Memoirs from the Biological Laboratory
OF THE
JOHNS HOPKINS UNIVERSITY
IV, 1
WILLIAM K. BROOKS, EDITOR
THE CUBOMEDUSÆ
A DISSERTATION PRESENTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY,
IN THE JOHNS HOPKINS UNIVERSITY, 1897
BY
FRANKLIN STORY CONANT
A MEMORIAL VOLUME
BALTIMORE
THE JOHNS HOPKINS PRESS
1898
PRINTED BY
The Lord Baltimore Press
THE FRIEDENWALD COMPANY
BALTIMORE, MD., U. S. A.
[Illustration: With the kind regards of Franklin Story Conant.
THE HELIOTYPE PRINTING CO. BOSTON]
FRANKLIN STORY CONANT
SEPTEMBER 21, 1870--SEPTEMBER 13, 1897
A BIOGRAPHICAL SKETCH
This Treatise is printed after the author’s death, as a Memorial by his
friends, fellow-students and instructors, with the aid of the Johns
Hopkins University. It consists of his Dissertation, reprinted from the
copy which was accepted by this University at his examination for the
degree of Doctor of Philosophy in June, 1897.
As he had made many notes on the embryology of the Cubomedusæ, and
had hoped to complete and publish them together with an account of
physiological experiments with these medusæ, he had described the
Dissertation on the title-page as Part I, Systematic and Anatomical, and
he went to Jamaica immediately after his examination to continue his
studies and to procure new material, and he there lost his life.
* * * * *
Franklin Story Conant was born in Boston on September 21, 1870, and he
died in Boston on September 13, 1897, a few days after his arrival from
Jamaica, where he had contracted yellow fever through self-sacrificing
devotion to others.
He was educated in the public schools of New England; at the University
of South Carolina; at Williams College, where he received the degree of
Bachelor of Arts in 1893; and in the Johns Hopkins University, where he
received the degree of Doctor of Philosophy in 1897, and where he was
appointed a Fellow in 1896 and Adam T. Bruce Fellow in 1897.
Most of his instructors have told us that they quickly discovered
that Conant was a young man of unusual intelligence and energy and
uprightness, and as his education progressed he secured the esteem and
the affectionate interest of all who had him in charge, so that they
continued to watch his career with increasing pride and satisfaction.
He entered the Johns Hopkins University in the spring of 1894, and at
once joined the party of students in zoology who were working, under
my direction, in the marine laboratory of the University at Beaufort,
North Carolina; and from that time until his death he devoted himself
continually, without interruption, to his chosen subject--spending his
winters in the laboratory in Baltimore, and devoting his summers to
out-of-door studies at Beaufort and at Wood’s Holl, and in Jamaica.
It is as a student and not as an investigator that we most remember
Conant, for most of his time was given to reading and study on subjects
of general educational value; although he had begun, before his death, to
make original contributions to science and to demonstrate his ability to
think and work on independent lines.
His study of the Chaetognaths was undertaken only for the purpose of
verifying the account of their anatomy and development in the text books,
but it soon showed the presence at Beaufort of several undescribed
species. Without interrupting his more general studies, he employed his
odd moments for three years in their systematic analysis, and at last
published two papers, “Description of Two New Chaetognaths,” and “Notes
on the Chaetognaths,” which show notable power of close and accurate
observation and of exact description; and, while short, are valuable
contributions to our knowledge of this widely distributed but difficult
group.
As he appreciated the value to one who has devoted himself to zoology
of thorough acquaintance with physiological problems and the means for
solving them, he wished, after he had completed his general course in
physiology, to attempt original research in this field; and, at the
suggestion of Professor Howell, he, in company with H. L. Clark, his
fellow student, undertook and successfully completed an investigation of
which Professor Howell gives the following account:
In connection with Mr. H. L. Clark, Mr. Conant undertook to
investigate the character of the nervous control of the heart
beat in decapod crustaceans. They selected the common edible
crab, Callinectes hastatus, and made a series of most careful
experiments and dissections which resulted in proving the
existence of one inhibitory nerve and two accelerator nerves
passing to the heart on each side from the thoracic ganglion.
They not only demonstrated the physiological reaction of
these nerves, but traced out successfully their anatomical
course from the ganglion to the pericardial plexus. It seemed
hardly probable from an a priori standpoint that in an animal
like the crab there should be any necessity for an elaborate
nervous mechanism to regulate the beat of the heart, but their
experiments placed the matter beyond any doubt, and have since
served to call attention to this animal as a promising organism
for the study of some of the fundamental problems in the
physiology of the heart. As compared with previous work upon
the same subject it may be said that their experiments are the
most definite and successful that have yet been made.
His chief completed work, the Dissertation on The Cubomedusæ, is here
printed; and through it the reader who did not know Conant must decide
whether he was well fitted, by training and by natural endowments, for
advancing knowledge. I myself felt confident that the career on which he
had entered would be full of usefulness and honor. I was delighted when
he was appointed to the Adam T. Bruce Fellowship, for I had discovered
that he was rapidly becoming an inspiring influence among his fellow
students in the laboratory, and I had hoped that we might have him among
us for many years, and that we might enjoy and profit by the riper fruits
of his more mature labors.
Immediately after his examination for the degree of Doctor of Philosophy
in June, 1897, he set out for Jamaica to continue his studies at the
laboratory which this University had established for the summer at Port
Antonio, and he there worked for nearly three months on the development,
and on the physiology of the sense-organs, of the Cubomedusæ.
His notes and specimens are so complete that I hope it will be possible
to complete in Baltimore, at an early day, the work which he had expected
to carry on this year.
After the sudden and alarming death of the director of the expedition,
Dr. J. E. Humphrey, Conant took the burden of responsibility upon
himself, and while he fully appreciated his own great danger, he devoted
himself calmly and methodically to the service of others who, in their
afflictions, needed his help, and he fell in the path of duty, where he
had always walked, leaving behind him a clear and simple account of all
the business of the laboratory and of his scientific work, and of his own
affairs, complete to the day before his death.
Immediately after the opening of the University in October his friends
and companions and instructors assembled to express the sorrow with which
they had heard the sad news of his death, and to record their love and
esteem for the generous, warm-hearted friend who in all the relations
of life had proved himself so worthy of their affectionate remembrance.
At this meeting those who had worked at his side in our laboratories
recalled his steadfast earnestness in the pursuit of knowledge, and the
encouragement they had found in his bright example; while those who
had been his instructors spoke of him as one who had bettered their
instruction and enriched all that he undertook by sound and valuable
observations and reflections. While all united in mourning the untimely
loss of one who had shown such rich promise of a life full of usefulness
and honor and distinction, it was pointed out with pride that his end
was worthy of one who had devoted it to the fearless pursuit of truth,
and to generous self-sacrifice and noble devotion to others; and it
was resolved, “That we prize the lesson of the noble life and death of
Franklin Story Conant.”
LIST OF THE PUBLISHED BIOLOGICAL PAPERS OF FRANKLIN STORY CONANT.
1. DESCRIPTION OF TWO NEW CHAETOGNATHS. Johns Hopkins University
Circulars, No. 119, June, 1895.
2. NOTES ON THE CHAETOGNATHS. Johns Hopkins University Circulars, No.
126, June, 1896.
3. THE INHIBITORY AND ACCELERATOR NERVES TO THE CRAB’S HEART (_an
abstract_), by F. S. Conant and H. L. Clark. Johns Hopkins University
Circulars, No. 126, June, 1896.
4. ON THE ACCELERATOR AND INHIBITORY NERVES TO THE CRAB’S HEART, by F. S.
Conant and H. L. Clark. The Journal of Experimental Medicine, Vol. I, No.
2, 1896.
5. NOTES ON THE CUBOMEDUSÆ (_an abstract_). Johns Hopkins University
Circulars, No. 132, November, 1897.
6. THE CUBOMEDUSÆ. (This was accepted in June, 1897, as his thesis for
the degree of Doctor of Philosophy, and it is here printed.)
TABLE OF CONTENTS.
PAGE
INTRODUCTION 1
PART I: SYSTEMATIC 3
Family I: CHARYBDEIDÆ 3
_Charybdea Xaymacana_ 4
“ II: CHIRODROPIDÆ 4
“ III: TRIPEDALIDÆ 5
_Tripedalia cystophora_ 5
PART II: GENERAL DESCRIPTION OF THE ANATOMY OF THE CUBOMEDUSÆ 7
A. CHARYBDEA XAYMACANA 7
a. Environment and Habit of Life 7
b. External Anatomy 8
2. Form of Bell 8
3. Pedalia 8
4. Sensory Clubs 9
5. The Bell Cavity and its Structures 10
(a) Proboscis 11
(b) Suspensoria, or Mesogonia 11
(c) Interradial funnels, or funnel cavities 11
(d) Velarium 12
(e) Frenula 12
(f) Musculature 12
(g) Nerve ring 13
c. Internal Anatomy 13
6. Stomach 13
7. Phacelli 14
8. Peripheral Part of the Gastro-Vascular System 14
(a) Stomach Pockets (Valves and Mesogonial Pockets) 14
(b) Marginal Pockets 17
(c) Canals of the Sensory Clubs and Tentacles 17
9. Reproductive Organs 19
10. Floating and Wandering Cells 20
B. TRIPEDALIA CYSTOPHORA 22
a. Habitat 22
b. External Anatomy 23
c. Internal Anatomy 24
PART III: DESCRIPTION OF SPECIAL PARTS OF THE ANATOMY 27
A. VASCULAR LAMELLÆ 27
B. NERVOUS SYSTEM 37
LITERATURE 57
TABLE OF REFERENCE LETTERS 58
DESCRIPTION OF FIGURES 60
INTRODUCTION.
Jelly-fish offer to the lover of natural history an inexhaustible store
of beauty and attractiveness. One who has studied them finds within him a
ready echo to Haeckel’s statement that when first he visited the seacoast
and was introduced to the enchanted world of marine life, none of the
forms that he then saw alive for the first time exercised so powerful an
attraction upon him as the Medusæ. The writer counts it a rare stroke of
fortune that he was led to the study of a portion of the group by the
discovery of two new species of Cubomedusæ in Kingston Harbor, Jamaica,
W. I., while he was with the Johns Hopkins Marine Laboratory in June of
1896.
The Cubomedusæ are of more than passing interest among jelly-fish,
both because of their comparative rarity and because of the high
degree of development attained by their nervous system. One fact alone
suffices to attract at once the attention of the student of comparative
morphology--that here among the lowly-organized Cœlenterates we find an
animal with eyes composed of a cellular lens contained in a pigmented
retinal cup, in its essentials analogous to the vertebrate structure.
Perhaps this and other facts about the Cubomedusæ would be more generally
known, had they not been to a certain extent hidden away in Claus’s
paper on Charybdea marsupialis (’78), which, while a record of careful
and accurate work, is in many respects written and illustrated so
obscurely that it is very doubtful whether one could arrive at a clear
understanding of its meaning who was not pretty well acquainted with
Charybdea beforehand.
Before Claus’s paper was received at this laboratory, H. V. Wilson went
over essentially the same ground upon a species of Chiropsalmus taken
at Beaufort, N. C. When the article on Charybdea marsupialis appeared,
however, the results were so similar that Wilson did not complete for
publication the careful notes and drawings he had made.
Haeckel’s treatment of the Cubomedusæ in his “System” (’79) in the
Challenger Report (’81) is much more lucid than Claus’s; but the extended
scope of his work and the imperfect preservation of his material
prevented a detailed investigation, and for a more complete and readily
intelligible account of the structure of the Cubomedusæ a larger number
of figures is desirable.
In the foregoing facts lies whatever excuse is necessary for repeating
in the present paper much that has already seen print in one form or
another.
PART I: SYSTEMATIC.
It seems advisable first of all to establish the systematic position
of the two newly found species, Charybdea Xaymacana and Tripedalia
cystophora. Haeckel’s classification, as given in his “System der
Medusen,” is an excellent one and will be followed in this case. One of
the new species, however, will not classify under either of Haeckel’s
two families, so that for it a new family has been formed and named the
Tripedalidæ. In showing the systematic position of the two new forms, an
outline of Haeckel’s classification will be given, so far as it concerns
our species, together with the additions that have been made necessary.
CUBOMEDUSÆ (Haeckel, 1877).
Characteristics: Acraspeda with four perradial sensory clubs which
contain an auditory club with endodermal otolith sac and one or several
eyes. Four interradial tentacles or groups of tentacles. Stomach with
four wide perradial rectangular pockets, which are separated by four long
and narrow interradial septa, or cathammal plates. Gonads in four pairs,
leaf-shaped, attached along one edge to the four interradial septa.
They belong to the subumbrella, and are developed from the endoderm of
the stomach pockets, so that they project freely into the spaces of the
pockets.
Family I: CHARYBDEA (Gegenbaur, 1856).
Cubomedusæ with four simple interradial tentacles; without marginal lobes
in the velarium, but with eight marginal pockets; without pocket arms in
the four stomach pockets.
Genus: _Charybdea._
Charybdeidæ with four simple interradial tentacles with pedalia; with
velarium suspended, with velar canals and four perradial frenula. Stomach
flat and low, without broad suspensoria. Four horizontal groups of
gastric filaments, simple or double, tuft or brush-shaped, limited to the
interradial corners of the stomach.
Species: _Charybdea Xaymacana_ (Fig. 1).
Bell a four-sided pyramid with the corners more rounded than angular,
yet not so rounded as to make the umbrella bell-shaped. The sides of the
pyramid parallel in the lower two-thirds of the bell, in the upper third
curving inward to form the truncation; near the top a slight horizontal
constriction. Stomach flat and shallow. Proboscis with four oral lobes,
hanging down in bell cavity a distance of between one-third and one-half
the height of bell; very sensitive and contractile, so that it can be
inverted into the stomach. The four phacelli epaulette-shaped, springing
from a single stalk. Distance of the sensory clubs from the bell margin
one-seventh or one-eighth the height of bell. Velarium in breadth about
one-seventh the diameter of the bell at its margin. Four velar canals in
each quadrant; each canal forked at the ends, at times with more than two
branches. Pedalia flat, scalpel-shaped, between one-third and one-half
as long as the height of bell. The four tentacles, when extended, at
least eight times longer than the bell. Sexes separate. Height of bell,
18-23 mm.; breadth, about 15 mm. (individuals with mature reproductive
elements); without pigment. Found at Port Henderson, Kingston Harbor,
Jamaica.
As may be seen from the above, C. Xaymacana differs only a little from
the C. marsupialis of the Mediterranean. Claus mentions in the latter
a more or less well defined asymmetry of the bell, which he connects
with a supposed occasional attachment by the proboscis to algæ. In C.
Xaymacana I never noticed but that the bell was perfectly symmetrical. C.
Xaymacana is about two-thirds the size given by Claus for his examples
of C. marsupialis, which were not then sexually mature. It has 16 velar
canals instead of 24 (32), as given by Haeckel, or 24 as figured by
Claus. Difference in size and in number of velar canals are essentially
the characteristics upon which Haeckel founded his Challenger species, C.
Murrayana.
Family II: CHIRODROPIDÆ (Haeckel, 1877).
Cubomedusæ with four interradial groups of tentacles; with sixteen
marginal pockets in the marginal lobes of the velarium, and with eight
pocket arms, belonging to the exumbrella, in the four stomach pockets.
This family is represented in American waters by a species of
Chiropsalmus, identified by H. V. Wilson as C. quadrumanus, found at
Beaufort, North Carolina.
Family III: TRIPEDALIDÆ (1897).
Cubomedusæ with four interradial groups of tentacles, each group having
three tentacles carried by three distinct pedalia; without marginal lobes
in the velarium; with sixteen marginal pockets; without pocket arms in
the stomach pockets.
Genus: _Tripedalia_.
For the present the characteristics of family and genus must necessarily
be for the most part the same. The genus is distinguished by having
twelve tentacles in four interradial groups of three each; velarium
suspended by four perradial frenula; canals in the velarium; stomach
projecting somewhat convexly into the bell cavity, with relatively
well-developed suspensoria; four horizontal groups of gastric filaments,
each group brush-shaped, limited to the interradial corners of the
stomach.
Species: _Tripedalia cystophora_ (Fig. 17).
Shape of bell almost exactly that of a cube with rounded edges; the roof
but little arched. The horizontal constriction commonly seen near the
top of the bell in the Cubomedusæ not present. Proboscis with four oral
lobes; hanging down in the bell cavity generally more than half the depth
of the cavity and at times even to the bell margin. In the gelatine of
the proboscis an irregular number (15-21) of sensory organs resembling
otocysts, from the presence of which comes the specific name. Phacelli
brush-shaped, composed of from seven to thirteen filaments springing from
a single stalk in each quadrant, or rarely from two separate stalks in
one of the quadrants. Distance of the sensory clubs from the bell margin
about one-fifth or one-fourth of the height of bell. Breadth of velarium
about one-sixth the diameter of bell at margin; with six velar canals in
each quadrant; the canals simple, unforked. Pedalia flattened, shaped
like a slender knife blade, about half as long as the height of the
bell. Tentacles at greatest extension observed two and a half times the
length of pedalia. Sexes separate. Height of bell in largest specimens
(reproductive elements mature) eight or nine mm. Breadth same as height
or even greater. Color a light yellowish brown, due in large part to eggs
or embryos in the stomach pockets. The reproductive organs especially
prominent by reason of their similar color. Found in Kingston Harbor,
Jamaica.
It will be seen from the above that Tripedalia possesses two of the
characteristics of the Charybdeidæ and two of the Chirodropidæ. The
family was named from the prominent feature of the arrangement of the
tentacles, in groups of three with separate pedalia. The small size of
T. cystophora is worthy of note in connection with the fact that of the
twenty species of Cubomedusæ given by Haeckel in his “System” only two
are smaller than 20 mm. in height, and those are the two representatives
of Haeckel’s genus Procharagma, the prototype form of the Cubomedusæ,
without pedalia and without velarium. While Tripedalia has both pedalia
and velarium, it may be perhaps that its small size, taken in connection
with characteristics just about midway between the Charybdeidæ and the
Chirodropidæ, indicate that it is not a recently acquired form of the
Cubomedusæ.