PUBLIC RECORD OFFICE
Reference :-
C.O. 885
23 PUBLIC RECORD OFFICE, LONDON
ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH-NOT TO
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the first week of August, and they were alive, almost unchanged, in the first week of May, so that it is a reasonable inference that this species-probably Hæmotopota pluvialis requires a year for its development.
Observations on the life history of Stegomyia fasciatu have been carried on since 23rd June, and are still in progress, the insects in all stages being kept in unwarmed rooms with open windows, the object being to see how far the species could adapt itself to conditions that might be found in ordinary dwellings near the
docks.
The eggs were very kindly sent from Sierra Leone by Mr. A. W. Bacot. They were immersed here at noon on the 22nd June, and when examined twenty-four hours later they all had hatched. Pond-water with living pond-weed and some dead flies were supplied to the larvæ. The first pupae were formed on the 4th July The first adult males appeared on the (minimum larval stage--twelve days). 6th July, and adult females on the 7th (minimum pupal stages-male two days, female three days). All the issue had become adult by the 10th July (maximum term from egg to adult-eighteen days).
A certain number of both sexes were caged, with appropriate food for the males; the females were given opportunities for biting, but did not bite eagerly until the third day. (The bites itched intermittently for hours if neglected, but if rubbed at once with bergamot oil they were never felt and quickly vanished.)
The insects flourished and paired freely, and on the 20th-21st July the first batch of eggs (about fifty) was deposited. On the 30th-31st July two more batches were deposited, one of which was dried and stored for future experiment.
A supply of eggs being now secured, the females were provided once a week with a guinea-pig. Unfortunately, at the seventh week, a young and presumably unexperienced rat was substituted, which ate all the females but two. These two lived on, producing plenty of eggs, one of them until the 6th-7th September (term of life at least fifty-eight days), the other until the 10th September (term of life at least sixty-eight days). Of the males several lived longer than eight weeks, and three of them (which, when all the females of their own generation had died, were kept with some females of a later generation) lived more than twelve weeks, the last survivor attaining the age of ninety-two days.
Several batches of eggs deposited in the laboratory were allowed to hatch, and as a result we have now a store of eggs from females of the second laboratory-bred generation, and from these eggs, which have been dried, an attempt will be made next summer to raise a third local generation.
Some of the adults of the second laboratory-bred generation are still alive, among them a male fifty-six and a female sixty-two days old.
The most interesting feature in the issue of eggs deposited in the laboratory was the very variable duration of the several developmental phases: e.g., in a single batch, kept under uniform conditions throughout, the egg-stage ranged from eleven to seventeen days, the larval stage eight to forty-four days, and the pupal stage seven to ten days. This is the history of the batch of eggs laid on the 20th-21st July, the first adult from which (a male) emerged on the 15th August and the last (a female) on the 13th September, the survivor of all the larvae being one that died unchanged on the 19th September.
In July and August-and this is, perhaps, an observation of more than academic interest several specimens of Anopheles maculipennis were caught in one of the outhouses. The larvae of this species (which is one of the known carriers of malaria) were abundant in the summer in some ponds of Epping Forest, and possibly the species breeds near the docks.
Advice and assistance have been given to numerous correspondents, among them being medical officers of the Expeditionary Force and of hospital ships.
Additions to the museum and material include, besides numerous desiderata reared in the vivarium, a large stock of blood-sucking flies presented by the Imperial Bureau of Entomology, a small consignment from our constant contributor, Dr. H. Bayon, and contributions from Dr. Č. W. Daniels (London), Dr. G. Dunderdale (East Africa), Dr. W. E. Glover and Dr. W. B. Johnson (West Africa), Dr. H. Kerr (Siam), Private William Macdonald (Egypt), Dr. W. E. Masters (South America), and Dr. C. Winter (Honduras).
London School of Tropical Medicine.
31st October, 1915.
A. ALCOCK, Lieutenant-Colonel,
Indian Medical Service (retired).
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Enclosure 2 in No. 133.
REPORT OF THE HELMINTHOLOGIST FOR THE HAI.F-YEAR Ending 31st October, 1915.
103, Corringham Road, Golders Green, N.W.,
21st October, 1915.
SIR,
I HAVE the honour to present the customary half-yearly report upon my work as Helminthologist to the London School of Tropical Medicine and to submit there- with copies of the following publications which have appeared since my previous report on 1st January, 1915.
These publications are:-
(a) "Parasitic Worms," being the final report, prepared in conjunction with Surgeon E. L. Atkinson, R.N., on the collections made by Scott's Antarctic Expedition. (b) Notes of the Occurrence of Parasites presumably Rare in Man, dealing with five parasites of man of unusual interest which have been received from abroad for identification during the summer. One of the Opisthorchis viverrini is recorded in man for the first time. From the recurrence of two others, namely, Physaloptera mordens and Tridontophorus deminutus, from Portuguese East Africa, it is thought that these helminths are probably of much more frequent occurrence in tropical Africa than has been supposed.
(c) Report on the Results of the Bilharzia Mission in Egypt, 1915. Part 1, Transmission; Part 2, Prevention and Eradication; Part 3, Development. This report covers the work upon which I have been chiefly engaged for the past nine months. The results of my inquiry into the transmission of Asiatic schistosomiasis were communicated to the War Office upon my return in October, 1914, and, in view of the widespread occurrence of an allied disease (bilharziasis) in Egypt and of the probable employment of large numbers of troops upon the Canal defences, I was authorized to proceed to Egypt to investigate bilharzia disease in that country and to advise as to the preventive measures to be adopted in connexion with the troops. In order to acquire quickly the facts upon which effective measures for prevention could be based it seemed necessary to undertake the examination of large numbers of fresh-water snails, and I accordingly obtained permission to take with me my colleagues, Drs. R. P. Cockin and J. G. Thomson, to assist in this work. The School Committee cordially agreed to the proposed inquiry, the details of which were sub- mitted to them, and granted permission to my colleagues and myself to accept tem- porary commissions for the duration of the investigation, while retaining our appointments at the School. The Committee also permitted me to use, for the purposes of the inquiry, the apparatus procured for the previous Wandsworth expeditions. The Medical Research Committee (Insurance Act) provided for the necessary field expenses and the cost of illustrating the report.
The mission arrived in Cairo on the 8th of February, and the field work was brought to a close on 15th July. Dr. Cockin, owing to a serious accident, had already been invalided home early in April. Dr. Thomson joined the Royal Army Medical Corps for the duration of the war, and remained behind in Egypt. I returned to London overland, having shipped home about fifty animals which, it was hoped, Several of these animals-viz.. were experimentally infected with bilharzia. monkeys, rats, mice, and guinea-pigs-died later of acute bilharziasis; the others The were used to test the efficacy of drugs in killing bilharzia worms in the body. results of the inquiry are given in detail in the printed reports now submitted.
In Part 1 it is shown that in all respects the Looss hypothesis is invalid, and that bilharziasis in animals follows upon their submission to infection (through the skin or by drinking water) with cercaria discharged from certain fresh-water molluscs which frequent the ditches of infected areas. From the experiments it is deduced that
1. Transient collections of water are quite safe after recent contamination. 2. All permanent collections of water, such as the Nile, canals, marshes, and birkets, are potentially dangerous, depending upon the presence of the essential intermediary host.
3. The removal of infected persons from a given area would have no effect, at least for some months, in reducing the liability to infection, as the inter- mediate hosts discharge infective agents for a prolonged period.
4. Infected persons cannot reinfect themselves or spread the disease directly
to others. They could only convey the disease to those parts of the world where a local mollusc could efficiently act as carrier.