LBS
Memoirs of the Museum cf Conipurative Zoology
AT HA RV ARD_ COLNE E.

Vou XXX No. 2.

REPORTS ON AN EXPLORATION OFF THE WEST COASTS OF MEXICO,
CENTRAL AND SOUTH AMERICA, AND OFF THE GALAPAGOS ISLANDS,
IN CHARGE OF ALEXANDER AGASSIZ, BY THE U. 8. FISH COMMISSION
STEAMER ‘ ALBATROSS,” DURING 1891, LIEUT. COMMANDER Z,. L.
TANNER, U. 8S. N., COMMANDING. |

XXXII.

THE RADIATING ORGANS OF THE
DEEP SEA FISHES.

By ROBERT VON LENDENFELD.

WITH AN APPENDIX ON THE STRUCTURE OF THE BUD-LIKE ORGANS
OF MALTHOPSIS SPINULOSA GARMAN. :

)

_ By EMANUEL TROJAN.

WITH ELEVEN PLATES,

AND A OHART OF THE ROUTE.

[Published by Permission of MarsHavn McDonatp and Groros M. Bowsrs, U. 8. Commissioners
of Fish and Visheries.]

CAMBRIDGE, U.S. A.:

Printes for the Museum,
Auaust, 1905.

: At

The following Publications of the Museum contain Reports on the Dredging Operations in
charge of Alexander Agassiz, of the U. S. Fish Commission Steamer “ Albatross,” during
1899 and 1900, Commander Jefferson F. Moser, U.S. N., Commanding.

I. A. Aaassiz. Preliminary Report and List of Stations. With Remarks on the Deep-Sea
Deposits by Sir John Murray. Mem. M.C. Z., Vol. XXVI. No.1. January, 1902.
114 pp. 21 Charts.

If. A.G. Mayer. Some Species of Partula from Tahiti. A Study in Variation. Mem. M. C. Z.,
Vol. XXVI. No. 2. January, 1902. 21 pp. 1 Plate.

Ill. A. Agassiz and A. G. Maykr. Meduse. Mem. M.C. Z., Vol. XXVI. No. 3. January,
1902. 40 pp. 13 Plates, 1 Chart. ms

IV. A. AGassiz. The Coral Reefs of the Tropical Pacific. Mem. M. C. a Vol, XXVIII.
February, 1908. 83, 410 pp. 288 Plates. ;

V. C.R. Eastman. Sharks’ Teeth and Cetacean Bones from the Red Clay of the Tropical
Pacific. Mem. M. C. Z., Vol. XXVI. No. 4. June, 1908. 14 pp. 8 Plates.

VI. W.E. Hoyts. ‘Cephalopoda. Bull. M.C. Z., Vol. XLII. No.1. March, 1904. 71 pp.
12 Plates.

VII. H. Lupwic. Asteroidea. Mem. M.C. Z., Vol. XXXII. July, 1905. 12, 292 pp. 35
Plates, 1 Chart.

Memoirs of the Museum of Comparative Zodlogy
AT HARVARD COLLEGE.

Vou, XXX, “NG; 2

REPORTS ON AN EXPLORATION OFF THE WEST COASTS OF MEXICO,
CENTRAL AND SOUTH AMERICA, AND OFF THE GALAPAGOS ISLANDS,
IN CHARGE OF ALEXANDER AGASSIZ, BY THE U. S. FISH COMMISSION
STEAMER ‘ ALBATROSS,” DURING 1891, LIEUT. COMMANDER Z. UL.
TANNER, U. S. N., COMMANDING.

XXXII.

THE RADIATING ORGANS OF THE
DEEP SEA FISHES.

By ROBERT VON LENDENFELD.

WITH AN APPENDIX ON THE STRUCTURE OF THE BUD-LIKE ORGANS
OF MALTHOPSIS SPINULOSA GARMAN.

By EMANUEL TROJAN.

WITH ELEVEN PLATES,

AND A CHART OF THE ROUTE.

[Published by Permission of Marswari McDonatp and Groras M. Bowrrs, U. S. Commissioners
of Fish and Fisheries.]

CAMBRIDGE, U.S. A. :

Printes for the Museum,
Auaust, 1905.

ER ee em

+
{
{

*

ly
2.

TABLE OF CONTENTS.

INTRODUCTION

DESCRIPTION OF THE RADI-
ATING ORGANS
(1) Tre Fists wir OcELLAR Ravr-
ATING ORGANS

Argyropelecus lychnus (PL. 6, Figs.

24, 25) .

Sternoptya obscura (PL. by

26, 20) .

>

Fis

Lychnopoles igintetles. (PL. 1,
Figs. 81-37) . . ‘
Cyclothone acclinidens (Pl. 6, ri igs

28-30) .

Myctophum cupolaterneienn ce 5,
Figs. 21-23) . :
Shauliodus barbatus (PL. 8, Fi gs.

38-40;

PL 9, Figs. 43-46)

Idiacanthus antrostomus ae 8,
Figs. 41, 42) .

Stomias hewagonatus (PI. 10, Fi

47-51)

*

g 3,

PAGE

169

170

PAGE
2) Tue Fisnes wire Raptatine
DISCS: os 197
Bassozetus Nasus (Pl 4, Figs. 14— 17) 197
Leucicorus lusciosus (Pl. 3, Figs.

10-18). ++ 198
Halosaurus rele (I als ‘LL, Bi igs.
sit). 199

Macrurus canus (PL x ies. 18-20) 202

Ipnops agassizit (Pl. 1, Figs. 8-5) 202

(3) Tum Fisues wire TUBULAR Ra-

DIATING ORGANS. co6 203
Malthopsis spinulosa (PL. 1, Figs.

, 2; Pl. 2, Figs. 6-9)... 208

§ CONCLUSIONS =+.. «= 205

4 LITERATURE «. © ss + 207

APPENDIX.

Tur STRUCTURE OF THE Bup-LikE
OrGANS OF oe SPINU-
1osA, BY HE. LROUAN «= = 209

LITERATURE «+ + + * 213

inasclaeete

b,

—_ i

THE RADIATING ORGANS OF THE
DEEP SEA FISHES.

1. INTRODUCTION.

Tue fishes collected by the “Albatross” in 1891 have been carefully
described by Mr. Samuel Garman (99). A+ considerable number of them
possess radiating, or, as they were formerly termed, phosphorescent organs.
Mr. Alexander Agassiz was so kind as to place many of these at my disposal
and to permit me to study the minute structure of their radiating parts.
For this valuable material and his subsequent furtherance of the work,
[ express my sincerest thanks. The results of the examination of these
organs are detailed in this paper.

The fishes sent to me belone to the following species : —
o o

Argyropelecus lychnus Garman. Lychnopoles argenteolus Garman.
Bassozetus nasus Garman. Macrurus canus Garman.
Chauliodus barbatus Garman. Malthopsis spinulosa Garman,
Jyclothone acclinidens Garman. Mixonus caudalis Garman.
Halosaurus radiatus Garman. Myctophum aurolaternatum Garman.
Idiacanthus antrostomus Gilbert. Sternoptyx obscura Garman,

Ipnops agassizii Garman, Stomias hexagonatus Garman.

Leuciocorus lusciosus Garman.

All, with the exception of Mixonus caudalis, were sufficiently preserved in
alcohol to allow of the examination of their radiating organs,

Since Garman did not pay particular attention to these organs, his state-
ments concerning their arrangement and number are not always sufficient.
This applies to the figures even more than to the descriptions. For this
reason the entire fishes are here figured again.

The minute structure of the organs was studied by means of paraffin

and celloidin sections. Various stains were employed. Van Gieson’s

haematoxylin-picric acid-fuchsin gave the best results. Most of the sections

2

170 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

photographs, and drawings were made by Mr. . Trojan while work-
ing in my laboratory. I must express my thanks for the great pains
Mr. Trojan has taken with this work ; and for his paper on the structure of
the bud-like organs of Malthopsis spinulosa which I add as an appendix to
this memoir.

Three types of radiating organs are represented by the fishes ex-
amined: —ocellar radiating organs, radiating discs, and tubular radiating

organs.

2. DESCRIPTION OF THE RADIATING ORGANS.
(1) THE FISHES WITH OCHLLAR RADIATING ORGANS.

Argyropelecus lychnus Garman.
Plate 6, Figs. 24, 25.

This species has been described by Garman (’99, p. 234, Plate J, Fig.
1, lb). The radiating organs are of considerable size, possess exceedingly
brilliant reflectors and are surrounded by a layer of dark pigment, so that
they are very conspicuous. There are on each side 1 anteorbital (Plate 6,
Fig. 25, ao), 1 postorbital (po), 2 opercular (op), 6 branchiostegal (br), 6
pectoral (pe), 12 ventrothoracic (vt), 2 anterior lateral (al), 6 medial lateral
(ml), 4 ventromedial (ve), 6 anal (a), and 4 ventrocaudal (ve), radiating
organs. Besides these there also exists, according to Garman ('99, p. 234),
a frontal.

The axis of all the organs lies very obliquely and nearly parallel to the
surface in such a way that it is directed vertically downwards. ‘The anteor-
bitals, the postorbitals, and the opercular are simple. ‘The others are joined
in longitudinal rows in which they lie side by side. The right and left
ventrothoracic organs form a double row which appears as a medial crest,
protruding ventrally. All the organs with the exception of the anteorbitals,
in which the sheaths are absent, are similar in structure, and size, and the
differences in their appearance are due chiefly to the different degrees of

coalescence. This is nil in the three cephalic organs mentioned, and greatest

in the ventrothoracics. ;

The organs are 2 to 3 mm. long and 1 mm. or alittle more broad. Hach
radiating organ (Fig. 24) is composed of a slender elongated ellipsoidal
proximal (A), and a narrow funnel-shaped distal part (D). These parts are

|

THE RADIATING ORGANS OF THE DEEP SEA FISHES. Ve

separated by a clearly marked constriction (C). The proximal oval part has
in the single organs a circular transverse section throughout; in the joined
organs it is not so regular. The distal funnel shaped part is in life probably
a rotation paraboloid, but on account of shrinkage appears somewhat irreg-
ular in the sections (Fig. 24). In accordance with the smallness of the
angle enclosed between the axis of the organ and the surface of the fish,
the funnel abuts very obliquely on the latter; it is long on the inner, and
very short on the outer face, a very oblique truncated cone with bulging
parabolic sides.

The whole organ with the exception of the funnel mouth, which is closed
by a transparent membrane, is surrounded by a thin layer of cells containing
a dark brown pigment. These form an outer pigment sheath (p). Inside
this lies another sheath composed of colorless, highly refractive fibres.
This (r) is exceedingly thick at the proximal end of the inner, oval part of
the organ and gradually thins out from here to the margin of the funnel.
It is most highly developed in the joined ventrothoracic organs, where it
forms a continuous mass. The fibres composing this layer are parallel,
pretty stout, lie close together, and extend longitudinally from the proximal
apex of the elliptical part to the distal margin of the funnel. In life these
fibres probably follow the curvature of the layer which they form, but are
not otherwise bent. In sections (Fig. 24) they often form zigzag lines in the
distal thin part of the reflecting layer (B). This also is probably attributable
to shrinkage.

In the tissue occupying the proximal and central part of the interior
space surrounded by the fibrous layer three regions can be distinguished :
an inner (@), a middle (1), and an outer (s). The limits between these regions
are well defined. The inner region extends to the constriction between the
oval and conic part of the organ and there ends with a slightly convex sur-
face vertical to the axis. In the joined organs, particularly in the ventro-
thoracics, the inner regions of adjacent organs coalesce to form extensive
cellular masses surrounded by common fibre and pigment, sheaths.

The tissue occupying the inner region (¢) has in all sections, whatever
their direction may be, an alveolar or reticulate appearance ; in the alveoles
or meshes residual masses of protoplasm and small spherical nuclei, both
readily staining with haematoxylin, are clearly visible. Very rarely a slight
indication of an arrangement of the meshes of this network in rows is met

|

with. The meshes or alveoles are about 20 » wide. Occasionally one sees

172 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

a capillary vessel traversing this tissue but these appear to be rare. The
residual protoplasmatic masses and the nuclei appear attached to the strands
of the network, or the walls of the alveoles. The structure of this tissue is
pretty much the same throughout the whole region it occupies.

The middle region (1) occupies the lower portion of the conic part of the
organ. Its limit towards the inner region is, as we -have seen, concave and
smooth. The outer limit is not well defined, the middle region gradually
passing into the outer, which is composed of small digitate papillae lying
close together. The middle region is composed of cells, which, in longt-
tudinal, axial sections (Plate 6, Fig. 24) appear transversely arranged and
mostly long, slender, and spindle-shaped. On the whole this tissue takes
stains, particularly haematoxylin, somewhat less readily than the parts
below and above it. It is traversed by numerous capillary vessels.
Whether the cells here in the proximal part of the middle region are
really spindle-shaped or lamellar, overlying each other like the cells in
the epithelium of the human skin, could not be decided. Distally, towards
the papillae, the arrangement of these cells becomes less regular and the
cells themselves become smaller, the nuclei lying much closer together.
The papillae forming the outer region are composed of similar cells; these
are often much curved, but also on the whole arranged paratangentially.
This outer region is poorer in blood vessels than the inner.

The distal part of the cone beyond the outer region contains only a
few doubtful traces of cells and chiefly consists of a gelatinous substance,
which takes haematoxylin and some other stains pretty readily and which
in some sections exhibits a very strongly marked stratification, the layers
being slightly oblique to the outer surface.

The structure of the radiating organs in the genus Argyropelecus was
first examined in A. hemigymnus by Ussow (79, pp. 103-104, Plate 1, Fig. 95).
According to his description these organs of A. hemigymnus are similar in
appearance and arrangement to those of A. lychnus described above. Ussow
states that the internal tissue of the inner region is composed of glandular
cells supported by a scaffolding (Geriist) of connective tissue.

Leydig (’81, pp. 26-39, Plate 1, Fig. 5; Plate 1, Figs. 13, 14; Plate 3, Figs.
19, 20, Plate 4, Figs. 22-27; Plate 5, Figs. 28-31; Plate 6, Fig. 35) has de-

scribed these organs in the same species. So far as their arrangement and

appearance are concerned, this description accords with that of Ussow. The

anteorbital organ is innervated by branches of the nervus trigeminus, which

Be

a as

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 178

enter it at various points. The stoutest nerve branch enters the organ at
the constriction between the oval and conic parts. The cells composing the
inner region are described as arranged in columns, Leydig suggests (1. c.,
p. 38) that the fish may swim on its side like a pleuronectid, and not verti-
cally. He supports this view by stating that the pigment is not equally
developed on the right and left side and by quoting a statement of Valenci-
ennes to the effect that the similar Sternopiyx hermanni “ flotait renversé sur
le cote.” Garman (1. ¢.) does not mention the occurrence of any difference
in the coloration of the two sides in A. lychnus, nor have I noticed it.
However the case may be with A. hemigymnus I do not think it likely that
A. lychnus swims on its side. In a previous paper (87, pp. 803-307) I have
described the radiating organs of A. hemigymnus and other fishes, in which
they have a similar structure. The fibrous layer in the organs of A. hemu-
gymnus was found to contain parallel and longitudinally arranged fibres
of considerable length; so there is no difference between these species
and A. dychnus in this respect. The statement there made that the inner
region is composed of tubes “ned with glandular cells does not apply to A.
lychnus, where such tubes could not be made out; there is hardly even a
trace of the columnar arrangement described by Leydig.

Brandes (99, p. 470), who also described A. hemigymnus, says that the
anteorbital organs are connected with muscles and can be moved about at
will so as to throw their radiation in any direction the fish may choose.
This statement has been contradicted by Handrick (01, p. 54). The fibre
sheath consists of long and slender tissue cells containing guanin and lime.
The tissue of the inner region is, according to Brandes (’99, p. 484), composed
of roundish gland cells and is without efferent ducts. These cells produce
a seeretion which, according to Brandes, disintegrates chemically and thereby
emits light. The light passes the middle region, considered by him as a
biconcave lens, and illuminates the gelatinous mass which occupies the
outer region, and which is backed by the inner face of the distal part of
the reflecting fibre layer. Thus the luminosity would be visible chiefly
from points at the side of the fish.

Chiarini (’00, pp. 7-10, Figs. 1, 4, 5) has likewise studied the organs in A.
hemigymnus. Te reproduces a figure (1) of an axial longitudinal section of
one of them, which—apart from its being . upside-down — closely corre-
sponds to the figure of a similar section of the anterior lateral organ in A.

lychnus here given (Plate 6, Fig. 24). According to Chiarini the pigment

———

ee

sieaosi

174 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

layer of the organs of A. hemigymnus is not quite continuous, but inter-
rupted by longitudinal lines free from pigment. The fibre layer is ex-
ceedingly thick. The internal tissue has no special covering membrane
and is in immediate contact with the fibre layer. The inner region of
the internal tissue is composed of polygonal cells. Each contains granules
and one or two nuclei. These cells are not regularly arranged; there
is, however, an indication of a concentric stratification near the outer limit
(towards the middle region). The cells of this inner region are supported
by reticulate connective tissue. The middle region is composed of cells
with a polygonal contour, arranged transversely. In the outer region the
cells are arranged more or less longitudinally. Also in this middle region
a supporting reticulation of connective tissue is met with. The distal
portion of the cone is occupied by gelatinous tissue.

Handrick .(’01) has published a detailed account of the nervous system
and the radiating organs of the same species. He appears to have been
unacquainted with Chiarini’s paper cited above. Tandrick (01, p 58, 59)
carefully worked out the innervation for most of the radiating organs COL,
pp. 58, 59). The anteorbital is —as Leydig had previously stated (see p. 173)
—innervated by the trigemius, the postorbital, opercular, and branchio-
stegal by the facialis, the others by spinal nerves. The radiating organs are
not movable relative to the body (versus Brandes, see p. 173) but the con-
cavity of the sheath can be changed by muscular action (01, p. 54). A few
very elongated nuclei belonging to the fibre cells were observed in the in-
ner sheath. The tissue of the inner region, the “ Leuchtkérper,” is very
minutely described ('01, p. 55). It is not in direct contact with the fibre
sheath (as stated by Chiarini), but separated from it by a special membra-
nous layer of connective tissue. From this, strands of connective tissue
extend inward. These are much branched and anastomizing form a net-
work along which nerves and blood vessels extend, and in the meshes of
which large round or polyedric cells lie. The columnar arrangement de-
scribed by Leydig (81, p. 31, see p. 173) cannot be made out. Handrick
(01, p. 56) gives a detailed description of the internal structure of these
cells and distinguishes two varieties of them. According to him they al-
ways have only one nucleus, not sometimes two as stated by Chiarini (see
above). The tissue of the middle region is, according to Handrick (01, p. 57),

also supported by a reticulation of connective tissue. He considers the cells

forming its proximal portion as spindle shaped, those forming the distal por-

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 175

tion as “ polygonal,” meaning perhaps polyedric. The latter are, as it has been
described above of A. dychnus, also in A. hemigymnus, smaller than the former.
Handrick found blood vessels but no nerves in the middle region. The ex-
tent of the gelatinous tissue occupying the distal part of the cone is dif-
ferent in the different organs; it is absent altogether in the anteorbitals.
In° this region a loose network of connective tissue with large nuclei ex-
tends, the interstices being occupied by a gelatinous substance (’01, p. 58).
According to this, the latest paper on A. henigymnus, the radiating organs

_ of this fish seem to have very much the same structure as those of A. dychnus.

Sternoptyx obscura Garman.
Plate 6, Figs. 26, 27.

This species was described by Garman (’99, p. 232, Plate 53, Fig. 1).
The radiating organs are, as in <Argyropelecus ychnus, very conspicuous.
There are on each side 2 opercular (Plate 6, Fig. 26 op), 5 branchiostegal
(br), 10 ventrothoraic (vt), 38 ventral (ve), 3 anterior lateral (al), 3 poste-
rior lateral (pl), 3 anal (a) and 4 ventrocaudal organs (ve). As in Argyrope-
lecus lychnus all these groups form rows in which they lie close together.
The 20 ventrothoracic organs of the two sides are joined to form a medial
crest protruding from the ventral side of the fish. The inner regions of
the internal parts of these organs are joined and form a continuous mass.
The axes of all the organs enclose very small angles with the outer surface
and thus lie nearly paratangentially. The 2 opercular of each side are
oblique, directed downwards and backwards, all the others more or less
vertically downwards,

Besides these organs observed by me, Garman (’99, p. 233) mentions ¢
silvery area below the eye which he thinks may be a rudimentary suborbital
radiating organ.

The structure of the organs is apparently the same as in Argyropelecus
lychuus. In some of them, however, chiefly in the ventrothoracic organs
(Plate 6, Fig. 27), the proximal part of the pigment sheath (p) is thicker
and the middle and outer region together are much less extensive than
in that fish, These appear here (1 and s) as a rather thin, oblique, lenticular
body separating the extensive gelatinous outer mass (gl) from the cellular

inner region (g). Traces of stratification could also be detected in the

outer region.

Se eS

176 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

I have described (87, p. 303, Plate 70, Figs. 15-24) the radiating organs
of Sternoplyx diaphana. In that species extensive radiating organs are met
with on the lips, and I think that such may also be present in S. obscura ;
but as that portion of the specimen at my disposal is somewhat injured
[ cannot express myself with certainty on this point. The glandular tubes
as figured (’87, Plate 70, Fig. 20) in the inner coalesced regions of the
ventrothoracic organs cannot be made out in S. obscura; in this fish they
appear to consist, as in Argyropelecus, of an alveolar network containing

large, roundish cells.

Lychnopoles argenteolus Garman.

Plate 7, Figs. 31-37.

This species has been described by Garman (’99, p. 244, Plate 53, Figs. 4,
4a). The radiating organs appear as spots, 700 4 in diameter, with a
silvery lustre, and are pretty conspicuous. There are on each side | ante-

o¢

orbital (Plate 7, Figs. 31, 32 ao), 1 mandibular (Figs. 32, 383 ma), 11 bran-
chiostegal (Fig. 33 br) 9 guttural (Figs. 83 g), 2 opercular (Figs. 31, 32 op),

14 ventrothoracic (Figs. 31, 32 vt) — Garman (’99, p. 245) counts 15 of

these —19 ventromedial (Figs. 31, 32 ve), 22 anal (Figs. 51, 32 a), 11 anterior
lateral (Figs. 31, 32 al), 10 mediolateral (Figs. 31, 32 ml), and 22 posterior
lateral (Figs. 31, 32 pl) radiating organs. Garman (99, p. 246) states that
there are besides these two parallel rows of radiating organs on the sides
of the body. In the partly injured specimen at my disposal these could
not be made out.

With the exception of the anteorbital organ which is somewhat peculiar
and which will be described below, all the radiating organs mentioned have
the same external and internal structure. They consist, as in Argyro-
pelecus and Sternoptyx, of two parts, a proximal and a distal. ‘The proxi-
mal part (Plate 7, Fig. 37 A) is approximately spherical and forms about
three quarters of a sphere. The constriction (C) between the proximal and
distal part is well defined but shallow, so that the “neck” of the organ has
a considerable breadth. The distal part (D) appears as a broad and some-
what short rotation paraboloid, obliquely cut off where it abuts on the

surface of the body. The blood vessels in the subcutaneous connective

tissue surrounding the organ (b) are more numerous close to the pigment

sheath than elsewhere. The pigment sheath (Plate 7, Figs. 35,37 p.) is stout,

:
&
:
I

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 177

dense, and of uniform thickness in the inner spherical part and the proxi-
mal portion of the outer pa rabolic part. ‘Towards the surface it thins out.
The reflecting layer (Figs. 35, 37 r) is about as thick as the pigment layer
and composed of longitudinally arranged fibrous cells. It does not extend
to the surface and terminates some distance within the margin of the
pigment layer. On the inner side of the reflecting layer a conspicuous
connective-tissue membrane (Figs. 85, 87 ¢) about as thick as the two other
layers, is met with. Distally this membrane passes into the gelatinous
portion of the outer region of the organ. .

Three regions (Plate 7, Fig. 37 g, |, s), can be distinguished in the tissue
forming the internal part of this organ in Lychnopoles as in Argyropelecus
and Sternoptyx ; in Lychnopoles, however, these are built on a somewhat
different plan.

From the connective-tissue membrane (Plate 7, Figs. 35, 37 c) mentioned
above membranous diverticula extend inward which join to form facets
arranged radially. In the proximal spherical part of the organ these mem-
branes are straight and each facet encloses a regular pyramidal space.
Its apex lies near the centre of the sphere, and its base abuts on the
connective-tissue membrane overlying the reflecting layer (Plate 7, Fig. 37).
The radial membranes (facets) do not extend quite to the axis. A some-
what irregular tubular cavity (Plate 7, Vig. 37 cc) occupies that portion
of the axial part of the organ which lies between the centre of the proxi-
mal sphere and the focus of the distal pa ‘aboloid. The margin of this
tube is so well defined that it looks as if a special limiting membrane were
present. Its cavity appears empty, neither blood corpuscles nor other
bodies were found in it. In the pyramidal spaces enclosed by the facets,
nuclei and residual protoplasmatic masses highly stainable with, acid-fuchsin
are met with. hese adhere chiefly to the connective-tissue membrane
at the base of the pyramid and to the adjoining parts of the radial membranes:
the central parts of the facets (Plate 7, Fig. 37 ci) are pretty free from
them.

The facets in the distal paraboloid are not so regular as those in the
proximal sphere. The inner (proximal) part of the paraboloid is occupied
by pretty narrow, more or less curved facets (Plate 7, Fig. 37, cm) extend-
distal end of the tubular cavity above

ing from the sides towards the

described. These facets are pyramidal, distally broad and proximally con-

tracted. The outer (distal) part of the paraboloid is occupied by regular
12

i

178 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

straight, prismatic facets (Plate 7, Fig. 37 co) which are parallel to the axis
of the organ; they are rounded off distally and drawn out proximally to
points converging towards the distal end of the tubular cavity. ‘The distal
ends of these facets lie in a surface convex outwardly and in folo vertical
to the axis of the whole organ. The triangular space outside these facets,
between them and the surface, is occupied by gelatinous tissue (gl).

The small curved facets and the proximal portions of the large straight
ones which together occupy the inner part of the paraboloid and form the
middle region of the organ (Plate 7, Fig. 37) are clothed with a single layer
of cylindrical cells which form a kind of simple epithelium (Plate 7, Fig. 36).
These cells take up the greater part of the space within the facet and only
leave an exceedingly narrow central canal (Plate 7, Fig. 36 en) free. This
canal extends longitudinally in the axis of the facet towards the tubular
space in the interior of the organ. Probably it opens into it, as I have seen
many indications of such a connection, but Iam not certain about it. The
cylindvical cells forming the epithelial clothing of these facets and surround-
ing the central canal are composed of two kinds of protoplasm. The proxi-
mal three quarters of each cell (lying next the canal) (Plate 7, Fig. 36 ph)
are transparent and only slightly stainable; the distal quarter (lying next
the facet wall) (Plate 7, Fig. 86 pt) is granular and takes stains very readily,
so that it appears dark and not transparent in the stained sections. In this
highly stainable, basal portion of the cell the nucleus (nu) is situated.

It is probable that the facets of the proximal spherical part of the organ
described above contain the same kind of tissue, but the condition of the
material does not allow of this being definitely determined.

The tissue occupying the distal parts of the large straight cylindrical
facets and forming the outer region of the organ (Plate 7, Fig. 37 s) is of
an entirely different character. Here we find elongated, slender cells,
which are rather indifferent to most stains, but become intensely yellow
after treatment with picric acid. Inthe distal basal part of each of these

facets these cells are very slender, spindle-shaped, and arranged longitudi-
nally, parallel to the axis of the facet (Plate 7, Fig. 34 sp). Towards the
proximal part they become stouter and shorter and here they often appear
club-shaped. The cells appear to rise from the walls of the facet. Those
joined to the terminal face of the facet arise more or less vertically ; those
joined to the sides arise very obliquely and extend nearly parallel to the
facet. wall to which they are attached. The cells in the distal part of the

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 17

co

facets are nearly straight throughout the whole of their length. As we
approach the proximal part of the facet we find these cells curving away
more and more from the walls of the facet so that their free ends come to
lie more or less obliquely (Plate 7, Fig. 34 sc). Finally they are situated
nearly transversely, the cells arising from the different sides interlacing
axially. :

In the sections one often finds a circular structure of considerable size
(Plate 7, Figs. 34, 35 0) in the centre of the facet. Sometimes it appears as
an empty space, and is perfectly colorless and structureless; sometimes it
has——in sections stained with acid-fuchsin—a bright red color and then
one occasionally notices traces of a granular structure within it. The tissue
surrounding the circle often shows a fine radial structure (Plate 7, Figs. 34,
35). Ihave not been able to ascertain the real nature of these circles and
their coronas with any degree of certainty. The circles seem to be the
expression of spherical spaces lying between the cells, and the radial
structure surrounding them might be due to the fact that the slender inner
terminations of the spindle cells abut vertically on this sphere.

The organ is rich in blood vessels. These follow the facet walls and

can often be traced for a considerable distance.

The gelatinous tissue (Plate 7, Figs. 34, 37 gl) mentioned above is com-
posed of a gelatinous ground substance ti ‘aversed in all directions by exceed-
ingly slender spindle cells. It passes into the connective-tissue membrane
overlying the reflecting layer. A thick granular lamella or cushion (Plate 7,
Fig. 37 er) underlies this gelatinous tissue and separates it proximally from
the reflecting, and distally, where this is absent, from the pigment layer.

As mentioned above, the anteorbital radiating organ differs in some
respects from the others. It appears to be much larger and measures
1.5 mm, in diameter. Closer examination shows that it is a duplex organ
composed of two, each similar to the other radiating organs of the fish.

These two organs point different ways and are enclosed in a common pig-

ment sheath which has the shape of a curved tube open at both ends. The

two orifices of this tube lie in the surface ; one is oblique, directed upwards

and forwards towards the eye, the other vertical, directed straight down-

wards. The spherical parts (inner regions) of the two organs occupy its

central, the paraboloidal parts (middle and outer regions) and the gelatinous

and granular tissue the terminal portions of the tube. These two joined

organs throw their radiation in different directions, one into the field of

180 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

vision and the other downward, neither inward nor backward, as Garman
(99, p. 245), who also noticed that this organ differs in structure from the

others, seems to think.

Cyclothone acclinidens Garman.
Plate 6, Figs. 28-30.

This species has been described by Garman (’99, p. 247, Plate J, Fig. 4),
whose statements concerning the radiating organs are, on the whole, in
accordance with my observations; in his figure (4), however, 2 opercular and
5 posterior lateral organs are drawn which do not exist and which Garman
himself does not mention in his description. The other organs are repre-
sented in the figure as lateral whilst they are in reality situated on the ven-
tral side of the body.

The radiating organs are very small, only 700 in diameter, and are
destitute of reflectors. On account of their insignificant size and want of
lustre, they are far from conspicuous and not easy to make out. There are
on each side 10 branchiostegal (Plate 6, Fig. 29 br), — Garman (99, p. 247)
gives their number as 13. 13 ventrothoracic (Figs. 28, 29 vt), 3 ventrome-
dial (Figs. 28, 29 ve), and 16 ventroanal (Figs. 28, 29 a) radiating organs.

All the organs seem to have the same structure. They are approxi-
mately spherical and enclosed in a pigment sheath which forms over three
quarters of a sphere and encloses them on all sides except where they abut
on the surface of the fish. A straight line drawn through the centre of the
sphere and the centre of the more or less circular superficial orifice of the
pigment sheath is vertical to the surface of the body.

The pigment sheath (Plate 6, Fig. 30 p) is composed of cells containing
dark brown pigment granules. It is very stout. Its inner surface is pretty
smooth, the outer covered with irregular protuberances. Within the pig-
ment sheath a connective-tissue membrane (Plate 6, Fig. 80 c) is met with.
Near the surface this splits up into two membranes, one covering the mass
of radiating cells proper on the outer side (Plate 6, Fig. 30 er) the other
forming a thick superficial cell layer (Plate 6, Fig. 30, 1 and cd).

Three zones can be distinguished in the organ: an inner, occupying
about three quarters of the whole sphere, an intermediate, and an outer.

The inner zone is composed of a mass of large polyedrical cells and

enclosed in a connective-tissue capsule. The part of this capsule which

covers the radiating cell mass inwardly and laterally and separates it from

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 181

the pigment sheath (Plate 6, Fig. 30 c) is the connective-tissue membrane
mentioned above. The part of the capsule covering the cell mass outwardly
and separating it from the intermediate zone (Plate 6, Fig. 30 cr) is the
innermost of the two layers into which the connective-tissue membrane splits
up near the surface. From this outward part of the covering membrane
lying near the surface diverticles extend inwards dividing the outer two
thirds of the cell mass into somewhat irregularly pyramidal facets, the (distal)
bases of which are closed by the outer capsule membrane whilst the (proxi-
mal) apices are wide and open. The innermost part of the cell mass is not
thus divided into facets. The facets are occupied by large polyedrical cells
(Plate 6, Fig. 30 r) arranged in radial rows. ach cell contains a large and
conspicuous spherical nucleus; its protoplasm is readily stainable with acid-
fuchsin. The same cells are met with on the inward side of the organ, but
here they form layers parallel to the surface of the organ and are not
arranged in radial rows. In the interior, a little below the centre, a mass
of much smaller cells (Plate 6, Fig. 30 m) is observed. These look like
closely packed blood corpuscles. Possibly there exists here a blood sinus; I
have not been able, however, to make out clearly a wall separating these
smaller internal cells from the larger ones around them.

The intermediate zone (Plate 6, Fig. 30 t) has in sections the appearance
of a nearly empty space. It is in life perhaps occupied by a gelatinous sub-
stance with few slender cells. It may, however, be a mere artifact pro-
duced by shrinkage.

The outer zone is composed of two layers, an inner layer of cylindrical
cells arranged vertically to the surface (Plate 6, Fig. 30 1) and an outer
layer of ordinary connective tissue composed of slender cells arranged para-
tangentially (ed) which forms the superficial covering of the organ in the
orifice of the pigment sheath. The protoplasm of the cylinder cells of the
inner layer is concentrated at their proximal ends which abut on the inter-
mediate zone. Here also the nucleus is situated. The rest of the cell body
is very transparent and the cell walls are difficult to make out. These cells
do not take stains readily and thus essentially differ from the polyedric cells
of the inner zone. In their microchemical behavior and their general ap-

pearance they resemble the cells of the middle region of the radiating organs

of Argyropelecus and Sternoptyx.
A blood vessel, artery, (Plate 6, Fig. 30 b) of considerable size entering

the organ at the innermost point was observed in several sections.

182 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

Myctophum aurolaternatum Garman.

Plate 5, Figs. 21-23.

This species has been described by Garman (99, p. 254, Plate 55, Fig. 3).
His statements concerning the distribution of the radiating organs agree with
my observations, but his figure (99, Plate 55, Fig. 3) differs in several
respects from what I find in the specimen examined.

The radiating organs are for the most part nearly equal in size about
600 » in diameter. They are provided with reflectors, lustrous, and there-
fore, although so small in size, quite conspicuous.

There are on each side 3 mandibular (Plate 5, Figs. 21, 22 ma), — these are
mentioned by Garman (’99, p. 265), but not represented in his figure (’99,
Plate 55, Fig. 3),—4 branchiostegal, 2 opercular (op),— the lower one,
which is smaller than the upper one, is not represented in Garman’s figure
(99, Plate 55, Fig. 3),—3 pectoral (pe) forming an are just behind the
gill slit, 5 ventrothoracic (vt), over the last of these | anterior lateral (al),
4 yventromedials (ve), 3 mediolaterals (ml) forming an oblique row, 10
anterior ventroanal (va), 1 posterior lateral (pl), over the last one of the
former 6 posterior ventroanal (vp) — according to Garman’s figure (99,
Plate 55, Fig. 3) 7, and 2 ventrocaudal radiating organs (vc) at the base
of the tail.

All the organs examined appear to have the same structure. Viewed
from the surface each appears as a lustrous spot enclosed above and at the
sides by a dark strip, which has the shape of a horseshoe open below.
Each radiating organ of the body lies between two scales. The outer one
which covers it (Plate 5, Fig. 23 ss) is convex and possesses near the centre an
II-shaped thickening (t) produced by a local accumulation of calcareous
laminae, which make the scale very brittle. On treatment with acid the
thickening disappears. The horseshoe-shaped pigment. stripe mentioned
above is attached to the inner side of this scale. An axial section of the
organ vertical to the medial plane of the fish passes through the apex of
the horseshoe (p). The lower scale (si) is concave; on its inner side a
continuous layer of pigment (pp) is observed. The lenticular space be-
tween the convex outer and the concave inner scale is for the most part

occupied by connective tissue (c). This is composed of a ground substance

traversed by slender, elongated cells which are somewhat irregularly curved.

|
|
|
|

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 183

This tissue is rich in blood vessels, The radiating organ proper, that is, the
mass of cells (pe) which probably emit the radiation, lies in the middle of
this connective tissue. It is pear-shaped, the thinner end extending outward
and downward. The cells composing it are flattened and extend parallel to
the surface of the body. The protoplasm is quite transparent and each cell
contains a large granular nucleus. The blood vessels form a fine-meshed
capillary network (b) on the surface of this cell mass, but do not penetrate
into its interior.

Radiating organs of this kind seem to be rare in fishes. Somewhat simi-
lar ones have been described by Emery (’84, p. 473) from the ventral series

of Scopelus elongatus.

Chauliodus barbatus Garman.
Plate 8, Figs. 38-40; Plate 9, Figs. 43-46.

This species has been described by Garman (’99, p. 271, Plate K, Figs. 2,
2a). The radiating organs are very numerous. Three different kinds of
them can be distinguished. The differences between these are considerable
and clearly discernible with the naked eye. Some of the organs are simple,
some composed, as in the fishes described above, of an inner spherical and an
outer paraboloidal part. The simple ones again are either uncovered or
provided with a pigment sheath. I have designated these three kinds of
organs accordingly as simple organs without pigment sheath, simple organs
with pigment sheath, and compound organs with pigment sheath.

The simple radiating organs without pigment sheath appear as very
small whitish dots. They are arranged in groups of from 4 to 16. These
groups are scattered over the medial part of the ventral surface (Plate 8,
Fig. 39 u) and also occur in great numbers on other parts of the surface,
chiefly on the back of the fish.

The simple organs with pigment sheath appear as dark spots 300 p in
diameter, They are scattered in great numbers over the whole of the sur-

face and seem to be most numerous on the sides of the head just behind the
eyes (Plate 8, Fig. 38 x). In the barbel there are 8 of these organs
(Plate 8, Figs, 38-40 Ba).

The compound organs with pigment sheath are lustrous, elongated,

Of these organs there are on each side lL
o

about 1mm. long and 600 y broad.
anteorbital (Plate 8, Fig. 38 ao), 1 suborbital (Fig. 38 so), 18 branchio-

184 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

stegal, 8 guttural (Plate 8, Fig. 39 ¢), 19 ventrothoracic (Figs. 38, 89 vt), 22
ventromedial (Figs. 88, 39 ve), 11 ventroanal (Figs. 38, 89 a), 17 ante-
rior lateral (Figs. 38, 89 al), and 22 medial lateral (Figs. 38, 39 ml).

The simple radiating organs without pigment sheath are not in a partic-
ularly good state of preservation. So far as they could be made out, their
structure corresponds with the same organs of Chauliodus sloani described by
Chiarini (’99, pp. 16, 17). They are spherical or oval, enclosed in a capsule
of connective tissue and composed of a layer of superficial, radial, cylin-
drical elements surrounding a group of central polyedrical cells.

The simple radiating organs with pigment sheath (Plate 9, Figs. 43, 44)
have an oval (Fig. 43) or irregular (Fig. 44) shape. They seem, however,
always to be elongated in the direction of their axis. The angle between
the axis and the part of the surface of the fish where they are situated is
very variable. It may be 90°, the organ then being vertical to the surface
(Fig. 43), or it may be smaller, sometimes so small that the axis of the
organ is nearly parallel to the surface of the fish (Fig. 44). It appears that
this angle is correlated to the shape of the organs, the regularly oval ones
being usually vertical to the surface, the irregular ones inclined to it; and
it seems that the organs are the more irregular the more obliquely they are
situated. These organs are not, as is generally the case, imbedded entirely
in the body of the fish, but protrude conside ‘ably over the surface, forming
rather conspicuous rounded protuberances (Plate 9, Figs. 43, 44). They
are covered distally by a layer of considerable thickness (Plate 9, Figs. 43,
44h) which appears structureless and transparent in the sections. Laterally
and proximally they are enclosed in a pigment sheath (p). In the regu-
larly oval organs of this kind the axis of which is vertical to the surface
(Fig. 43) the pigment sheath extends only over the part of the organ
imbedded in the body of the fish. In the irregular ones (Fig. 44) with
oblique axis it covers also the proximal portion of the protruding part.
The pigment sheath is thickest at the proximal apex of the organ and
gradually thins out towards the margin. Its distal orifice is of considerable
extent, and occupies about a third of the whole surface. In this a fine
connective-tissue membrane (Plate 9, Figs. 43, 44c) is extended which here
replaces the pigment sheath. In this thin layer which separates the radiat-
ing cell mass proper from the structureless outer covering mentioned above,

nuclei, appearing paratangentially elongated in axial sections of the organ,
are observed. The interior of the organ is occupied by a mass of poly-

THE RADIATING ORGANS OF THE DEFP SEA FISHES. 185

edrical cells in the centre, and cylindrical elements on the surface. The
latter (Plate 9, Figs. 43, 44 pe) resemble a cylinder epithelium clothing the
pigment sheath and distal connective-tissue membrane internally. They
are not vertical to this surface however, but so arranged as to converge
to a point within the organ very near its proximal apex. In the distal
part of the organ these cells are short, hardly longer than broad. Inwardly
they increase very rapidly in length and those situated at the sides are
nearly half as long as the organ itself. The nucleus is conspicuous, spheri-
cal, or radially extended, oval, and always situated at the distal end of the
cell. The protoplasm is granular, The limits between these cells are
distinct enough distally, but become very indistinct centrally and finally
vanish altogether; in the proximal part of the organ to which these cells
converge, no trace of cellular division is discernible. ‘This part of the organ
is occupied by a granular protoplasmatic mass (Plate 9, Figs. 43, 44 m)
in which neither cell walls nor nuclei are met with. The proximal apex
itself is in the regular oval organs free from these cells, or cells of any kind,
the granular mass (m) extending here right up to the pigment sheath
(Plate 9, Fig. 43). In the axial sections of irregular organs, however, a net-
work of cell limits with nuclei in the meshes is usually observed in the part
appearing as the proximal apex (Plate 9, Fig. 44). It seems to me, however,
that this point does not exactly correspond to the proximal apex of the
regular organs and that the “cells” seen there are transverse sections of
the same kind of superficial cylinder cells as appear cut longitudinally else-
where. These organs being so very irregular in shape, an irregularity in
the arrangement of the superficial cylinder cells, giving rise to such an
appearance of axial sections, would be not at all surprising.

The inner mass of polyedrical cells (Plate 9, Figs. 43, 441) has the shape
of a bee-hive or truncate cone resting with its broad base on the distal
cylinder cells and extending inward a good way beyond the centre of the
organ. The distal cells of this mass are smaller and arranged irregularly,
the proximal ones larger and situated in more or less clearly pronounced
In their appearance these cells differ essentially from

longitudinal rows.
the cylindrical elements surrounding them. ‘Their nuclei are pretty large,
spherical, or flattened radially, and their protoplasm is transparent and free
from granules. Picric acid stains them a bright yellow. The superficial
cylindrical cells are comparable to the cells forming the inner region of
such radiating organs as those described above of Argyropelecus and Ster-

186 THE RADIATING ORGANS OF THE DEEP.SEA FISHES.

noptyx; the inner polyedrical cells on the other hand resemble the cells
of the middle region of the organs of these fishes.

Three of the simple radiating organs with pigment sheath in the barbel
are joined to form a composite mass. Two of these are irregular and lie
symmetrically right and left opposite each other. The third is a regular
one and lies between the other two. The axes of the two former lie
in a plane vertical to the axis of the barbel; the axis of the latter is ori-
entated longitudinally, parallel to the axis of the barbel. A close inspection
of a continuous series of sections through this organ reveals the remarkable
fact that the central one of these three organs is completely enclosed by the
pigment layer on all sides, a thing I have not observed in any other radiat-
ing organ, although Leydig (’79, p. 369) mentions having occasionally
seen simple organs with pigment sheath of C. sfoani thus entirely enclosed by
pigment. Supposing, as one surely has a right to do, that the pigment sheath
intercepts the radiation, we would have in that organ of the barbel, and in
the similar ones observed by Leydig, radiating organs unable to radiate.
A careful examination of these organs completely surrounded by pigment in
Chauliodus may be warmly recommended to future investigators.

According to Chiarini’s description (’00, p. 16, Plate 5, Fig. 6) the simple
radiating organs with pigment sheath of Chauliodus sloani are very similar ;
his figure (6) however differs somewhat from mine (Plate 9, Figs. 43, 44).
Chiarini states that in staining the superficial cylinder cells with haema-
toxilin-eosin the nucleus absorbs the former, the protoplasm the latter.

The compound radiating organs with pigment sheath (Plate 9, Figs. 45,
46) on the body are directed downward. ‘Their axis is vertical, and parallel
to the median plane of the fish. Thus the angle between it and the adjacent
part of the surface is much larger in the vent ral rows than in the lateral.
In the latter it is very small, often appearing to be nearly mi, the axis then
being approximately parallel to the adjacent surface. In their external

shape these organs resemble the compound organs of Lychnopoles wrgenteolus

described above. They are composed of a proximal spherical (Plate 9, Fig.
45 A) and a distal paraboloidal part (D). These parts are separated by a
sharp and well-defined stricture (C) of considerable depth. The proximal
part forms about three quarters of a very regular sphere. The distal part
is short, broad, and cut off obliquely at the base, where it abuts on the sur-
face. With the exception of the oblique terminal face of the distal para-

poloidal part, the whole organ is enclosed in a stout pigment sheath (Plate

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 187

9, Figs. 45, 46 p). The cells composing the sheath contain brown pigment.
They are very closely packed towards the inner well-defined and perfectly
smooth surface. Towards the outer side they are farther apart and this
surface is not so well defined, the pigmented tissue passing here somewhat
gradually into the unpigmented tissue surrounding the pigment sheath. In
the distal paraboloidal part of the organ a lustrous reflecting layer (Plate
9, Fig. 45 r) composed of slender fibres, is found within the pigment
sheath. In the proximal. spherical part no such reflecting layer could be
made out. A connective-tissue membrane (Figs. 45, 46 c) clothes the whole
organ. In the proximal spherical part it appears to rest immediately on
the pigment sheath, in the distal paraboloidal part it rests on the reflecting
layer. Distally this membrane merges into the transparent connective tissue
(Fig. 45 d) which occupies the triangular space between the distal limit of
the radiating cell mass proper and the outer surface of the fish. From the
whole of the connective-tissue capsule fine radial septa extend inward.

The radiating cell mass proper is composed of three regions, an inner
(Fig. 45 i), a middle (m) and an outer (0). The inner region occupies the
whole of the proximal spherical part of the organ with the exception of a
distal conic sector. It is composed of large, elongate pyramidal cells (Migs.
45,46 pe). These are arranged radially in a very regular manner and
nearly vertical to the connective-tissue capsule, on which their bases rest.
They do not quite reach the centre to which they converge. ‘This is occu-
pied by a plug-shaped mass of small cells (Plate 9, Figs. 45, 46 a) which
appears to be connected with the radial septa extending inward from the
connective-tissue capsule enclosing the radiating cell mass. These septa
can often be made out between the pyramidal cells. In sections large blood
vessels (Plate 9, Fig. 46 b) are frequently seen extending radially inward
from the surface to the central cell mass. Here they continue their course
between the latter and the proximal ends of the pyramidal cells, and seem
to give off exceedingly fine branches which extend radially outward between
the pyramidal cells (Plate 9, Fig. 46) along the connective-tissue septa,
separating the latter from one another. The pyramidal cells themselves
(Plate 9, Figs. 45, 46 pc) are occupied at their distal end by protoplasm
staining deeply with haematoxylin (Plate 9, Fig. 46 pt) whilst their central
and proximal parts (ph), about five sixths of the whole, show no great affin-
The protoplasm occupying this

ity for haematoxylin and other stains.
central part of the cell is, however, not hyaline but distinctly granular. In

188 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

the distal highly stainable terminal part of each cell one rather small nucleus
(nu) is situated.

The middle region (Plate 9, Fig. 45 m) occupies the distal sector of the
proximal spherical part of the organ and the proximal portion of the distal
paraboloidal part. The proximal limit is conic, the distal limit very regularly
convex. The cells occupying the space between these limits (1) are well
defined and polyedric in shape. The distal ones are small. From here they
increase in size inwardly, the innermost ones being four to five times as large
as the outermost ones. The protoplasm of these cells is homogeneous, not
granular, and hardly stainable with haematoxylin. It shows a great affinity
to picric acid and the whole cell mass of this region appears bright yellow
in sections stained with picric acid-haemotoxylin. The nucleus is nearly
spherical and larger in the large cells than in the small.

The distal limit of the outer region is nearly a plane vertical to the axis
of the organ, and so, its inner limit being concave and some distance away,
the outer region (Plate 9, Fig. 45 0) has the shape of a thick plane concave
lens. From the mass of connective tissue which abuts distally on the outer
region, septa, nearly vertical to the limiting surface and parallel to the axis
of the organ, extend inward, dividing the outer region into prismatic facets
rounded off distally. These facets are occupied by small elongated cells,
the protoplasm of which behaves towards stains in a similar manner as the
protoplasm of the cells of the middle region.

The compound radiating organs of Chauliodus were first studied in 0.
sloani by Leuckart (64, pp. 153-155). According to his description these
organs of C. sloawi are similar to those of C. barbatus. Leuckart chiefly
studied the branchiostegal radiating organs (1. ¢., p. 154). These are
cylinders, 1 mm. long and 500 p broad. Their distal portion is occupied by
a structure Leuckart considers as a lens. From the proximal face of this a
conic protuberance arises, penetrating some distance into the inner cell
mass; as mentioned above such a cone is also observed in C. barbatus. The
reflecting layer consists of hexagonal pavement cells occupied by numerous
crystals. In the outer part of the distal mass, that is, in the “lens,” Leuckart
claims to have seen fibres, whilst the inner part, and the proximal cone are
composed of closely packed rods 5 p thick radiating from the apex of the
cone. The substance composing these rods is highly refractive. No fibres

or rods of this description occur in the middle and outer regions, which cor-

respond to Leuckart’s “lens,” in the compound organs of C. barbatus. The
, =)

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 189

proximal mass which Leuckart terms “ Glaskirper,” and which corresponds
to the inner region, is composed of large crystal-clear radial cones similar to
cells; Leuckart, however, does not consider them as such, not having been
able to find a nucleus in them. Each organ is supplied by a slender nerve.
Leuckart considers these organs as accessory eyes, “ Nebenaugen.” It is
noteworthy that in the discussion following the reading of this paper Claus
(Leuckart, ’64, p. 155) drew attention to the similarity between these organs
and the well-known structures of EKuphausia, which were at that time also
considered as accessory eyes.

Ussow (’79, pp. 94-97, Plate 1, Figs. 1, 2, Plate 4, Figs. 25, 26) has also
described the structure of the compound radiating organs of ©. sloani. He
finds them composed of two semispherical parts, the outer one of which is
occupied by a gelatinous mass, colorless and transparent in the living fish,
but coagulating and becoming opaque on being treated with the reagents
used for preserving the specimen. Below this gelatinous mass a mushroom-
shaped “lens” (79, Plate 2, Fig. 6 Kl) is seen, the cylindrical stalk
of which extends inwards, whilst the semispherical upper part, com-
posed of conic elements, protrudes into the outer gelatinous mass. This
“Tens” appears to correspond to our middle region. The conic elements
of its distal, semispherical part are according to Ussow attenuated proxi-
mally to fine threads, which extend inward parallel to the axis of the organ
and form the stalk of the mushroom, in which they are connected with
granular multipolar cells, Concerning the inner region Ussow merely
corroborates the previous statements of Leuckart. These, however, he does
not seem correctly to have understood. Ussow also states that a slender
nerve leads to each organ. His description and also his figures are very
different from what subsequent authors have seen in these organs of C.
sloani and show very little similarity to the structure of these organs in
C. barbatus described above.

Leydig (79, pp. 8365-382, Plate 15) examined the radiating organs of (.
sloam simultaneously with and independently of Ussow. His material, a
specimen preserved in spirits for several years, was not good, but nevertheless
his results were more valuable than those of Leuckart and Ussow. He algo
chiefly studied the compound organs; his notes on the others have been
referred to above. The compound organs are surrounded by annular blood

vessels and a slender nerve branch leads to each. The distal portion of the

compound organ is composed of two parts, an outer cap and a lower mass.

190 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

The proximal cone described by Leuckart is part of this latter. In the distal
cap club-shaped cells are met with, the distal end of which is the thicker
one. It is laterally enclosed by stout cell walls, but destitute of a terminal
membrane. The thin proximal end passes into a fine thread of considerable
length. The nucleus is situated in the lower end of the thick part of the
cell. The cells of the lower mass of the distal portion are of greater size,
more finely granular, and have a larger nucleus. The proximal cone
appears to be composed of processes of these cells which converge towards
its apex. This cell mass is traversed by fibrous strands, extending inward
from the surface and forming a kind of scaffolding which has the shape of a
honey comb. The cells of this honey comb evidently correspond to the
connective-tissue facets described above of C. barbatus. 'The cones occupy-
ing the proximal part (inner region) of the organ are cells. Leydig found a
nucleus in their granular outer end. The centre to which these conic cells
converge is occupied by a finely granular substance (‘‘ Punktsubstanz’’).
Leydig thinks that the nerve leading to the organ terminates in this “ Punkt-
substanz” and that the cells both above (cone of the middle region) and
below (inner region) are connected with it. A portion of the reflector form-
ing half a ring outside the stricture has a distinctly golden lustre. Leydig
calls these organs accessory eyes, but uses this term (“ Nebenaugen”’) with
a certain amount of mistrust. From this and from a quotation of Willemoes-
Suhm, which he publishes, one can conclude that he was already at that
time, although calling these organs eyes, quite open to the view that they
had in fact a radiating function.

The descriptions given by these authors are based on material insuffi-
ciently preserved and studied without the application of modern methods.
They can therefore claim hardly more than an historical interest. Now,
however, we have to review the papers by Brandt (1899) and Chiarini (1900)
in which the compound radiating organs of Chauliodus sloani are described in
a far more exact manner,

According to Brandt's description (99, pp. 447-450) these organs of
C. sloani seem. to be identical in structure with those of C. barbatus. We
considers the cells. of the inner region as gland cells in which a secretion
is formed and then oxidized whereby light is produced, whilst the middle

and outer region have no other function than that of conveying the ra-

diation produced to the outer world.
Chiarini (00, pp. 14-17, Figs. 6-7) also describes the radiating organs of

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 191

C. sloani in detail. To his statements concerning the simple organs we have
referred above. ‘The compound organs of this fish (01, pp. 14, 16, Fig. 7)
consist, according to him, as in C. barbatus, of a proximal, nearly exactly
spherical part, to which a funnel-shaped neck, separated by a distinct
incision, is attached. In the compound organs of the body the funnel is
cut off obliquely where it abuts on the surface of the body. In the
branchiostegal organs transversely. Hach compound organ consists of an
outer pigment layer, a reflector, a connective-tissue capsule, and a central
cell mass, in which three regions, an outer, middle, and inner ean be distin-
guished. These regions correspond to the three regions in the organs of
C. barbatus. Beyond the outer region gelatinous tissue is met with, occupy-
ing the space between its outer face and the surface of the fish. The outer
region is divided by connective-tissue membranes into very narrow facets di-
verging distally. The middle region is clearly divided into an outer portion,
occupied by polyedrical cells, and an inner portion divided into radial facets.
The inner region consists of radially arranged conic cells, the larger central
parts of which are fine grained and stainable with eosin but not with haema-
toxylin, whilst the much smaller peripheral portions forming about a quarter
of the length of each cell are readily stainable with haematoxylin. Each of
these cells contains one or two nuclei situated in the peripheral portion.

[t will be seen from this that the structure of these organs in C. s/oani is
very similar to that in C. barbatus. The chief differences between them are
the following: in C. sloan’ the facets of the outer region are narrow, the
middle region is distinctly divided into an outer and an inner portion, and
the cone cells of the inner region contain one or two nuclei; in C. barbatus,
on the other hand, the facets of the outer region are broad, the middle
region is not divided into two clearly distinct parts, and the cone cells of the

inner region always contain a single nucleus.

Idiacanthus antrostomus Gilbert.

Plate 8, Figs. 41, 42.
This species was first described by Gilbert (’90, p. 54), later more in detail
It possesses two kinds of radiating organs, one
The former are exceedingly
roups (Plate 8, Fig. 41 u) on the

by Garman (99, p. 280).
without, the other with, a pigment sheath.

small and arranged in two large elongate g

192 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

sides of the head under the large suborbital organ with pigment sheath, and
in six longitudinal rows, three on each side, of smaller groups on the body.
The intervals between these small groups on the body are equal in extent to
the intervals between the larger organs with pigment sheath, and the
former alternate with the latter.

The radiating organs with pigment sheath have a silvery lustre. Those
of the body measure about 300 in diameter; the suborbitals are larger.
There are on each side 1 suborbital (Plate 8, Fig. 41 so), 13 branchiostegal,
10 guttural (Fig. 42 @), 25 ventrothoracic (Figs. 41, 42 vt), 20 ventromedial
(Figs. 41, 42 ve), 35 ventroanal (Figs. 41, 42 a), 25 anterior lateral (Mig. 41
al), 20 medial lateral (Fig. 41 ml), and 85 posterior lateral (Tig. 41 pl),
radiating organs with pigment sheath.

The small organs without pigment sheath are spherical, enclosed in a
connective-tissue capsule, and composed of radially arranged cells, which
usually enclose a central cavity.

The organs with pigment sheath closely resemble the compound organs
of Chauliodus barbatus described above. The suborbital organs are so dis-
posed as to throw their radiation into the field of vision; the organs of the

body are directed downward.

Stomias hexagonatus Garman.
Plate 10, Figs. 47-51.

This species has been described by Garman (99, pp. 276, 277, Plate 96,
Fig. 5). It possesses five different kinds of radiating organs. An organ in
the barbel, a pair of suborbital organs, and on the body simple organs
without pigment sheath, simple organs with pigment sheath, and compound
organs with pigment sheath.

The radiating organ in the barbel (Plate 10, Figs. 47, 48, 50), lies in a
thickening 1.5 mm. long at the end of the barbel (Fig. 47,481). From
its distal part three short terminal threads arise. The radiating organ itself
(Plate 10, Fig. 50), is oval and placed transversely in the swelling of the

barbel, the long axes of the two crossing nearly at right angles. It is
enclosed in a stout connective-tissue sheath (Plate 10, Fig. 50 c), and com-
posed of two parts, an upper, dorsal, smaller, dorsoventrally compressed (A),
and a lower, ventral, spherical part (B). The smaller upper part is enclosed
in a somewhat loose pigment sheath (p), lying within the upper part of the

‘and lateral parts of the upper chamber.

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 193

connective-tissue sheath enclosing the whole organ. The upper portion of
this pigment sheath forming the roof of the upper part is dome-shaped, the
lower portion, forming its floor and separating it from the lower spherical
part, is flat or even a little concave. At the circular line where the upper part
joins the lower a conspicuous ring-shaped thickening of the pigment layer
(pt) is observed. From this a small annular ridge extends outwards and
downwards, forming the rudiment of a cup enclosing the basal, upper portion
of the lower, spherical part of the organ.

The interior of the upper part of the organ is traversed by a horizontal,
strongly pigmented membrane (pm), which divides it into a larger upper
and a smaller lower chamber. In both these chambers large cavities (cv)
are seen. In the upper one there seems to be only one such cavity. This
is situated ventrally and surrounded by a special endothelial cell layer,
separating it from the transparent connective tissue occupying the dorsal
In the lower chamber more

cavities than one are seen. ‘These lie dorsally. Below them in the ventral

part of this chamber large sinuous blood vessels (b) extend.

The lower part of the organ (B) is covered dorsally by the pigmented
floor of the upper part of the organ and the annular rudiment of a pigment
cup referred to above. Laterally and ventrally it is surrounded by the
transparent connective-tissue sheath only. From the middle of the roof
of this lower spherical part of the organ a cylindrical thread composed of
connective tissue (z) arises which extends vertically downward to its centre.
This thread is composed of longitudinally arranged, spindle-shaped connec-
tive-tissue cells with oval nuclei. Along this thread blood vessels (b) and
probably also a nerve extend from above down to the centre of the sphere.
The lower end of the thread is thickened to form a terminal knob in which
a sinuous cavity, filled with blood corpuscles, is observed. Apart from this
thread with its terminal knob the whole of the sphere is occupied by large
radially arranged conic cells (pe) equal in length to its radius. In arrange-
ment and structure these cells are similar to the conic elements in the inner
region of the compound organs of Chauliodus barbatus described above.
They are, however, more slender. The inner seven eighths are occupied by
finely granular, transparent protoplasm not re
eighth of the length coarser grained protoplasm showing grea

hematoxylin and other stains is observed. In the peripheral part of each

adily stainable ; in the outer
t affinity to

cell one small, spherical nucleus is situated.
13

194 THE RADIATING ORGANS OF THE DEEP SEA FISHES,

The suborbital radiating organs (Plate 10, Fig. 47 so) are represented
by Garman in his figure (’99, Plate 56, Fig. 3), but not mentioned in his
description (’99, pp. 276, 277). The suborbital organ lies below and behind
the eye; it appears nearly spherical, is 800 fin diameter, and enclosed
in a pigment sheath and a connective-tissue capsule. The pigment sheath
forms a sac, the opening of which abuts on the surface of the fish. It is
composed of concentric layers of rather loosely scattered cells containing
brown pigment. Within this pigment sheath lies the connective-tissue cap-
sule. The structure of the inner cell mass could not clearly be madé out, as
these organs were somewhat injured in the specimens at my disposal.

The simple radiating organs without pigment sheath appear as small
white dots 100 in diameter. They are scattered in great numbers over
the ventral side of the fish and also occur in the three terminal threads of
the barbel mentioned above. They are more or less spherical, enclosed in
connective-tissue capsules and composed of pretty large radially arranged
cells with conspicuous nuclei,

The simple radiating organs with pigment sheath are met with on the
hexagonal scales of the body and also on the head of the fish. They appear
as dark spots and measure 300 in diameter. On each ventral scale a
group of 7 of these organs occurs, upwards they gradually become scarcer,
and near the dorsal medial line of the fish only one such organ is found on
each scale. In their structure these organs resemble the simple radiating
organs with pigment sheath of Chauliodus barbatus described above. The
hyaline mass which in the latter covers the organ outside, is, however,
absent in these organs of Stomias heaagonalus.

The compound radiating organs with pigment sheath (Plate 10, Figs. 47,
48, 49, 51) appear as conspicuous dots with a silvery lustre and are 300-
900 in diameter. On the whole they are largest in front and decrease in
size backwards. There are on each side of the bod y 12 guttural (Plate 10,
Figs. 47, 48 g), 16 branchiostegal, 38 ventrothoracic (Figs. 47, 48 vt), above
these in a parallel row 37 anterior lateral (Figs. 47, 48 al), 10 ventromedial
(Figs. 47, 48 ve), 10 medial lateral (Figs. 47, 48 ml), and 19 ventroanal
(Figs. 47, 48 a) compound radiating organs with pigment sheath.

Two different kinds of these organs can be distinguished. The first
somewhat larger kind is represented by the anterior compound organs of
the body which form the ventrothoracic and anterior lateral rows. All the

other compound organs belong to the second, smaller kind.

/~,

cae

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 195

The compound organs of the first kind (Plate 10, Figs. 49, 51) are
spherical and have a short process directed downwards towards the outer
surface. They might be compared to spherical bottles with small necks
placed upside down. The axis of the organ is vertical, parallel to the median
plane of the fish. The ventral organs, that is, those belonging to the ventro-
thoracic row, therefore abut nearly vertically on the surface, whilst the lateral
ones, that is, those belonging to the anterior lateral row, are very oblique and
enclose but small angles with the surface of the fish. In the former the
“neck” appears cut off transversely ; in the latter, obliquely.

The pigment sheath (Plate 10, Fig. 51 p) enclosing the organ is rather
thin and composed of cells containing brown pigment. It surrounds all
parts of the organ with the exception of the terminal face of the “neck.”

As in other compound radiating organs we also find in these below the
pigment layer a reflecting layer. This is however not at all extensive, being
confined to the distal part of the neck-shaped portion, where it forms a ring
(Plate 10, Fig. 51 r) surrounding the “neck.” This reflecting layer is com-
posed of highly refractive threads.

Within the pigment sheath and, where this is developed, the reflecting
layer, a connective-tissue membrane is met with which entirely surrounds
the inner cell mass and forms a perfectly closed capsule, from which diver-
ticula extend inwards.

The greater part of the interior of the proximal, spherical part of the
organ is occupied by large radially arranged conic cells which converge

towards the centre of the sphere. These cells are very similar to the conic

elements in the inner region of the compound organs of Chauliodus barbatus

and like them consist of a long, proximal, finely granular part (ph) not
readily stainable, and a short, distal part (pt) showing great affinity to
haematoxylin. The nucleus is remarkably small and situated in the distal
staining part of the cell. These cells are divided from each other by fine
connective-tissue membranes extending from the outer connective-tissue

capsule radially inward towards the centre. In these membranes small

adial blood vessels (b) can be made out.
The “neck” of the organ (Plate 10, Fig. 951 cy) above referred to is a
stout cylinder, circular in transverse section, the axis of which coincides with

the axis of the whole organ. This cylinder is surrounded by an extensive

annular cavity (s) dividing it from the connective-tissue capsule forming the

innermost layer of the outer covering of the organ. The outer, distal, ter-

196 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

minal face of the cylinder is rounded off, simple, convex; the inner, proxi-
mal face is drawn out to form a regular cone about as high as broad, which
penetrates the mass of radial conic cells occupying the proximal spherical
part of the organ. The apex of this cone lies a little way above the centre
of this sphere. The whole appears as a cylindroconic plug (Plate 10, Fig.
51). From that part of the connective-tissue capsule of the organ which
covers the terminal face of this plug, diverticula extend inwards parallel to
the axis. These form parallel facets. The central (axial) facet (cc) is the
longest ; it extends to the apex of the cone, whilst towards the sides of the
cylinder the facets become shorter. Transverse (Plate 10, Fig. 49) and
longitudinal axial (Plate 10, Fig. 51) sections of the plug-shaped outer part
of the organ show that the contents of the central facet (Plate 10, Figs. 49,
51 cc) are different from those of the other facets (pc). In staining with
Van Gieson’s haematoxylin-picric acid-fuchsin one finds that the latter take
up haematoxylin and acid-fuchsin very readily, whilst the substance in the
central facet absorbs only the picric acid. It also stains with eosin. In the
distal parts of the outer facets nuclei and cell limits can be distinctly seen ;
here pretty large elongate cells are situated. In transverse sections of the
distal part of the plug one sees two or three cell sections lying side by side
in each facet (Plate 10, Fig. 49). In the proximal parts of the outer facets
and throughout the whole length of the central facet cell limits cannot be
made out and nuclei are hardly to be seen.

Ussow (’79, p. 91) has described these organs in Slomias barbatus. Te
says that they are similar to those of Chauliodus, but that the middle region,
which he represents as a mushroom-shaped body (see above) in Chauliodus
sloant, is absent, in Stomias barbatus.

Organs similar to these have been described by Chiarini (’00, p. 12, Fig. 3)
from Maurolicus poweriae, Te says that each of the cells of the inner spheri-
cal part and also of the cylindroconic plug, that is, the “neck” of the organ,
often contain ¢wo nuclei. These cells are always mononuclear in Sfomias
hexagonalus. In longitudinal sections the limits between the cells are often
so indistinct that one can indeed be easily misled on this point and imagine
that the two or three nuclei seen imbedded in an apparently continous pro-
toplasmatic mass belong to one and the same cell. Transverse sections, how-

ever, show, at least in the distal part, the cell limits well enough and make it

clear that here each nucleus belongs to a separate cell.
The compound radiating organs of the second kind which are met with

sean ae

emma

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 197

on the hinder part of the body have the same structure as the compound
nope a aN A ee ‘+ ae .
organs of Chauliodus barbatus described above. It is therefore not necessary

to give a detailed account of them.

(2) THE FISHES WITH RADIATING DISCS.

Bassozetus nasus Garman.

Plate 4, Figs. 14-17,

This species has been described by Garman (’99, pp. 159, 361, Plates 77, 78).
Its head shows a number of deep depressions (Plate 4, Fig. 14). On remov-
ing the semitransparent skin from it a number of subdermal, clearly defined,
white, somewhat elongated, rhombical patches 1-3 mm. long are exposed to
view. A stout nerve fibre leads to each one of these. There are on each
side of the head 3 maxillary, 6 orbital, 3 ethmoidal, 3 frontal, 5 oceipito-
parietal, 5 mandibular, and 4 opercular patches of this kind. These I desig-
nate as radiating discs.

Each radiating dise appears as a thickening of the membrane which lies
close to the bone and can be easily withdrawn therefrom. The basal part
of the thickening, that is, the part lying next the bone, contains pigment
cells, which form a pretty continuous basal layer (Plate 4, Figs. 15-17 p).
Numerous blood vessels (Plate 4, Fig. 17 b), enter the thickening from all
sides and form a dense capillary reticulation in its central part, just below
the upper surface. The stout nerve (Figs. 15-17 n), mentioned above,
which I designate as the main disc nerve, also enters the thickening at its
margin, Without appreciably diminishing in width it extends through the
basal part of the thickening to its centre where it abruptly divides into a
number of fine branches. These lie in a paratangential plane and radiate
in all directions in it. Repeatedly ramifying they approach the margin of
the thickening where they become obscured by the pigment cells which
form a dense reticulation (Figs. 15, 16 p), lying at a rather lower level than
the nerves. No peculiar histological differentiation could be made out
within the disc. In transverse sections (Fig. 17) one merely sees faint
paratangential lines and elongated nuclei also disposed paratangentially.
Thus it appears to be composed of paratangentially extended plate-like or
fibrous cells overlying each other in several layers. Between these cells the

nerve branches extend. Judging from the appearance of the whole organ

°

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sama sonora wen Neng

198 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

one should say that the radiation — supposing that a radiation is really
emitted from it—Jis produced by the nerve branches themselves and that
the paratagential cells are merely packing.

These organs of Bassozetus resemble the basal part of the radiating discs
of Halosaurus to be described below and so one might suppose that the
superficial layer of cylindrical cells there present also occurs here but has
been lost post mortem. It must however be remarked that no trace of a
previous presence of such a cell layer could be made out in transverse sec-

tions of the radiating discs of Bassozelus nasus,

Leucicorus lusciosus Garman.

Plate 3, Figs. 10-13.

This species has been described by Garman (’99, pp. 148, 361, Plates 38, 74,
Fig. 1). After removing the semitransparent skin of the head the radiating
discs underlying it. are exposed to view. They appear as roundish white
spots 1.5-3 mm. in diameter overlying the bones of the skull. They are
remarkably hygroscopic. If one places one of the discs preserved in alcohol
in water it rapidly increases in size and swells to the bulk of a pea. On
each side of the head there are 3 maxillary, 4 orbital, 2 ethmoidal, 3 fron-
tal, 7 occipitoparietal, 4 mandibular, and 5 opercular radiating discs.

These organs are similar to, but in their finer structure more highly
differentiated than, those of Bassozetus nasus described above. <A very stout
nerve (Plate 3, Figs. 11, 12 n) enters the disc from the side and extends, as
in Bassozetus, to its centre without decreasing in thickness. Besides this
main disc nerve there are other smaller nerves (Figs. 11-13 n’), which
enter the disc in a similar manner. In some cases it appeared as if the latter
connected different discs with each other. Numerous large blood vessels
(Figs. 11-13 b) are met with. These chiefly extend from two opposite
sides towards the centre of the organ and here, bending abruptly at nearly
right angles, and ramifying, form a vascular ring of rhomboidal shape. From
this ring numerous branches are given off towards the interior which supply
the central part of the disc. These blood vessels form a dense superficial
reticulation (Fig. 13). 2

The large main dise nerve extends through the basal part of the disc and

terminates in the centre of the rhomboidal space surrounded by the blood-

vessel ring. Here it abruptly divides into numerous branches all diverging

pg

aT

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 199

radially in a paratangential plane. In the central part of the lower portion
of the disc numerous large cavities, which appear empty in sections (Fig. 13
ev), are observed. At the base of the disc a layer of scattered pigment cells
(Fig. 13 p) occurs. No particular structures could be made out in the
tissue forming the dise itself. In transverse sections (Fig. 13) through it
one sees paratangentially orientated plate-like or spindle-shaped elements,
probably connective-tissue cells, sections of nerves and blood vessels and
here and there granular elements which look like nerve cells.

As in the case of Bassozetus (p. 198), also here in Leucicorus lusciosus the
possibility of the discs examined being incomplete must be taken into con-
sideration. If the discs as observed were covered by a layer of cylindrical
cells these organs of Leucicorus would become very similar to those of Ha-
losaurus described below. Such a cylinder cell layer may have been
present on these organs during life; I failed however to find any trace of

it in the sections.

Halosaurus radiatus Garman.
Plate 11, Figs. 52-57.

This species has been described by Garman (99, pp. 298, 364, Plate 60,
Figs. 2, 2a, Plate 84, Figs. 3-6). The radiating dises are situated on the
head and, according to Garman (’99, p. 298, Plate 60, Fig. 2, Plate 34, Figs.
3-6), also in a longitudinal row on each side of the body. They lie under
the skin and are spindle-shaped, the long axis being disposed paratangen-
tially. The largest are 3 mm. long. On each side of the head there are 7
maxillary, 7 orbital, 8 ethmoidal, 4 occipitoparietal, 4 mandibular, and 9
opereular radiating discs. ‘Those on the body could not be made out in the
somewhat injured specimen at my disposal.

In Halosuwrus radiatus the radiating dises are obviously connected with
the slime-canal system. They are in fact local differentiations of the walls
of certain slime canals. The cephalic slime canals in which the organs of
the head lie, extend as usual paratangentially below the outer skin. These
slime canals are enclosed in a stout, apparently structureless sheath (Plate 11,
Fig. 56s). Within this a layer of connective tissue (Figs. 56, 57 c) is met
with, in which slender, probably spindle-shaped cells arranged paratangen-
tially can clearly be made out. This connective-tissue layer is stouter on the

lower side, that is, in the floor, than on the upper side, that is, in the roof of

a

200 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

the canal (Fig. 56 cv). The outer structureless sheath of the canal is
separated from the periost of the bone on which it rests by a thin layer of
scattered pigment cells (Fig. 56 p). The radiating disc is situated in the
floor of the canal. Seen from the surface (Plate 11, Figs. 58-55) it has the
shape of a rhomboidal spindle with obtuse points. The most important part
of it is a single layer of slender somewhat irregularly cylindrical cells (Plate
11, Figs. 56, 57 d) which form an epithelial layer. A stout main disc nerve
(Plate 11, Figs. 53-56 n) and one or two smaller accessory nerves (Figs. 53-
55 n’) lead to this cylinder cell layer. The main nerve rises obliquely
towards the centre of the cylinder cell layer, arrived at the base of which it
suddenly divides into numerous radiating branches extending paratangen-
tially below the cylinder cell plate. Here also an exceedingly dense capillary
network (Figs. 56, 57 b) is met with forming a conspicuous blood-vessel
layer between and under the basal parts of the cylinder cells. The large
vessels leading to this network (Figs. 53-56 b’) are very conspicuous, particu-
larly in surface views (Figs. 53-55).

The cylinder cell plate (Figs. 56, 57 d) is perhaps not wholly composed
of cylinder cells equal in length to the thickness of the plate. There is a
marginal zone (Fig. 56 m), where in transverse sections through the plate
the cells appear to be polyedrical and to form several layers. It is probable,
however, that also here the cells are in reality cylindrical and form a single
layer and that the appearance seen is only the consequence of the marginal
cells not extending, as the others do, in the plane of the section. They
would therefore not, as the cells of other parts of the plate, be cut longi-
tudinally, but more or less transversely, and thus assume the appearance of
polyedrical elements lying in several layers. Also in the centre of the plate
there seems to occur a slight irregularity.

The greater part of the elongated rhomboidical plate formed by this
cell layer is flat. Its margins, in which the apparent multiplication of cell
layers mentioned occurs, are markedly raised. In the middle, along the

short diagonal of the elongate plate, a transverse groove extends. All

the cylinder cells with the exception of the marginal ones, arise vertically
from the floor of the plate. Most of them show a distinct curvature increas-
ing towards the upper end (Fig. 57). In the central groove the cylinder
cells lie close together, in the other parts of the plate they are apparently
separated by intercellular spaces of considerable width (Fig. 57). Possibly
this appearance is merely the expression of the presence of thick lateral cell

Bains

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 201

walls similar to those observed by Leydig and others in certain cells of the
ocellar radiating organs described above. If on the other hand intercellular
spaces are really present — and the appearance is in favor of this assumption
— the question arises whether they are present in these cell plates in life or
merely artifacts produced post mortem by transverse cell shrinkage. In the
lower end of each of these cells a large oval granular nucleus is observed.
These nuclei form a single layer in the basal part of the plate. In the
marginal zone nuclei are also observed higher up, and the same is the case
in the central groove, where a few nuclei are likewise seen at a higher level.
It is doubtful, however, whether these latter belong to the cylinder cells. It
seems rather that they are the nuclei of slender spindle cells here interposed
between the cylinder cells. The protoplasm of the cylinder cells is pretty
granular and stainable with acid-fuchsin and haematoxylin. These stains
are taken up more by the terminal than by the central parts of the cells.
The cells of the central groove show a marked affinity for picric acid; other
stains are hardly at all absorbed by them.

Transverse sections (Plate 11, Figs. 56, 57) show that the intercellular
spaces between the cylinder cells above mentioned do not extend quite to
ends of the cells, in

the upper surface of the cell plate. Here the upper
with each other and

most cases considerably curved, are in direct contact
form a superficial pellicle apparently quite continuous and in sections some-
what resembling a cuticle.

[ have previously described (’87, pp. 809-313, Plate 73, Figs. 45-48, 54-64)
the structure of the radiating discs in another species of Halosaurus, H.
macrochir, In this species a pair of large glandular radiating organs also
have a different structure. The

c

occurs under the gill covers. These
smaller spindle-shaped discs on the sides of the body, however, resemble the
radiating discs on the head of /7. radiatus pretty closely. These are in H,
macrochir attached to the outer side of the scales over the great lateral slime
canal. Below the centre of each digse the scale is perforated by an oblique
tube through which a nerve and blood vessels ascend to the base of the disc.
In the disc itself a lower layer, chiefly occupied by an exceedingly close
reticulation of capillary blood vessels, and an upper composed of slender
cells arising vertically, standing side by side, and forming a high epithelium
The individual elements of the latter are spindle-

can be distinguished.
In transverse sections through the disc

shaped or irregularly cylindrical.

these cells appear separated by clear intervals wider than in the cylinder

v
I
]
'

202 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

cell plates of the cephalic discs of HZ. radiatus. In H. macrochr the upper
ends of these cells are strongly curved and pass into a superficial pellicle
which looks as if it were composed of the upper ends of the cells them-

selves, drawn out in a thread-like fashion and laid down tangentially.

Macrurus canus Garman.
Plate 5, Figs. 18-20.

This species has been described by Garman (99, pp. 217, 364, Plates 49,
84, Figs. 1,2). The radiating discs are situated in the floors of the cephalic
slime canals. In surface views they appear elongate hexagonal (Plate 5,
Figs. 19, 20). They are 2-4 mm. long, white in color and very conspicu-
ous. The wall of the slime canal is lustrous and the part surrounding the
discs occupied by large and richly ramified dark brown pigment cells (Migs.
19, 20 p) so that they stand out as brilliantly white patches from a dark sur-
rounding. On each side of the head there are 3 maxillary, 6 orbital, 2 eth-
moidal, 16 occipitoparietal, 7 mandibular, and 6 opercular radiating dises.
A stout nerve, the main dise nerve, (Plate 5, Figs. 19, 20 n) approaches each
of these organs from the side and extends through its basal part towards its
centre, where it abruptly divides into numerous paratangentially extending
branches. ‘These discs are exceedingly tender structures, and unfortunately
not sufficiently well preserved to allow of their minute structure being
clearly made out. A square patch occupying the central part of the hex-
agonal dise is much less transparent than the remainder (Figs. 19, 20), and
it seems that the ramifications of the main disc nerve are confined to this.
The dises here are certainly not so simple in structure as in Leucicorus and
Bassozetus and seem to approach those of Halosaurus. They probably have

a structure similar to that of Halosaurus.

Ipnops agassizii Garman.
Plate 1, Figs. 3-5.
This species was described by Garman (’99, p. 259, Plate H, Figs. 2,
2a). On the upper side of its dorso-ventrally compressed head a whitish °

patch 12 mm. long and equally broad, composed of two symmetrical halves,

aright and a left one, is met with (Plate 1, Figs. 3-5 d). Moseley (87, pp. 269-

276, Plates 67, 68) has found similar discs in another species of this genus,

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 2038

I. murrayi, and has examined and carefully described their minute struc-
ture. In the material of J. agassizii at my disposal these discs are not suffi-
ciently well preserved to allow of their minute structure being studied.
All I can say is that I have seen nothing in them that would justify one in

supposing that they differed in any way from the organs described by

oo
Moseley in 7. murray’. The hexagonal cylinder cells of the dises of J.

agassizii are about 20 pw long and 6 p thick.

(8) THE FISHES WITH TUBULAR RADIATING ORGANS.

Malthopsis spinulosa Garman,

Plate 1, Figs. 1, 2, Plate 2, Figs. 6-9.

This species has been described by Garman ('99, p. 106, Plates 21, 24). It is
(Plate 1, Figs. 1, 2) a flat fish of horseshoe-shape with a stout conic tail.
The organ here to be deseribed which may have a radiating function is
a medial tentacular papilla on the forehead just above the mouth (Plate 2,

Fig. 6 te). Garman (99, p. 106) states that this papilla is contractile and

can be extended and retracted at the will of the fish. In the state observed

by me it is about 6 mm. long and 1.5 mm. thick. This papilla is situated in

a depression so that it protrudes when retracted only slightly beyond the

general surface of the fish. The apex of the papilla is divided into three

lobes, an upper somewhat leaf-shaped one and a pair of lower massive

ones.
The trilobed terminal part of the tentacular papilla of the only specimen

of Malthopsis spinulosa at my disposal was cut into a series of transverse
sections. These (Plate 2, Figs. 7, 9) show that its trilobed distal part is
stout longitudinal rods of semicartilaginous tissue (Figs.

supported by four
upper ones joined to

8, 9s). The two lower ones are separate, the two
form a band-shaped structure. These rods are enclosed in sheaths of con-
nective tissue from which septa (Figs. 7, 8, 9 ce) radiate, chiefly into the
the interior of which is divided by them into a

massive ventral lobes,
Tn the middle of the ventral surface

number of longitudinal compartments.
connecting the two ventral lobes a conspicuous longitudinal ridge is ob-
s occupied by a pair of longitudinal muscles,

served, the interior of which i
are, no doubt, the muscles which

lying close together (Migs. 8, 9 mj. itese
retract the tentacular papilla, while its extension is probably brought about

\
|
4
|
,
a

204 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

by the elasticity of the semicartilaginous rods described above or the ac-
cumulation of blood in the large longitudinal, sinus-like bloodspace (Figs. 8,
9 b’) which occupies the centre of the tentacular papilla. Other smaller
blood vessels (Figs. 8, 9 b) are met with in its superficial parts.

The longitudinal chambers formed by the connective-tissue septa men-
tioned above, are large and dorsoventrally depressed in the dorsal leaf-like
part, whilst they are radially arranged like a fan in the two lower lobes.
The connective-tissue walls of these chambers are clothed by a high epithe-
lium composed of a single layer of cylindrical cells. In the sections this
cell layer (Figs. 7, 8, 9 pe) is, however, by no means in direct contact with
the connective-tissue walls, but separated from them by an apparently empty
space of considerable extent (Figs. 7, 8, 9). Thus these cylinder cells form
tubes lying within the likewise tubular chambers formed by the connective-
tissue septa. The lumina of these tubes (Figs. 7, 8, 9 cv) are narrow and
either empty or occupied by a structureless mass, apparently a secretion.
The cylinder cells themselves contain a pretty transparent protoplasm, which
is strongly stained with picric acid, but hardly at all with haematoxylin.
The large, oval, granular nucleus lies in the outer (lower) termination of
the cell. Pigment is found chiefly in the outer skin of the dorsal leaf-shaped
lobe. —

In structure these organs resemble the inner portions of the suborbital
organs of Pachystonias microdon (Lendenfeld ’87, p. 8320-322, Plate 71, Figs.
30, 31), where however the cells forming the tubes are not so high. It is
particularly to be remarked that also in this part of the suborbitals of
P. microdon one finds in the sections the tubes formed of these cells sepa-
rated from the connective tissue surrounding them, by apparently empty
spaces.

Chun (03, pp. 568, 569) has mentioned the occurrence of a frontal ten-
tacular papilla in other species of Malthopsis. He thinks that the organ may
emit light, but is doubtful on this point.

On the margin of the body of this fish bud-like protruding organs of
peculiar structure (Plate 1, Figs. 1, 2, Plate 2, Fig. 6 0) oceur, which I will
not describe here, being of the opinion that their function is not to radiate.

They are ramified, rich in blood vessels, and may be accessory gills, or sense

organs. These structures are dealt with in the Appendix.

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 205

3. CONCLUSIONS.

The results of the examination of the minute structure of the organs
of the fishes collected by the “ Albatross” which one can, with more or less
certainty, consider as radiating, as described above, illustrate again their
great diversity. Not only do the ocellar, dise-shaped, and tubular organs
fundamentally differ, but even within these three main groups very great
variations are met, with.

The best known of those organs are the ocellar. A highly developed
apart

organ of this kind, such as the compound organ of Chauliodus is
from the connective-tissue support, the nerves and blood vessels — composed
of a pigment sheath, a reflecting layer, an inner region of large, highly
specialized conic cells, and a middle and an outer mass of specialized
polyedrical cells of another kind. Apart from the blood vessels, nerves,
in all organs, of course do not

are found in adi of the ocellar

and connective tissue, which, as occurring
concern us here, none of these structures
organs described above as radiating. The pigment sheath is absent in the
smallest organs of Chauliodus itself. In these, and in others with a pigment
sheath, the reflecting layer is absent. The large conic cells of the inner
region are absent in the simple organs and in the highly differentiated
compound organs of Argyropelecus. The polyedrical cells of the middle
and outer region of the compound organs of Chauliodus which usually
occur in simple organs are replaced by long spindle-shaped cells in all the
compound organs of Lychnopoles and in the anterior compound organs
of Stomias.

An analogous diversity is met with in the radiating dises. Whilst in
Halosaurus and Ipnops_ highly specialized cylindrical or spindle-shaped
elements, obviously forming a very essential part of the organ, are met
with, such cells seem to be entirely absent in the dises of Bassozetus and
Leucicorus.

In the tubular organs the diversity is not so great, although here also
we find the cells forming the walls of the glandular tubes sometimes high,
as in Malthopsis, and sometimes low, as in Pachystomias.

Even the rule, in general holding good, that the outer covering of these

organs is transparent and suited to allow the radiation to pass, is not univer-

Se ee ae mai = eet eae»
ei Si pean

206 THE RADIATING ORGANS OF THE DEEP SEA FISHES.

sally applicable, for we have found at least in one instance in Chauliodus —
and Leydig has found the same in other instances — organs, otherwise
identical with simple ocellar radiating ones, entirely enclosed in a pigment
sheath and therefore unable to radiate at all.

The diversity is in fact so great that we are forced to assume that either
not all the organs described as radiating really emit ethereal waves, or if
they do, that the waves emitted by different organs are either differently
produced, or different inecharacter, or both. Although direct observations
of the radiation of these organs are but few, we know (7) that some of them
at least do emit light, and (2) that the light emitted by different organs is

often different in color.

It is remarkable that such observations have not been made more
frequently, and that Chun who took every deep sea fish caught immediately
to the photographic dark chamber, so often failed to observe any light
emitted from these organs.

On the whole [ should consider it most. probable — although very far

from scientifically certam—that: (7) The organs produce a radiation.

(2) In the simple ocellar organs and the radiating dises this radiation is an

ia ethereal wave movement directly emitted into the surrounding water.
| (3) In the compound ocellar organs this radiation is either also such a
movement or an emission of corpuscles (electron bombardment) and origi-
nates in the inner part. It is here not emitted directly into the surround-

ing water, but acts on the outer part and induces this to phosphoresce and

emit ethereal waves. (4) The length of the ethereal waves thus directly

Hl : or indirectly produced by one and the same organ is always the same;

that of the ethereal waves produced by different organs is often different.

| (5) In. some cases the wave length lies within the visible part of the
i spectrum; in other cases it may be smaller or greater, and then the radi-
i ation is invisible. (6) The ethereal waves of the invisible radiations are
probably of greater length than those producing the red end of the

spectrum because such probably penetrate the water to greater distances

and because the remarkable telescopic eyes of some deep sea animals seem

to be peculiarly adapted to their perception. (7) These long ethereal waves

i may (if not too long) be of the nature of (ultra red) light, or (if longer) of

the nature of electricity.

L899,

1900.

1900.

1903,
1884,

L899.

1890.

1899.

1887.

1901.

1809.

1877.

1865.

L370.

L881.
1902.

1887.

1881,

1879.

THE RADIATING ORGANS OF THE DEEP SEA FISHES. 207

4, LITERATURE.

Branpes, G. Die Leuchtorgane der Tiefseefische Argyropelecus und Chauliodus.
Zeitschr. Naturwiss., Vol. LXXI, pp. 447-452.
Burckmarptr, R. On the luminous organs of Selachian fishes. Ann, Mag. Nat.
Hist., ser. 1, Vol. VI, pp. 558-568.
Curarmi, P. Ricerche sulla struttura degli organi fosforescenti dei pesci. Ricerche
Kis. L. Luciani Milano, pp. 881-402, 1 ‘Taf.
Cnun, C. Aus den Tiefen des Weltmeeres. Jena. Kd. 2.
Emery, C. Intorno alle macchie splendenti della pelle nei pesci del genere Scopelus.
Mitt. Zool. Stat. Neapel., Vol. V, pp. 471-482, Pl. 27.
Garman, 8. Reports . . . U.S. Fish Commission steamer Albatross during 1891.
XXVI. The fishes. Mem. Mus. Comp. Zodlogy, Vol. XXIV.
Ginbert, C. H. A preliminary report on the fishes collected by the steamer Alba-
tross on the Pacifie coast of North America during the year
1889, with descriptions of twelve new genera and ninety-two
new species. Proc. U. S. Nat. Mus., Vol. XIII, pp. 49-126.
Greenn, C. W. Phosphorescent organs in the Toadfish Porichthys notatus Girard.
Journ. Morphol., Vol. XV, pp. 667-696, Pl. 88-40.
Gunrumr, A. Report on the deep-sea fishes collected by H, M.S. Challenger during
the years 1873-76. Challenger Rept. Zool., Vol. XXII.

Hanprick, K. Zur Kenntnis des Nervensystems und der Leuchtorgane des Argy-
ropelecus hemigymnus. Zoologica, Vol. XIII.
Jonann, L. Ueber cigenthiimliche epitheliale Gebilde (Leuchtorgane) bei Spinax
niger. Zeitschr. wiss. Zool., Vol. LXVI, pp. 136-160, Pl. 10-11.
Lenpenreip, R. V. Report on the structure of the phosphorescent organs of fishes.
Challenger Rept. Zool., Vol. XXU, pp. 277-829, Pl. 69-73.
Levckanrr, R. Ueber muthmassliche Nebenaugen bei einem Fische, Chauliodus slo-
ani. Amtl. Ber. Vers. Deutsch. Naturf. u. Aerzte 1864, pp. 1538-155.
Leypie, F. Ueber die Nebenaugen con Chauliodus sloani. Arch. Anat. Phys.,
Anat. Abth. 1879, pp. 865-882, PI. 15.
——— Die augenihnlichen Organe der Fische. Bonn.
———- Bemerkung zu den * Leuchtorganen” der Selachier. Anat. Anz., Vol.
XXII, pp. 297-301.
Mosriny, H. N. Report on the structure of the peculiar organs on the head of
Ipnops. Challenger Rept. Zool., Vol. XXII, pp. 269-276.
Soueer, B. Zur Kenntniss der Verbreitung von Leuchtorganen bei Fischen. Arch.
mikr. Anat., Vol. XUX, pp. 147-152.
Ussow, M. Ueber den Bau der sogenannten augeniihnlichen Flecken einiger
Knochenfische, Bull, Soc. Imp, Nat. Moscou, Vol. LIV, pp. 79-115,
Pls. 1-4.

|

APPENDIX, 209

APPENDIX.

THE STRUCTURE OF THE BUD-LIKE ORGANS OF
MALTHOPSIS SPINULOSA GARMAN.

By EMANUEL TROJAN.

Among the Albatross fishes sent to Professor von Lendenfeld for exami-
nation was a specimen of Malthopsis spinulosa Garman. ‘This fish is pro-
vided with peculiar bud-like sense organs, which, on account of their function
apparently not being a radiating one, were not described in Professor von
Lendenfeld’s report. Professor von Lendenfeld entrusted me with the
examination of the minute structure of these organs. The results are given
below.

Garman (1899, pp. 106, 107, Plates XX, X XVI) has described and figured
d, the tail has a circular
The lateral line
continued on

this species. ‘The body is dorsoventrally compresse
transverse section. Thorn-like scales cover the surface.
extends along the narrow lateral margin of the body, and is
the tail. It appears as a distinct lateral furrow. The margins of this
furrow bear fringes. In the furrow itself a row of bud-like protuberances
is observed. Above and below each one of these a lobular excrescence with
fringed margin is met with. The fringes of the margins of the furrow and
the lobes are composed of filiform parts, richly pigmented and dark in color.
Garman’s description and illustrations of the bud-like protuberances are insuf-
ficient. He mentions them only from the lateral line and the symphysis
below the mouth. Closer inspection shows that they also occur on the head.
There are on each side (text figs. 1, 2): in the lateral line (furrow) of the
body 12 ventral (v); between the 9 and 10 of the lateral line, one above
the other, 2 lateral (1); in the lateral line of the tail 12 caudal (c); ina
4 mandibular (m); in a line

horizontal row behind the corner of the mouth
(x); between the 4

parallel to and above the preceding one 7 maxillary
organs of the two last named rows | inframaxillary (i); and on the lower
jaw 4 inframandibular (n); together 84 bud-like organs.

The bud-like organs are cream colored, button-shaped, and composed of
a short, stout, cylindrical peduncle only 70 long and on a semispherical
head 400-500 p» in diameter. The histological structure of these organs can
best be made out in longitudinal, axial sections (Fig. 3). The corium is very
highly developed and covered by a pavement epithelium with large nuclei as
in other parts of the skin. It forms two different kinds of papillae. In the
one the corium predominates and the epithelium is only slightly developed,

14

a |
|
1

|
a
a

oN aa

mr ma ea nee

210 APPENDIX.

Fig. 1 Ventrat, AND Fia. 2 Lateran Virw or tHE Fisn.
Natural size. x, maxillar; i, inframaxillar; m, mandibular; n, inframandibular; v, ventral;
eral; c, caudal bud-like organs.
1, lateral; c, lal bud-like organs
Fie. 8. AxraL Section rHrovuaGH A Bup-Likn ORGAN.

Magnified 1: 125, A, artery; V, vein; b, capillary blood vessels; c, connective tissue; co, co-
rium; e, payement epithelium; n, nerve; t, cuticle.

APPENDIX. Zi

in the other the reverse is the case. The papillae of the first kind are very
numerous, they form the “ scales”’ ; those of the second are less numerous
and smaller, they form the basal parts, that is, the peduncles of the bud-like
organs here described. Hach bud-like organ is supplied with a nerve about
70 w thick (Fig. 3 n) which traversts the layers of the corium. ‘These layers
bend outward around it and thus form a tubule. Besides the nerve also
the artery passes through this tube. The terminal thickened part, the head
of the organ, consists principally of spindle-shaped connective-tissue cells
with oval nuclei (Fig. 3 c) and blood vessels (Fig. 3 b). On entering, the
organ the artery (Fig. 3 A) immediately divides to form a capillary network,
These capillaries decrease in width from the centre towards the periphery ;
the narrowest are 12 » wide. The capillaries unite to form a vein (Fig. 3
This vein extends for a consid-
erable distance subcutaneously and does not pass through the tube in which
the nerve and the artery are contained. The branching of the nerve com-

mences at a higher level than the branching of the artery, above the centre
Just beyond the centre

v) which has the same width as the artery

v

of the head. Its proximal parts bear no branches.
of the head it splits up into several bundles of primitive fibres. These
ramify and thus a mass of separate nerve fibres are produced, interlacing with
the capillary blood vessel net which is densest at the apex of the organ.
The final termination of the nerves could not be made out, on account of the
specimen not being specially preserved for the purpose. A continuous cuti-
cle covers the whole organ (ig. 3 t).

Organs comparable to these have been described by F. Leydig (1850,
p. 172, 1851, pp. 235-239) as “Nervenknipfe.” These differ, however, in
several respects from the bud-like organs of Malthopsis examined by me.
The differences in shape and size would not be important ; but the cylinder
epithelium which forms a principal part of the “ Nervenknépfe,” and to which
the authors attach so great an importance, is missing in the buds of Malthopsis.
If we were to imagine the organs of Malthopsis covered by a sensitive
cylinder epithelium they would be “ Nervenknipfe,” still, however, differing
from those described by F. Leydig (I. ¢.) in some respects. Leydig found
the “ Nervenknipfe” always in slime canals; whilst the organs of Malthopsis,
are free, The “free lateral organs” described by F. E. Schulze (1870; p. 71),
which might also be compared to the buds of Malthopsis, are superficial
swellings in the floor of the lateral canals. According to B. Solger (1880,
Plate XVI, Fig. 6) they are oval plates. Thus these organs also differ con-
siderably from those of Malthopsis. Neither can the “ Nervenknipe”’ of
Lepidoleprus coclorhynchus (Leydig 1850, pp. 235-239) be compared with them.
’ is hardly applicable to the organs of Malthopsis

The term “ Nervenknépfe’
because their heads are not endswellings of nerves, but composed of con-
nective tissue and abundant blood vessels. In so much as they are richly

RTE MES COROT RT NE

212 APPENDIX,

innervated distally, they correspond to the “Nervenknipe” of Acerina
cernua, but Leydig (1879, p. 163) says concerning these that the con-
nective tissue of the swelling, which surrounds the nerves and blood vessels
is tender, nearly gelatinous, It seems therefore that they do not belong to
the class of structures designated as “Nervenknépfe.” The essential differ-
ence, the absence of a cylinder epithelium in the buds of Malthopsis, can in
so far not be relied upon, as it may be present in the living fish and absent
in the specimen examined only because it has fallen off on account of its
perishable nature; the circumstances however that the organs are entirely
surrounded by a cuticle and that the tender and perishable sensitive epithe-
lium would, if present, be coverless and exposed, make it appear improbable
that such is the case,

Concerning the physiological function of the organs it must be borne
in mind that they must either be radiating or sensory, because so rich an
innervation must have some purpose. The general appearance of the organs,
their semispherical shape and the abundance of connective tissue in them
are in favor of the latter view and make it probable that the function per-
formed by them is the perception of hydrostatic pressure, a knowledge of
which must be of great importance to any fish able to live only within cer-

tain bathymetrical limits.

1899.

1850.

1861.

1857.
1879.

1880.

APPENDIX. 213

LITERATURE.

Garman, 8S. Reports . . . U. S. Fish Commission Steamer Albatross during 1891.
XXVI. The Fishes. —Mem. Mus. Comp. Zodlogy. Vol. XXIV.

A ° Y . 2 r re wal © Phvs
Luypia, Fr. Uber die Schleimkaniile der Knochenfische. Arch. Anat, Phys. 1850,

pp. 170-181, pl. 4.

——— Ueber die Nervenknépfe in den Schleimkanilen von Lepidoleprus, Umbrina
und Corvina. Arch. Anat. Phys. 1851, pp. 285-240, pl. 9.

——— Lehrbuch der Histologie.

— Neue Beitriige zur anatomischen Kenntniss der Hautdecke und Hautsinne-
sorgane der Fische. Festschrift der Naturforscher-Gesellschaft in Halle. pp. 129-
186, pls. 7-10.

——Integument und Hautsinnesorgane der Knochenfische.
Anat. Vol. 8. pp. 1-152, pls. 1-7.

Scuutze, F,E. Ueber die Nervenendigung in den sogenannten Schleimkanilen der
Fische und tiber entsprechende Organe der durch Kiemen athmenden Amphibien.
Arch. Anat. Phys. .1861, pp. 759-769, pl. 20.

——— Ueber die Sinnesorgane der Seitenlinie bei Fischen und Amphibien. Arch.
mikr. Anat. Vol. 6. pp. 62-88, pls. 4-6.

Sorarr, B. Neue Untersuchungen zur Anatomie der Seitenorgane der Fische. UI
Die Seitenorgane der Knochenfische. Arch. f. mikr. Anat. Vol. 18.

Zool. Jahrb. Abth.

Fig. 1.

Vig. 2.

Puats 1.

Figs. 1, 2. Malthopsis spinulosa Garman.

The ventral side of a specimen. Drawing; slightly reduced; 0, doubtful bud-like
marginal organs.

Ventral side of the left half of a specimen. Photograph; slightly magnified; 0,
doubtful bud-like marginal organs.

Figs. 8-5. Ipnops agassizii Garman.

The head seen from above. Drawing; natural size; d, radiating dises.
The head seen from above. Photograph; slightly magnified; d, radiating discs.
The fish seen from the side. Drawing; natural size; d, radiating disc.

|
|

1ao4 TSHES-RADIATING ORGANS nero sh

| Mati opsis SPINULOSA Garm

|
|

=
=|
ay

PLATE 2.

Figs. 6-9. Malthopsis spinulosa Garman.
too)

. 6. The head in three quarter profile. Drawing; natural size; 0, doubtful bud-like

marginal organs; te, frontal tentacular papilla,

7. Part of a transverse section of the interior of one of the ventral lobes of the distal
trilobed part of the frontal tentacular papilla. Stained: haematoxylin-picric
acid-fuchsin. Drawing. ¢, connective-tissue septa between the longitudinal
chambers; cv, lumina of the glandular tubes; pe, walls of the glandular tubes
composed of cylindrical cells.

8. Transverse section of the distal trilobed part of the frontal tentacular papilla.
Stained: haematoxylin-picric acid-fuchsin. Photograph, magnified 1: 41. b,
peripheral blood vessels; b/, large central sinuous blood vessel; ¢, connective-
tissue septa between the longitudinal chambers; cv, lumina of the glandular
tubes; m, muscles; p, groups of pigment cells; pe, walls of the glandular tubes
composed of cylindrical cells ; s, longitudinal strands of semicartilaginous tissue.

. 9. Transverse section of the distal trilobed part of the frontal tentacular papilla.

Stained : haematoxylin-picric acid-fuchsin. Drawing, magnified 1:41. b, peri-
pheral blood vessels; b’, large central sinuous blood vessel; c, connective-tissue
septa between the longitudinal chambers; cy, lumina of the glandular tubes; m,
muscles; p, groups of pigment cells; pe, walls of the glandular tubes composed
of cylindrical cells; s, longitudinal strands of semicartilaginous tissue.

1 | ee a =| ie T A
ke FISHES -RADIATING ORGAN: PLATE

I rie
hy

4 eK
Teper eitt

oO

ssc stti rcinammnacenraoms

|
|

Puate 3.

PLATE 3.

Figs, 10-13. Leucicorus lusciosus Garman.

d
Fig. 11. A radiating dise in transmitted light. Photograph; magnified 1: 41.

Fig. 10. The fish seen from the side. Drawing: natural size.
Do tae]

b, blood

vessel; n, main dise nerve; n/, smaller accessory dise nerves.

Fig. 12. A radiating disc in transmitted light. Photograph, magnified 1:21. b,
vessels; n, main disc nerve; n’, smaller accessory disc nerves.

Fig. 13. Transverse section of a radiating disc. Stained: haematoxylin. Drawing; mag-
nified 1:42. b, blood vessels; c, paratangentially arranged connective-tissue
cells; cv, cavities in the basal part of the radiating disc; n/, small accessory
disc nerve; p, pigment cells.

blood

mmaetreert itt ||

\
i

EN A AAT CARE ED ow

FISHES-RADIATING ORGANS

‘ALBATROSS’ EX

oy

tere
coud

10-15 Leucicoris lusciosus Garman

i

PuaTE 4.

'
i
i
'

Fig.

Fig.

Puate 4.

Fig. 14-17. Bassozetus nasus Garman,

14. The fish seen from the side, Drawing ; natural size.
15. A radiating dise in transmitted light. Photograph; magnified 1: 58, n, main dise
nerve; p, reticulation formed by the pigment cells with their long processes.
16. A radiating disc in transmitted light. Photograph; magnified 1: 27. n, main dise
nerve; p, reticulation formed by the pigment cells with their long processes.

_17. Transverse section of a radiating dise. Stained: haematox jin. Drawing; mag-
fe] “ 1 ae =

nified 1:42. b, blood vessels; ¢, paratangentially arranged connective-tissue
cells; n, main disc nerve; p, basal pigment cells.

Ltd

a
oa Soe
aa So
a 3

ee

a
4
1
u
i (nis

Puiate 5.

Fig. 18.

Fig. 19.

Fig. 20.

Fig. 21.

Fig. 22.

Fig. 23.

Puate 5.

Figs. 18-20. Macrurus canus Garman,

The fish seen from the side. Drawing; natural size.

A radiating dise in transmitted light. Photograph; magnified 1:41. n, main
dise nerve; p, branched pigment cells.

A radiating disc in transmitted light. Photograph; magnified 1:17. n, main dise
nerve; p, branched pigment. cells.

Figs. 21-23. Myctophum aurolaternatum Garman.

The fish seen from the side. Drawing; natural size. al, anterior lateral radiating
organs; ma, mandibular radiating organs; ml, mediolateral radiating organs ;
op, opercular radiating organs; pe, pectoral radiating organs; pl, posterior
lateral radiating organs; va, anterior ventroanal radiating organs; ve, ventro-
caudal radiating organs; ve, ventromedial radiating organs; vp, posterior ven-

:
troanal radiating organs.

The fish seen from below. Drawing; natural size. al, anterior lateral radiating
organs; ma, mandibular radiating organs; ml, mediolateral radiating organs ;
op, opercular radiating organs; pe, pectoral radiating organs; pl, posterior
lateral radiating organs; va, anterior ventroanal radiating organs; ve, ventro-

iS Ne ) ’ Be ) ’
caudal radiating organs; ve, ventromedial radiating organs; vp, posterior
ventroanal radiating organs,

Axial section vertical to the median plane of the fish through a posterior lateral
radiating organ. Stained: haematoxylin-picric acid-fuchsin. Drawing; magni-
fied 1: 140. b, blood vessels ; c, connective tissue of the interior of the organ;

‘4 J bi Db ’
p, section through the outer horseshoe-shaped pigment cell band; pe, radiating
cells; pp, internal pigment cell layer; si, scale underlying the radiating organ ;
8s, scale covering the radiating organ; t, section through the H-shaped thicken-

ing of the covering scale.

ce TE

rT

“ALBATROSS Ex. 1891. FISHES -RADIATING ORGANS PLATE &.

B. Meisel, lith. Boston

l8-20 MACRURUS CANUS Garm. 21-23 MycTOPHUM AUROLATERNATUM Garm

©
4
—
a

Puate 6,

Figs. 24, 25. Argyropelecus lychnus Garman.

Fig. 24, Axial section vertical to the median plane of the fish through an anterior lateral

Fig.

2

pe

vo.

Fig. 26.

Fig. 27.

30.

radiating organ. Stained: picrie acid-carmin. Drawing; magnified 1: 84. A,
proximal oval part of the organ; B, zigzag fibres of the reflecting layer; C,
constriction between the proximal and distal part of the organ; D, distal para-
boloidal part of the organ; g, inner region; 1, middle region; p, pigment
sheath; r, reflecting layer; s, outer region,

The fish seen from the side. Drawing; natural size. a, anal radiating organs ;
al, anterior lateral radiating organs; ao, anteorbital radiating organs; br,
branchiostegal radiating organs; ml, medial lateral radiating organs ; op, oper-
cular radiating organs; pe, pectoral radiating organs; po, postorbital radiating
organs; ve, ventrocaudal radiating organs; ve, ventromedial radiating organs ;
vt, ventrothoracic radiating organs.

Figs, 26, 27. Sternoptyx obscura Garman.

The fish seen from the side. Drawing; natural size. a, anal radiating organs ;
al, anterior lateral radiating organs; br, branchiostegal radiating organs ; Op,
opercular radiating organs; pl, posterior lateral radiating organs; ve, ventro-
caudal radiating organs; ve, ventral radiating organs; vt, ventrothoracic radi-
ating organs.

Axial section vertical to the median plane of the fish through a ventrothoracic radi-
ating organ. Stained: haematoxylin-picric acid-fuchsin. Drawing ; magnified
1:42. g, inner region; gl, gelatinous tissue occupying the distal part of the
organ; 1, middle region; p, pigment sheath; r, reflecting layer; 8, outer
region.

Figs. 28-30. Cyclothone acclinidens Garman.

The fish seen from the side. Drawing; natural size. a, ventroanal radiating
organs; ve, ventromedial radiating organs; vt, ventrothoracic radiating organs.

The fish seen from below. Drawing; natural size. a, ventroanal radiating organs ;

br, branchiostegal radiating organs; ve, ventromedial radiating organs; vt,
ventrothoracic radiating organs,

Axial section vertical to the median plane of the fish through a ventrothoracic
radiating organ. Stained: haematoxylin-picric acid-fuchsin, Drawing; magni-
fied 1: 520; b, blood vessel leading to the organ; c, connective-tissue capsule
within the pigment sheath; cd, transparent connective tissue forming the super-
ficial covering of the organ in the orifice of the pigment sheath; cr, distal part
of the connective-tissue capsule covering the mass of radiating cells outside ;
1, cylindrical cells of the outer zone; m, central part of the organ composed of
small irregularly arranged polyedrical cells; p, pigment sheath; r, outer part
of the organ composed of cells arranged in regular rows; t, transparent inter-

mediate zone.

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Fig. 31.

Fig. 32.

Fig. 33.

e

Fig. 34.

Fig. 35.

Fig. 36.

Fig. 37.

PLATE 7.

Figs. 81-37. I sychnopoles argenteolus Garman.

The fish seen from the side. ° Drawing; natural size. a, anal radiating organs ;
al, anterior lateral radiating organs; 0; anteorbital radiating organs; ml,
medial lateral radiating organs; OP» opercular radiating organs; pl, posterior
lateral radiating organs; Ve, ventromedial radiating organs ; vt, yentrothoracic
radiating organs.

The fish seen from below. Drawing; natural size. 4, anal radiating organs ;
al, anterior lateral radiating organs; a0, anteorbital radiating organs; ™a,
mandibular radiating organs ; ml, medial lateral radiating organs; OP, opercular
radiating organs ; pl, posterior lateral radiating organs; VS, ventromedial
radiating organs; V6, yentrothoracie radiating organs.

The head of the fish with distended lower jaw seen from below. Drawing ; nat-
ural size. br, pranchiostegal radiating organs; g, guttural radiating organs;
ma, mandibular ‘adiating organs.

Part of an axial section vertical to the median plane of the fish through a medial
lateral radiating organ showing the outer region. Stained : haematoxylin-picric
acid-fuchsin. Drawing; magnified Le LOO? 2, connective-tissue membrane
forming the walls of the facets; gl, gelatinous tissue occupying the distal part
of the organ; 0, cavity in the central part of the facets; sc, curved oblique
cells in the proximal part of the facets; sp, straight longitudinal spindle-
shaped cells in the distal part of the facets.

Transverse section of the outer region of a medial lateral radiating organ.
Stained : haematoxylin-picric acid-fuchsin. Drawing ; magnified 1:350. ¢, con-
nective-tissue membrane forming the walls of the facets; 0, cavity in the
central part of a facet; Pp, pigment sheath; 1, reflecting layer; §Dp, straight
longitudinal spindle-shaped cells in the distal part of the facets.

Part of an axial section vertical to the median plane of the fish through a medial
lateral radiating organ showing part of a facet of the middle region in longi-
tudinal section. Stained : haematoxylin-picric acid-fuchsin. Drawing ; magnified
Lei00..-€; connective-tissue membrane forming the wall of this facet; en, slen-
der axial canal in the facet; nu, nuclei of the cells; ph, only slightly stainable
proximal portion of the cells; pt, highly stainable distal portion of the
cells. é

Axial section vertical to the median plane of the fish through a medial lateral
radiating organ. Stained : haematox ylin-picric acid-fuchsin. Drawing; magni-
fied 1:110. A, proximal spherical part of the organ; b, plood vessels outside
the pigment sheath; ©, constriction between the proximal spherical and the
distal- paraboloidal part of the organ; ¢, connective-tissue capsule lying within
the reflecting layer; Cc, tubular cavity in the axial portion of the proximal part
of the organ; Ci, radiating facets of the inner region of the organ; ¢m, radial
facets of the inner part of the middle region; Co, longitudinal facets of the
outer part of the middle region; er, outer connective-tissue sheath of the organ;
D, distal paraboloidal part of the organ; g, inner region of the organ; ol, gel-
atinous superficial portion of the tissue occupying the distal part of the organ;
gr, granular basal portion of the tissue occupying the distal part of the organ;
1, middle region of the organ; Pp, pigment sheath; 1, reflecting layer; 8, outer

region of the organ.

2)

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PLATE

Puate 8.

Figs. 38-40. Chauliodus barbatus Garman.

Fig. 38. The fish seen from the side. Drawing; natural size, a, ventroanal compound
radiating organs; al, anterior lateral compound radiating organs; a0, anteor-
bital compound radiating organs; Ba, simple radiating organs with pigment,
sheath in the barbel; ml, medial lateral compound radiating organs; so, subor-
bital compound radiating organ; ve, ventromedial compound radiating organs;
vt, ventrothoracic compound radiating organs; X, simple radiating organs
with pigment sheath on the gide of the head.

Fig. 39. The fish seen from below. Drawing; natural size. 4, ventroanal compound

radiating organs; al, anterior lateral compound radiating organs; Ba, sim-

ple radiating organs with pigment sheath in the barbel; g, guttural compound

radiating organs; ml, medial lateral compound radiating organs; u, groups of

simple radiating organs without pigment sheath; ve, ventromedial compound
radiating organs; yt, ventrothoracic compound radiating organs.

Fig. 40. The lower jaw seen from below. Drawing ; magnified 1:2; Ba, simple radiating

organs with pigment sheath in the barbel.

Figs. 41, 42. ITdiacanthus antrostomus Gilbert.

Fig. 41. The fish seen from the side. Drawing; natural size, 4, ventroanal radiating

organs with pigment sheath ; al, anterior lateral radiating organs with pigment
sheath; ml, medial lateral radiating organs with pigment sheath; pl, posterior
lateral radiating organs with pigment sheath; so, suborbital radiating organ
with pigment sheath; u, suborbital group of small radiating organs without,
pigment sheath; ye, ventromedial ‘adiating organs with pigment sheath; vt
ventrothoracic radiating organs with pigment sheath.

Fig. 42. The fish seen from below, Drawing; natural size. 4, ventroanal radiating organs

with pigment sheath; ¢, guttural radiating organs with pigment sheath; ve,

ventromedial radiating organs with pigment sheath; vt, ventrothoracic radiating

organs with pigment sheath.

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PLATE 9.

Figs. 43-46. Chauliodus barbatus Garman,

Fig. 43. Axial section vertical to the median plane of the fish through a regular simple
radiating organ with pigment sheath. Stained: haematoxylin-picric acid-fuchsin.
Drawing; magnified 1: 280. c, connective-tissue membrane forming the cover-
ing of the mass of radiating cells on the outer side; h, outer apparently struct-
ureless covering of organ; 1, central mass of polyedrical cells; m, granular
protoplasmic mass at the base of the organ; p, pigment sheath; pe, peripheral
cylindrical radiating cells.

Fig. 44. Axial section vertical to the median plane of the fish through an irregular simple
radiating organ with pigment sheath. Stained: haematoxylin-picrie acid-fuchsin.
Drawing ; magnified 1: 280. ec, connective-tissue membrane forming the cover-
ing of the mass of radiating cells on the outer side; h, outer, apparently
structureless covering of organ; 1, central mass of polyedrical cells; m, gran-
ular protoplasmatic mass at the base of the organ; p, pigment sheath; pe,
peripheral cylindrical radiating cells.

Fig. 45. Axial section vertical to the median plane of the fish through a medial lateral
compound radiating organ. Stained: haematoxylin-picrie acid-fuchsin. Draw-
ing; magnified 1: 140. A, proximal spherical part of the organ; a, mass of
small cells in the central portion of the proximal spherical part of the organ ; C,
constriction between the proximal and distal parts of the organ; e, connective-
tissue capsule within the pigment sheath; D, distal paraboloidal part of the
organ; d, gelatinous connective tissue occupying the distal part of the organ ;
f, cells in the facets of the outer region; i, inner region; 1, cells composing
the middle region; m, middle region; 0, outer region; p, pigment sheath; pe,
large conic cells of the inner region; r, reflecting layer.

Fig. 46. Transyerse section through the centre of the proximal spherical part of a medial
lateral compound radiating organ. Stained: haematoxylin-picric acid-fuchsin.
Drawing; magnified 1: 840, a, mass of small cells in the central portion of the
proximal spherical part of the organ; b, blood vessels extending radially to
the centre of the sphere; e, connective-tissue capsule; nu, nucleus of the conic
cells; p, pigment sheath; ph, proximal only slightly stainable part of the

conic cells; pt, peripheral highly stainable part of the conie cells.

Puate 10.

i
li
lf
I

Puiate 10.

Figs. 47-51. Stomias hexagonatus Garman.

Fig. 47. The fish seen from the side. Drawing; natural size. a, ventrocaudal compound
radiating organs; al, anterior lateral compound radiating organs; g, guttural
compound radiating organs; L, radiating organ of the barbel; ml, medial
lateral compound radiating organs; so, suborbital radiating organ; ve, ventro-
medial compound radiating organs; vt, ventrothoracie compound radiating
organs.

Fig. 48. The fish seen from below. Drawing; natural size. a, ventrocaudal compound
radiating organs; al, anterior lateral compound radiating organs; g, guttural
compound radiating organs ; ml, medial lateral compound radiating organs; ve,
ventromedial compound radiating organs; vt, ventrothoracic compound radiating
organs.

Fig. 49. Transverse section through the outer distal part of the eylindroconic plug-shaped
part of a ventrothoracic compound radiating organ. Stained: haematoxylin-
picric acid-fuchsin. Drawing; magnified 1: 280. ce, central facet of cylindro-
conie plug; pe, transverse sections of cells in the outer facets of the cylindroconie
plug.

Fig. 50. Axial section transverse to the barbel through the radiating organ of the barbel.
Stained: haematoxylin-picric acid-fuchsin. Drawing; magnified 1: 120. A,
upper (dorsal) part of the organ; B, lower (ventral) part of the organ; b,
blood vessel following the axial thread, and sinuous blood vessels in the lower
chamber of the dorsal part of the organ; c, connective-tissue sheath inclosing
the organ; ev, cavities in the upper part of the organ; p, dorsal pigment
sheath; pe, large radial conie cells of the lower spherical part of the organ ;
pm, pigmented membrane traversing the upper part of the organ; pt, annular
thickening of the pigment layer; z, axial thread in the lower spherical part of
the organ.

Fig. 51. Axial section vertical to the medial plane of the fish through a ventrothoracic com-
pound radiating organ. Stained: haematoxylin-picric acid-fuchsin. Drawing ;
magnified 1: 160. d, blood vessels in the septa between the conic cells of the
proximal spherical part of the organ; ¢, connective tissue covering the distal
part of the organ on the outer side; cc, central facet of cylindroconie plug

forming the distal part of the organ; co, conic proximal end of the outer plug-
shaped part of the organ; cy, cylindroconie plug-shaped outer part of the organ ;
p, pigment sheath; pe, longitudinally elongated cells in the outer facets of the
plug-shaped distal part of the organ; ph, inner only slightly stainable part. of
the radiating conic cells in the proximal spherical part of the organ; r, annular
reflecting membrane surrounding the plug-shaped distal part of the organ; 8,
annular cavity surrounding the plug-shaped distal part of the organ.

“ALBATROSS” EX. 1891. FISHES -RADIATING ORGANS PLATE10

al nel

ssoaneuninmnnrante-weeetenseranaass

B.Meisel,lith. Boston

47-51 STOMIAS HEXAGONATUS Garm

Puate 11.

Fig.

Fig.

Fig.

Fig.

Fig.

Fig.

Puate 11,

Figs. 52-57. Halosaurus radiatus Garman.

52, The fish seen from the side. Drawing; natural size.

53. Radiating cephalic disc in transmitted light. Photograph; magnified 1:17. bi’,
large blood vessel leading to the disc; n, main disc nerve; n/, smaller ac-
cessory dise nerves.

54. Radiating cephalic disc in transmitted light. Photograph ; magnified 1: 41. b’
large blood vessels leading to the disc; n, main dise nerve; n‘, smaller ac-
cessory disc nerves.

55. Radiating cephalic disc in transmitted light. Photograph; magnified 1:17. b’,
large blood vessel leading to the disc; n, main disc nerve; n’, smaller ac-
cessory dise nerves.

56. Transverse section through a cephalic radiating disc along its longer axis. Stained :
haematoxylin-picric acid-fuchsin. Drawing ; magnified 1:42. b, close capillary
network of blood vessels underlying the cylinder cell layer; b’, large blood vessel
leading to the disc; ¢, thickened connective tissue of the inner wall of the slime
canal on which the cylinder cell layer rests; cv, cavity of slime canal; d, cyl-
indrical cells of the radiating disc; m, marginal zone of the radiating disc; n,
main dise nerve; s, outer wall of slime canal.

57, Part of a transverse section through the cylinder cell layer of a cephalic radiating

disc. Stained: haemotoxylin-picric acid-fuchsin. Drawing ; magnified 1 : 200.
b, close capillary network of blood vessels underlying the cylinder cell layer :
c, thickened connective tissue of the inner wall of the slime canal on which the
cylinder cell layer rests; d, cylindrical cells of the radiating discs.

ALBATROS

‘Trojan de
f yan del

“ey

52-57 Halosaurus radiatus Garman.

a

PLatE 12.

Piatre 12,

teh of the Pacific from the Gulf of California to Northern Ecuador, with
891.

Hydrographic Ske
the Track of the ‘¢ Albatross,” February 22 to April 23, 1

Acassiz AIBATROSS CRUISE. 189].

1500 fathoms

The following Publications of the Museum contain Reports on the Dredging Operations in

charge of Alexander Agassiz, of the U. 8. Fish Commission Steamer “Albatross,” during
IS91, Lieut. Commander Z, L. Tanner, U.S..N., Commanding.

Three Letters from Anwxanper AGAssrz to the Hon.
Marshall McDonald, U. S. Commissioner
of Fish and Fisheries, on the Dredging
Operations of the “Albatross” in 1891.
Bull. M. C. Z., Vol. XXI. No. 4. June,
1891. 16 pp.

. AGASSIZ,
new Stalked Crinoid from the Galapa-
gos. Mem: M.C. Z., Vol. XVII. No. 2.
January, 1892. 95 pp. 32 Plates.

. Acassiz. General Sketch of the Expe-
dition of the “ Albatross,” from February
to May, 189]. Bull. M. C. Z., Vol.
XXIII. No. 1. February, 1892. 89 pp.
22 Plates,

. Goks. Neusina Agassizi. Bull. M.C. Z.,
Vol. XXIII. No, 5. December, 1892.
4 pp. 1 Plate.

I. Lupwia. Vorliufiger Bericht iiber die
erbeuteten Holothurien. Zeit. Anz., No.
420, 1893. Bull. M. C. Z., Vol. XXIV.
No. 4. June, 1898. 10 pp.

. Gro. P. Mrrrint. The Rocks of the
Galapagos.
No. 18. July, 1893. 3 pp.

Faxon. Preliminary Deseriptions of

new Species of Crustacea. i

Vol. XXIV. No.7. August, 1893. 72 pp.

. 8. H. Scupprr. The Orthoptera of the

Galapagos. Bull. M. C. Z, Vol. XXYV.

No. 1, September, 1808. 26 pp. 3

Plates.

ScuimKeéwirscu, The Pygnogonide.

Bull. M. C. Z., Vol. XXV. No. 2. Decem-

ber, 1893. 17 pp. 2 Plates,

. W. MoM. Woopworrta. The Planari-
ans. Bull. M. C. Z., Vol. XXV. No. 4.
January, 1894. 4 pp. 1 Plate.

Tu. Sruper, Note préliminaire sur les
Aleyonaires. Bull. M. C. Z., Vol. XXV.
No. 5. February, 1894. 17 pp.

_ 8. FB. Crarkn. The Hydroids. Bull.
M.C. Z., Vol. XXV. No, 6. February,
1894. 7 pp. 5 Plates.

- H. Lupwie. The Holothurians.
M. €, Z., Vol. XVII. No. 8.
1894. 188 pp. 19 Plates.

R. Beran. Die Opisthobranchien. Bull. M.
C. Z., Vol. XXV. No, 10. October, 1894.
109 pp. 12 Plates.

. A. Ortmann. The Pelagic Schizopoda.
Bull. M. C. Z, Vol. XXV. No. 8 Sep-
tember, 1894. 13 pp, 1 Plate.

- W. Faxon, The Crustacea, Mem. M. C. Z.,
Vol. XVIIL April, 1895. 992 pp. 67
Plates. —

- W. Giessrecnt. Die Pelagischen Cope-
poden. Bull, M. 0.Z, Vol. XXV. No.
12. April, 1895. 20 pp. 4 Plates.

» C. Il, Townsenn. The Birds of Cocos
islaiid: Bully M..G, 2. Vol. XX VU.
No. 3. July, 1895. 8 pp. 2 Plates.

vi. W.

Ww.

October

On Calamocrinus Diomeds, a

Bull. M. C. Z,; Vol. XVI.

Bull. Me Ge, |

Mem. |

XVUI. C, Hartraun. Die Comatuliden. Bull.
M.C. Z., Vol. XXVII. No. 4. August,
1895. 26 pp. 4 Plates.

G. W. Mittier, Die Ostracoden. Bull.
M. C. Z:, Vol. XXVIL. No. 5. Octo-
ber, 1895. 10 pp. 8 Plates.

A. Gos. The Foraminifera. Bull. M.
C. Z., Vol. XXIX,. No. 1. February,
1896. 108 pp. 9 Plates.

- O. Maas. Die Medusen. Mem. M. C. Z,,

Vol. XXIII. No. 1. September, 1897.
92 pp. 15 Plates.

. H. J. Hansen. The Isopoda.
C.Z,, Vol. XXXI.- No. 5.
1897. 88 pp. 6 Plates,

. A. A@assiz. Preliminary Report on the
Hehint. Bull M. CnZ., Vol. XXXII,
No. 5. June, 1898. 18 pp. 14 Plates.

%. L. Mark. Preliminary Report on
Branchiocerianthus urceolus. Bull. M.
C. Z, Vol. XXXII. No.8. August,
1898. Spp. 3 Plates.

. PF, Liirken and Tr. Mortensen, The
Ophiuride. Mem. M.C. Z., Vol. XXUL.
No, 2. November, 1899. 114 pp. 22
Plates and Chart. i:

GARMAN, The Fishes. Mem. M.C. Z.
Vol. XXIV. November, 1899. 426 pp.
97 Plates aud Chart.

W. McM. Woopworrn. Preliminary
Account of Planktonemertes Agassizii.
Biull Me. 2 Vou ARXV. No 1.
July, 1899. 4pp. 1 Plate.

. STEINEGER. ‘Two new Lizards of the
genus Anolis, from Coeos and Malpelo
Islands. Bull: M. C. Z., Vol. XXXVI.
No.6. November, 1900. 6 pp. 1 Plate.
. W. KB, Norte, The Cephalopoda. Bull.

M. C, Z., Vol. XLIII, No. 1. March,
1904. 71 pp... 12 Plates. :

.X. Hl. V. Winsox. The Sponges. Mem. M.

C.Z., Vol. XXX. No.1. July, 1904.

164 pp. 26 Plates. :

VON LENDENFELD.

Organs of the Deep Sea Fishes. Mem.

M. C. Z., Vol. XXX. No.2. August,

1905. 48 pp. 11 Plates, 1 Chart.

A. Aqassiz. ‘The Panamic Deep Sea
Echini. Mem, M. C. Z., Vol. XXXI.
November, 1904. 10, 248 pp. 112

_ Plates.

XXXII. EF. von Marenzriuer. Stein-und
Ilydro-Korallen. Bull. M. C. Z,
Vol. XLHT. No. 2. August, 1904.
16 pp. 8 Plates.

I. von MARENZELLER. Lagisca Irritans,
sp, nov., ein Symbiont von Hydro-
korallen. Bull. M. C. Z., Vol. XLIIL.

No. 8. August, 1904. 6 pp. 1 Plate.

Hi. Lupwie. Asteroidea. Mem. M. C: Z.,
Vol. XXXII. July, 1905, 12, 292 pp.
35 Plates, 1 Chart.

XIX.

XX.

Bull. M.
December,

AXVI.

XXVII.

XXVIII.

POO The Radiating

XXXIV.

AAR.

PUBLICATIONS

OF THE

MUSEUM OF COMPARATIVE ZOOLOGY

AT HARVARD . COLLEGE.

There have been published of the BuLLerin Vols, I. to XLII,
and also Vols. XLIV., XLV:, and XLVII.; of the Memorrs,
Vols. I. to XXIV., and also Vols. XXVIII., XXIX., XX XI., and
XXXII.

Vols. XLII, XLVI., and XLVIII. of the Buntrrin, and
Vols. XXV., XXVI, XXVII., XXX., and XXXIII. of the
Memoirs, are now in course of publication. ©

A price list of the publications of the Musewm will be sent
on application to the Librarian of the Musewm of Comparative

Zovlogy, Cambridge, Mass.