Page:The Journal of Tropical Medicine, volume 6.djvu/217
Che Fournal of Tropical Medicine. CONTENTS.—JUNE 15th, 1903. ORIGINAL COMMUNICATIONS.
On Pre-pupal Changes in the Larve of the Culicide.
By G. M. Giuus, M.B., F.R.C.S., F.R.M.S.
Typhoid Fever amongst the Natives of Southern China.
By J. Preston Maxwett, M.B., F.R.C.S. 188 Tropical Hygiene. By W. J. Srmpson, M.D., F.R.C.P. 192 Business Notices 195 Reprints 195
EDITORIAL. ‘The Care of Invalids on Ships 195
Original Communications.
ON PRE-PUPAL CHANGES IN THE LARVA OF THE CULICIDA.
By G. M. Gus, M.B., F.R.C.S., F.B.M.S. Lieut-Col. I.M.S. (Retd.).
Pernars no other of the curiosities of development are so striking, alike to the popular and scientific imagi- poston, as the changes that take place during the pupal
age of insect life, whereby the worm-like larva is
siormed into the complete insect; and this is especially the case where the change, as in the case of the Cuwlicide, is accomplished to all appearance in what appears a most inadequate allowance of time.
We have always been accustomed to regard the
wide as insects undergoing a “complete meta- morphosis,” that is to say, that the changes which trans- form the larva into the adult are not spread gradually pver the period of growth, with its various changes of kin, but are all effected during one and the last ecdysis, iz., that of pupal life; during which the insect . to eat, and is often reduced to a more or less 0 SReahlens bundle, which no longer grows, but re- ranges the nutritive materials which it has collected as a larva into the shape of the widely different anatomy of
e adult. In the Cwlicide, however, the pupa, though r capable of feeding, is never quite motionless and elpless; and so far from the sum total of the changes
transform the larva into the imago being com-
d into the three or four days of pupal existence,
st of the adult appendages are, as we shall see, well dvanced in development within, at any rate, the last atval skin. It is never practically possible to be sure if the age of a larva with any exactitude, as to its stage i ecdysis, as, like the adults, they vary much in size ; certain full-grown larve just ready to enter upon their ast, or pupal, change of skin being quite frequently
TRANSLATION.
The Technique of Staining Malarial Parasites. By a
Dr. Josrer Koreck ae oe bs ei ee 2 96
REPRINT.
Filaria Perstaus. By Grorcr C. Low, M.A., M.B.,C.M. 198 Reviews oe a ae et i bs So Log New Drugs, &c. 199 Notes and News 199 Prescriptions .. 200 Recent and Current Literature 200 Notices to Correspondents .. 200
less in actual dimensions than others that may be junior to them by one or two larval ecdyses; and on this account, although many larve have been examined, it is quite a matter of chance that one obtains for examination a specimea which has actually fully com- pleted its stage of larval life.
In the accompanying plate I have placed, for com- parison, in the middle of the page a drawing of the transverse section of the pupa of Anopheles Rossi through the mesothorax at the level of the roots of the wings, and have grouped round it four drawings of transverse sections of a full-grown larva at various levels.
Taking first the key section of the pupa (fig. 1), we find that like that of the adult, at the same level, the body consists essentially of a solid mass of the muscles which for the most part actuate the somewhat complex movement of the wings above and the legs below. Almost on the middle of the section is the cesophagus with, immediately below it, the rudiment of the pneu- matic vesicle. Grouped round these are four glandular cords, the shrinking remains of the hepatic crypts of the larva; and, immediately above the upper pair of these are cut across the two great main longitudinal air-vessels. Further below, on the middle line, im- bedded between the two sets of muscles that are to actuate the coxe of the middle pair of legs, is seen the section of the thoracic mass of ganglia.
So far, save in the incomplete development of the pneumatic vesicles and in the presence of the still recognised remnants of the hepatic crypts, there is really very little to distinguish the section from one cut across an adult ; but it will be cbserved that this forms only the middle portion of the section, and, except in its dorsal aspect, has no share in forming its outer boundaries ; their ventral aspect and sides being enveloped in a thick sac, separated from the body by a large air space, which, as will be seen, imparts to the larva the necessary buoyancy to keep it afloat.