NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
52 Scientific Memoirs by
Wilson, Pro. Roy Soc. Edinb. XX, 1895, p. 309 (Reproduction of Cancer pagurus).
Brandes, Biol. Centralblatt, XVII, 1897, p. 346 (Galathea strigosa and Eupagurus
prideauxii : Dromia and Maia also mentioned).
3. On Certain Primary Sexual Characters in Certain Bony Fishes.
A good many Teleostei are known to be viviparous, - and in the males of
these viviparous species various organs of impregnation, such as modified fin-
rays, post-anal papillæ, etc., have been described.
The " Investigator " has discovered three species of Bony Fishes, belonging
to the family Ophidiidœ, which possess intromittent male organs , of the post-
anal-papilla type, of remarkable size and complexity. These three Ophidioids
are Diplacanthopoma raniceps, Hephthocara simum, and Saccogaster maculata.
In Diplacanthopoma raniceps the male organ is very large, its free portion,
in a fish about six inches long, standing clear of the abdomen for about a quarter
of an inch. A description and figure of the organ will be found in Ann. Mag.
Nat. Hist. for August 1898, p. 155, and in pl. xxvi of the Illustrations of the
Zoology of the Investigator : Fishes. Its walls are of cartilaginous consistence, es-
pecially at the apex, and its cavity is lined by thickened peritoneum, so that it is a
sort of hernia of the body-cavity. Its free end is thrown into folds of remarkable
intricacy : the posterior folds form a capacious " personate" sac, into the depth
of which the testes open : the anterior folds enclose a smaller cavity, which is
nearly filled by a pair of projecting papillæ.
The corresponding organ of the female is a prominent cone, also lined by
peritoneum, and lodging the ends of the ovaries : these have a common opening of
large size, at the spongy apex of the cone.
In Hcphthocara simum the male organ exactly resembles that of
D i p l a c a n t h o p o m a r a n i c e p si
n a l l
b u t s i z e
t h e f e m a l e o r g a n , h o w e v e r , i s n o t s o p r o m i n e n t .
In Saccogaster maculate the male organ, which is relatively smaller than
that of Diplacanthopoma raniceps, is billobed, with—in a well preserved speci-
men—a long filament standing in the crevice between them : the testes open bet-
ween and behind the lobes. In the female of this species the skin round the
single large genital orifice is thickened and spongy, but there is no special prom-
inence. The male organ is figured illustrations of the Zoology of the
I n v e s t i - g a t o r : F i s h e s ,
p l .
x x i x .
Not to mention Elasmobranchs, or the curious racemose organ, of doubtful function, of
Plotosus, the following papers, in addition to some of those quoted in the paragraphs on
Viviparlty in Bony Fishes, relate to this subject:—
Hyrtl, in Denk. Kais. Akad. Wien, I, 1850, p. 391, pl.lii,liii.
Blake, Proc. Calif. Acad. Nat. Sci., III , 1868 , p. 371.
Medical Officers of the Army of India.
53
Günther, Ann. Mag. Nat. Hist. (4) , XVII , 1876, p. 403. and Introduction to the
Study of Fishes, p. 162.
Lidth de Jeude, Notes Leyden Mus. IX, 1887, p. 137.
Surbeck, Zool. Anzeiger, April 1900, p. 229.
4. On Certain Secondary Sexual Characters in Certain Bony Fishes.
Darwin in the Descent of Man (2nd ed., pages 330-347) has collected.
numerous observations on this subject. To the cases, quoted by him, in which the
male is more brilliantly coloured or highly ornamented than the female, probably
with the object of attracting the female, the " Investigator" is able to add the
following :—
In the Pleuronectoids Arnoglossus macrolophus and Brachypleura xantho-
sticta the first few rays of the dorsal fin are, in the adult male alone, enormously
lengthened to form an elegant erectile crest. In Arnoglossus macrolophus the
longest of these rays are more than half, and in Brachypleura xanthosticta they
are nearly half the total length of the body.
In the Ophidioid Neobythites pterotus the male alone has the rays of the
pectoral fins much prolonged, with spathulate tips, the corresponding fins of the
female being of the ordinary length and form. As however this species is an
inhabitant of the dark or gloomy depths, it is probable that the curious fin-rays of
the male, though undoubtedly ornamental to our eyes, are òrgans of touch useful
for detecting the presence of the female.
In the Pleuronectoid Rhomboidichthys asureus the male alone has a short
horizontally-directed horn on its snout, and is ornamented on the broad space in
front of the eyes with two rows of azure blue spots of extraordinary brilliance.
In Rhomboidichthys valde-rostratus the male is armed and ornamented in
the same way, but as the female is unknown, we cannot say whether or not this is
a sexual character.
In the Gobioid Callionymus carebares the sexes differ in colouration only,
not in size of body or in length of fins. But in this species, contrary to the usual
state of things—though parallel cases are known in certain birds—it is the female,
and not the male, that is the brighter.
5. A Case of Pairing in an Eel.
In November and December eels, of the common reef-haunting species
M urœna pseudothyrsoidea, are sometimes found in swarms in the tidal pools of the
Laccadives and Andamans. Their behaviour is then very aggressive, and if dis-
turbed, instead of making off, they await the enemy with open mouth and may
even begin the attack. Once, when collecting among the pools of Betra Par reef
in the Laccadives, I was glad, on account of these eels, to be wearing thick boots.
54
Scientific Memoirs by
On one occasion Ie n c o u n t e r e d a m a l e a n d f e m a l ei
n c o p u l a ,
i n a h o l e
i n
a
coral-rock, and captured them, the male biting savagely, though not quitting
his hold of the female. The edges of the vent and genital pore of the female
were found to be swollen, everted, and inflamed, with eggs protruding from
the pore.
De Joannis (Revue Zoologique par la Societe Cuvierienne, 1839, p. 52) states of
Anguilla that they are frequently found in swarms, when he believes that they are pairing.
See also an abstract of a paper De anguillarum sexu et generatione, in Müller's Archiv,
1843, p. ccliv.
On the pairing and sexual behaviour of fishes see Darwin, Descent of Man, the section
of Chapter xii on secondary sexual characters in fishes. Also Bolau, Zeits. Wiss. Zool.,
X X X V , 1 8 8 1 ( p a i r i n g o f D o g - f i s h ) .
Carbonnier, Ann. Mag. Nat. Hist. (5) , VII, 1881, p. 73 (pairing of nest-building
Cat-fish—Callichthys fasciatus).
Blum, Zool. Garten, XXIII, 1882, p. 124 (pairing of Zoarces viviparus).
Guitel, Arch. Zool. Experim, (2) X, 1892, p. 499, and (3) I , 1893, p. 326 and p.
611, and (3) III, 1895, p. 263 (Gobies and Blennies)
Holt, Proc. Zool. Soc. 1898, p. 281 (pairing of the Dragonet).
6. On Viviparous Bony Fishes.
Exclusive of the numerous nutricant species that guard the developing
ova in brood-pouches, or in specially constructed nests, or simply deposited in
the pharynx or attached to the body, a considerable number of Teleosteans are
now known to be truly viviparous, the young completing their development
within the ovary of the mother.
Cuvier and Valenciennes (Hist. Nat. Poissons, Vol. I, p. 540) mention
" les silures, les anableps, certains blennies, etc.," as viviparous.
Dr. Gunther in his Introduction to the Study of Fishes mentions (p. 159)
" the Embiotocidœ, many Blenniidœ and Cyprynodontidœ, Sebastes viviparus,
etc.", and in the systematic and descriptive part of the same work he alludes to
these again and to Hemiramphus.
Professor Eigenmann, in the Bulletin of the United States Fish Commission,
Vol. XII for 1892, gives a very detailed account of the viviparous Teleosteans
of the American Pacific, to which is appended a valuable bibliography.
In the true viviparous Teleosteans the nourishment of the developing em-
bryo is effected in various ways. Two principal methods are recognized by
Eigenmann, in one of which the yolk furnishes the chief supply and the ovarian
wall nothing, while in the other the main provision comes from the ovarian wall.
In the Cyprinodonts of the genera Gambusia and Poecilia and in the
viviparous Scorpœnidœ, according to Eigenmann, the growing embryo is
nourished almost entirely from the yolk.
Medical Officers of the Army of India.
55
In some of the Embiotocidœ, according to Blake and Ryder, the vertical
fins of the embryo are greatly enlarged and have a special blood-supply, by
which means oxygen, and probably nourishment also, are absorbed from the
vascular ovarian wall of the mother, these specially vasculized fins being, in short,
a sort of fœtal placenta.
In other Embiotocidœ, according to Eigenmann, the ovarian wall -secretes
a nutritive fluid by the dissolution of its own epithelium, the fluid being further
enriched by spermatozoa left over from the original impregnation by the male,
this fluid is ingested and assimilated by the embryo, while respiration is carried
on partly by the general surface of the body and fins (through which also some
nutriment may be absorbed) where they come in contact with the ovarian wall,
and partly by the current of ovarian fluid passing through the alimentary canal.
According to Eigenmann the surplus spermatozoa of the male parent here play
an important part, for not only do they form part of the food-supply of the
developing young, but by their activity they prevent the ovarian fluid from
stagnating, by setting up useful currents.
In Anableps alone, in which as in other Cyprinodonts the yolk sac is vas
-cular, do we find anything at all approaching the yolk-sac placenta of the
Elasmobranch fishes. In Anableps, according to Wymann, the yolk-sack
increases greatly in size after all the yolk has been used up, and its surface
becomes covered with small papillæ or villi whose function is probably to absorb
nutriment furnished by the wall of the maternal ovary.
On the " Investigator" we have discovered a small section of the family
Ophidiidœ, including the three genera Dipiacanthopoma, Saccogaster, and
Hephthocara, to include species that are truly viviparous, and I believe, from
significant external characters, that all the species of this section will be found
to bring forth their young alive.
Of the three members of this family noticed by the " Investigator " to be
viviparous, namely Diplacanthopoma rivers-andersoni, Saccogaster maculata,
and Hephthocara simum, only the first named is represented by material suffi-
ciently well preserved for satisfactory investigation, but the arrangements seen
in it are certainly the same in Hephthocara simum.
I have described the intra-ovarian gestation of Diplacanthopoma
r i v e r s -
a n d e r s o n i ,
i n t h e
A n n a l s a n d M a g a z i n e o f N a t u r a l H i s t o r yf
o r A u g u s t 1 8 9 5 .
Both ovaries of a specimen over 15 inches long were distended and had
exceedingly vascular, though thin and tough, walls.
On opening an ovary the contents shelled out without the slightest forcing.
The contents were embryos and unchanged eggs, the embryos forming a
thick surface layer, the unaltered eggs forming a sort of kernel.
P
56
Scientific Memoirs by
The embryos were from 6 to 8 mm. long and were firmly adherent one
to another by their tails, though not in the slightest degree adherent to the
ovarian wall. The remains of the yolk were enclosed in the belly, causing a
slight bulging of its whole length, but there was no vitelline constriction or
pedicle. The vertical fins alone were present, and consisted of a single fold.
running from the occiput to the vent, without interruption: this fold was entirely
made up of numerous layers of large nucleated cells.
It appears to me that this gland-like fin-fold is an absorbent surface, as in the
Embiotocidœ. Where the nourishment to be absorbed comes from, I am unable
to say ; but I think it probable that it may be derived from the unchanged ova
in the centre of the ovary, in which no trace of an embryo, or of a germinal disk,
or of anything but yolk-spherules, can be detected. There is nothing more
improbable in the dissolution of spare ova for the use of the developing embryos
than there is in the dissolution of superfluous spermatozoa and of ovarian epithe-
lium, as described by Eigenmann.
Our maternal specimens of Hephthocara simum are ill-preserved, and all
that can be said about them is that the embryos and blind ova are disposed in
the same way, and that there is no adhesion between the ovarian wall and its
contents.
In Saccogaster maculata all that I can say is that there is no adhesion
between the little embryos (which in a pregnant female of three and a quarter
inches length were about 1.5 mm. long) and the ovarian wall. Here too there
are ova which show no traces of development.
In addition to the works quoted at the outset, of which that of Eigenmann is ex-
tremely important, the following papers refer to the subject of viviparturient Teleostei:—
Rath ke, Abhandlungen zur Bildungs-und Entwickelungs-Geschichte &c., II, p.
1
Cuvier et Valenciennes, Hist. Nat. Poissons, XVIII, p. 257.
Duvernoy, Ann. Sci. Nat. Zool. (3) I, P. 313, 1844.
Agassiz, Amer. Journ. Sci. & Arts, (2) XVI, 1853, p. 380.
Troschel, Wiegmann's Archiv f. Nat. XX, 1854, p. 163 (systematic).
Dowler, Ann. Mag. Nat. Hist. (2) XV, 1855, p. 206.
Wymann, Boston Journ. Nat. Hist. VI, 1850-57, p. 432.
Peters, Monatsber K. Akad. Berlin, 1865, p. 132.
Blake, Proc. Calif. Acad. Nat. Sci. III, 1867, p. 314.
Ryder, Proc. U. S. Nat. Mus. VIII. 1885, p. 128; and Bull. U. S. Fish Commission,
VI, p. 92 ; and Proc. Acad. Nat. Sci. Philad., 1893, p. 95.
Eigenmann, American Naturalist, XXIII, 1889, p. 923 (and paper already cited).
Alcock, Proc. Zool. Soc., 1891, p. 226, and Ann. Mag. Nat. Hist., August 1895,
p.146.
Medical Officers of the Army of India.
57
7. On Viviparous Elasmobranch Fishes.
As is well known, the impregnation of the ovum in this group is always
effected internally. In some Elasmobranchs, such as the Dog-fishes, the true
Rays, and the Chimæras, the female lays large eggs, enclosed each in a tough
horny envelope which is often of fantastic shape or curiously ornamented.
In others— e.g., according to T. J. Parker, in Mustelus antarcticus— the
embryo develops in the uterus, which is merely a membranous bag having no
special structures for supplying the embryo with nutriment, and not being in any
vascular contact with the yolk-sack ; so that though the fœtus is nourished by
the mother, the exact steps of the process are still unknown.
In others, including a large number of species of sharks, the embryo develops
in the uterus, and when all the yolk is consumed the vascular yolk-sack
becomes applied to the vascular uterine wall to form a yolk-sack placenta.
In others, as in several species of Sting-rays, Eagle-rays, and Torpedoes,
the embryo completes its development within the uterus, and is nourished—as the
observations made on board the " Investigator " prove beyond dispute—not by a
placenta, but by what may, without laxity of language, be called a kind of milk,
secreted by special glands of the uterine mucous membrane.
Of the eggs of the oviparous Elasmobranchs the " Investigator " has had
little experience. Empty egg-cases, similar to those of Callorhynchus and
Chimœra, have been dredged in the Andaman Sea and the Bay of Bengal.
Again, off the Travancore Coast, at a depth of 824 fathoms, a developing
egg that belongs, probably, to some gigantic species of Ray was dredged. This
egg is shaped just like the ordinary " Mermaid's purse " of British seas, and the
shell, measured without the filamentous appendages, is over 6½ inches long and
mo r e t h a n 4 ¾ i n c h e s b r o a d . I t c o n t a i n s a l i t t l e e mb r y o i n wh a t ma y b e c a l l e d
the Selachian stage, that is, the stage in which the pectoral fins are of no great
size and have not pushed the gill-clefts out of their lateral position.
Of Viviparous Elasmobranchs in which the young is nourished by a yolk-
sack placenta, three species have come into our hands, namely Carcharias
melanopterus, Carcharias dussumieri, and Zygœna blochii.
A female of Carcharias melanopterus, five feet long, taken in the month of
January, contained six young, each a foot long,—three in either oviduct.
Each young one lay, head forwards, in its own separate compartment of the
uterus, i n wh i c h , f u r t h e r , i t wa s c o mp l e t e l y e n v e l o p e d i n a v e r y d e l i c a t e me mb r a n e
of its own. This delicate envelope is evidently the pseudamnion of Parker, which,
according to that author, corresponds with the horny egg-shell of oviparous
Elasmobranchs.
58
Scientific Memoirs by
The placenta, formed by the yolk-sack, is a compact arborescent mass
adherent to a vascular disk on the uterine wall near its after end : its cord is
about 18 inches long. Its blood-vessels are the ramifications of a single artery
and a single vein: the artery takes off from a glandular pouch at the level of the
duodenum, but its connexion with the dorsal aorta was not made out ; the vein
passes by two branches into the liver.
A female of Carcharias dussumieri, 7½ feet long, taken in the month of
April, contained ten young, each two feet long—five in either oviduct.
The arrangements differ from those of Carcharias melanopterus only in the
one particular that the artery conveying the blood to the yolk-sack placenta had
no glandular dilatation near its point of origin.
A female of Zygœna blochii nearly five feet long, taken in the month of
January, contained ten young, each about 15 inches long—five in either oviduct.
The arrangements as regards the packing and envelopment of the fœtus,
and as regards the formation and vascularization of the yolk-sack placenta do not
differ from those of Carcharias melanopterus, except that the umbilical artery
has no gland near its point of origin, and that the greater part of the placental
cord is festooned with leaf-like villi, as in Zygœna tiburo and in a species of
Carcharias described by Leuckart and Cuvier.
These villi are very characteristic. Each consists of (1) a core of delicate
connective-tissue supporting a plexus of blood-vessels and masses of cells in its
meshes, and (2) an envelope formed of numerous layers of round or cuboid large-
nucleated cells. Their vascularity and their richly cellular structure show that
they must be the seat of active metabolism, but as there is also a large placenta,
their necessity is not immediately apparent.
I may add that I have verified my original observations on this species from
specimens since brought to the Museum by local fishermen.
Of the Elasmobranchs that nourish the fœtus on a uterine milk, which the
fœtus swallows and digests, the " Investigator " has discovered certainly five
species—namely, Trygon bleekeri, walga, and zugei, Pteroplatœa micrura, and
Myliobatis nieuhoffii—and probably a sixth, namely Narcine timlei.
In all, the process is, in essence, the same. The embryo at first lives on
the copious yolk of the egg, and when the yolk is all absorbed (a process which,
in Pteroplatœa micrura at any rate, is effected not by any vascularization of the
yolk-sack, but, in part at least, by special vascular external gill-filaments) the
yolk-sack, instead of forming a placenta, simply shrivels up.
No enveloping membranes of any sort have been formed, so that the fœtus
lies quite naked in the uterine cavity.
Medical Officers of the Army of India.
59
The walls of this cavity, however, are thickly beset with special secreting
villi or " nursing-filaments." Each of these nursing-filaments consists of a long
narrow arterial loop, a superficial capillary plexus which gives the filament a
scarlet hue, and a central vein—all held together by a minimum of connective
tissue. The meshes of the capillary network are filled by tubular follicles which
are either simple or slightly branched.
These follicles, of which in Pteroplatœa micrura and Trygon bleekeri there
must be considerably over twenty thousand in each filament, secrete a glairy,
sticky, greasy fluid—sometimes creamy or pus-like in appearance—having
a heavy, sweetish, meaty smell, and containing many corpuscles and nuclei : it
coagulates when heated and leaves a greasy smear, which shows that it contains
albumin and fat, but no sugar has been detected in it.
The spiracles of the fœtus are always widely open : in Pteroplatœa micrura
and sometimes in Trygon walga, bunches of nursing-filaments actually pass
through the spiracles into the pharynx of the fœtus ; and in certain specimens
of Myliobatis nieuhofii and Trygon bleckeri their secretion has actually
been found unchanged in the spiral gut of the fœtus ; so that there can be no
doubt that the secretion is swallowed and absorbed by the fœtus.
The following papers refer to viviparous Elasmobranchs :—
Everard Home, Phil. Trans. Roy, Soc. 1810, p. 208 (Acanthias). John Davy, Phil,
Trans. Roy. Soc., 1834, p. 531 (Torpedo).
Johannes Müller, Müller's Archiv., 1837, p. lxvii (external gill-filaments, villi on
placental cord, etc.).
Johannes Müller, Ueber den glatten Hai des Aristoteles, etc., in Abhand.
Berlin, 1840 (the classical work on this subject).
Cantor, Ann. Mag. Nat. Hist., 1845, p. 372 (Zygæna).
Leuckart, Zeits. Wiss. Zool., II, 1850, p. 254 (embryo of Torpedo).
Hill, Ann. Mag. Nat. Hist. (2) VII, 1851, p. 353 (general).
John Davy, Trans. Roy. Soc., Edinb., XXII, 1861, p. 491 (Rhina,Galeus,Acanthias
Centrina, Carcharias).
Parker, Trans. New Zealand Inst. XV, 1882, p. 219 (Mustelus, Scymnus), and
XXII, 1889 (Mustelus).
Haacke, Zoologische Anzeiger, 1885, p. 488 (uterus of Trygonorhina).
Jungersen Zool. Anzeiger, 1885, p. 560 (remarks on Haacke's paper).
Balbiani, Revue Scientifique (3) XXXVII, 1886, p. 732 (general).
Haswell, Proc. Linn. Soc. N. S. Wales, 1888, p. 1716 (Urolophus, Trygon).
Alcock, Journ. As. Soc. Bengal, 1890, pt. 2, p. 51 (Trygon, Myliobatis, Carcharias,
Zygæna).
Mehrdorf, Zool. Jahresbericht fur 1891 , Vertebrata, pp. 24 and 67 (general).
Wood-Mason and Alcock. Proc. Roy. Soc., Vol. 49, 1891, p. 359, and Vol. 50, 1892,
p. 202 (Pteroplatæa, Trygon.)
Q