NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
296
Sex-Dimorphism in Macrones gulio
We have dissected a number of specimens to examine their gonads and
we have been able to confirm our observation regarding their sexes and we
are in a position to say definitely that in each and every male, the so-called
' penis ' can be found.
Regarding females, we have observed that there is an additional aperture
behind the anal opening.
On dissection we have found that the generative opening terminates on
to the so-called ' penis' and not to the common aperture, or to a separate
aperture as in other fishes.
In case of females the generative openings terminate to the aperture
behind the anal opening and this probably represents the ' vagina ' (Fig. 2).
It should be mentioned here that in case of the female, the generative
aperture is far behind the anal opening and is simple.
The sex dimorphism in these cases is interesting and on referring to the
literature we could only find a reference to some such organs in Glyptosternum
reticulatum McClelland by Mukerji [1936] in which he reports ' In males there
is a sharp, conical and well defined papilla projecting behind the anal opening.
In the female there is no papilla but the vent is broadened by prominent
fleshy lips. The secondary sexual characters noted above are well marked in
the specimens under report '.
Mukerji's specimen belongs to the family, Sisoridæ which is akin to Silu¬
roid and it is interesting to note that the two families of a closer range have
these generative organs showing their closer relationship.
We referred to Dr S. L. Hora of the Zoological Survey of India who has
mentioned in his letter, ' I may say that I am not aware of the occurrence of
copulatory organs in Cat-fishes of any continent '. We take this opportunity
of expressing our thanks to Dr S. L. Hora for his kind remarks.
REFERENCES
Mukerji (1936). Mem. Conn. Acad. 10, Art. XVIII.
THE DENTITION OF FISHES AND REPTILES WITH
SPECIAL REFERENCE TO THE REPLACEMENT OF
TEETH*
BY
F. GORDON CAWSTON, M.D. (CANTAB.)
(Received for publication on 2 September 1939)
(With Plates XXI and XXII)
M OST species of fish have a front row of erect teeth for cutting through
food. To prevent slipping, the hinder rows of teeth are hinged
anchylosed or embedded in sockets [Peake, 1915]. Teeth on the palate and
throat and loose on the tongue direct food inwards, usually head-first
because of the scales. The palatine and vomerine teeth, as in rock cods, are
mostly recurved, but are not so strong as the premaxillary.
Trichiurus
haumela (Forsk.) has specially strong recurved teeth. The single row of teeth
in the lower jaw of some fishes, e.g. Sphyraena, fit between the premaxillary
and palatine, as they do in some snakes. The hinder teeth are not
symmetrical and it is not easy to count the number of rows when there are
more than three.
Only vertical succession occurs in fishes. The rate of succession varies
in different species and is evident in both premaxillary and palatine rows, as
in the wrasse, Lepidaplois hirsutus (Laceps.), for example. It is well seen
where tooth-roots extend deep into the jaw, as in Glyphidodon saxatilis Linn.
X-ray examination shows new teeth developing in the jaw of Pagrus
nasutus (Cast.) before they erupt into empty alveoli. In this species vertical
succession has been seen by both dissection and X-ray examination, even with
the deeply-set front teeth. These teeth increase in size with the jaw and there
is no approximation to close empty spaces. They would be too heavy, if not
partially hollow.
Replacement of piscine teeth, which are easily lost unless firmly anchy-
losed, takes place near the base of alveoli, but it is a slower process than what
occurs in the crocodile. New teeth were observed undermining the erupte d
teeth of Crocodilus niloticus Laurenti, but prolonged search failed to revea
such at the base of the teeth of Salmo fario and Salmo iridens. In Pagrus, the
alveolus of a shed tooth remains empty for a while before a new tooth erupts.
Once in use, the tooth becomes firmly anchylosed.
In some species there are small teeth in front of a row of large teeth. In
others, e.g. Atractoscion aequidens (C. & V.), the foremost and hindermost teeth
are the biggest thus removing the likelihood of lateral revolving of the tooth¬
bearing surface [Cawston, 1938], and diagonal placing of teeth [Vorstman,
1922], is no evidence of it.
The hinder teeth of some species of Serranidae are not repressible [Barnard,
1927], but Dentex, e.g. Dentex praeorbitalis (Gnthr.) and Dentex undulosus
* Comimmicated to Section D at 37th Annual Meeting of the South African Associa-
tion for the Advancement of Science, East London, July 3-8, 1939.
( 297 )
298
Dentition of Fishes and Reptiles
Regan, have seven to ten rows of hinged teeth. Elagatis bipinnnulatus (Q. &
G.) has numerous upper and lower villiform teeth but is provided with
about 20 well-developed gill filters.
GILL FILTERS
Teeth of fishes do not come away with the gum as in Elasmobranchids or
as gill filters (rakers) may be removed with the covering of an arch.
Gill filters are added to at the extremities of the arches. They might be
replaced from the scattered clusters of denticles [Payne, 1938], but injury must
be rare. Denticles in all stages of growth have been noted on the covering of
gill arches in two species of Carcharhinus (the black-fin and the grey shark),
in Sphyrna zygaena (Linn.) and in the black bass, Micropterus salmoides.
In the former one sees (1) flat, fan-like denticles with merely an indication
of a median keel at the centre of its apical margin, (2) the three-keeled denticle
with tooth-like projections from the exposed border, set on a wide pedicle
growing from the centre of a rhomboidal base, and (3) the fully developed five-
keeled denticles at right angles to the pedicles, as described for American
sharks [Radcliffe, 1914]. Occasionally I have seen seven-keeled denticles in
the three species of shark I have examined.
In Micropterus salmoides I have noted the denticles in all stages of growth
from the buds, lying in clusters on the gill arch. I have also seen its palatine
teeth in all stages of development from tooth-buds.
REPTILES
Reptilian teeth are sharp and recurved, being well adapted for holding
prey.
X-ray examination of a young specimen of Crocodilus niloticus Laurenti
showed 18 erupted teeth on each side of the upper jaw and 15 on each side of
the lower. The third and tenth of the upper and the first, fourth and tenth
of the lower jaw were the biggest, the first mandibular fitting into a deep notch
in the upper jaw. Successional teeth at the base of erupted teeth were re-
vealed by dissection and tooth-buds, apparently representing the undeveloped
rows of lizards and snakes, were visible in the gum microscopically.
Toads, e.g. Bufo regularis Reuss, are edentulous, but vertical succession
was seen in the upper jaw of the frog, Rana grayi Smith.
In the jaw of the so called Iguana or Monitor lizard, Varanus niloticus
Linn., I counted nine upper teeth on each side besides 10 premaxillary, and 10 on
each side of the mandible. The twelfth upper tooth was the largest on
each side. The teeth were pleurodont, i.e. growing on the inner side of a
ridge of bone, becoming anchylosed in course of use. They had no sockets
and shed teeth from an old jaw left merely empty spaces. There was nothing
to show that the small loose teeth in the gum on the inner side of the maxillary
were successional.
No sign of replacement was noted of the deeply embedded front teeth of
izards, but new teeth were seen growing among the roots of those set in rows.
These success onal teeth are visible in Mabuya capensis Grey, Pachydactylus
bibroni Smith and Corodylus (Zonurus) corodylus, but not in Agama atra
rudis which has no provision for loss of its shallow acrodont teeth.
Ind. J. Vet. Sci. & Anim. Husb., Vol. X, Part III ]
PLATE
XXI
1. Naja nivea Boie
4. Causus rhombeatus Lichts
2. Sepedon haemachates Lacep
5. Psaonmaphis sibilans
3. Dendroaspis angusticeps Smith
6. Dispholidus typus
Ind. J. Vet. Sci. & Anim. Husb., Vol. X, Part III ]
PLATE
XXII
1.
Pagrus
nosutus
2.
Epinephelus
albomarginatus
3.
Sphyracena
commersoni
4.
Atractocion,
aequidens
5.
Sarda
sarda
6.
Epinelephelus
lauvona
7.
Dentex
paracorbitalis
F.
GORDON
CAWSTON
299
There are approximately the same number of upper and lower teeth in
these lizards. New teeth between the roots of their teeth can hardly justify the
designation ' endless ' succession. It would be interesting to know how far new
teeth may grow in very old lizards and crocodiles. I have noted an incom-
plete set in the jaw of an old crocodile. Mr. J. W. Bell Marley reports that a
complete set is seldom found in old crocodiles from Zululand and that the jaws
of some old fishes show impaired replacement.
SNAKES
Besides maxillary teeth some snakes, e.g. Python sebae Gmel., Crotap-
hopeltis hotamboeia Laur. and Pseudaspis cana Linn., have well-formed palatine
teeth. This enables them to seize fast-moving prey without relying on a strong
or easily injected venom, for the mandibular come to lie between two upper
rows when these snakes bite.
Replacement of teeth is not effected by revolving of the gum for the teeth
are set in the jaw, neither are empty sockets filled by the small loose teeth in
the gums, as occurs in pythons.
The teeth of pythons are said to be polyphodont [Widdowson, 1915],
the successional teeth erupting vertically. But X-ray examination of adult
jaws does not show new teeth in the area of tooth development, so that replace-
ment must be limited, possibly to immature specimens.
Whilst examining teeth, they are easily displaced and a prone position
may suggest immaturity, though all are vertical in the adult. X-ray exami-
nation of a mature jaw of several species, with or without removal of the gum,
shows no vertical succession. This indicates that shed teeth are not replaced
in adult snakes.
Teeth in serial deve opment in the vagina dentis of Crota-phopeltis hotam-
boeia Laur. illustrates how back fangs and, perhaps, the palatine rows may
be added to. Forty-three successional teeth were counted in a specimen
of this relatively harmless snake which was 22 in. long [Fitzsimons, 1919].
Each maxillary row had about fifteen erupted teeth. No sign of succession of
maxillary or other erupted teeth could be determined.
SUMMARY
Besides their erect cutting teeth, fish are provided with numerous teeth as
well as the gill filters for directing food down the throat.
Lost teeth are replaced by others developing vertically. Lateral displace-
ment of rows never occurs.
Vertical succession is readily seen in our local Barracuda and Bonito fishes
and occurs in premaxillary and palatine teeth. X-ray examination shows
that replacement is slower in the mussel-crusher than in many fishes of this
class.
Replacement of gill filters has not been seen, but development of denticles
has been studied, especially on the gill arches, and these are also attached to the
gill filters.
Reptilian teeth are recurved. Both the crocodile and some lizards have
small accessory teeth, as found on the nner side of the maxillary in some
snakes. Vertical succession occurs in the crocodile and has been observed in
the South African frog.
300
Dentition of Fishes and Reptiles
Succession has been observed in lizards with deeply-set teeth. Species
with shallow teeth do not exhibit it.
It is not possible to say how frequently shed teeth can be replaced. Further
invest gation is needed to decide if it persists throughout life. The small
supplementary teeth in the gum of some reptiles would not appear to be
success onal any more than the hinder rows of teeth in fishes.
The palatine teeth of snakes with little or no venom afford extra power
for their bites.
Though numerous successional teeth have been seen in the vagina dentis,
such teeth have not been observed in the maxillary rows.
ACKNOWLEDMENTS
Valuable assistance from the Albany Museum (Grahamstown), the Port
Elizabeth, Durban and Botha's Hill Snake Parks and from the Natal Estates
has enabled me to include illustrations of all reptiles mentioned in this paper.
Most of the fishes were identified by Mr J. W. Bell Marley, some were
sent me by Mr C. Scott, Inland Fisheries Officer for Natal and Doctor J. W. E.
Graham, L. D. S., of Durban kindly prepared the X-ray photographs. The
diagrams have been drawn by aid of the camera lucida.
REFERENCES
Albany Museum (1937). A Guide to the Vertebrate Fauna of the Eastern Cape Province
of South Africa. Grahamstown
Barnard, K. H. (1925, 1927). Ann. S. Afric. Mus. 21
Cawston, F. G. (1938). S. Afric. J. Sci. 35, 321-6
—(1939).
Dental Rec. 59, No. 10
Fitzsimons, F. W. (1919). The Snakes of South Africa, pp. 134 : T. Maskew Miller Ltd.
Payne, J. Lewin (1938). Brit. Dent. J. 64, 370
Peake, G. A. (1915). Notes on Dental Anatomy, pp. 48 : Claudius Ash, sons & Co.
Widdowson, T. W. (1915). Notes on Dental Anatomy & Dental Histology, pp. 122:
John Bale, Sons & Danielsson Ltd.
Vorstman, A. G. (1922).
Ueber die Anordnung und die Entwicklung der Zaehne be
Teleostiern
SELECTED ARTICLES
CHRONIC FLUORINE INTOXICATION IN DOMESTIC
ANIMALS
BY
A. W. PEIRCE
Division of Animal Health and Nutrition, Council for Scientific
and Industrial Research (Australia), Animal Nutrition Laboratory
University of Adelaide, South Australia
(Reprinted from the Nutrition Abstracts and Reviews, Vol. 9, No. 2, October 1939)
A LTHOUGH symptoms which are now recognised to be the result of ex-
cessive ingestion of fluorine have been recorded for at least 800 years,
it is only within the last two or three decades that the subject has attracted
especial attention. The recent wide and active interest in fluorine poisoning
has been inspired by the recognition that certain functional disabilities suffer-
ed by stock and also by human beings are due to chance ingestion of fluorine.
A voluminous literature has resulted, which is, for the most part, devoted to
the description and study of the symptoms, the relative toxicities of different
fluorine compounds and the quantities which bring about chronic changes
in different animals. The physiological mechanisms involved have received
less attention.
Several reviews have appeared dealing with various phases of chronic
fluorine poisoning (32, 34, 81, 101), but only in Roholm's admirable mono-
graph (101) have the effects on domestic animals been accorded more than
passing consideration. In preparing the following short review of the subject,
the author has been guided by several years experience with experimentally
induced fluorosis in sheep. It is not possible here to consider all relevant
publications and with little doubt some important contributions have been
overlooked during the perusal of the extensive and widely dispersed literature
of the subject.
A discussion of chronic fluorosis of domestic animals may be divided
into a consideration of the disease as it occurs under natural conditions and
a consideration of the changes which have been induced experimentally in
an endeavour to interpret further the extent to which fluorine contributes
to the natural malady. A large proportion of these latter investigations have
been initiated in an attempt to overcome the troubles encountered when farm
stock are fed with phosphatic supplements that are manufactured from raw
materials which contain fluorine.
OBSERVATIONS IN REGIONS WHERE FLUORINE POISONING IS ENDEMIC
Outbreaks of chronic fluorine intoxication have been described in flocks
and herds grazing in many parts of the world and at times these have assumed
considerable economic importance. Naturally occurring chronic fluorosis,
seemingly, has not been observed in domestic animals in Australia nor
in Asia, although mottled enamel of human teeth, which is now a recognised
( 301 )
312 Chronic Fluorine Intoxication in Domestic Animals.
(100) Roholm, K. J. Indust, Hyg., 1937, 19, 126
(101) Roholm, K. Fluorine Intoxication, London 1937, H. K. Lewis
(102) Salinas Y Ferrer T. Thesis, Madrid, 1934. Quoted by Roholm, Fluorine Intoxica-
tion (1937)
(103) Schroder, J. V. and Reuss, C. Die, Beschadigung der Vegetation durch Rauch,
Berlin, 1883, 98, and 171. Quoted by Roholm, Fluorine Intoxication (1937)
(104) Sette, N. C. R. Soc. Biol, 1928, 98, 1094
(105) Sharpless, G. R. Proc. Soc. Exp. Biol. Med., 1936, 34, 562
(106) Sharpless G. R. and McCollum, E. V. J. Nutrition, 1933, 6, 163
(107) Slagsvold, L. Norsk Vet., 1934, 46, 2. Quoted by Roholm, Fluorine Intoxication
(1937)
(108) Smith, M. C. and Leverton, R. M. Indus. Eng. Chem., 1934, 26, 791
(109) St. Jacques, C. Indust, Eng. Chem. News. Ed., 1937, 15, 29
(110) Stœltzner, W. Virchows Arch., 1897, 147, 430.
(111) Taylor, G. E. Michigan Agric. Exp. Stat. Quart. Bull, 1929, 11, 101
(112) Thormahlen, E. Diss. Hannover, 1931. Abstracted in Munch. Tierarztl.
Wochenschr., 1934, 85, 349
(113) Tolle, C. and Maynard, L. A. Cornell Agric. Exp. Stat. Bull. 530, 1931
(114) Ullmann, F. Enzyklopadie der technischen Chemie, 1930, Vol. 5,403, 752, Vol. 4„ 27.
Quoted by Roholm. Fluorine Intoxication (1937)
(115) Velu, H. Arch. Inst. Pasteur Algérie, 1932, 10, 41
(116) Velu, H. Bull. Soc. Pathol, Exot, 26, 616 ; Bull. Acad, Med., 1933, 109, 289
(117) Velu, H. Bull. Acad. Méd., 1933, 110, 799
(118) Velu, H. Bull. Acad. vét., 1934, 7, 108
(119) Velu, H. and Zottner, G. C. R. Soc. Biol, 1932, 109, 354
(120) Vestal, C. M. Swine World, 1922, 10, 18
(121) Wilczek, E. Bull, Soc. vaud. Sci. nat., 1914, 50, 19
(122) Wislicenus, H., Jahr. Berg.-u. Huttenwesen Konigr. Schsen, 1913, A 47. Quoted
by Roholm, Fluorine Intoxication (1937)
THE PARASITIC ENVIRONMENT AND PLAN OF
CONTROL
BY
T. W. M. CAMERON
Director, Institute of Parasitology, McGill University, Macdonald College, P.Q.
(Reprinted from the Canadian Journal of Comparative Medicine, Vol. 3, No. 8,
August, 1939)
T HE parasitic existence of a parasite is dependent on its finding a suitable
environment in which it can mature and reproduce.
FOUR SETS OF FACTORS ARE NECESSARY TO ENSURE THIS
(a) Successful Admission to the Host.—The host must traverse the ground
where the free stages of the parasite are found ; it must eat suitable food-stuffs
in or on which the larval stages occur ; it must be exposed to the intermediate
host, and so on. Even slight differences in habits ; e.g. such as exist between
a sheep and an ox in eating grass, may make all the difference in the parasite
gaining admission. The anatomy of the host, including the thickness of the
skin, are factors to be considered under this heading.
(b) Suitable Environmental Conditions in the Host.—Once inside the host,
the parasite must find a suitable habitat—type of mucosa in the intestine,
length of intestine, presence of suitable food, and so on. There is a belief,
which is not so strongly held now as it once was, that the temperature of the
host is of paramount importance, especially in warm-blooded animals. The
influence of hibernation is not well understood nor is the influence of fever.
However, clinical experience has shown repeatedly that a high fever will
often cause a large proportion of helminths to leave the body, just as an en-
teritis will cause many intestinal forms to pass out.
(c) Possession of a Suitable Protective Mechanism Against the Normal
Metabolic Processes of the Host.—When the parasite lies in the alimentary
system, it must possess some means of preventing itself being digested or
being passed out by peristalsis, etc.
(d) Absence of a Host Reaction that would Interfere with the Normal Meta-
bolism of the Parasite.—This factor applies most obviously to parasites that
leave the lumen of the alimentary tract at some period of their life, but it
may apply to all helminths. If there is any host reaction, the parasites must
be able to resist its effects.
These groups of factors are essential for the proper development of the
parasite to full and functional maturity. If it finds the environment suitable
for its development, we may define the stage as one of ' compatibility', if
unsuitable, as ' incompatibility '. If the parasite dies at once or is passed
out unchanged, the condition is ' complete incompatibility'. If it develops
normally with no unfavourable results to either itself or the host, the condi-
tion is ' complete compatibility'. However, intermediate stages exist and
the parasite may grow to some intermediate extent. This intermediate
( 313 )
316
Parasitic Environment and Plan of Control.
groups, disease depends on numbers, but whereas the entrance of a single
bacterium into the body may cause disease, the entrance of a single larval
worm usually does not. Parasitic disease depends, therefore, on actual
numbers entering the body.
III. The stages which leave the body, are never immediately infective.
Some essential development must take place before they are ready to re-
enter and this development takes a definite period of time and requires a
definite set of favourable conditions—heat, moisture, oxygen, presence of
correct intermediate host and so on—before they are able to infect. Once,
however, the infective stage is reached, they are often able to live for a long
period before re-entry ; while the minimum time necessary outside of the body
can be fairly accurately ascertained, the maximum time is much more difficult
to determine.
IV. In many cases, after entrance, to the body, complicated migrations
through various organs are an essential part of the life-cycle and the greatest
damage to the host is often caused at this period. We know of no means of
preventing these migrations and we know of no therapeutic agents which can
effect the parasites during migration. Accordingly, prevention of ingress
is often of the greatest importance.
CONTROL OF PARASITES
Scientific control of parasites consists in making their development
as difficult as possible and so depends essentially on a knowledge of the life-
history and bionomics of the parasite involved. This necessitates the correct
identification of the parasite concerned. The need for correct identification
is most important as not only are no two parasites quite alike in their bio-
logy, but treatment is often different.
We are concerned with two great faunistic groups of internal parasites,
with fundamentally different life-cycles.
(a) Helminths.—We may recapitulate the generalized life-cycle of a
parasitic worm as follows : the adult lives in the body, producing eggs or
larvae, which pass to the exterior generally in the excreta, occasionally through
the skin or by being eaten by the next host. Outside of the body an essential
development occurs, and only after this is the young worm able to return to
the host. In most cases, it returns in the food occasionally it penetrates
the skin. In many cases, the larva has to undergo an essential migration—
more or less extensive—in the body before it can develop to maturity. In
the vast majority of important parasites, egress is in the excreta and ingress
on the food.
(b) Arthropods.—The position here is almost exactly the reverse. The
larvae are parasitic, the adults free living and the egg laid outside of the body
to enter by the skin, the mouth or the nose.
CONTROL MEASURES
In determining control methods it is important to remember that there
are economic aspects of the problem to be considered. The cost of control
may be excessive and it must be balanced against the loss to the stock-owner
and loss should include not only actual, but potential future loss. It is often
accordingly necessary to adopt several methods of control simultaneously