Licence: Public Domain Mark
Credit: A discussion on ankylostomiasis / G.M. Giles [and others]. Source: Wellcome Collection.
6/16 (page 540)
Licence: Public Domain Mark
Credit: A discussion on ankylostomiasis / G.M. Giles [and others]. Source: Wellcome Collection.
![niaed in all the warmer parts of the old and new world wherever civilisation and sanitation are so little developed as to admit of its progress. It has however not yet been cer¬ tainly found above latitude 52° N., and above 470 N. the parasite apparently can only flourish in the sheltering warmth of mines. , This was then the state of our knowledge in 1889. As to the serious effects of the parasite on its human host all were fully agreed, for no one had then advanced the fantastic notion that it was a mere harmless tenant of the human bowel. It was at this date the Indian Government became alarmed at the very high mortality prevailing in Assam, alike among the indigenous population and among labourers brought from other parts of India to work in the extensive tea-gardens of that province. In the case of the latter, the causation of the mortality had already been made out to be ankylostomiasis by Dr. Ruddock, though it had unfortunately come to be known by the erroneous denomination of beri-beri, while among the indigenous'population the mortality was called, kala-azar. I will not here enter into the old controversy as to whether this increased mortality known by that name is due, as I maintain, to ankylostomiasis plus malaria, or to malaria plus ankylostomiasis, as advanced by Captain Rogers and Major Ross. We are all agreed that both.these causes of cachexia are present in Assam, and it is probable that our real differences are of les9 dimensions than the volume of £he controversy would,suggest. It is, however, obvious that, from my particular point of view, the exact ascertainment of the life1 history of the worm was the first importance. In the course , of the investigation I was enabled to bring to light many en¬ tirely new points. Of these by far the most important was the demonstration of the fact that the full life history of ankylostoma doudenale is an example of dimorphism or heterogenesis. , My attention was first drawn to this by my fibding sexually mature nematodes, the females heavy with eggs, wnich were absolutely identical in form and dimensions wiih those of the parasitic form, in ordure contained in a small pit such as is common in Assamese villages. I then set myself to se^ if I could breed a similar sexually mature free form in the laboratory, and after a few experiments hit upon the follow¬ ing method: A layer about an inch in depth of clean white river sand is spread over the bottom of a crystallising dish or other suitable vessel. Nematode worms are extremely rare in river sand, but it is well, before employing an apparatus so prepared, to moisten the sand and examine it for several successive days to ensure that no such organisms are present. Having selected a suitable case of ankylostomiasis—-that is, a case in which repeated examination of the dejecta has demonstrated the absence of other parasites or their ova, such as the embryo of anguillula stercoralis or the ova of oxyuris, etc., a small quantity of the dejecta is mixed with about three or four times its bulk of water, and poured on to the surface of the sand. The dish is then covered with a sheet of window glass, and placed on a shelf in the laboratory, in ordinary diffused light. Every day a small portion of the thin upper faecal layer is removed on a spatula, and mixed with water in a shallow glass tray and examined, either under the simple microscope or under a low power of. the compound; but the former is preferable, and suffices for all but tde study of the minute anatomy of the worms. Working in this way it will be found that the embryos batch out in the course of a few-< days, the time varying with the air temperature from five days at a temperature of 6o° F. to the next day at 84° F.; at 70° usually on third or fourth day. .As found in the fresh dejecta the ova are usually 2 4 segmented, but unsegmented ova may often be found. Day by day it will be found that the specimens are more advanced, the segmentation gets finer, till a morula and finally a fully- formed embryo is developed. It is useless to attempt to observe the further development of these embryos in clear water, for in this they cannot thrive, and slowly die for want of nourishment; but by taking samples from the cultiva¬ tion at intervals and placing in water, the process can be can be followed with ease. On emerging from the egg the embryo measures 0.085 inch in length by 0.005 inch in diameter. At this stage they show little else than an intes¬ tine and oesophageal bulb. Within the next forty-eight hours (at 70° F.) they have increased to three times their original length and have undergone several ecdyses, the exact number pf which I am unable to state, owing to the difficulty of keeping an individual properly nourished while under con¬ tinuous observation, but roughly about twice in the twenty- four hours. In large faecal masses under natural conditions, in the plains (temperature 8o° to 90° F.), the embryos may de¬ velop into free sexually-mature worms in as little as four days, but under the somewhat less favourable conditions of my laboratory they occupied from six to ten days. As far as I could make out, the sexual organs were first clearly distinguishable in the last ecdysis but one, at which period the male measures about 3’e inch in length by T0‘0C> inch. When completely grown up, he may reach inch in length by in diamete^-, while the females may attain ,V inch ip length by in thickness. It would occupy too much of your time to enter into the details of the anatomy and de¬ velopment of these free foims, for which I must r^-fer you to- my report on the subject, published by the Assam Secretariat Press, Shillong, 1890—but it may be well to meet here objec¬ tions that have been advanced as to the validity of the above mentioned observations, and as far as I have been able to follow the literature of these subject, these objections are all based on a short paper by Dr. Sonsino [L. Anchylostoma E. La Sua Profilassi, 1889], the other criticisms I have met with being apparently mere mechanical transcripts of this paper, by commentators who obviously have not been at the pains to consult my report of the original. Dr. Sonsino's criticism throws doubt on the accuracy of my observations on the two following grounds:— (a) That the organisms described by me are rhabdites terricola or other Iree nematodes; (6) that the appearances were really tbe free form of rhabdomena intestinale. The first objection is obviously quite untenable in view of the method of examination adopted. Owing to the absence of suitable nourishment, clean river sand is, at best, an un¬ likely habitat for rhabdites terricola, but, as already noted,, the sand used was always carefully examined, in a manner that entirely excluded the presence of such intruders, nefore being used for the cultivations. Moreover I have, on more- than one occasion, made successful cultivations in which the sand as well as the water used for dilution of the infected ffecal matter was sterilised by boiling. That experiments conducted in this way do not succeed so uniformly as those in which the sand has merely been pre¬ viously examined by the biological test of moistening and ex¬ amining on several successive days, and the water simply filtered, is probably owing to the destruction of bacteria suit¬ able to bring about the decomposition of the faecal matter surrounding the eggs, as the rhabdites of the ankylostoma can thrive only in decomposed fceces. As to the Becond ob¬ jection, I can only say that the absence of anguillula ster¬ coralis, that is, of the embryos of rhabdomena intestinale was carefully noted in the case of each specimen of dejecta used for experiment: Had the so-called anguillula stercoralis been present it is inconceivable that it should have been overlooked in any examination that detected the presence of the ova of ankylostoma. Assam is a paradise for the helminthologist, and I was therefore greatly surprised at never once meeting with this* particular human parasite in any of the many hundreds of examinations that I made of human dejecta. Further, at the same time as I was conducting these observations of ankylo¬ stoma rhabdites I did a good deal of general helminthological work on animals, detecting many parasites at least as insig¬ nificant as the rhabdomena intestinale, and had that parasite been present in the duodenum it could not have been over¬ looked in the specially minute examinations I made of the human intestine in all cases in which a necropsy was obtain¬ able. It is true that the adult parasite (rhabdomena intestinale) was not known at the time of my investigation, that the embryos (anguillula) had been met with in Africa and in China, and being anxious to compare them with my ankylo¬ stoma rhabdites, I was keenly on the look out for them ; but they did not exist in the parts of Assam I visited, nor have I heard that they have been met with by any other observer in any part of Continental India, though I gather that Macdonald has met with them in Ceylon. In addition to this it is to be noted that it is stated that](https://iiif.wellcomecollection.org/image/b30477281_0006.jp2/full/800%2C/0/default.jpg)
