left first abdominal appendage of young male. Length of lobster 19.3 mm. (0.76 inch) 

eighth stage. August 14, 1892. 63 times natural size. 
Fig. 9L. Ventral view of young male. No. 1, table 32. Length of lobster 40.3 mm. (1.59 inches.) 

3.5 times natural size. 

Plate 33. 

Fig. 92. Left cheliped of fourth larva (No. 23, table 34) in process of regeneration from stump, seen. 
from below. Length of larva 13 mm. Drawn from molted shell of fourth larval stage 
August 9, 1893. X, plane of fracture. 1-7, segments of limb. 22 times natural size. 

Fig. 93. Left fourth pleopod of second larva, from outer face. 95 times natural size. 

Fig. 94. Left second pleopod of third larva, from outer face. 36 times natural size. 

Fig. 95. First abdominal segment of shell of lobster No. 34, table 34, in sixth stage, seen from behind. 
Raised from egg, and followed from third larval stage. Length of lobster 16.3 mm. A 
colored drawing of this lobster is given in tig. 38, plate 25, and a drawing of the first 
abdominal appendage in fig. 82. 16 times natural size. 

Fig. 96. Left cheliped of molted sbell of fifth larva, seen from above. Regenerated from the condi- 
tion shown in fig. 92 after the intervention of a single molt. X, plane of fracture. 1-4, 
segments of limb. 22 times natural size. 

Fig. 97. Left second pleopod of fourth larva, from anterior face, end, endopodite. 36 times natural 
size. 

Fig. 98. Sterna of the last three thoracic somites of fifth larva. From No. 36. table 34. Length of 
lobster 14 mm. ; sex doubtful. July 30, 1892. 47 times natural size. 

Fig. 99. Left fourth pereiopod of fourth larva, in process of regeneration. No. 23, table 34. Length 
13 mm. 1-7, segments of limb. 22 times natural size. 

Fig. 100. Right second antenna of lobster in seventh stage, in process of regeneration, seen from above. 
No. 34, table 34. Drawn from molted shell, August 8, 1892. 22 times natural size. 

Plate 34. 

Fig. 101. Respiratory organs of second larva, from left side. 8-14, appendages of corresponding 

somites of body. 36 times natural size. 
Fig. 102. Telson of second larva, from above. 36 times natural size. 
Fig. 103. Telson of first larva, from above. 50 times natural size. 
Fig. 104 Caudal fan of third larva, from below. 36 times natural size. 
Fig. 105. Caudal fan of fourth larva, from above. Alcohol-glycerin preparation. Setse all plumose. 30 

times natural size. 
Fig. 106. Podobrancbia of left second pereiopod of lobster, probably in fourth stage, from inner side. 

The gill now carries four rows of branchial filaments. 36 times natural size. 

Plate 35. 
Fig. 107. Left first antenna of the embryo shown in figs. 27, 28, plate 17. Frontal view. 63 times 

natural size. 
Fig. 108. Right second antenna of the same embryo, from below. 63 times natural size. 
Fig. 109. Rostrum of second larva, from above. 37 times natural size. 
Fig. 110. Profile view of carapace of first larva. 13 times natural size. 
Fig. 111. Profile view of carapace of second larva. 13 times natural size. 
Fig. 112. Profile view of carapace of third larva. 13 times natural size. 
Fig. 113. Profile view of carapace of fourth larva. From molt, July 15. Dorsal view of same given 

in fig. 115. The entire outer surface is now studded with short seta j ,. 13 times natural size. 
Fig. 114. Profile view of carapace of fifth larva, showing tendon marks. General color of larva 

brownish-green; carapace brown. 6 times natural size. 
Fig. 115. Dorsal view of carapace of fourth larva, from molted shell. Profile view of same is given 

in fig. 113. The median area of absorption is now a broad band which widens in the 

rostral regions and unites with the cervical groove on either side to form a cross-shaped 

figure. 13 times natural size. 



THE AMERICAN LOBSTER. 245 

Plate 36. 

Fig. 11(5. Section of reproductive organ of embryo near time of hatching. 513 times natural size. 

Fig. 1 IT. Section of right reproductive organ of first larva. R. O., reproductive organ. 513 times 
natural size. 

Fig. 118. Right second antenna of an adult female lobster, overgrown with alga? (chiefly Ulva and 
l.iiinhuiria), seen from above. Length of lobster about 10^ inches Taken from lobster 
pound at Vinal Haven Island, Maine, August 26, 1893. Two-thirds natural size. 

Fig. 119. Oviduct and part of ovarian lobe from left side, showing a row of unextruded eggs in duct. 
Length of female about 10 inches. External eggs in yolk segmentation. Woods Hole, 
Massachusetts, August 3, 1894. Of?, oviduct. Two-thirds natural size. 

Fig. 120. Reproductive organs of adult male lobster from above. Duct of testis in natural position 
on right side, dissected out on the left. Dotted lines (2 to 5) mark planes of section of 
the vas deferens and refer to figures on plate 37. a, proximal segment; b, glandular 
segment ; c, ductus ejaculatorius ; in, intestine ; gg, gastric gland. Two-thirds natural size. 

Fig. 121. Disk-shaped concretion, probably containing glycogen, from maxilla; cracked by pressure. 
133 times natural size. 

Fig. 122. Large granular cell from first maxilliped, probably glycogenous in function. August 17, 1893. 
733 times natural size. 

Fig. 123. Reproductive organs of adult female dissected out, viewed from above; ovary nearly ripe. 
Length of lobster lOf inches. No. 77, table 20. August 21, 1890. od, oviduct. Two- 
thirds natural size. 

Plate 37. 

Fig. 124. Transverse section of proximal end of vas deferens of adult lobster. Plane of section marked 
"1" in fig. 120. Duct filled with sperm ; lining-epithelium consists of small Hat cells. This 
and figs 125-128 are from the same organ and illustrate the anatomy of the different parts of 
the male duct, sp, sperm cells ; mb, connective tissue sheath of duct. 36 times natural size. 

Fig. 125. Transverse section of vas deferens of adult lobster. Plane of section marked " 2 " in rig. 120. 
ep, epithelial lining of duct. 36 times natural size. 

Fig. 126. Transverse section of vas deferens of adult lobster, showing thick muscular walls. Plane 
of section marked "4" in fig. 120. emu, circular muscles; I. ma, longitudinal muscles; 
Bl. S., blood sinus. 36 times natural size. 

Fig. 127. Part of transverse section of vas deferens, in plane marked "5" in fig. 120. bin, basement 
membrane; emu, circular muscles; ep, epithelial lining constituting the spermatophoral 
glands; l.mu, longitudinal muscles; mb, membranous sheath. 190 times natural size. 

Fig. 128. Part of transverse section of vas deferens through glandular portion, in plane marked "3," 
fig. 120, showing spermatophores, contained sperm and glandular lining-epithelium. The 
gelatinous spermatophore is a secretion of the latter, a, b, compartments of duct; /, 
inward fold of epithelium of duct ; Sp, sperm ; Spr, inner gelatinous substance of sperma- 
tophore. 36 times natural size. 

Fig. 129. Ripe sperm cells : b, c, from the vas deferens of an adult male and a, from the seminal 
receptacle of a female. About 550 times natural size. 

Plate 38. 

Fig. 130. Seminal receptacle of adult female, from above. Natural size. 

Fig. 131. Ovaries of immature lobster, seen from above. Length of lobster 44 mm. (1.73 inches). 
Length of ovary 15 mm.; diameter of lobe J mm. From No. 2, table 32. Color opaque 
white. Oviducts, though undoubtedly present, not seen in dissection. Natural size. 

Fig. 132. Ovaries of immature lobster, seen from above. Length of lobster 74.5 mm. (2y| inches). 
Length of ovary 41 mm. ; diameter of lobe 1 mm. From No. 98, table 20. Natural size. 

Fig. 133. Egg teased from fresh ovary shown in fig. 138. Represents relative size of ovarian eggs one 
year older than those shown in fig. 134. 44 times natural size. 

Fig. 134. Ova teased from fresh ovary shown in fig. 136. Drawn to same scale as fig. 133. This illus- 
trates the size at the time of egg-laying of the immature eggs which are to form the next 
generation, and "which will be ready for extrusion two years hence. One year later they 
attain the relative size shown in fig. 133. 44 times natural size. 

Fig. 135. Ova teased from fresh ovary shown in fig. 137. The difference in relative size between these 
eggs and those shown in fig. 134 represents a growth of about six weeks in summer. 
44 times natural size. 



246 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Fig. 136. Ovary immediately after egg laying, seen from below. From lobster No. 52, table 20. Tbe 
oviducts are rilled with unextruded eggs; a few of these ova are also seen in tbe ovaries. 
Immature eggs from this ovary are shown in fig. 134. The yellow flecks are the remains 
of unextruded eggs of a former egg generation ; that is, they have been in the ovary two 
years at least. Drawn in natural size and color from life. July 28, 1891. 

Fig. 137. Ovary of lobster No. 87, table 20, bearing external eggs. The latter have been laid about 
six weeks (date of laying about July 10). The ovarian eggs possess a dark-green core and 
lighter periphery. At the period of ovulation they are colorless, as shown in figs. 134 
and 136. August 21, 1891. Drawn in natural size from life. 

Fig. 138. Ovary of female which has recently hatched a brood. Taken July 30, 1891. For description 
of lobster see No. 95, table 20. The pea-green color is characteristic of the ovary at this 
time. The contained eggs, one of Avhich is shown in fig. 133, are approximately one year 
old. The difference in relative size between the ova shown in figs. 133 and 134 thus 
represents a year's growth, while the relative difference in size between the ova shown in 
figs. 134 and 135 represents only six weeks of summer growth. 

We thus see that a generation of ovarian ova grow very rapidly during the first sum- 
mer following tbe last ovulation. They then enter upon a period of quiescence, growing 
but slowly, like the external embryos during the succeeding winter. The second summer 
following ovulation is marked by a second period of rapid growth, followed in turn by a 
second period of quiescence during the succeeding winter. At the beginning of the third 
summer after ovulation this generation of eggs is ready for extrusion. That the spawn- 
ing periods are thus two years apart is a valid inference drawn from the study of the 
anatomy of the reproductive organs. Yellow spots mark as before the remains of degen- 
erate eggs which failed of emission at the last reproductive period. The characteristic 
condition of the ovary shown in this drawing proves that annual breeding is an 
impossibility. Drawn in natural size and color from life. 

Plate 39. 
Fig. 139. Part of transverse section of ovary of lobster, No. 52, table 20, with external eggs in early 

segmentation, the ova having been laid about thirty-six hours. The peculiar glandular 

organs are now seen in the peripheral parts of the lobes. O. G., ovarian gland; O. W., 

wall of ovary. 36 times natural size. 
Fig. 140. Part of transverse section of ovary of lobster No. 94, table 20. Glands absent; ovaries 

approaching maturity. 36 times natural size. 
Fig. 141. Part of transverse section of nearly ripe ovary, from lobster No. 75, table 20. August 19, 1890. 

Tbe nucleus or germinal vesicle is shown in one of the nearly ripe eggs. (For more 

detailed drawing of nucleus, see fig. 160.) Bl. S., blood sinus; Ct, nodule of connective 

tissue. O. G., ovarian gland 22 times natural size. 
Fig. 142. Part of transverse section of ovary of lobster No. 52, table 20, showing follicle cells which 

have wandered into the egg and are undergoing degeneration. Dg, vesiculated masses of 

chromatin, the fragments of degenerated cells; Bl. S., blood sinus containing blood 

cells. 457 times natural size. 
Fig. 143. Part of transverse section of ovary, the same as in fig. 141, showing the gland-like organs. 

Bl. S., blood sinus (dotted line should be continued across gland). 211 times natural size. 

Plate 40. 
Fig. 144. Eight pleopod of adult female lobster, seen from posterior surface. Drawn from alcoholic 

preparation, with camera and dissecting microscope, the cuticle being removed from one 

side to show distribution of cement glands in swimmerets. 4 times natural size. 
Fig. 145. Fold of glandular epithelium from transverse section of ovary of lobster No. 75, table 20. 

From same as fig. 141. ys, body resembling yolk spherule. 190 times natural size. 
Fig. 146. Transverse section of lobe of ovary shown in fig. 131, plate 38. From No. 2, table 32. 67 

times natural size. 
Fig. 147. Part of transverse section of ovarian lobe from a lobster with external eggs near the point 

of hatching. The condition of this ovary closely corresponds to that shown in fig. 138. 

June 30, 1890. Bl. S., blood sinus. 36 times natural size. 



'THE AMERICAN LOBSTER. 247 

Fig. 148. Part of transverse section of ovary of lobster No. 51, table 20, showing the inner or primary 
egg membrane (shaded dark), and tlio follicular epithelium by which it is secreted. HI. S., 
blood .sinus. 211 times natural size. 

Fig. 149. Fart of transverse section of ovary of lobster No. 52, table 20, showing part of an egg and 
follicular cells in contact with it. Those which have wandered into the yolk after- 
wards degenerate. The external eggs borne by this lobster were in an early stage of 
segmentation. /. c, follicle cells immersed in the yolk. 211 times natural size. 

Plate 41. 

Fig. 150. Degenerating cells from the ovary of lobster No. 76, table 20. The larger body to the left is 
the remains of what was once a mature egg, which having failed of emission at the time 
of egg-laying has suffered degeneration. The tough egg membrane seems to defy com- 
plete absorption. To the unaided eye such an egg appears as a yellow fleck, if visible at 
all (see fig. 136). 510 times natural size. 

Fig. 151. Part of horizontal section of ovary from lobster No. 76, table 20, showing ova inclosed in 
folds of follicular epithelium. This ovary was slit open along the mid-dorsal line, pinned 
out, hardened, and sectioned in longitudinal, horizontal planes. 67 times natural size. 

Fig. 152. Part of transverse section of ovary of lobster No. 52, table 20, showing the developing ovum 
and its relation to the folds of glandular epithelium. Remnants of degenerating cells can 
bedetectedin this egg. (See figs. 139 and 149.) B. H., basement membrane; Bl. S., blood 
sinus; G. E., glandular epithelium. 281 times natural size. 

Fig. 153. Glandular epithelium from transverse section of ovary of lobster No. 75, table 20. F. G., 
vacuoles, probably representing fatty globules which have been removed in the process of 
preparing the tissue for sectioning ; ys, bodies resembling yolk spherule. 253 times natural 
size. 

Plate 42. 

Fig. 154. Ovum in early stage of growth, from ovary of lobster No. 52, table 20. Diameter of egg 
Jj mm., of nucleus -^ mm. 353 times natural size. 

Fig. 155. Young ovum from same ovary as the last. Diameter of egg tV mm., of nucleus ■£$ mm. 353 
times natural size. 

Fig. 156. Young ovum from same ovary as the last. This nucleus contains two nucleoli. Diameter 
of egg -^ mm., of nucleus t> 1 4 - mm. 353 times natural size. 

Fig. 157. Young ovum from same ovary as the last. Diameter of egg a little over -^ mm., of nucleus 
iV mm. 353 times natural size. 

Fig. 158. Nucleus of ovum from transverse section of ovary of lobster with external eggs about to 
hatch. From same as fig. 147. Diameter of egg ^ mm., of nucleus ^ mm. 353 times 
natural size. 

Fig. 159. Nucleus of ovum from nearly ripe ovary of lobster No. 94, table 20. See fig. 140 for ovarian 
section. Diameter of egg 1^ mm., of nucleus tV mm. 353 times natural size. 

Fig. 160. Nucleus of ovum from ovary of lobster No. 75, table 20. For ovarian section and position 
of nucleus, see fig. 141. Ovary ripe. Diameter of egg If mm., of nucleus -fa mm. 353 
times natural size. 

Fig. 161. Nucleus of egg in process of emitting polar cells. From section of unextruded egg taken 
from the oviduct. Diameter of egg 1.31 mm., of nucleus -^ mm. The nucleus is in process 
of karyokinesis and lies close to the surface of the egg. The axis of the nuclear spindle 
appears somewhat oblique to the surface. July 28, 1891. 353 times natural size. 

Fig. 162. Bifurcated rostrum of lobster taken at AVoods Hole, Massachusetts. Dorsal view. Two- 
thirds natural size. 

Fig. 163. Profile view of the same. Two-thirds natural size. 

Fig. 164. Ovaries of lobster, from below, showing bifurcation in left anterior lobe. Ovary light golden- 
yellow color. Ova very immature. May 19, 1892. Two-thirds natural size. 

Fig. 165. Part of gastrolith, separated into its constituent spicules, taken fresh from the wall of the 
stomach of a lobster nearly ready to molt. For chemical analysis, see No. 0a of table, 
Appendix II. Compare cut 8, plate C. The broad flattened spicule at the lower right- 
hand corner of the drawing is from the peripheral convex margin of the gastrolith. 5.3 
times natural size. 



248 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Plate 43. 

Fig. 166. Bud of right fourth pereiopod iu process of regeneration from young lobster probably in 
fourth stage. August 3, 1893. 47 times natural size. 

Fig. 167. Part of transverse section of oviduct of lobster, with ovary nearly ripe. July 25, 1893. 270 
times natural size. 

Fig. 168. Part of transverse section of oviduct of lobster, with external eggs in early yolk segmentation. 
For a drawing of this ovary see fig. 119, plate, 36. August 3, 1894. 270 times natural size. 

Fig. 169. Longitudinal section of first, second, and third segments of right first pereiopod of young 
lobster in sixth stage. Plane of section shown in cut 15. Length of lobster 18 mm. The 
right cheliped of this lobster was regenerated between the molts of the fifth and sixth 
stages. When the animal was preserved, August 17, 1893, the right regenerated cheliped was 
slightly smaller and more translucent than the left. No rudimentary tissue out of which 
the new limb is differentiated can be detected in the series of sections through plane of 
fracture, x y, plane of fracture; 1, 2, 3, segments of limb. About 47 times natural size. 

Fig. 170. Internal surface of cuticle of second joint (basis) of first maxilla macerated in Bela Haller's 
fluid, showing chitinons tubules of tegumental glands, and characteristic rosettes of what 
appears to be calcareous matter. From male lobster 10 inches long. July 31, 1893. 140 
times natural size. 

Fig. 171. Part of section of gastrolithic plate from female lobster with hard shell. August 10, 1893. 
Shown in its natural position in wall of stomach, in fig. 183. Fixed in picro-sulphuiic 
acid; stained in borax-carmine; embedded in celloidin. GP., cuticular portion of gastro- 
lithic plate. The demarcation between the layers is not so sharp as shown in the drawing. 
171 times natural size. 

Fig. 172. Section of left first pereiopod of lobster 9 inches long, in process of regeneration. At a a 
mass of large disk-shaped concretions, probably of a glycogenous nature, is seen. Compare 
figs. 121 and 122. The blackened margins of cuticle on either side of appendage repre- 
sent the remains of clotted blood on surface of the stump. About 6 times natural size. 

Fig. 173. Section of bud of right first (crushing) cheliped of adult male lobster, showing the columnar 
epithelium, the new cuticle, blood sinuses, and connective tissue. Fixed in picro-sul- 
phuric acid; stained in Ehrlich-Biondi mixture; embedded in celloidin. August 9, 1892. 
47 times natural size. 

Fig. 174. Part of longitudinal section of first larva through heart (-EY.) and right rudimentary repro- 
ductive organ (or), cutting also intestine (in) and gastric glands (gg). 67 times natural size. 

Plate 44. 

Fig. 175. Right fourth pereiopod of adult lobster in process of regeneration, from below. Color, 

bright coral red. Two-thirds natural size. 
Fig. 176. Stump of right first pereiopod of adult lobster in course of regeneration, from below. Bud 

and surface of scar dull white. August 9, 1892. Two-thirds natural size. 
Fig. 177. Surface view of membrane between old and new shells of molting lobster. This membrane 

is conspicuous at the time of shedding. It is noncellular, but is marked by the cell 

impressions of the chitinogenous epithelium. 733 times natural size. 
Fig. 178. Right second pereiopod of adult male in process of regeneration, from below. New append- 
age reddish, tinged with blue at the joints. August 4, 1892. Two-thirds natural size. 
Fig. 179. Left second antenna of adult lobster in process of regeneration, from above. June 30, 1892. 

Two-thirds natural size. 
Fig. 180. Antennas of the Isopod, Ligea oceanica, from above; that of the left side in the course of 

regeneration. Beaufort, North Carolina, June, 1885. 4.7 times natural size. 
Fig. 181. Regenerating left antenna of the-same, showing the new flagellum inclosed in the exoskeleton 

of the joint, which serves as a brood pouch. 16 times natural size. 
Fig. 182. Left first cheliped of adult lobster in process of regeneration, seen from the inner and 

anterior side. Color, bright red, bluish at joints; cuticle thrown into thin creases. 

Longitudinal axis of body in direction of arrow. 5.3 times natural size. 
Fig. 183. Profile view of masticatory stomach of lobster, showing gastrolithic plate, for the structure 

of which see fig. 171, plate 43. Lobster with hard shell, approaching the molting time 

August 10, 1893. Two-thirds natural size. 



THE AMERICAN LOBSTER. 249 

Fig. 184. Profile view of masticatory stomach of male lobster 7.5 inches long. Nearly ready to molt, 
showing gastrolith in place in the wall of stomach. For drawings of the gastrolith as it 
appears when it is dissected out and separates into its constituent spicules, see tig. 165, 
plate 42. Two-thirds natural size. 

Plates 45a and 45&. 

Fig. 185. Molted shell of lobster shown in fig. 186. No. 1, table 24. This represents the size of the 

lobster before the molt. Length 5J inches. Natural size. 
Fig. 186. The soft lobster, shortly after the shell shown in fig. 185 was cast off. Length, 61 inches. 

Natural size. These drawings show the average increase in size which is effected by a 

single molt 'see Chapter III). 

Plate 46. 

Fig. 187. Left cheliped of lobster, from below, showing budding and repetition of parts in propodus or 

sixth joint. 
Fig. 188. Same as fig. 187, seen from above. Both figures from photographs, and both natural size. 

Plate 47. 

Fig. 189. Part of right crushing-chela of female lobster, 11 inches long, seen from above, showing 

budding of dactyl. Woods Hole, Massachusetts, July 13, 1894. Two-thirds natural size. 
Fig. 190. Propodus of left crushing-claw, from below. This and figs. 191-196 are from specimens in 

Peabody Academy of Science, Salem, Massachusetts, all from adult lobsters. Two-thirds 

natural size. 
Fig. 191. Left crushing-claw, seen from above. Outgrowth from dactyl in horizontal plane ; dactyl 

closes under propodus. Two-thirds natural size. 
Fig. 192. Left crushing-chela, from above. Secondary dactyl bent downward slightly; no teeth; 

dactyl laterally compressed. S, spine of dactyl in primary symmetry; S', spine of dactyl 

in secondary symmetry. This supernumerary appendage probably represents two dactyls 

fused together. Two-thirds natural size. 
Fig. 193. Right cutting-chela, from below. Fingers bent up; dactyls articulate at joint with pro- 
podus ; primary dactyl and one of the adjacent secondary dactyl united. S, supernumerary 

dactyl in primary symmetry. Two-thirds natural size. 
Fig. 194. Dactyl of left cutting-claw, seen from below. It is bent horizontally upon itself, into an 

angle of about 80°, this being probably due to irregular growth in the regeneration of a 

lost part. Two-thirds natural size. 
Fig. 195. Chela of second or third pereiopod, from below, showing two supernumerary dactyls. 

Two-thirds natural size. 
Fig. 196. Right dactyl of cutting-chela, seen from outer side. Bifurcating branches bear teeth, which 

are not, however, apposed. Two-thirds natural size. 

Plate 48. 

Fig. 197. Deformed right cutting-claw. Accessory appendage bent downward from horizontal plane 
about 50°. The small terminal joint of the superadded part probably represents two 
dactyls fused together. S, spine of dactyl in primary symmetry; S>, spine of dactyl in 
secondary symmetry. Two-thirds natural size. 

Fig. 198. Right cutting-claw. Propodus apparently deformed by the irregular growth produced in 
the regeneration of a lost part. Two-thirds natural size. 

Fig. 199. Double monster of first larva of lobster. Raised at Fish Commiosion station, Woods Hole, 
Massachusetts, by Professor J. A. Ryder; seen from above. 13 times natural size. 

Fig. 200. Double monster of first larva of lobster, from Professor J. A. Ryder. Fusion of the organs at 
the anterior extremity has been carried to such a degree that the compound eyes are now 
represented by a small median spot of pigment. 13 times natural size. 

Plate 49. 

Fig. 201. Gland-cell from tegumental gland of second maxilla. Macerated in Be"la Haller's fluid for 

several days, and stained in methyl green. 733 times natural size. 
Fig. 202. Gland-cell from same preparation as fig. 201. 733 times natural size. 



250 BULLETIN OF THE UNITED STATES FISH COMMISSION. 

Fig. 203. Part of macerated tegumental gland from metastoraa. Compare also fig. 214. From female 
with ripe ovaries. August 9, 1893. Stained in methyl green. Central cell takes on deepest 
stain, gd.c, gland-cell; B, central reticulated body ; s.c, ganglion cell. 773 times natural 
size. 

Fig. 204. Cell from macerated tegumental gland of first maxilla.. Stained in methyl green. 773 times 
natural size. 

Fig. 205. Gland-cell from same preparation as fig. 204. 773 times natural size. 

Fig. 206. Cell from macerated tegumental gland of abdominal appendage of female before egg extru- 
sion. Ovaries nearly ripe. Attenuated, central end of cell very refractive. Small 
bodies, apparently accessory nuclei, are present in cell. 773 times natural size. 

Fig. 207. Same preparation as last, rolled under cover-slip and seen from o2rposite side. 773 times 
natural size. 

Fig. 208. Tegumental gland from metastoma of female -with ripe ovaries. Macerated three days in 
Bela Haller's fluid and stained in methyl green. The duct (d) of the gland conld be seen 
to open directly into a small central chamber, as in fig. 212. 513 times natural size. 

Fig. 209. C41and-cell from tegumental gland of abdominal appendage of female, which had recently 
laid eggs in an aquarium at the United States Fish Commission station, Woods Hole, Mas- 
sachusetts. Macerated in Bela Haller's fluid. August 14, 1893. 773 times natural size. 

Fig. 210. Tegumental gland from abdominal appendage of female lobster 10i inches long, preparing to 
molt. Chromic acid preparation, stained in the Ehrlicb-Biondi anilin mixture. Picro- 
sulphuric acid gives same result. Cells apparently shrunken, transparent, non-granular; 
nuclei clear. August 17, 1893. 513 times natural size. 

Fig. 211. Tegumental gland from abdominal appendage of female after ovulation. External eggs in 
yolk segmentation. Central ends of gland-cells are filled with dark zymogen granules. 
Nucleus of gland-cell stains green, that of central cell always red, in the Ehrlich-Biondi 
mixture. August, 1893. gcl.e, gland-cell; s.c, ganglion coll. 513 times natural size. 

Fig. 212. Section of tegumental gland from abdominal appendage of female lobster with mature 
ovaries. Central part of gland has a bluish clouded appearance. Nuclei may be green or 
red according to the degree with which the stain is extracted. Stained in the Ehrlich- 
Biondi mixture. August 4, 1893. d, duct of gland; », nerve-supplying gland; B, central 
reticulated body. 513 times natural size. 

Fig. 213. Gland-cells from same preparation as figs. 204, 205. Central ends of cells attenuated, and 
strongly refractive. 773 times natural size. 

Fig. 214. Macerated tegumental gland from metastoma of female, showing the central reticulated 
body, gland-cells, ganglion cell, and duct of gland. From female with ripe ovaries, d, 
duct of gland ; B, reticulated body. 773 times natural size. 

Plate 50. 

Fig. 215. Egg before yolk has segmented. The whitish spots are due to the presence of cells which 
are approaching the surface on one side of the egg. The yolk is later massed up about 
these in hillocks, as in fig. 218. 29 times natural size. 

Fig. 216. Surface view of egg with 16 cells present near the surface, two double rows of eight cells 
each." The cells have just divided. This drawing was made at 10.30 p. m. ; at 10.55 p. m. 
20 cells could be discerned near the surface. 29 times natural size. 

Fig. 217. Same egg as fig. 216; drawing made 1| hours later (12 p. m.), showing the cells more diffused 
over the surface. 29 times natural size. 

Fig. 218. Same egg as in figs. 216 and 217; rolled to show animal pole and yolk hillocks in profile. 
Drawing made at 10.55 p. m., when 20 yolk elevations had been formed. On the outskirts 
of these, other cells can be seen lying below the surface and destined soon to become the 
centers of new hillocks. 29 times natural size. 

Fig. 219. Surface view of egg showing yolk segments in active division; 10.15 p. m., segmentation 
furrows complete. This side of egg corresponds to the side shown with yolk hillocks in 
profile, in fig. 218. Nuclei all dividing at 10 p. m. ; at 10.10 p. m., furrows began to appear, 
separating cells. Same egg as shown in fig. 220. 29 times natural size. 

Fig. 220. Reverse side of egg shown in fig. 219, corresponding to the right side of the egg shown in 
fig. 218, opposite the yolk hillocks. When drawn at 9.30 p. in., nuclei were invisible; at 
10 p. m. they were very distinct and in diaster phase; at 10.15 p. m. segmentation furrows 
completed. 29 times natural size. 



THE AMERICAN LOBSTER. 251 

Fig. 221. Surface view of segmenting egg, under observation 5 Lours (8 p. m. to 1 a. m.). At 12 o'clock 
the segments shown in the drawing were very convex at surface, standing far apart as if 
the egg were breaking up. At 1 a.m. the segments were closer together and nuclei were 
about to divide again. Drawing made at 11 p. in., after completion of division. 29 times 
natural size. 

Fig. 222. Surface view of segmenting egg. Drawing begun at 11 a. in. ; when completed, half an hour 
later, the nuclei had divided and segmentation furrows were making their appearance. 
29 times natural size. 

Fig. 223. Surface view of same egg, drawn at 12 m. Division of cells mostly completed. 29 times 
natural size. 

Fig. 224. Surface view of same egg as in figs. 222 and 223, at 9 p. m., in advanced stage of segmen- 
tation. At 2.45 p. m. nuclei were dividing; at 6.45 p. m., when examined, division was 
completed. Drawing made at 9 p. m. 29 times natural size. 

Fig. 225. Surface view of egg in advanced stage of yolk segmentation. Free-hand drawing. 29 times 
natural size. 

Fig. 226. Surface view of egg in abnormal yolk segmentation, showing a larger yolk mass at the lower 
part of the figure and a number of smaller regular segments. A similar large yolk mass 
occurs on the opposite side of the egg next to the one shown in the drawing. 29 times 
natural size. 

Plate 51. 

Fig. 227. Surface view of egg in invagination stage. August 3, 11.30 a. m. 29 times natural size. 

Fig. 228. Surface view of abnormal embryo in egg-nauplius stage. August 10. 29 times natural size. 

Fig. 229. Surface view of abnormal embryo. August 8. 29 times natural size. 

Fig. 230. Surface view of abnormal embryo in egg-nauplius stage. P, cells approaching surface; 
r, outward fold of surface epithelium ; y, yolk. August 9. 29 times natural size. 

Fig. 231. Surface view of abnormal embryo in egg-nauplius stage. August 8. 29 times natural size. 

Fig. 232. Lateral view of embryo, showing large white patch behind abdomen. August 5. 29 times 
natural size. 

Fig. 233. Lateral view of embryo about 5 weeks old, showing lateral fold of carapace covering the 
antenna 1 , the heart (St.), the intestine containing characteristic concretions (P), the 
telson (T) overlapping brain and optic lobes, and the lateral indentations of the yolk 
corresponding to divisions of the midgut. July 29. 48 times natural size. 

Fig. 234. Surface view of embryo about 25 days old, showing the large optic lobes of cephalo-thoracic 
appendages. The telson touches the brain, and the crescentic fold of the carapace 
extends forward as far as the first maxillipeds. August 3, 1892. 29 times natural size. 

Fig. 235. Lateral view of double monster in egg-nauplius stage. August 13. 29 times natural size. 

Plate 52. 

Fig. 236. Part of transverse section of egg in stage between that shown in figs. 224 and 225, yolk cells 

(y c) being formed by tangential division. About 70 times natural size. 
Fig. 237. Part of longitudinal section of egg in egg-nauplius stage, showing degenerating cell (Dg). 

457 times natural size. 
Fig. 238. Part of section of segmenting egg, showing cell migrating from surface. July 31. 40 times 

natural size. 
Fig. 239. Section of segmenting egg, showing yolk cell near center. July 31. 40 times natural size. 
Fig. 240. Degenerating cells from same preparation as shown in fig. 237. y s, bodies resembling yolk 

spherules. 457 times natural size. 
Fig. 241. Vesiculated masses of chromatin (Bg) undergoing degeneration in the yolk. From 

transverse section of early egg-embryo. July 18. 457 times natural size. 
Fig. 242. Section of segmenting egg. Drawn July 31, 4 p. m. ; 34 cells present. 40 times natural size. 
Fig. 243. Section of egg in late segmentation, showing formation of yolk cells and division of these 

in yolk. August 1. s c, cell at surface undergoing tangential division; y c, yolk cell in 

process of division. 40 times natural size. 
Fig. 244. Surface view of egg in late segmentation of yolk. July 11. Fixed in Perenyi's fluid. 

About 50 times natural size. 



252 BULLETIN OF THE UNITED STATES PISH COMMISSION. 

Fig. 245. Part of transverse section, showing multiple karyokinesis and formation of nests of nuclei. 
Stage like that shown in fig. 252. Part of section behind and to one side of invagination 
area. Same series as fig. 241. c n, cell nest at surface; y n, cell nest in yolk; y n ] , cell in 
multiple karyokinesis, situated in yolk hall. 457 times natural size. 

Fig. 246. Part of transverse section through embryo in invagination stage, in, area of invagination. 
211 times natural size. 

Fig. 247. Part of section of egg to show nest of nuclei at surface. 211 times natural size. 

Fig. 248. From section through embryo in invagination stage, showing multiple karyokinesis and 
formation of nuclear nests at surface, like that shown in fig. 247. 211 times natural size. 

Fig. 249. Part of section of egg containing two nuclei, this one near surface. 285 times natural size. 

Platk 53. 

Fig. 250. Surface view of embryo in invagination stage. The embryonic area of this egg lies in front 
of the shallow pit. Cells are most numerous immediately in front of this depression and 
about the extreme anterior margins of the exposed surface. The rapid proliferation of 
cells in these regions gives rise on the one hand to the thoracic-abdominal plate, and to 
the optic disks on the other. Karyokinetic figures of dividing cells are seen scattered 
over the entire surface of the egg. The equatorial plate is in each case vertical, and may 
make any angle with the longitudinal axis of the embryo, or with a iine drawn through 
any proliferating center. Numerous grannies, the products of cell degeneration, are 
commonly seen. The reverse side of this egg shows nothing peculiar. Nuclei are there 
less numerous, and the superficial cells are larger. Flecks or clouds of granules, floating 
in the yolk below the surface, are seen here and there with no regularity. The nuclei 
over most of the surface, excepting those at the extreme periphery, were drawn by aid of 
the camera lucida, as were the cell outlines in the more central parts. From a picro- 
sulphuric acid preparation, stained in borax carmine, the egg cut in two, and the 
hemispheres mounted in balsam. August 6, 1892. 500 times natural size. 

Plate 54. 

Fig. 251. Part of transverse section through area of invagination (in), showing columnar surface cells 
(ec) filled with yolk and invaginate cells, lying between and within yolk masses. Some 
of the latter cells just below the surface are undergoing degeneration; some in the 
deepest parts of the egg are creeping with their long pseudopodia between the yolk 
spherules. These play the part of phagocytes and also contribute to the tissues of 
the embryo. 360 times natural size. 

Fig. 252. Surface view of embryo in region of invaginate area, showing clusters of cells at surface, 
produced by multiple karyokinesis. A, anterior; P, posterior end of egg; Deg, degener- 
ating cells; e a, embryonic area; In, area of invagination; y n, cell nest, produced by 
multiple karyokinesis. 89 times natural size. 

Fig. 253. Part of longitudinal section of intestine of embryo in a late stage of development, showing 
concretions in the lumen of the organ, bm, basement membrane; ep, intestinal epithe- 
lium; }'■> intestinal concretion. 360 times natural size. 

Fig. 254. Part of transverst section through invaginate area of an earlier stage than last, showing 
in-wandering masses of cells. A, anterior; P, posterior; In, pit of invagination; y c, 
invaginate cells. 89 times natural size. 

Fig. 255. Part of longitudinal section through area of invagination, showing the advancing cumuli 
of cells, which are pressing into the deeper parts of the egg and investing large masses of 
yolk. The distinctly columnar superficial cells, gorged with yolk, are also shown. In the 
embryonic area these become very tall, and beneath them there are clouds of disorganized 
chromatin granules, the remains of degenerated cells. A, anterior; P, posterior; Deg, 
degenerating cells ; e c, ectoderm ; Mes-ent, mesendoderm ; In, pit of invagination ; OD, 
optic disc. 89 times natural size. 

Fig. 256. Concretion from intestine of an embryo which was nearly ready to hatch. Teased from 
picro-sulphuric acid preparation and mounted in glycerin. 360 times natural size. 



Bull. U. S. F. C. 1895. The American Lobster. 



Plate 1. 




From photograph. 



MALE LOBSTER. Weight, 23 pounds 



Bull. U. S. F. C. 1895. The American Lobsttn. 



Plate 2. 




From photograph . 



VENTRAL VIEW OF MALE LOBSTER. Weight, 23 pounds. 
VENTRAL VIEW OF FEMALE LOBSTER. Weight, Impounds. 



Bull. U S. F. C. 1895. The American Lobster. 



Plate 4. 




Photographed from life 



ADULT MALE LOBSTER. Dorsal' 



Bull. U. S. F C 1895. The American Lobster. 



Plate 5. 




Photographed from life. 



ADULT MALE LOBSTER. Ventral viev 



Bull. U S. F C 1895 The American Lobste 



Plate 6. 




Photographed from life. 



ADULT FEMALE LOBSTER WITH EXTERNAL EGGS. Dorsal viev 



Bull. U S F C 1895. The American Lobster. 



Plate 7. 




Photographed from UJ 



ADULT FEMALE LOBSTER WITH EXTERNAL EGGS. Ventral view. 



Bull. U. 5 F C. 1895. The American Lobster. 



Plate 8 




From plmtogriijih. 



I Vinul'.-s 



Male 



IMMATURE LOBSTERS. Natural size 



Bull. U S F C. 1895. The American Lobster. 



Plate 10. 




IMMATURE FEMALE LOBSTER. Natural size. Dorsal view 



Bull. U. S F. C 1895 The American Lobster. 



Plate. 1 1, 




From, photograph 



IMMATURE FEMALE LOBSTER Natural size. Ventral view. 



Bull U S. F. C. 1895. The Ameiican Lobster. 



Plate 12. 




From photograph. 



IMMATURE MALE LOBSTER. Natural size. 



Bull U S F C 1895 The American Lobster. 



Plate 13. 




From pholoyraplt 



IMMATURE MALE LOBSTER. Natural size. 



Buii. U S. F. C. 1895. The American Lobster. 



Plate 14 




From photograph. 



ADULT MALE LOBSTER WITH ABNORMAL SYMMETRY IN LARGE CLAWS. 



\ 



'Fi^20 a 



F. H. Herrick ud iiat. del. 



\ 



Bull, U. S. F C. 1855. The American Lobster. 




F. H. ETeiTick »d na t. del. 



RIGHT CRUSHING-CLAWS OF LOBSTERS WHICH WEIGHED 23 AND It POUNDS Lf ' 



Plate 17 



1 1 : H 




Fig. 23. 




Fig. 25. 




Fig. 24. 




Fig. 26, 





Fig. 27. 

F.H.ffcrriek ad. nat.del. FRESHLY LAID EGGS AND ADVAN 



Fig. 28. 



CED EMBRYOS. 



Plate 19 




F. H Hcmck ad nai d, I 



THE FIRST LARVA, or First Fi-ee- Swim mi no S 



<5 Stage of the Lobster 



Bull. U S. F. C. 1895. The American Lcbste 



Plate 20. 




F. H. Herrick ad vat. del. 



FIRST LARVAL STAGE. 



Bull. U. S. F. C. 1895. The American Lobster 



Plate 21. 




F. H. Her rick ail nat del. 



SECOND LARVAL STAGE. 



Bull U S. F. C. 1895. The American Lobster. 



Plate 22. 




F. H. Herrick ad nut. del. 



THIRD LARVAL STAGE. 



Plate 23. 




F 11. TIerriek rid nat d < I 



FOURTH FREE-SWIMMING STAGE. 



Plate 24. 




F.H.Herriek ad nat.del. 



SIXTH STAGE 



Bull. U. S F. C. 1895. The American Lobster 



Plate 27. 




F. U. Herrick ad nat. del. 



MORPHOLOGY OF APPENDAGES 



jll U. S F. C. 1895. The American Lobster. 



Plate 28. 




F. H. Merrick ad ual. del. 



MOUTH PARTS AND APPENDAGES OF THE YOUNG. 



Bull. U. S. F, C. 1895. The American Lobster. 



Plate 29. 




Fig. 6i 



F. H. Herrick ail naf. del. 



MORPHOLOGY OF APPENDAGES. 



Bull. U. S. F. C. 1895. The American Lobster, 



Plate 30. 




F. H. Herrick ad nat. del. 



MORPHOLOGY OF APPENDAGES. 



3ull U SF.C 1895. The American Lobster 



Plate 31. 




F. H. Eerrick ad nat. del. 



MORPHOLOGY OF APPENDAGES. 



Bull. U. S. F. C. 1895. The American Lobster. 



Plate 32. 



Fig. 86 



Fig. 87 




p J ~ - • ' 

Fig. 89 



Fig. oo 



F. H. Herr'wh ad nat. del. 

DEVELOPMENT OF FIRST PAIR OF ABDOMINAL APPENDAGES AND SEMINAL RECEPTACLE. 



Bull. U. S F. C 1S95 The American Lobster. 



Plate 33. 




F. H. Heriick ad nut. del. 



REGENERATION AND DEVELOPMENT OF APPENDAGES. 



Bull U S. F C 1895. The American Lobstei. 



Plate 34. 







F. H. Herrivk ad nal. del. 



MORPHOLOGY OF APPENDAGES AND BRANCHI/E. 



3ull. U. S. F. C 1895 The American Lobster 



Plate 35. 




F. H. TJerrick ad nat, del. 



THE CARAPACE AND ANTENN/E. 



3ull. U. S. F. C. 1895. The American Lobster. 



Plate 36. 



Fig. 116 



Fig . 118 



R.O 




Fig. 120 J 




Fig . 119 





Fig. 121 





€//■ ^ 



Fig. 122 




F. H. Herrick ad nat. del. 



THE REPRODUCTIVE ORGANS AND OTHER STRUCTURES 



Bull U S . F C 1895. The American Lobster. 



Plate 37 




F. E. Herrick ad nai. del. 



STRUCTURE OF VAS DEFERENS AND SPERM CELLS. 



Plate 3 8 




Fig. 130. Figi31 




Fig. 134. 




Fig. 132. 



py-ri 












Fig. 133. 




Fig. 135. 



Fig. 136. 



Fig. 137. 




F.H.Hcrrick ad nat del. 



THE OVARY AND SEMINAL RECEPTACLE 



3ull. U S. T. C. 1895. The American Lobster. 



Plate 39. 



Fig. 139 




F. H. Herrick ad nat. del. 



STRUCTURE OF THE OVARY. 



Bull. U. S. F. C. 1895. Tha American Lobster. 



Plate 40. 



Fig. lvi- 




Fig. 14-9 f c - 



F. H. Herrick ad not. del. 



OVARY AND TEGUMENTAL GLANDS. 



Bull U S. F. C 1895. The American Lobster 



Plate 41, 




F. H. Herrick ad nat. del. 



STRUCTURE OF OVARY 



Bull U. S. F C 1895 The Amencan Lobster 



Plate 42. 




Fig. 154 




V\K. 155 









u: oX 



Fig. 161 



Fig. 156 






■^ i > .- 



^^ 



Fig. 159 




Fig 102 



Fig. 157 



&"•":':■'■ "-'-v> 



'<&.■;•; 



Fig. 160 




Fig. 163 





Fig . 164 



Fig. 165 



F. H. Herrick ad nut. del. 

METAMORPHOSIS OF GERMINAL VESICLE. SPICULES OF GASTROLITH, AND OTHER STRUCTURES 



Bull. U S. F. C. 1895. Tho American Lobster. 



Plate 43. 



Fig. 166 



Fig. 167 




Fig. 173 



F. H. Herrick ad nat. del. 



REGENERATING LIMBS, THE OVIDUCT, AND OTHER ORGANS. 



Bull U, S. F C. 1395 The American Lobster. 



Plate 44. 



Fig. it; 



Fig. 176 



Fi£. 177 



Fi£. 178 





Fig. 18Z 






Fig. 179 





Fig. 183 



ml;. 184 



F. H. Herrick ad nat. del. 



REGENERATION OF APPENDAGES. THE GASTROLITHS. 



Bull. U. S. F. C. 1895. The American Lobster. (To face Plate 45 6.) 



Plate 45". 




jF. H. Herrick ad not. del. 



CAST-CFF SHELL. Natural size. 



U. S. F. C. 1895. The American Lobster. (To face Plate 45 n.) 



Plate 45''. 




F. B. Herrick ad nat. del. 



SOFT LOBSTER AFTER ESCAPE FROM SHELL SHOWN ON THE LEFT. Natural sue. 



Bull. U.S. F C 1895. The American Lobster. 



Plate 46. 





Fig. 187. 



Fig. 188. 



From photograph 



ABNORMAL CHELIPtD. Natural size 



Bull. U. S. F. C 1895. The American Lobster, 



Plate 47. 




Fig. 192 



F. H. Herrick ad nat. del. 



DEFORMED CLAWS. 



Bull. U. S. F. C. 1895. The American Lobster. 



Plate 48. 




F. H. Herrivk ad nat. del. 



DEFORMED CLAWS IN ADULT AND DOUBLE MONSTERS IN FIRST LARVA, 



Bull. U. S. F. C. 1895. The American Lobster. 



Plate 49. 



Fig. 201 Fig. 202 



Fig. 203 



( lg. 204 




Fig. 212 



F. M. Herrick ad nat. del. 



STRUCTURE OF TEGUMENTAL GLANDS. 



Plate 50 




Hg. 215. 



Fig. 218. 



Fig. 221. 



rig. 210. 

;- ' ' ' V 



Fig. 219. 






Fig. 222. 






rig. 21" 



Fig. 220. 
ilY'lftii 



Fig. 223. 



m 



\ 



V : ''> 



w'\ 



m 



Fig. 224. 



FH.Hcrrick ad, nat.del. 



Fig. 22: 



SEGMENTATION OF THE EGG. 



rig. 22«. 






Plate 51 




Fig. 230. 




Fig. 228. 




Fig. 23i. 




MMBB^b 




Fig. 229. 




Fig. 232. 




Fig. 235. 



F. H. Herrick ad nai del . 



M 8 RYO. 



Bull. U. S. F. C. 1895. The American Lobster, 



Plate 52. 




F. H. Herrick ad nat. del. 



DEVELOPMENT OF EMBRYO. 



3ull U S F C 1895. The American Lobster. 



Plate 53. 



L^f*i 



'■■■■ 



















■ife 




% 

»■.•■•' 



. & 
- 

■ 

■ §> 



F. H. Herrich ad nat. del. 



EGG-EMBRYO. INVAGINATION STAGE. 



Bull. U. S. F. C. 1895, The American Lobster. 



Plate 54. 



ec. 




e.a. 



Deg 



-iy- 









.»«" 



> ; 



' » no 







.' '> ' 



In. 



P 
Fig. 252 









-y- c 



ft 







Fig. 254 




.F. i7. Merrick ad nat. del. 



DEVELOPMENT OF EMBRYO. 



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