NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
( 4 )
There is also no good evidence in favour of the opinion that leprosy is a disease
of malarial origin. In those parts of the country in which the greatest number
of lepers are found, they are more numerous among the town populations and in
the more populous localities than in the uncultivated jungle tracts. Cases do not
occur with unusual frequency in localities which are reported malarious.
With regard to the measure of providing asylums for lepers proposed by
Dr. Vandyke Carter, with the view of separating them from the mass of the people,
the evidence that has been adduced in favour of leprosy being transmitted in
families for several generations, may be sufficient to warrant a belief that if all
persons in whom the leprous taint had become evident could be eliminated, and kept
strictly separate from the general population, the frequency of the disease would, in
the course of three or four generations, be greatly diminished ; but to effect this
amount of good, it would be necessary to enact very stringent laws rendering the
confinement of all lepers (irrespective of rank and position in life), and even their
families, compulsory, at the same time restricting them from marriage and sexual
intercourse. It is not likely that any Government will enact such laws, and without
them the use of asylums will continue, as at present, to be limited to affording relief
and sustenance to lepers of the poorer classes.
U. C. P.—Home, Kev. & Àgri, Dcpt. Frees—No. 464—20-8-70—100.
( 3 )
The Hospital Assistant at Dubri reports tbat 28 cases were discovered in thirteen
villages. Neither geological formation nor the presence of jungle and swamps are
considered by the Civil Surgeon to have any noticeable effect in developing the
disease, but where it occurs elephantiasis is also prevalent.
The khessary dâl (Tathyms Satraus) and putrid fish are articles of diet
largely consumed, and these may exercise a prejudicial effect : the former is supposed
to possess poisonous properties cumulative in effects, and only manifested after
protracted use. The people are scantily clad, filthy in habits, and undergo much
privation nnd exposure.
Dr. Slane inclines to a belief in the hereditary nature of the malady, but has
not been able to procure confirming evidence from Natives, who, he "supposes,
dread the social ostracism likely to be entailed on their families by confession.
No reliable evidence of the contagious nature of the disease is obtainable.
The anæsthetic form of the disease with slight tuberculization of the skin of
the face and ears is chiefly observed. The skin presents a glazed and prickered
appearance with fissures and ulcers about the fingers and toes, which become
successively destroyed, but the Civil Surgeon states that he has not met with any
case in which a fatal result could be attributable solely to the disease.
GARO HILLS.—The Civil Surgeon states that he has been unable to discover
the existence of the disease in these hills.
SYLHET.—The Civil Surgeon doubts the efficacy of gurjun oil treatment, and
does not consider that dispensary practice offers favourable opportunities for testing
the experiment. He considers that it could be more completely carried out in jails
among prisoners undergoing a long term of imprisonment. He records twenty-two
cases, in which, however, the accessories of alteration in diet and rubbing with
dry earth were omitted. Of these twenty-two cases one was cured, six improved
and the remainder discontinued attendance. Mendicants, who constitute the
majority of sufferers, will not submit to the restraints imposed in undergoing a
course of treatment. Accustomed to a free and roving mode of life, they have a
decided distaste for any measures savouring of discipline. On the other hand,
patients who are able to obtain a livelihood by employment are unable to absent
themselves from their avocations for a sufficiently long period. The disease does
not prevail in the district to any great extent: the proportion of lepers to
inhabitants being calculated at one to 2,000 inhabitants. In certain portions of the
district it prevails to a greater extent than in others, and it is considered that it
prevailed to a much greater extent in former years.
CACHAR.—Very few cases are met with, and the disease does not appear to be
in any way localised. Three cases were treated as in-patients, but without any
improvement. Only one of these cases afforded evidence of probable hereditary
transmission.
N. C. D.—Home, Rev. & Agri. Dcpt. Press—No. 467—18-8-79—100.
( 2 )
The Civil Surgeon, Akola, states that the disease is not common in Akola
District, except at Julgaon, and that those affected are chiefly Telees and Buraes, and
that their homes and habits are dirty.
In this case also Mr. Chamarett's information is more full than that submitted
from other districts.
5. Forwarding this correspondence to you I hope you will not find me fault-
finding. The real object in my doing so is that, when information of a certain
nature is asked of an officer, it is his duty to give it as fully as he can, or to say
he cannot give it, while from this correspondence you will observe that all but one
officer missed the points of enquiry in the first instance, and that some of them
repeated their mistake on these points being put again in the plainest words
possible, with a result that time has been lost, correspondence increased, and no
information gained ; whereas a little forethought on the part of these gentlemen
would have saved all this.
6. Please return all the papers now enclosed at your early convenience.
No. 3853, dated Amraoti, the 6th December 1875.
Endorsed by the Commissioner, Hyderabad Assigned Districts.
FORWARDED for the information of the Resident with reference to First Assist-
ant Resident's endorsement No. 1890, dated 28th March 1875. The Commissioner
will not trouble the Resident with the large amount of correspondence with the
Civil Surgeons which Dr. Abbott has forwarded with his report, because Dr. Abbott
has given a summary of it, and because it contains no information that would be of
the slightest practical use to Government.
E, DES.—Home, Rev, & Agri. Dcpt. Press—No. 469—18-8-79—100.
IP/QB, 10
No. 25.
( NEW SERIES. )
SCIENTIFIC MEMOIRS
BY
OFFICERS OF THE MEDICAL AND SANITARY DEPARTMENTS
OF THE
GOVERNMENT OF INDIA.
ON THE IMPORTANCE OF LARVAL CHARACTERS
IN THE CLASSIFICATION OF MOSQUITOES.
BY
CAPTAIN S. R. CHRISTOPHERS, M.B., I.M.S.
ISSUED UNDER THE AUTHORITY OF THE GOVERNMENT OF INDIA
BY THE SANITARY COMMISSIONER WITH THE GOVERNMENT
OF INDIA, SIMLA.
CALCUTTA:
OFFICE OF THE SUPERINTENDENT OF GOVERNMENT PRINTING, INDIA.
1906.
Price annas eight or 9d.
No. 25.
(NEW SERIES. )
SCIENTIFIC MEMOIRS
BY
OFFICERS OF THE MEDICAL AND SANITARY DEPARTMENTS
OF THE
GOVERNMENT OF INDIA.
ON THE IMPORTANCE OF LARVAL CHARACTERS
IN THE CLASSIFICATION OF MOSQUITOES.
BY
CAPTAIN S. R. CHRISTOPHERS, M.B., I.M.S.
ISSUED UNDER THE AUTHORITY OF THE GOVERNMENT OF INDIA
BY THE SANITARY COMMISSIONER WITH THE GOVERNMENT
OF INDIA, SIMLA.
CALCUTTA:
OFFICE OF THE SUPERINTENDENT OF GOVERNMENT PRINTING, INDIA.
1906.
Agents for the Sale of Books published by the Superintendent of Government
Printing, India, Calcutta.
IN ENGLAND.
IN INDIA.
H. S. KING & CO., 65, Cornhill, & 9, Pall Mall,
London.
THACKER, SPINK & CO., Calcutta and Simla.
NEWMAN & CO., Calcutta.
E. A. ARNOLD, 41 & 43, Maddox Street, Bond
Street, London, W.
S. K. LAHIRI & CO., Calcutta.
CONSTABLE & CO., 16, James Street, Hay Market,
London, W.
R. CAMBRAY & CO., Calcutta.
HIGGINBOTHAM & CO., Madras.
P. S. KING & SON, 2 & 4, Great Smith Street,
Westminster, London, S.W.
V. KALYANARAMA IYER & CO., Madras.
G. A. NATESAN & CO., Madras.
KEGAN PAUL, TRENCH, TRÜBNER & CO., 43, Gerrard
Street, Soho, London, W.
S. MURTHY & CO., Madras.
BERNARD QUARITCH, 15, Piccadilly, London, W.
THOMPSON & CO., Madras.
B. H. BLACKWELL, 50 & 51, Broad Street, Oxford. TEMPLE & CO., Madras.
DEIGHTON BELL & CO., Cambridge.
THACKER & CO., LD., Bombay.
GRINDLAY & CO., 54, Parliament Street, London,
S.W.
A. J. COMBRIDGE & CO., Bombay.
D. B. TARAPOREVALA, SONS & CO., Bombay.
RADHABAI ATMARAM SAGOON, Bombay.
ON THE CONTINENT.
SUNDER PANDURANG, Bombay.
R. FRIEDLÄNDER & SOHN, 11, Carlstrasse, Berlin,
N.W.
N. B. MATHUR, Superintendent, Nazair Kanun
Hind Press, Allahabad.
OTTO HARRASSOWITZ, Leipzig.
RAI SAHIB M. GULAB SINGH & SONS, Mufid-i-Am
Press, Lahore.
KARL W. HIERSEMANN, Leipzig.
ERNEST LEROUX, 28, Rue Bonaparte, Paris.
Superintendent, American Baptist Mission Press,
Rangoon.
MARTINUS NIJHOFF, The Hague, Holland.
RUDOLF HAUPT, Halle A. S., Germany.
A. M. & J. FERGUSON, Ceylon.
ON THE IMPORTANCE OF LARVAL CHARACTERS IN
THE CLASSIFICATION OF MOSQUITOES.
IN collaboration with Stephens, I described, in a previous publication,1 the
ovum and larva of most of the common Anopheles mosquitoes of India.
We gave at that time a division of Anopheles into natural groups, largely based
upon variations in the immature stages. The groups noted by us, so far as
the species investigated were concerned, were practically identical with the
genera which Theobald instituted later upon variations in the scale structure of
the adult insects ; but greater prominence was given to some of these genera,
by a consideration of the immature stages, than was apparent from the scale
structure of the adults alone.
Of the immature stages of mosquitoes other than Anopheles, we unfortunately
know very little. The larva of Anopheles and that of Culex were described by
Meinert in 1886.1Howard's2description of the larva ofC. pungensis accurate
and detailed. James 3 has described and figured the larva of Stegomyia, and
was the first to draw attention to the occurrence of cannibal larvæ.4 The
larvæ of species of Megarhinus, Toxorhynchites, Desvoidea, Theobaldia, Mela-
noconion, Grabhamia, Acartomyia, and Deinocerites have been to some extent
described by Theobald,5 who also figures parts of C. fatigans, C. tigripes, and
C. mimeticus. In very few of these descriptions, unfortunately, have the points
which appear to be of most use in classification been noted. In many cases, indeed,
only characters common to nearly all mosquito larvæ have been given.
Before proceeding to describe what has been determined regarding the larval
characters of a number of genera of culicidæ other than anopheles, it will be
well to briefly mention features which appear to be common to all larvæ, and to
single out those which, in my researches, I have found to vary in the different
genera or species.
I.
All mosquito larvæ possess a head, an enlarged thorax, and nine abdominal
segments.
The Head. —The size and shape of the head vary in the different genera.
It is large in Culex and Melanoconion, smaller in Anopheles, Stegomyia, and
Tæniorhynchus.
NOTE.—Mr. Theobald has kindly identified the species of mosquitoes mentioned in this paper from
specimens of the adults which I have sent to him.
B
The upper surface is smooth and convex and carries certain hairs,
2
which are usually six in number. Anteriorly the head forms a rather prominent
rounded mass (the clypeus). In some cases the clypeus carries small hairs
(clypeal hairs) as in Anopheles and Stegomyia. As a rule it carries only two thorn-
like spines. When present, the clypeal hairs are of specific importance.
The clypeus, instead of projecting, may be concave and form a cup-like hollow
(cannibal larvæ). In old larvæ of certain species a sharp beak-like process cov-
ered with hairs or spines may project from below the clypeus. At the side of the
head are the large compound eyes, and immediately behind these are the ocelli of
the simple eyes.
The lower surface of the head is smooth and convex and is marked by two
grooves which pass from the outer angles of the mental plate backwards. About
the middle of the lower surface of the head is a small, dark triangular plate—the
mental plate or lower lip (Meinert). The mental plate forms a hard and sharp
lower lip to the mouth. The upper lip is formed by the prominence already
mentioned (clypeus). Arising on each side of the under surface of the clypeus
are the feeding brushes. These consist, except in cannibal larvæ, of numerous fine
curved hairs arranged so as to look very like a shaving brush. In cannibal species
these are much modified, each consisting of a series of stout, curved chitinous
bars, and are used as a clasping organ for seizing their prey. The mouth is
closed in beneath by two plate-like structures,— the maxillæ, which can be opened
to expose the buccal cavity, or approximated to almost meet in the middle line.
Each maxilla carries on its outer edge a stout, more or less conical, maxillary
palp. Some variations occur in the maxillæ and palps of different genera ; for
example, both are very small in Mucidus (Pl. III, fig. 14). Lying just behind
the maxillæ are two very stout and large plates of chitin— the mandibles. On the
inner side of each of these there is a variable number of large, strongly chitinised
teeth, which meet together, when approximated, in the neighbourhood of the
mental plate. Each mandibular plate also has, arising from its anterior edge,
a variable number of long processes which are used in combing the feeding
brushes and which vary in size and number in different genera.
On each side of the head, arising from prominences in front of the eyes, are
the antennæ. These vary very considerably in different genera, and have already
been shown by us to have great significance in the classification of the anophelina.
Each antenna consists of a basal segment immoveably fixed and more or less
blended with the head mass, and a loosely jointed distal segment carrying various
spines, hairs, etc.,—the antenna proper. When fully developed, three distinct
portions, which, however, form a single unjointed piece, may be distinguished
in the distal segment, a proximal, a median, and a shorter distal portion, which
I have called the first, second, and third portion respectively. At the junction
3
of the first and second portions a large series of long stout hairs arises which
I have termed the basal tuft. At the junction of the second and third
portions there are generally two large and very stout hairs or spines. I have, for
descriptive purposes, termed these the median spines. From the end of the
third portion, one or more spines project. I have called these terminal spines.
There is also, at the extreme end of the antenna, a papilla, which may be
large and conspicuous, possibly a sense organ. I have named it the terminal
papilla (Pl. II, fig. 16).
The antennæ are often very small and poorly developed. In the case of
some species ( Stegomyia) this appears due to retrograde changes, since most
of the above-mentioned structures are represented only by small hairs or spines.
The Thorax. —The thorax is more or less globular in shape, and greater in
diameter than the abdominal segments. The exact size and shape depend upon
the genus concerned. On each side, arising from papillæ, are three main series
of large, stout hairs. The papillæ, from which these arise, may or may not
carry a stout spine resembling a thorn. The hairs are of various lengths in
different species and may be simple, branched, or feathered. On the whole
they do not appear to be very important from the point of view of ascertaining
the affinities of different genera. In addition to the above there are usually a
few small hairs which arise immediately behind the head and overhang the
occiput. In certain species (open water species, e.g., Melanoconion Tænior-
hynchus) these are large and may form very prominent objects in the living larvæ,
projecting to a great distance and appearing to act as tactile organs.
The Abdomen. —The first seven abdominal segments do not appear to be of
sufficient importance to be described in detail in the present connection. In
the Anophelina oar-like feathered hairs arise from the first three segments.
This sub-family also differs from all other Culicidae in having palmate hairs
on some or all of the segments. The eighth and ninth segments require
separate mention.
The eighth abdominal segment. —This segment is profoundly modified by
the presence of the respiratory openings and their armature. In all genera but
the Anophelina a tube carries the spiracles to a distance from the segment.
This tube has usually been called the respiratory siphon or siphon tube.
The siphon tube consists of an unbroken tubular piece of chitin of varied
shape and size in different species. It usually carries a few small branched
hairs, and on the posterior aspect, on each side of the median line, there are
two rows of conspicuous spines, the number of which is of specific importance.
Each of these spines, is a compound one consisting of three or more long tooth-
like processes. Their actual shape seems to be much the same, even in widely
different genera, but their appearance varies considerably with the different points
B 2
4
o f v i e w. I n a f e w c a s e s o n l y ( c e r t a i n c a n n i b a l l a r v æ) a c o n s p i c u o u s s e r i e s o f
hairs, forming a rudder-like expansion, springs from the median line posteriorly.
On the eighth segment there are, on either side, a number of claw-like spines.
Several small branched hairs also rise near the base of the siphon tube.
Neither the spines nor the hairs appear to be of much importance in relation
to classification, since they do not vary to any extent in the genera
examined. The characters of the siphon tube are of importance, since this
organ is subject to great variations in different genera and even in different
species. The relative shortness or tenuity of the organ is an important
character. In descriptions of larvæ the terms employed in describing this
tube do not allow of accurate information being conveyed. I have therefore
employed what I have termed the siphonic index. This is obtained by dividing
the length by the greatest breadth of the tube. I have employed an eyepiece
micrometer for the purpose of measurement. The figures given by the
different genera have been very constant.
Stegomyia sugens
.
.
.
.
. 2
, ,
fasciata
.
.
.
.
. 1.8
»
?
.
.
.
.
.
1.6
Desvoidea
.
.
.
.
.
.
1. 7
Culex
fatigans .
.
.
.
•
4.3
, ,
?
.
.
.
.
.
4.1
, ,
impellens
.
.
.
. 5
, ,
?
.
.
.
.
.
5
Melanoconion
.
.
.
.
.
.
7.5
T æ n i o r h y n c h u s
t e n a x .
.
.
. 13
, ,
N. SP.
.
.
.
. 13
In describing the siphon tube, it is desirable that a drawing accurately
measured should be given, since the siphon tube is subject to the most
extraordinary variations in size and shape. In tæniorhynchus it is developed
into a long and slender tube. In certain species not yet determined, the siphon
tube is enormous.
The ninth abdominal segment.— This very much modified segment lies, during
life, so as to form an angle with the rest of the abdomen, and when the siphon
tube is large has the appearance of an appendage rather than of an abdominal
segment. It is cylindrical in shape, and covered dorsally and laterally by a
single curved piece of chitin. The ventral surface of the segment is, for the
most part, soft and membranous. Posteriorly is the opening of the anus and
.around this arranged symmetrically are the four anal papillæ. In most
larvæ these papillæ are of considerable size, reaching to about one-tenth of the
body length. In others they are still larger and very conspicuous (Desvoidea).
I n s o m e c a s e s t h e y a r e v e r y s m a l l a n d r u d i m e n t a r y ( c a n n i b a l l a r v a ) . T h e p a p i l l æ
5
appear to be of the nature of gills. In the case of a species of Stegomyia, in
which these were of very great size, the larvæ habitually remained long periods
without rising to the surface. Dorsally, immediately above the anus, four or six
long hairs arise from one or two small chitinous plates. Ventrally, a double
row of hairs forms a large fan-like expansion. The variations in the hairs of the
ninth segment are not great in the different genera and their arrangement is
very similar in Anopheles, Stegomyia, and Culex.
The Nymph. —The nymph consists of a large body formed by the conjoined
head and thorax and of a tail composed of nine segments. The general shape
and appearance of the nymph varies a little in the larger groups of mosquitoes,
and it is possible by this means to distinguish the nymphs of Anopheles, Culex,
and Mochlonyx. The most important structures showing variations are:
—
The breathing trumpets. —These rise from the dorsum of the thorax and
show variations in the manner in which they project from the nymph, and in the
details of their structures. No distinct differences were found by me in species
of the same genera, but in different genera important variations were detected.
The shape of the breathing trumpets of the nymph are of important generic
significance.
The tail fins and last segment are also subject to some variations.
II.
The larval features characteristic of many of the genera can in some degree
be noted.
Stegomyia.— T h e o v a o f
S . f a s c i a t a
w e r e f i r s t d e s c r i b e d b y D a n i e l s a n d
Ross.7 T h e y a r e l a i d s i n g l y o n t h e w a t e r , a n d f o r m p a t t e r n s a s d o t h o s e o f
Anopheles. Each ovum is surrounded by numerous small air chambers.
The larvæ of Stegomyia are very characteristic and can be distinguished at
once by the naked eye. They are found especially in water of a dark brown
colour from decayed vegetable matter, but they are also found in ordinary rain or
waste water or indeed in any small collection of water and even in nearly pure
water in chatties or other receptacles. Their general appearance is more worm-like
than that of other larvæ. The full-grown larvæ are generally loaded with fat and
havé a plump look. When disturbed they travel by means of a curious twisting
and lashing motion seen in some small aquatic worms. When breathing at the
surface they adopt a nearly vertical attitude quite different from that of most
Culex l a r v æ w h i c h r e s t a t a d i s t i n c t a n g l e t o t h e v e r t i c a l ( P l . I I I , f i g s . 2 2 a n d
20). Stegomyia larvæ spend much of their time at the bottom. They are vora-
cious feeders and can be seen nibbling at solid substances such as dead insects.
The body of the larva (Pl. I, fig. 19) is cylindrical. The thorax and head